Properties, physical

Properties of materials can be divided into two groups physical and mechanical. Physical properties are those properties of a material which do not require the material to be deformed or destroyed in order to determine the value of the property. Mechanical properties indicate a material s reaction to the application of forces. These properties require deformation or destruction tests in order to determine their value. The value of these properties can be altered by subjecting the material to heat treatment and cold or hot working. 

This is a measure of the amount by which the length of a material increases when the material is heated through a one-degree rise in temperature. Thus 

Different metals expand or contract by different amounts for a given temperature change e.g. aluminium expands at a greater rate than cast iron. That different metals have different values for the coefficient of linear expansion can be useful on some occasions while on other occasions it can be a disadvantage. 

A typical application of advantage is in the construction of a thermostat. This device makes use of two strips of different materials clamped together, the different expansion rates when heated causing the strip to bend and so make or break an electrical contact. Fig. 13.1. 

The disadvantages are many and have to be allowed for during design. For instance, the clearance between the aluminium piston and 

Physical characterizations of nanocellulose include particle size analysis, surface charge, contact angle, etc. Particle size analysis of nanocellulose can be done using dynamic light scattering (DLS) and surface charge, which can be measure by zeta potential [130]. 

Regarding chemical analysis of nanocellulose, some of the properties including chemical composition, crystallinity and functional group analysis can be measured. Chemical composition analysis can be utilized to measure the amount of lignin, hemicellu-loses and cellulose in nanocellulose. Cellulose, lignin and hemicellulose contents are measured according to TAPPl standards [34]. Table 11.1 shows an example of measuring chemical composition of NFC and CNC before and after each process measured by TAPPl standards. 

Changing the crystallinity of nanocellulose can be evaluated by X-ray diffraction patterns. In this test method the sample is scanned by CuK radiation (wavelength = 0.154 nm) with the diffraction angle in the ranged of 4 to 40° [135]. The crystallinity of fibers can be calculated through the following equation  

In this equation, 1 (20 = 18°) shows amorphous cellulose intensity and I g (20 = 22.5°) represents intensity of crystalline cellulose [63]. For instance, the degree of crystallinity for CNC from cotton linter was more than cotton Enters [136], while this characteristic for NFC from sugarcane bagasse was 36% [63]. Fourier Transform Infrared Spectrometer (FTIR) is an instrument for studying the change of the functional groups 

The physical characteristics of a powder are i) the state of agglomeration, ii) shape and size of the particles, iii) density and iv) specific surface area. 

The grain size of ceramic particles can vary significantly according to the purpose of the products. In the case of refractory or construction materials, the particle size varies between a micrometer and a few millimeters. On the other hand, certain chemically synthesized powders have a size close to 10 nanometers. In general, the scale varies from a few microns to a few ten micrometers in the case of traditional ceramics, whereas it ranges between 0.1 and 10 pm for technical ceramics. 

In addition to their size, the particles also differ by their shape. Their shape is determined by the nature of the atomic lattice (crystalline cell) and by the processes used to obtain the powders. The particles can thus be spheroid, eqttiaxed, in the form of plates, fibers or needles. We can define an anisotropic coefficient which corresponds to the ratio of the greatest size of the particle to the smallest. Optical or scanning electronic microscopy helps us to observe the shape and to characterize the anisotropy of the particles. Particles with high anisotropic coefficient have a weak 

Stacking aptitude (porous structure) and result in a shear-thickening behavior of suspensions for small powder concentrations. We can, however, take advantage of a preferential orientation of these particles to obtain a property (mechanical, magnetic, etc.) enhanced in a particular direction. 

Physical properties are important considerations in any study of accidents and emergencies. A substance may exhibit certain characteristics under one set of conditions of temperature, pressure, and composition. However, if the conditions are clianged, a once-safe operation may become a liazard by virtue of vulnerability to fire, explosion, or mpturing. To promote a better understanding of these effects, many of which are covered in Chapter 7, a brief rc iew of some key physical and chemical properties is provided in tliis and the next section. 

The volume of a gas would theoretically be zero at a temperature of approximately -273°C or -460°F. Tliis temperature, wliich lias become known as absolute zero, is tlie basis for tlie definition of two absolute temperature scales, tlie Kelvin (K) and Rankine (°R) scales. The former is defined by shifting tlie Celsius scale by 273-Celsius degrees so that 0 K is equal to -273°C. Equation (4.2.3) shows tliis relation. 

The Rankine scale is defined by shifting the Falirenlieit scale 460 Falirenlieit degrees, so tliat 

Temperature is an important parameter for safety. At extreme temperatures, tlie risk of metal fatigue, stress corrosion cracking, and vessel rupture increases dramatically. 

A number of units are used to express a pressure measurement. Some are based on a force per unit area for e.xample, pound (force) per square inch (psi) or dyne per square centimeter (dyne/enr). Otliers are based on a fluid height, such as inches of water (in H O) or millimeters of mercury (iimiHg) units such as these are convenient when tlie pressure is indicated by a difference between two levels of a liquid, as in a imuiometer or barometer. Barometric pressure is a measure of the ambient air pressure. Standard barometric pressure is 1 atm and is equivalent to 14.696 psi and 29.921 in Hg. 

In tlie gaseous state, molecules possess a liigli degree of translational kinetic energy, which means tliat tliey arc able to move quite freely tlirougliout the body of the gas. For e.xamplc, when gas is in an enclosed container, tlie molecules are constantly bombarding tlie container walls. The macroscopic effect of this bombardment by a tremendous number of molecules - enough to make the effect measurable - is called pressure. Hie natural miits of pressure are those of force per unit area. 

Physical Properties of Thiazoles.—An X-ray crystallographic study of the cycloadducts formed from anhydro-4-hydroxythiazolium hydroxide and dimethyl maleate and dimethyl fumarate indicates that the dipole and dipolarophile approach in an exo manner, which can be accounted for by steric effects.A comparison of the melting and clearing points of various 2,4- and 2,5-disub-stituted thiazoles indicated that the former exhibited no mesophases whilst in certain cases the latter show liquid-crystalline properties. The exchange 

Goetzschel, W. Kochmann, M. Pallas, and W. Walek, Ger. (East) P. 131 933/1978 Chem. Abstr., 

Rajappa, M. D. Nair, B. G. Advani, R. Sreenivasan, and J. A. Desai, /. Chem. Soc., Perkin Trans. 

Kvitko, V. A. Smirnova, and A. V. El tsov, Khim. Geterotsikl. Soedin., 1980,36 (Chem. Abstr., 

Investigation of the pK values of some 2- and 5-substituted thiazoles shows that the pK is very sensitive to changes of substituent in the 2-position.  

Physical Properties.—Christensen and Thom have reported the A -ray crystallographic structure determination for 2-dimethylsulphuranylidene-1,3-indanedione (2). The significant structural features of this molecule 

Ishihara, M. Mizuta, and Y. Hirabayashi, Bull. Chem. Soc. Japan, 1971, 44, 2469. 

Three groups have carried out spectral investigations on dimethyl-sulphoniumcyclopentadienylide (3). Yoshida et al. were able to reproduce 

Dale and Froyen have reported detailed i.r. and n.m.r. studies on numerous -keto- and j8-alkoxycarbonyl-substituted sulphonium ylides and their comparison with analogous phosphorous and arsenic ylides. It was concluded that the keto-ylides were the more enolic in solution, as previously has been indicated by alkylation data, but the authors were unable to explain the long-standing inability of several groups to detect both geometric isomers of phenacylidenedimethylsulphurane by n.m.r. spectroscopy.  

Chemical Stability.— The previous Report discussed in some detail the conversion of sulphoniumphenacylides into 1,2,3-tribenzoylcyclopropanes. 

Physical Properties.—The molecular and electronic structures of thioureas have been studied by various methods. 

A -Ray diffraction of (19) has shown that the four sulphur atoms lie on a straight line, but that the S—S- and C=S-distances are not equal, indicating the 

Restricted rotation about the CN bond of alkylthioureas (AC = 53.3 1 kJmol in JViV -di-t-butylthiourea ), and diselenobiuret (17 X = Se ), and 5 /i-fl //-isomerization of 5-methylisothioureas by an inversion mechanism has been studied by n.m.r. spectroscopy. The extent and site of protonation (namely at the S atom) of thioureas have been studied in HSO3CI, and in aqueous HCl, by conductivity, n.m.r., and u.v. spectroscopic methods. Aryl derivatives are weaker bases than alkyl-thioureas.  

Physical Properties.— The structure of 2-isopropylidene-l,l,7,7,9,9-hexa-methyl-3,5,10,1 l-tetrathiodispiro[3,l,3,2]undecane-8-thione, which contains 

Harrit, K. Bechgaard, O. Buchardt, and S. E. Haraung, J.C.S. Chem. Comm., 1972, 1125 V Symposium Organic Sulfur Chemistry, Lund, Sweden, June, 1972, Intemat. J. Sulfur Chem. (A), 1972, 2, 194. 

Formation.— Treatment of epichlorohydrin with potassium thioacetate yields 3-acetoxythietan 2-chloromethylthiiran with potassium thioacetate or potassium di-(0-ethyl)dithiophosphate gives the corresponding 3-sub-stituted thietan. 3,3-Bis(hydroxymethyl)thietan is obtained by treatment of pentaerythritol with diethyl carbonate followed by treatment of the cyclic carbonate with potassium thiocyanate.  

The photocycloaddition of thiocarbonyl compounds to olefins often gives thietans. The thietan (137) formed from thiobenzophenone and acrylonitrile at 366 nm is derived from the thermal decomposition of the 1,3-dithian (136) believed to be produced via the second excited singlet state ( ir, ir ) of the thioketone. Irradiation at 577 nm gives only a very small amount of thietan. The thietan reacts further with thiobenzophenone to give disulphide (138).  

Many simple physical attributes of fibers can be quite important. We describe some of these attributes and the methods used to measure them. 

Fiber diameter. This a very important parameter in characterizing a fiber. One can make a direct measurement of fiber diameter by means of an optical or scanning electron microscope. There is an ASTM standard (D 578) for this purpose. 

The main problem with direct measurement is that fiber diameter may not be uniform along the length. An indirect method that gives an average fiber diameter is to weigh a known length of fiber and use the following simple relationship  

Often fibers have an irregular cross-section. The above method will give an equivalent diameter of a fiber having an irregular cross-section. One can also take a photograph of such a fiber and measure the area planimetrically. 

Fiber diameter can also be measured by laser beam diffraction (Haege and Bunsell, 1988). The technique can be rapid and systematic. The radius of the fiber is given by 

In general, properties that are additive and could be estimated by group contribution metliods, such as density and heat of fusion, tend to follow the order of PET, PTT and PBT properties dependent on the conformational arrangement of the methylene units, such as modulus, show an odd-even effect, at least among diese tluee polyesters. 

Some of the physical constants of pyrrole and of a selection of its derivatives are collected in Table 4,1, The boiling point of pyrrole is higher than might have been expected, and the closer similarity in this property of 1-methylpyrrole to, say, toluene suggests that in pyrrole the imino group is responsible for some sort of association (see below). The characterization of pyrrole and simple alkylpyrroles through the formation of crystalline derivatives is not always easy. Picrates are usually unstable. In cases where picric acid causes dimerization, the dimer picrate is often a satisfactory derivatively, 233 xhe reaction with phenyl isocyanate (p. 66) is useful. 

From the general discussion of its geometry and stability already given (p. 17), it has been seen that in these respects pyrrole shows a fairly highly developed aromatic character. 

The vibrational spectra of pyrrole and some deutero-pyrroles have been analysed for C2V symmetry and assignments made for the twenty-four normal vibrational modes (Chapter 2, p. 17). The occurrence of a weaker band at 

There is no support from spectroscopic studies for the occurrence of pyrrole-pyrrolenine tautomerism . 

The proton magnetic resonance spectrum of pyrrole shows a very broad line at low field due to the proton of the imino group, and a spectrum of 8 lines due to the other protons. Temperature effects show the broad peak to arise from quadrupole-induced relaxation of N. In pyrrole, the spin couplings of the imino proton with the protons at C(2 and C(3) are nearly equal. 

The mechanical properties of various types of carbon nanotubes have been extensively studied by both theoretical and experimental studies. In 1993, Overney et al. firstly calculated the rigidity of short SWNTs and the calculated Young s modulus was estimated to be about 1500 GPa, similar to that of graphite (65). Then a range of studies predicted that the Young s modulus of carbon nanotubes was approximately 1 TPa (66). The tensile strength of SWNTs was also estimated from molecular dynamics simulation to be 150 MPa (67). 

The gap between the predictions and experimental results arises from imperfect dispersion of carbon nanotubes and poor load transfer from the matrix to the nanotubes. Even modest nanotube agglomeration impacts the diameter and length distributions of the nanofillers and overall is likely to decrease the aspect ratio. In addition, nanotube agglomeration reduces the modulus of the nanofillers relative to that of isolated nanotubes because there are only weak dispersive forces between the nanotubes. Schadler et al. (71) and Ajayan et al. (72) concluded from Raman spectra that slippage occurs between the shells of MWNTs and within SWNT ropes and may limit stress transfer in nanotube/polymer composites. Thus, good dispersion of CNTs and strong interfacial interactions between CNTs and PU chains contribute to the dramatic improvement of the mechanical properties of the 

Kwon et al. compared WPU/MWNT with WPU/nitric acid treated multiwalled carbon nanotube (A-CNT) composites (20). The tensile strength and modulus of the WPU/A-CNT composites were higher than those of the WPU/MWNT composites with the same CNT content. The better mechanical properties of WPU / A-CNT composites can perhaps be attributed to higher content of polar groups of A-CNTs thus inducing higher interfacial interactions between A-CNTs and WPU chains. 

The physical properties of the pyridopyrimidines closely resemble those of their nearest A-heteroeyclie neighbors the quinazolines and the pteridines. Thus, in common with the pteridines, the presence of groups capable of hydrogen-bonding markedly raises the melting point and lowers the solubility. - The acid dissociation constants (pif a values) and ultraviolet absorption spectra of all four parent pyridopyrimidines have been determined by Armarego in a comprehensive study of covalent hydration in these heterocyclic systems. The importance of these techniques in the study of covalent hydration, and 

The pyridopyrimidines possess the same 7r-electron structure as naphthalene. The electronic transitions between the 77-orbitals would therefore be expected to give rise to similar ultraviolet spectra. As in the case of the quinazolines and the pteridines, this has proved to be so. 

Calculations have been made, first by a semiempirical treatment due to Parisier and Parr, and to Pople, and then by a simplified version of this method, of the transition energies and intensities of the 77— 77 bands in pyridopyrimidines (cf. Table I). 

These results were in fair agreement with the experimentally determined values for the parent compounds in nonionio solvents. Additional values for the n it transitions have been determined for pyrido[3,2-d]pyrimidine (345 mp loge 2.07) and for pyrido[4,3-d]-pyrimidine (330 mp, loge 2.49).  

Substituted pyridopyrimidines show the same tluee principal (77 77 ) absorption bands as the parent compounds but with batho-chromic shifts which may obliterate hands du e to the n n transitions. 

The physical properties of fluoroorganic compounds are governed by two main factors (1) the combination of high electronegativity with moderate size, and the excellent match between the fluorine 2s or 2p orbitals with the corresponding orbitals of carbon, and (2) the resulting extremely low polarizability of fluorine [2]. 

Perfluorinated amines, ethers and ketones usually have much lower boiling points than their hydrocarbon analogues. 

Another consequence of the low polarizability of perfluorocarbons is the occurrence of large miscibility gaps in solvent systems composed of perfluorocarbons and hydrocarbons. The occurrence of a third, fluorous , liquid phase in addition to the organic and aqueous phases has been extensively exploited in the convenient and supposedly ecologically benign fluorous chemistry, which will be discussed in detail in Chapter 3. 

Another very prominent characteristic resulting from their weak intermolecular interaction is the extremely low surface tension (y) of the perfluoroalkanes. They have the lowest surface tensions of any organic liquids (an example is given in Table 1.4.) and therefore wet almost any surface [2]. 

Solid perfluorocarbon surfaces also have extremely low surface energies Thus, poly(tetrafluoroethylene) (PTFE, Teflon) has a y value of 18.5 dyn cm which is the reason for the anti-stick and low-friction properties used for frying pans and other applications. That this effect is directly related to the fluorine content becomes obvious on comparison of the surface energies of poly(difluoro-ethylene) (25 dyn cm ), poly(fluoroethylene) (28 dyn cm ), and polyethylene (31 dyn cm Y If only one fluorine atom in PTFE is replaced by more polarizable chlorine, the surface energy of the resulting poly(chlorotrifluoroethylene) jumps to 31 dyn cm , the same value as for polyethylene [8]. 

The physical properties of known C24 allo-acids and several of their 

The trans fusion of rings A and B in the allo-acids produces a more planar molecule than the 5 3 acid and contributes to the poorer detergency of glyco allodeoxycholate and consequent poorer solubility of the calcium salt (36). The Krafft point (critical micellar temperature) of several allo-acids has been determined and discussed (64). In contrast to the notorious character of deoxycholic acid to complex with a large variety of other substances, no evidence has been reported for the formation of choleic acids by allodeoxycholic acid. 

The specific rotations of the acid and methyl ester are given in Table I with the solvent and concentration molecular rotations have been calculated for the methyl esters where specific rotations are available. Agreement between the calculated and found values is reasonably good for most substances. Although allolithocholic, allochenodeoxycholic, allodeoxycholic, and allo-cholic acids are less dextrorotatory than their corresponding 5 acids (65), the specific rotations of a number of the other allo-acids are either equivalent to or more dextrorotatory than the comparable 5 -epimer, thus precluding a general conclusion for this class of compounds. Optical rotatory dispersions of a few 3-keto-allo derivatives have been reported (34, 66, 67, 68, 40). 

Some physical properties of the main species are listed in Table 5.2. Bringing phenol in reaction conditions implies vaporization at low partial pressure. Vacuum is necessary for carrying out separations by distillation. Phenol forms azeotropes with both cyclohexanol and cyclohexanone. If unconverted phenol should be recycled this could affect the global yield by recycling desired product too. If water appears as a byproduct, it gives azeotropes with both cyclohexanone and cyclohexanol. Because these azeotropes are low boilers they can be removed easily by distillation. 

Some physical properties of PTMSN are presented in Table 3.2. This is an amorphous glassy polymer with very high Tg. Its glass transition is very close to the decomposition temperature and can be discerned only by accurate analysis of the TGA curves. Its mechanical properties are rather modest, though sufficient for preparation of stable films if the molecular mass of the sample is 400 000 Da or higher. 

The density of PTMSN is relatively small, which results in a high value of the fractional free volume (FFV) according to Bondi, as will be discussed in more detail later. 

A feature of PTMSN is a relatively high gas permeability coefficient P, higher than those of other addition-type polynorbomenes and comparable with permeability coefficients of 

poly(trimethylsilylpropyne) AF2400, random copolymer of 87 mol% 2.2bls(trlfluoromethyl)-4,5-dlfluoro-1,3-dioxole and 13 mol% tetrafluoroethylene. 

Permselectivity or separation factors alMi/Ma) = P(Mi)/P(M2) are compared in Table 3.4 for PTMSN and some other high permeability polymers. It is seen that this polymer is more permselective than PTMSP and AF2400 in the most cases. However, the observed 

The physicochemical properties of fluopicolide (Table 19.1) allow it to be easUy redistributed via the xylem (acropetal systemic activity) and translocated within the leaf tissues, providing a translaminar activity. 

There are many hquid properties that are important to the performance of a reaction solvent - heat capacities, viscosities, and so on. These for ionic hquids have been very well reviewed elsewhere and are not detailed here [1, 71). These properties are controlled by the selection of both the cation and the anion. This has led to the concept of ionic liquids being designer solvents [72]. However, achieving this requires not just a post hoc rationahzation of ionic liquids properties, but the ability to predict these as well. 

Molecular volume data have been used to predict a number of physical properties of ionic liquids, such as densities [73-75] and viscosities [76]. Given the potential importance of molecular volume data for predicting physical properties of ionic liquids, it is useful that they have also been the subject of prediction using a variety of methods [21, 76). 

When an ionic liquid is supported on a surface as a fine layer, such as in SILP, the surface properties, both at the liquid/solid support interface and the Hquid/gas interface, will increase in their importance in comparison to when using the same ionic liquid as a bulk liquid. 

There has been more work on the liquid/gas interface and surface tensions, and these have been recently reviewed [79]. These measurements, although relatively simple to make, can be very sensitive to impurities in the ionic liquids, particularly those that have a tendency to concentrate at the liquid/gas interface [80]. For example, secondary ion mass spectrometry (SIMS) of [C2Cjim][NTf2] showed the presence of poly(dimethylsiloxane) - commonly used to lubricate ground-glass joints [81]. This makes it difficult to compare across the work of different research groups, who have used different, often only partially described, synthesis and purification techniques. However, some general trends can be seen. 

ionic liquid surface tensions are unremarkable and lie in the range of conventional molecular liquids [79]. The surface tension of a series of [C,jCjim]X n = 2, 4, or 6 X = [OTf or [BF4] ) ionic liquids has been shown to decrease as the alkyl chain length increases [82]. This would be expected from standard relations that show that surface tension is inversely proportional to molecular volume [79]. Similar results were found for the N-alkylpyridinium ionic liquids [C pyr][NTf2] (n = 2, 4, or 5) [83]. Rebelo et al. [84] found that for the ionic liquids [C,jCjim][NTf2] (n=l, 2, 4, 6, 8, 10, 12, or 14) this trend held, whereas Maier et al. [85] found that for many of the same ionic liquids [C,jCjim][NTf2] (n= 1, 2, 4, 6, 8, 10, or 12) this trend held up to n = 8, after which the surface tensions leveled. Although 

Listed below are some key properties of ADN. The crystals are yellowish and often very irregularly shaped. They are quite hygroscopic, of the same order of magnitude as ammonium nitrate (AN). Samples should therefore be kept under dry conditions. It is important that crystalline ADN does not undergo any phase transition, in contrast to AN. 

Both the physical properties and the general chemical character determine the properties of a solvent. Again a clear distinction between them cannot be made and it is hard to estimate the contribution of a particular property to the general solvent properties. The usefulness of a solvent is also influenced by certain other factors, such as convenient liquid range, the ease of purification and handling, or its physiological properties. 

A high dipole moment [jl will contribute to the chemical interaction between a polar solvent and ions as well as between the solvent molecules themselves and will, although physical in nature, be discussed in relation to the chemical properties of the solvent. According to the concept of soft and hard acids and bases the degree of polarizability is also important and will be discussed later. 

The main physical properties of acetylene (ethyne) are shown in Table 8.2 

In addition to the mechanical properties with their temperature and time dependence, other properties can have decisive roles as well [2, 3] Thermal properties (insulating foams for refrigerators, buildings, window frames, protective shields in 

Coefficient of linear thermal expansion a [10 /K] St 10 T Ri 100 D 30 E 200 see Fig. 10 in Chapter Processing (Primary Forming) of Plastics Into Structural Components xl0 /K 

Electr. volume resistance Plastics 10 -10 K with metal powder 1 Qcm 

The following figures supplement and add details to the presentation in Table 14 [20]. 

Many of the physical properties of ion exchangers play key roles in the operation of ion exchange unit processes. Relevant properties include color, density, mechanical resistance, particle size, and porosity. For example, a larger resin particle size would cause lower separation kinetics. 

Similar to particle size, the porosity of an ion-exchanger particle plays an important role in the exchanger s capacity. Porosity can be defined as a ratio (usually expressed as a percentage) of volume of voids to total volume of the resin. The porosity of conventional resins ranges from 20% to 55% (4-8). 

The shape and size distribution of pores in an IXR particle can vary significantly, and this distribution is influenced by the manufacturing process. For the same resin material, different pore size ranges can be incorporated. A large number of smaller pores should 

Porosity can be determined using a solution containing ions of known size and similarity, and by using capacity measurements. The same measurement can also be made using vapor pressures. It should be noted these methods provide values related to the mean particle size but such information can be useful in both the design and operation of an application. 

The chemical properties of ion exchangers which determine performance include active groups, capacity, selectivity, degree of cross-linking and swelling. 

2 deals with physical properties of the uncomplexed molecule and includes both theoretical and experimental work Section 2.2.4.3 deals with complexed BH3, mostly involving the tetrahydrofuran complex Section 2.2.4.4 deals with BH3-CO Section 2.2.4.5 deals with substituted monoboranes and Section 2.2.4.6 deals with ions derived from BH3. 

The proton affinity of BH3, corrected to 298 K, is found to be 138.5 kcal/mol, and AfHggg for [BH3] is 296.6 kcal/mol [7]. Integral-partitioned multiple perturbation theory has been applied to small boranes, but with poor success for very small species such as BH3, since many integrals are needed for a complete treatment [8]. The NMR chemical shifts and shift derivatives upon bond extension have been calculated for BH3 to be 36.5 ppm and 3.5 ppm/A, respectively [9]. 

A theoretical study, based on the methods HF/3-21G for structural parameters and MP2/6-31G for single point calculations, of the reaction of boranes (including BH3) with NH3 provides 

The hydride affinity of BH3, measured in a tandem flowing afterglow-triple-quadrupole apparatus, is 74.2 2.8 kcal/mol [13]. As mentioned above, experimental measurements on the appearance potentials for [BH] , [BH2Y, and [BH3] from BH3 were obtained using photoionization mass spectrometry. The values are 13.372 0.015 eV, 12.819 0.02 eV, and 12.026 0.024 eV, respectively. The study gives AfHo values ranging from 22.2 3.4 kcal/mol to 25.8 1.7 kcal/mol, depending on the value used for the heat of atomization of boron [6]. 

Excitation of B5H9 in the gas phase by ArF laser irradiation at 193 nm causes primary dissociation into B4H6 and BH3. The quantum yield of BH3 was measured by conducting the experiments in the presence of PF3 and monitoring BH3-PF3 by its IR absorption at 943 cm As the amount of excess PF3 present increases, the quantum yield of BH3 approaches the limiting value of 1.00 at a PF3 to borane ratio of 70 1 [14]. 

The principal physical properties to be considered in evaluating the practical utility of a substance for use as a war gas are as follows  

Miscellaneous Physical Properties. The microwave spectrum of 2,3-dihydro-thiophen shows the molecule to be puckered and to have a barrier to inversion of 328 cm The non-planarity of 2-oxotetrahydrothiophen has been demonstrated by microwave spectroscopy.  

The saturated vapour pressures of chloro and chlorosilyl derivatives of thiophen have been determined. Liquid vapour isothermal equilibrium for thiophen with benzene and with alcohols has been measured. The formation constants, extinction coefficients, and total absorption intensities for complexes between thiophens and iodine have been determined.  

The adsorption of thiophen on montmorillonites and on other catalysts has been investigated. Several papers of an analytical nature and on the separation of thiophen from benzene have appeared.  

Polychloroprene vulcanizates possess good physical strength, and with optimum formulations, the level is comparable to that of NR, SBR, or NBR. 

Tear resistance of CR vulcanizates is better than that of SBR. Tear propagation resistance of CR vulcanizates containing active silica may be greater than that of those with natural rubber. CR vulcanizates show good elasticity, although they do 

Basic Properties Chloroprene Rubber Nitrile Rubber Natural Rubber Butadiene- Styrene Rubber 

Abrasion resistance A ebonite hardness A ebonite hardness B-C ebonite hardness B 

Note A = Excellent B = Very Good C = Good D = Fair E = Unsatisfactory, llie ratings are compound composition dependent, hence all optimum values may not be obtained simultaneously. 

The chemical and physical properties of cytochrome c oxidase have been widely studied in intact mitochondria, in mitochondrial particles, and as the isolated enzyme. Aside from variations in activity mentioned above and the recently observed effect of detergent on intensities of electronic spectra (52), the properties have proved remarkably insensitive 

Electronic spectra provide a simple and convenient way to monitor changes induced in the oxidase by various chemical treatments. Indeed, spectral observations were at the core of the pioneering observations of MacMunn (12), Keilin (96), and Warburg (97) and more recently many investigators have examined the spectra of isolated oxidase, mitochondrial particles, and electron transport particles. The spectra of the fully oxidized [oxidase (IV)] (97a) and the fully reduced [oxidase (0)] oxidase have been well characterized (52) (Table V). In Table VI are spectral parameters for ligand complexes of various oxidation states (98-103). Although the spectra of most of these complexes have been 

Hereafter, the oxidation state (number of electrons removed) of cytochrome oxidase will be represented by a roman numeral, 0 to IV, in parentheses. 

Electronic Absorption Spectral Data for Cytochrome e Oxidase with and without Df.tergent  

Wavelengths of Absorption Maxima for Visible and Soret Spectra of Complexes of Cytochrome c Oxidase  

MG and DG are surface-active agents. Their properties can be further modified by esterification with acetic, lactic, fumaric, tartaric or citric acids. These esters play a significant role as emulsifiers in food processing (cf. 8.15.3.1). 

The importance of physical properties in drug action underlies many aspects of modern drug discovery in particular, compound lipophilicity (as estimated by LogP, the logarithm of the 1-octanol-water partition 

Carbon is a typical main group element due to its properties. It is a nonmetal with the ground state electron configuration [He]2s 2p. The electronegativity of 2.55 on the Pauling scale is quite close to that of adjacent elements in the periodic table, for example, P (2.1), B (2.0), or S (2.5). The first energy of ionization is 

Besides the most abundant isotope (98.89%) there are also the isotope C (1.11%) and the radioactive C (traces). The molar weight of carbon (12.011 gmol ) results from this isotopic composition. C is employed to determine the age of archeological objects (radiocarbon dating). The stable isotope is a valuable tool for molecular structure elucidation by NMR spectroscopy because its nuclear-spin quantum number is I = 

In any further discussion of physical properties the considerable differences between modifications must be accounted for, so it is sensible not to describe the element s characteristics, but those of the respective allotropes. 

An overall review of physical properties is presented here, including some properties that are specific to plastics. For more details, refer to the ASTM standard references and Chapter 9. 

The density of any material is a measure of its mass per unit volume, usually expressed as grams per cubic centimeter (g/cc) or pounds per cubic inch (Ibs./in. ) (see Tables 2-22 and 2-23 and Figs. 2-22 to 2-24). See Fig. 2-23 for determining the specific gravity of filled compounds. It is necessary to know the density of a particular plastic in order to calculate the relationship between the weight and volume of the material in a specific product. 

Specific gravity is the ratio of the mass of a given volume of plastic compared to the mass of the same volume of water, both being measured at room temperature (23°C/73.4°F) in other words, it is the density of the plastic divided by the density of the water. Since this is a dimensionless quantity, it is a convenient one for comparing different materials. Like density, specific gravity is used extensively in determining parts cost, weight, and quality control. 

The ASTM D792 standard provides the relationship of density to specific gravity at 

Opacity or transparency are important when the amount of light to be transmitted is a consideration. These properties are usually measured as haze and luminous transmittance. Haze is here defined as the percentage of transmitted light through a test specimen that is scattered more than 2.5° from the incident beam. Luminous transmittance is the ratio of transmitted light to incident light. Table 2-24 provides the optical and various other properties of different transparent plastics. Some definitions of key terms used in identifying optical conditions follow  

All matter, whether solid, liquid or gas, exhibits properties that follow patterns that have been determined experimentally and are well established and proven. This section looks at some of the factors that influence the state of matter in its various forms. 

Temperature is a measure of the hotness of matter determined in relation to fixed hotness points of melting ice and boiling water. Two scales are universally accepted, the Celsius (or Centigrade) scale which is based on a scale of 100 divisions and the Fahrenheit scale of 180 divisions between these two hotness points. Because Fahrenheit had recorded temperatures lower than that of melting ice he gave that hotness point a value of 32 degrees. Converting from one scale to the other  

Man has long been intrigued by the theory of an absolute minimum temperature. This has never been reached but has been determined as being —273°C. The Kelvin or absolute temperature scale uses this as its zero, O K thus on the absolute scale ice melts at +273 K. 

Devices for measuring temperature include the common mercury in glass thermometer, thermocouples, electrical resistance and optical techniques. 

Pressure is the measure of force exerted by a fluid (i.e. air, water, oil etc.) on an area and is recorded as newtons per square metre (N/m ). V ftth solids the term stress is used instead of pressure. Datum pressure is normally taken as that existing at the earth s surface and is shown as zero by pressure gauges which indicate gauge pressure (i.e. the pressure above atmospheric). However, at the eartii s surface the weight of the air of the atmosphere exerts a pressure of IN/m or 1 bar. Beyond the earth s atmosphere there is no pressure and this is taken as the base for the measurement of pressure in absolute terms. Thus  

Hardness/abrasiveness Friability GrindabiUty Dustiness index Thermal properties Calorific value Heat capacity Thermal conductivity Plastic/agglutinating Agglomerating index Free swelling index 

Electrical properties Electrical resistivity Dielectric constant 

True density as measured by helium displacement Apparent density 

Specification of the porosity or ultrafine structure of coals and nature of pore structure between macro, and transitional pores Determination of total surface area by heat of absorption Useful in petrographic analyses 

Specification of scratch and indentation hardness also abrasive action of coal AbiUty to withstand degradation in size on handling, tendency toward breakage Relative amount of work needed to pulverize coal Amount of dust produced when coal is handled 

The effects of extractives on physical properties of wood have not been clarified because this question involves chemistry (especially organic chemistry), physics, and structural dynamics. However, it is well known empirically that wood species containing large amounts of extractives have better durability, dimensional stability, and plasticization for these reasons, extractives-rich woods have been used for construction and fancy goods since ancient times. 

As seen from the application examples, polyamide-imides possess a unique blend of high-performance properties. An overview of polyamide-imide properties for compounded materials is shown in Table 12.1. 

In this chapter genesis of soil and distinction with clay are discussed. Soil mechanics and related properties are also elaborated. 

Clay mineral particles are commonly too small for measuring precise optical 

Name of Size, shape andform of natural occurrences 

Keolinite Well formed, six-sided flakes, with a prominent elongation in one direction. 

Halloysite Tubular units with an outside diameter ranging from 0.04 to 0.15 micrometre. 

What happens for a nonracemic mixture of enantiomers Is it possible to calculate the values of the chiral properties of the solution from knowledge of the properties of the enantiopure compound In principle, yes, on the condition that there is no autoassociation or aggregation in solution. Then, the observed properties will be simply the weighted combination of the properties of two enantiomers. A nice example of where this normal law may be broken was discovered by Horeau in 1967 it is the nonequivalence between enantiomeric excess (ee) and optical purity (op, with op = [a]exi/[ ]max) for 2,2-methylethyl-succinic acid. In chloroform op is inferior to ee, while in methanol op = ee. This was explained by the formation of diastereomeric aggregates in chloroform, while the solvation by methanol suppresses the autoassociation. 

The formation of diastereomeric aggregates may perturb the achiral properties as well, when compared to homochiral solutions, since the aggregation state will be not necessarily the same. It has been observed that the NMR spectra of racemic and enantiopure dihydroquinine in chloroform are significantly different.  

Various terms have been used to characterize the physical properties of ceramic powders. In this book, the terminology proposed by Onoda and Hench [18] and later adopted by Rahaman [19] will be used with minor or without any modifications. A powder can be characterized as an assemblage of small units with distinct physical properties. The small units are usually known as particles, which can exhibit complicated structures. 

A primary particle is a discrete unit with relatively low porosity, which can be either a single crystal, a polycrystalline particle, or an amorphous/glass. They can be isolated if pores are present. A primary particle could be defined as the smallest unit of the powder with clearly defined surfaces. Therefore, it cannot be broken down into even smaller units by some physical agitations, such as ultrasonic agitation in a liquid. A polycrystalline primary particle consists of liny crystals, which are also known as crystallites or grains. 

Particles are those small units that are movable as separate entities when the powder is dispersed by agitation and can be made of primary particles, agglomerates, or combinations of them. 

Floes are elusters of partieles that are usually present in liquid suspensions. The elusters are formed when partieles are held together through weak forees, sueh as eleetrostatie forees or bounding of organie polymers. As a result, these partieles ean be easily separated or redispersed by appropriately modifying the interfaeial properties, so that the weak foree interaction disappears. The presence of floes will decrease the packing homogeneity of the consolidated body and thus is undesirable. 

A colloid means systems consisting of finely divided phases in a fluid state. A colloidal suspension, also known as sol in some cases, is made of fine particles that are uniformly dispersed in a liquid. These particles are called colloidal particles, which exhibit Brownian motion and almost have no sedimentation under normal gravity. The colloidal particles have sizes ranging from 1 nm to 1 pm. 

Whilst the inter-relation of cross-link density and physical properties is far from simple with hydrocarbon rubbers, with polyurethane rubbers it is even more complex. 

The effect of the type of cross-link structure on properties was 

Many of these properties may be useful in the identification of natural materials. The tests for most physical properties are destructive and so should be used with care, and only when absolutely necessary. Optical properties are most easily tested and can often be done with minimal handling of an object. Optical properties should be tried first, before potentially harmful physical tests are performed. 

Crystal structure describes the orderly arrangement of atoms within a substance. This term is most often applied to crystalline solids such as minerals, but organic compounds may also be described in this way. 

Crystal structure is described in terms of symmetry. In mineralogy, there are six crystal systems and within those, thirty-two crystal classes. All crystals of 

Crystal system Internal symmetry Common forms Examples 

Isometric (cubic) Three equal axes, at right angles to each other Cube, dodecahedron, octahedron Halite (salt), pyrite, diamond, fluorite, garnet 

As a representative member of the glycosyl ureides, the physical properties of 1-D-glucosylurea are listed here in detail. 

Melting point Specific gravity Index of refraction Molecular volume Molar heat of combustion Specific rotation 

1-D-Glucosylurea consists of colorless, odorless, rhombic crystals with a slightly sweet taste. It crystallizes with one mole of urea of crystallization per mole and is very readily soluble in water. It is slightly soluble in methanol (0.215%) and in 86% ethanol (0.72%). It is very slightly soluble in absolute ethanol (0.042%), and virtually insoluble in w-amyl alcohol, ethyl ether, ethyl acetate, n-hexane, benzene, chloroform, and acetone. 

In general, the physical properties of the glycosyl ureides and thioureides and glycosylguanidines resemble those of 1-n-glucosylurea. However, the properties of 3-AT-substituted glycosyl ureides are markedly modified by the 3-AT-substituent. Modifications of the glycosyl residue (for example, acylation) also result in drastic changes in the physical properties of the molecule. 

Many correlations are available in the literature to measure physical properties such as density, viscosity, and specific heat as a function of temperature. 

The strength of a compound s intermolecular forces determines many of its physical properties, including its boiling point, melting point, and solubility. 

The boiling point of a compound is the temperature at which a liquid is converted to a gas. 

In boiling, energy is needed to overcome the attractive forces in the more ordered liquid state. 

Increasing strength of intermolecular forces Increasing boiling point 

Recall from Sample Problem 3.1, for example, that the relative strength of the intermolecular forces increases from pentane to butanal to 1-butanol. The boiling points of these compounds increase in the same order. 

The stronger the intermolecular forces, the higher the boiling point. 

Pu is a typically silver-white appearing metal which has a number of peculiar physical properties. The metal undergoes a total of five allotrppic modifications below the melting point, two of which have negative coefficients of thermal expansion. Table IV-1 summarizes the more important physical properties. 

The structures of the azaindoles were discussed in terms of tt-electron density calculations in Section IV. Tautomeric forms of the azaindoles will be discussed under the various physical methods below. 

Gold has 30 known isotopes, but only one, Au, is stable. The nucleus of Au contains 79 protons and 118 neutrons. Isotopes of mass numbers 177-183 are all a emitters and all have a physical half-life of 1 minute. Isotopes of mass numbers 185-196 decay by electron capture accompanied by y radiation and in some cases by positron emission. The only long-lived isotope is Au with a half-life of 183 days. The neutron-heavy isotopes of 198-204 all decay by b emission accompanied by y radiation. The isotope Au is widely used in radiotherapy, in medical diagnosis, and for tracer studies. 

The color of gold alloys depends on the metal mixture. Red gold is comprised of 95.41% Au and 4.59% copper (Cu) yellow gold of 80% gold and 20% silver (Ag) and 

Gold-silver-copper alloys are frequently used in coinage and gold wares. A purple alloy results with 80% Au and 20% aluminum, but this compound is too brittle to be made into jewelry. Gold forms alloys with many other metals, but most of these are also brittle. As little as 0.02% of tellurium, bismuth, or lead makes gold brittle. 

with three methylene units in its glycol moiety, is called an odd-numbered polyester. It is often compared to the even-numbered polyesters such as PET and PBT for the odd-even effect on their properties. Although this effect is well established for many polycondensation polymers such as polyamides, where the number of methylene units in the chemical structures determines the extent of hydrogen bonding between neighboring chains and thus their polymer properties, neighboring chain interactions in polyesters are weak dispersive, dipole interactions. We have found that many PET, PTT and PBT properties do not follow the odd-even effect. While the PTT heat of fusion and glass transition temperature have values between those of PET and PBT, properties such as modulus 

Higher tensile strength is obtained with the higher molecular weight materials. The effect of branching on the physical properties of polysulfide liquid oligomers is shown in Table 2 [35]. 

Cured liquid polysulfide compositions have excellent resistance to a wide variety of oils and solvents, for example, aliphatic and aromatic hydrocarbons, esters, ketones, and dilute acids and alkalis. Table 3 shows the properties of two polysulfide oligomers cured with conventional filled formulations [36]. The data presented are only trends and not absolute, since the results depend on the efficiency of cure. Systems that are not properly compounded have poorer solvent resistance. 

Degradation results in weight loss and loss of flexibility due to formation of monosulfide structure, since disulfide and formal groups offer a flexibilizing effect 

Physical Properties of Molded Sheets after Curing 10 min at 160°C 

Physical Properties of Sheets after Heat Aging 70 h at 100°C 

The benzyl ethers of sugars and their derivatives are often crystalline compounds, and many can be distilled. Table III gives some physical properties of some benzyl ethers of sugars and of some of their derivatives. 

Benzyl Ethers of Sugars and Some of Their Derivatives 

Compound Boiling point, C./mm. Melting point, C. Rotation solvent Refer- ences 

Compound Boiling points Melting Point, Wo. Rotation solvent Refers ences 

To calculate heat-transfer rates, physical-property data for the fluids being treated must be available. Physical property data should be as accurate as possible, especially as more accurate heat-transfer correlations become available. However, most physical properties of mixtures must be calculated or estimated consequently there is little need to attempt to determine true film temperatures. Physical-property data at the average bulk fluid temperature are generally sufficient. 

The following physical properties are usually required in order to obtain satisfactory calculated heat transfer rates  

When condensing or vaporizing over a temperature range, a curve representing heat load as a function of temperature should also be available. In addition, any concentration effects should be known. 

Chlorine 17782-50-5], EINECS no. 231-959-5, exists in all three physical states. At STP it is a greenish-yellow pungent, poisonous gas, which liquefies to a mobile yellow liquid. Solid chlorine forms pale yellow rhombic crystals. The principal properties are given below more details, including thermodynamic values are given in [40] and in New Property Tables of Chlorine in SI Units (41). There are small differences in the values of some properties in different references. 

Electronic configuration in the ground state Term symbol in the ground (Nel 3 y 

The density up to 300 °C is higher than that of an ideal gas because of the existence of more complex molecules, for exaiqple, CI4. In the range 400-1450 T, the density approximates that of an ideal gas, and above 1450 °C thermal dissociation takes place, reaching 50% at 2250 °C. The density of chlorine gas as a function of temperature and 

The vapor pressure can be calculated over the temperature range 172-417 K from the Martin-Shin-Kapoor equation [41]  

Thermodynamic information is given in Table 1, from which the data required for working with gaseous and liquid chlorine can be obtained [42]. The Joule-Thomson coefficient is 0.0308 KAPa at STP. 

Because these materials are the first examples of highly oxidized nonstoichiometric ceramic oxide superconductors, the determination and optimization of the physical properties has been a major technical and scientific challenge. The observed properties, and the impact of chemistry on them are reviewed here. 

The glass polyalkenoate cement sets rapidly within a few minutes to form a translucent body, which when young behaves like a thermoplastic material. Setting time (37 °C) recorded for cements mixed very thickly for restorative work varied from 2-75 to 4-7 minutes, and for the more thinly mixed luting agents from 4-5 to 6-25 minutes. Properties are summarized in Table 5.15. 

Strength develops rapidly and after 24 hours in water (37 °C) can reach 225 MPa (compressive) and 39 MPa (flexural) (Williams Billington, 1989 Pearson Atkinson, 1991 Pearson, 1991). Compressive modulus reaches 9 to 18 GPa after 24 hours (Paddon Wilson, 1976 Wilson, Paddon Crisp, 1979). 

Lewis Wilson (1976a) found that for two early types of glass-ionomer cement (ASPAII and ASPAIV) compressive strength continued to increase for at least a year. Recently, Williams Billington (1989) have found that this behaviour does not hold for all modem commercial 

Load 2-5 Kgf for filling materials, 220 gf for luting agents, applied after 2 minutes 

Flexural strength and fracture toughness are clinically more significant than compressive strength. The flexural strength of a glass-ionomer cement can reach 39 MPa after 24 hours (Pearson Atkinson, 1991) which is a much higher value than that attained by any dental silicate cement. 

The performance of P EMs can be characterized by either their electrochemical parameters, which include their equivalent weight (EW) and proton conductivity, or by their physical properties, which include thickness, gas permeability, mechanical strength, water uptake, and swelling, and so on. 

The proton conductivity (a expressed as S cm ) is the most important property of the PEMFC membranes for minimizing cell resistance and maximizing cell efficiency. In general, the proton conductivities of sulfonated PEMs tend to increase with the acid group concentration and hydration level. 

Because the ionic resistance of the PEM is proportional to its thickness, this parameter is extremely important for cell performance [8]. It is necessary to minimize membrane thickness, while maintaining an acceptable mechanical strength. 

Another important parameter of the PEM is that of gas permeability. The active oxygen species are produced in the membrane when oxygen transfers from cathode to anode, which in turn leads to membrane degradation. On the other hand, if the fuel gas is able to diffuse to the cathode and react chemically with oxygen, this will cause efficiency losses. Therefore, reactant gas leakage will results in a reduced cell performance in all cases. 

During the course of membrane electrode assembly (MEA), manufacture and PEMFC operation, the membranes are exposed to the impacts of temperature, humidity, and pressure. Consequently, it is important that the membranes possess a good mechanical stability, and in particular a high mechanical strength and minimal swelling. 

Enhancement of nonisothermal crystallization up to 10 °C was achieved for PVDF (Priya and Jog, 2002) by the addition of clay platelets. Enhancement was also achieved in isothermal crystallization. The coefficient of thermal expansion was lowered for nanocomposites compared with polymers without nanoclay platelets, which indicates the more stable dimensional properties of the material. 

Dielectric properties are directly related to piezoelectric properties. The dielectric constant, which is the ratio of the permittivity of the material to its permittivity to free space, is an indicator of how the material concentrates on electric flux. An increase in permittivity with the addition of fillers is observed in nanocomposites, which means that the nanocomposite can hold electric charge for a long time and/or hold many charges. 

The increase in dielectric constant is attributed to the formation of many small capacitors of fillers (electrodes) with a dielectric thin polymer film between them, which can increase the dielectric constant. The distribution of the fillers inside of the polymer can highly affect the dielectric constant. The filler distribution depends on nanocomposite preparation techniques. 

Nanosized fillers increase the permittivity more than micro-sized fillers, and the percolation threshold is lower (Putson et al., 2011). The addition of 0.1 wt% GO to PVDF (Rahman et al., 2013) significantly increases the dielectric constant. 

Nanoadditives can increase the crystallinity behavior of a material and the transformation to polymer crystal. This effect was observed in poly(vinylidene fluoride-co-hexafluoropropylene), PVDF—EVA, enhanced by organically modified clay (Kelarakis et al., 2010). The transformation from the a-phase type to the P-phase of the crystalline stmcture depends on the nature of the clay surface modifier and scales as well as the strength of the interactions between the clay and polymer 

As may be expected from the isosteric relationship between the two ring-systems, 1,2,4-thiadiazoles and the corresponding pyrimidine derivatives show certain similarities in their physical properties. Thus, the boiling points of the parent compounds are strikingly similar5 (see Table V). 

5-Amino-3-methyl-l,2,4-thiadiazole has a relatively high melting point and low solubility in water, compared with that of the 3-ethyl homolog and the parent compound the isosteric 4-aminopyrimidines show a parallel behavior (see Table VT).6 5-Amino-3-methoxy-l,2,4-thiadiazole melts at a higher temperature than does the ethoxy homolog.83 

The ionization constants of a number of 1,2,4-thiadiazoles have been determined potentiometrically87,88 or by Hammett s method205 based on the measurement of ultraviolet absorption spectra in media of different hydrogen ion concentration.126 The results are given in Table VTI. 2- and 4-Aminopyrimidine differ in their basicities (pA  

54 and 5.71, respectively) 3-amino-5-phenyl- and 5-amino-3-phenyl-1,2,4-thiadiazole exhibit a similar, though less pronounced, difference126 (see Table VII). 

In a systematic polarographic investigation180 the half-wave potentials of a number of 1,2,4-thiadiazoles were determined and the results correlated with their structures. Measurements were made in neutral buffered solutions, the salt concentration being kept constant by the addition of lithium chloride. 

The previous sections in this chapter address the creation of pseudocomponents by cutting an assay curve into a set of discrete components based on boiling-point ranges. We also briefly alluded to physical properties and process thermodynamics selection in the earlier workshops of this chapter. In this section, we consider, in detail, the problem of how to represent these components in the process modeling software. There are two major concerns in this area physical properties of pseudocomponents and selection of a thermodynamic system that can deal with these hydrocarbon pseudocomponents in the context of refinery modeling. 

A correct selection of physical properties and process thermodynamics results in a process model that can accurately account for material and energy flows in both vapor and liquid process streams. 

For any process simulation that involves only vapor-liquid phases, certain key physical and thermodynamic properties must be available for each phase. Table 1.3 lists these properties for all phases. We can typically obtain these properties for pure components (i.e. n-hexane, n-heptane, etc.) from widely available databases such as DIPPR [2]. Commercial process simulation software (including Aspen HYSYS) also provides a large set of physical and thermodynamic properties for a large number of pure components. However, using these databases requires us to identify a component by name and molecular structure first, and use experimentally measured or estimated values from the same databases. Given the complexity of crude feed, it is not possible to completely analyze the crude feed in terms of pure components. Therefore, we must be able to estimate these properties for each pseudocomponent based on certain measured descriptors. 

It is important to note the properties given in Table 1.3 are the minimal physical properties required for rigorous accounting of the material and energy flows in the process. As we will discuss in the subsequent sections, process models may require additional properties (especially vapor pressure) depending on the type of thermodynamic models being considered. 

Latent Heat of Vaporization (ALfvAp), Vapor Pressure (Pvap) 

The color of vinegar during aging changes from yellow/brown to brown/ black, due to the accumulation of chromophore-labeled melanoidins (Falcone and Giudici, 2008). At least four classes of melanoidins contribute to this coloration. Falcone and Giudici (2008) propose the ratio between the absorbance at 420 nm of TBV and the absorbance of the cooked must (brown index, BI) as a descriptor of the vinegar color and physical age (PRT)  

Adachi, O., Moonmangmee, D., Toyama, H., Yamada, M., Shinagawa, E., and Matsushita, K. (2003). New developments in oxidative fermentation. Appl. Microbiol. Biotechnol. 60, 643-653. 

Benedetti, B. (2004). Fatti in casa l aceto balsamico. Manuale illustrato per la formazione e conduzione di una acetaia. II Fiorino, Modena (Italy). 

and Van Boekel, M. A. J. S. (1994). Degradation of lactose during heating of milk. Neth. Milk Dairy J. 48,157-175. 

Bononi, M. and Tateo, F. (2009). Determination of furan by headspace solid-phase micro-extraction-gas chromatography-mass spectrometry in balsamic vinegars of Modena. ]. Food Compost. Anal. 22, 79-82. 

Caution must be exercised in interpretation of the physical data for the tetracyanoplatinate complexes (as well as all other one-dimensional systems) because purity and morphology are extremely critical for one-dimensional systems. For example, a 1.00 x 0.01 x 0.01 mm perfect needle crystal of K2Pt(CN)4Xo.3 would contain — lx 10 parallel strands each of 3.5 x 10 collinear platinum atoms. Thus, purity (foreign impurities, end groups, and/or crystalline defects) levels of one part per million indicate that each strand averages more than three defects, which may drastically alter some (and in particular transport) measurements. Besides the intrinsic purity problem of one-dimensional systems, the physical properties of K2Pt(CN)4-Xo.3(H20)a are a strong function of hydration. Dehydration alters the crystal structure and thus properties of the complexes (78). Care must be maintained to ensure that dehydration is not caused by the measurement technique. For 

All of the aforementioned tetracyanoplatinate complexes. Table IV, form columnar structures in the solid. The partially oxidized complexes exhibit short uniform metal-metal spacings and the physical properties characteristic of metallic systems. The K2Pt(CN)4Xo.3(HaO)a complexes, due to the ease of growing large defect-free crystals, have been the most extensively studied inorganic one-dimensional systems. In addition, the ability to carve these crystals with a sharp knife (364a) is an aid in performing some physical measurements. 

Schematic illustration of oxidation of a filled dt energy band (a) forming a partially occupied 4 electron energy band, (b) assuming a constant bandwidth before and after partial oxidation. Note that the change in metal-metal spacing will affect the bandwidth. 

Recently Whitmore (572) has performed an electron energy band structure calculation for linear square planar platinum complexes using a multiple scattering technique and a potential determined from a self-consistent calculation of the unit cell. The calculation was evaluated for uniform Pt-Pt spacings of 2.8 and 2.9 A. For Pt-Pt spacing of 2.9 A, the electron energy band derived 

Zeller and Bruesch (581) have examined the results of numerous experiments and concluded that the conduction electron energy state in K2Pt(CN)4-Bro.3o(H20)3 can be represented by a one-dimensional nearly free electron band structure, Fig. 28. In terms of wavefunctions, frre electrons implies 

In general, pyridazine can be compared with pyridine. It is completely miscible with water and alcohols, as the lone electron pairs on nitrogen atoms are involved in formation of hydrogen bonds with hydroxylic solvents, benzene and ether. Pyridazine is insoluble in ligroin and cyclohexane. The solubility of pyridazine derivatives containing OH, SH and NH2 groups decreases, while alkyl groups increase the solubility. Table 1 lists some physical properties of pyridazine. 

Hydrochloride, yellow solid, m.p. 161-163 °C Monopicrate, yellow solid, dec. 170-175 °C 

Methanol, or as it is termed in full methyl alcohol, with the chemical formula CH3OH is the first of the long series of alcohols. Its molecular weight is 32.04 and it is a neutral, colourless liquid in pure condition having an odour similar to that of ethyl alcohol. Methanol dissolves well with other alcohols, esters, ketones as well as with aromatic hydrocarbons and water. It can be less well mixed with fats and oils. It dissolves a number of organic substances including numerous salts. The most important physical data for methanol are assembled in Tables 3.1 to 3.5. Further data on the physical properties of methanol can be taken from the literature under [3.3-to 3.10]. 

The dipole moment p. is a molecular property defined as the product of charge (usually just a fraction of the electronic change, of course) and distance between the centers of positive and negative charge in the molecule. The dipole moment is usually expressed in debyes (D), where 1 D = 1(T esu in SI units 1 D = 3.3356 X 10 ° C-m. so, for example, the dipole moment of water is 1.84 D or 6.14 in units of 10 C-m. Again a rough correspondence is seen between this property of a molecule and its polarity, though e and p. are not precisely correlated. 

The molar refraction, / m, is a measure of the size of a molecule. It is calculated with Eq. (8.5), the Lorenz-Lorentz equation, where , d, and M are the refractive index, the density, and the molecular weight, respectively. 

The three properties e, p., and / m are related. One way to determine p. is by means of measurements of the dielectric constant of dilute solutions of the molecule in an inert solvent. Equation (8-6) was derived by Debye.  

The quantity on the left side of the equation is called the molar polarization, and this expression is the Clausius—Mosotti equation. On the right side the quantity a is the polarizability, which measures the ease with which an induced moment is 

Source Most of the data in this table are from References 197 and 198. At 25°C or room temperature. 

TABLE M4. SUBSITTUTION EFFECTS OUALITATTVE VARIATIONS OF 7T NET CHARGE INDUCED BY THE SUBSTITUTION OF A CHLORINE OR AN AMINO GROUP (123)  

As with methylation, substitution by -Cl or -NHj induces a decrease in 77 electronic density on the substituted carbon atom and a slight increase in both adjacent positions. The perturbation of an -NH2 group is slightly larger than that of a -Cl group. 

Quinoxalines, because of the 1 4 arrangement of their ring nitrogen atoms, are only weakly basic. The effect of substituents on basic strength is illustrated in Table II thus -Me, -NH2, a-NHMe, and 

5- hydroxyquinoxaline is nitrogen-1, Thus reaction of 5-hydroxyquin-oxaline with methyl iodide gives a methiodide which must be the 1-methiodide, because of its ability to form a strongly bound nickel complex.  

The acidic strength of various quinoxaline derivatives is also listed in Table II. -Methyl groups have an acid-weakening effect and quinoxalin-2-one (2-hydroxyquinoxaline) is, as expected, a weaker acid than quinoxaline-2-thione (2-mercaptoquinoxaline), The marked enhancement of the acidic strength of 5-hydroxyquinoxaline 1-methiodide compared to 5-hydroxyquinoxaline itself, is due to the electron-attracting property of the positively charged nitrogen,  

The ultraviolet absorption spectrum of quinoxaline in cyclohexane shows bands with vibrational fine structure at 340 (log e 2,84), 312 (log 3.81), and 232 m/j. (log e 4.51) and which are attributable to n — 7T and tt — tt transitions. In ethanol the vibrational fine structure disappears and the less intense n—w band appears as a shoulder on the long-wave tt — tt band, but in methanol and water the less intense n — tt band is obscured by the long-wave tt — tt band. In the latter solvent, the absorption maxima are at 316 (log e 3.79) and 234 mjj. (log 4.47). The weak n—w bands in the ultraviolet spectra of 

6- chloro- and 6-bromo-quinoxaline and certain 2-substituted quin-oxalines also show similar shifts to shorter wavelengths on change from a nonpolar to a polar solvent, whereas the tt — tt bands are not 

Optical Rotatory Dispersion and Circular Dichroism Spectra 

In general, an increase in steric demand of the substituents on silicon atoms appears to lead to the formation of more stable disilenes. For example, 3, which has two f-butyl groups, is more stable than 1 while 4, which has two 1-adamantyl groups, is more stable than 3.9 Disilene 4 

The stable disilenes are pale yellow to orange-red in the solid state and have electronic absorption maxima in solution between 390 and 480 nm (Table I). The longest wavelength absorptions have been assigned to the ir-ir transition.28 

An almost 60-nm red shift on going from f-butyl-substituted disilene 

Each of the three tetrakis(trialkylsilyl)disilenes 22-24 has an absorption band near 420 nm but compound 24, which bears the largest substituents, also exhibits a rather strong absorption at exceptionally low energy, max 480 nm.21 The likely explanation of this anomaly is that a strongly twisted conformation of 24 may exist in solution. Among the tetraalkyldisilenes, the unusually long wavelength absorption at 433 nm for 21 may also result from a twisted conformation.4 

Thermochromism was already noted for the first stable disilene l.2a In dialkyl- or bis(trimethylsilyl)diaryldisilenes, the size of the aryl groups affects the thermochromism Tip-substituted ones (9,10) are thermochro-mic,10 while Mes-substituted ones (3,4) are not.9 Interestingly, tetrakisftri-alkylsilyl)disilanes 22 and 23 are highly thermochromic hexane solutions of 22 and 23 are light yellow below 0°C but dark red above 50°C.21 These observations were interpreted in terms of a thermal equilibrium between the bent and twisted conformations. Compound 24, having an absorption band at 480 nm, is dark red in solution even at room temperature. 

Orbital period of the Saturnian system around the Sun 29.5 years 

The next most likely possibility is cometary delivery of the atmosphere but again there are some problems with the isotope ratios, this time with D/H. The cometary D/H ratios measured in methane from Halley are 31 3 x 10-5 and 29 10 x 10-5 in Hayuatake and 33 8 x 10-5 in Hale-Bopp, whereas methane measurements from Earth of the Titan atmosphere suggest a methane D/H ratio of 10 5 x 10-5, which is considerably smaller than the ratio in the comets. The methane at least in Titan s atmosphere is not exclusively from cometary sources. Degassing of the rocks from which Titan was formed could be a useful source of methane, especially as the subnebula temperature around Saturn (100 K) is somewhat cooler than that around Jupiter. This would allow volatiles to be more easily trapped on Titan and contribute to the formation of a denser atmosphere. This mechanism would, however, apply to all of Saturn s moons equally and this is not the case. 

The volatile-trapping mechanism has a further problem associated with the temperature. Very volatile molecules such as N2, CO and CH4 are not easily trapped in laboratory ice simulation experiments unless the ice temperature is 75 K, which is somewhat lower than the estimated Saturnian subnebula temperature. This has led to the suggestion that the primary source of nitrogen within the Titan surface ices was NH3, which became rapidly photolysed to produce H2 and N2 upon release from the ice. The surface gravity is insufficient to trap the H2 formed and this would be lost to space. However, the origin of methane on Titan is an interesting question. Methane is a minor component of comets, with a CH4/CO ratio of clCT1 compared with the present atmospheric ratio of 102. The D/H ratio is also intermediate between that of comets and the solar nebula, so there must be an alternative source of methane that maintains the carbon isotope ratio and the D/H isotope ratio and explains the abundance on Titan. 

The conditions on Titan, both in the atmosphere and in the oceans, can be investigated using the kinetics and thermodynamics introduced in the modelling of the ISM and the prebiotic Earth, now tuned to the surface temperature and atmospheric temperature conditions on Titan. We have seen previously what happens to reaction rates in the ISM and the atmosphere using the Arrhenius equation but we have not yet extended the concepts of AG and thermodynamics to low temperatures. 

Apart from DAB-dendr-(CN)4, which is a white crystalline solid, all generations are colorless to slightly yellow oils. The amine-terminated dendrimers are transparent, whereas the nitrile-terminated products are somewhat turbid. The solubility of the dendrimers is determined primarily by the nature of the end-group DAB-dendr-(NH2)n is soluble in H20, methanol and toluene, whereas DAB-dendr-(CN)n is soluble in a variety of common organic solvents. 

All dendrimers consist of inner tertiary amines, located at the branching points of the various dendritic shells (layers). The amine-terminated dendrimers, furthermore, have basic primary amine end-groups. Basicity is therefore one of the most dramatic properties of the polypropylene imine) dendrimers, and has been studied via titration experiments and calculations. Titration experiments of the dendrimers have been performed in water using 1 M hydrochloric acid. Only two equivalence points are observed for DAB-J nJr-(NH2)4 in a ratio of 2 1. From these titrations, pKa values of 10.0 (primary amine groups) and 6.7 (tertiary 

Titration experiments on the nitrile-terminated dendrimers in water show for DAB-dendr-(CN)A pKa values of 3.2 and 4.8. The corresponding calculated pKa values are 3.1 and 4.1 respectively (using the pKalc program, version 2.0, Com-pudrug chemistry). For DAB-dendr-(CN)s only the two inner nitrogen atoms can be protonated in acetonitrile, due to the low basicity of the four other ones. This is confirmed with calculated pKa values of the four outer tertiary nitrogen atoms in DAB-dendr-(CN)s, ranging from 2.0 to 3.2. The presence of the electropositive nitrile-functions and the protonated inner tertiary amines can account for this phenomenon. 

The hexitols are colorless crystalline solids of sweet taste and varying solubility in water. Sorbitol is very soluble in water and is quite hygroscopic, being used commercially as a humectant. In general, the hexitols may be recrystallized from solutions in the lower alcohols, but they are insoluble in most other common organic solvents. 

The melting point of sorbitol has been reported over a wide range for many years. The precise work of Rose and Goepp showed that sorbitol occurs in a stable and an unstable form (freezing points, 97.2° and 92.7°, respectively). This accounts for the discrepancies, since most preparations are probably mixtures of the two forms, which are interconvertible. A value of 89-93° is usually encountered.  

The optical activity of the hexitols is of a low order. It may be enhanced by the addition of various complex-forming salts, borax and ammonium molybdate being the ones most used. Since the amount of enhancement is a function of the relative proportions of polyol and booster, it is regrettable that definite amounts of borax or molybdate have not always been reported in the past. 

The melting points and rotations of the hexitols are given in Table I, page 219. 

The chemical reactions of the hexitols are similar to those of the simple sugars, uncomplicated by the presence of a carbonyl group. The hexitols exhibit a higher order of stability to acid, alkali and heat. They are readily converted to stable anhydro products. These anhydrides are known as hexitans when one mole of water is removed and hexides when two moles are removed. 

These have been comprehensively reviewed [6, 12, 17]. There is only one form of the solid [206] despite early claims that there were two. It is pale yellow and, like OsO, has a substantial vapour pressure at room temperatures it melts at 25.4 0.1 °C [206], boiling at 129.6 0.2°C [207]. Its density is 3.28 g/cm the solubility in water at 0°C is 1.7% and 2.11% at 50°C, but it is very soluble in those organic solvents with which it does not react such as CCl [6]. 

The X-ray crystal structure of the solid shows that there are two crystal modifications, one cubic and one monoclinic, but within both forms the molecule is tetrahedral with Ru=(0) 1.695(3) A [208]. Electron diffraction measurements on the vapour show the molecule to be tetrahedral with an Ru=(0) distance of 1.705(8) A [209]. Similarity of the profiles of the Raman spectra of the solid, liquid and aqueous solution suggest that the molecule has tetrahedral symmetry in all three phases (Fig. 1.3) [210]. Aqueous solutions of RuO are stable only at pH below 7 [211, 212]. 

IR spectra have been reported of isotopomers of RuO with and 0 in argon matrices [223], Force-field calculations were made on the molecule [220, 224-226], 

Other electrochemical data on RuO have been obtained [228-230]. A Pourbaix (E-pH) diagram was given for RuO, [Ru Og] % [Ru Og] % [RuO ] , RuO, Ru, Ru(OH) and Ru [231]. Thermodynamic data on RuO and other Ru species were summarised [230,232,233], andreviewed[234]. Static electric dipole polarisabilities of RuO, OsO and HsO were calculated [235], 

The infrared spectra of l,4-anhydro-3,5-0-methylene- and -2-0-methyl-DL-xylitol have been studied.60 The 2-methyl ether was obtained by converting l,4-anhydro-3,5-0-methylene-DL-xylitol into its monomethyl ether, and then hydrolyzing off the methylene group. A methyl ether prepared from the known l,4-anhydro-3,5-0-isopro-pylidene-2-O-methyl-DL-xylitol proved to be identical with this compound, thus establishing at the same time that the methylene group in the known acetal is attached to 0-3 and 0-5 of 1,4-anhydro-DL-xylitol. The methylene group, having a 1,3-dioxolane structure, was characterized by an absorption band at about 2800 cm 1. 

Frequencies (cm-1) of Absorption Bands of 3,6-Anhydro-D-glucitol (1), 1,4-Anhydro-D-mannitol (2), 1,4 3,6-Dianhydro-2,5-di-0-methyl-D-mannitol (3), and l,4 3,6-Dianhydro-D-glucitol (4) 

Proton coupling-constants were determined65 for the tri-O-acetyl derivatives of bis(ethylsulfonyl)-a-D-lyxopyranosylmethane [2,6-anhydro-l,l-bis(ethylsulfonyl)-l-deoxy-D-galactitol] (29) and bis(eth- 

J — Jo cos26 — 0.28 Hz and values of J0 = 9.26 Hz for angles between 0 and 90° and/ = 10.35 Hz for angles between 90 and 180°) were almost in agreement with those required for the paired hydrogen atoms of a chair conformation, namely, 1C (d). 

The acetoxyl-proton resonances were also in accordance with the 1C (d) conformation, namely, one equatorial and two axial acetoxyl resonances for 29, and the converse for 30 (see Table III), since methyl groups of axially oriented acetoxyl substituents of a pyranoid ring generally resonate at lower field than those of similar, equatori-ally attached groups. 

The spectral features in the UV and visible re ons of phosphamethin-cyanines resemble those of the correspondingly substituted methin- and azamethin-cyanines. The position and extinction coefficient of the maxima as well as the general shape are quite similar (Fig. 1). 

In the phosphamethin-cyanine series with benzimidazolium substituents, the effect of the size of the N-alkyl groups on the absorption spectra (Fig. 2) was also investigated Table 1,8a-8e, shows that with increasing alkyl size, the long- 

In this review the negative signs of H6-values have been omitted. 

At present we do not know which of these processes accounts for the NMR spectrum. 

The two N-methyl groups of 1.2.3-trimethyl-benzimidazoliumiodide in DMSO also absorb at 4,05 ppm, while the signal due to the methyl groups at C2 appears at 2,9 ppm  

Nitroguanidine exists in two crystalline forms. The a-form results from the action of sulphuric acid on guanidine nitrate followed by the precipitation of the product with water. This form crystallizes from water in long, fairly flexible needles. 

The y -form is produced either alone or together with some of the a-compound, by the nitration of the mixture of guanidine sulphate and ammonium sulphate which results from the action of sulphuric acid on dicyandiamide. The /Worm crystallizes from water in thin, elongated plates. It is converted into the a-compound by solution in sulphuric acid and precipitation with water. Both forms of nitroguanidine melt at the same temperature. Several authors quote different melting points 232, 246, 257°C. 

The two forms appear to differ slightly in their solubility in water, neither form being converted into the other. At 25 and 100°C the solubility of the a-form is 4.4 g/1. and 82.5 g/1. respectively. Between these temperatures the /Worm appears to be more soluble. 

The apparent dens ty of the crystals is 0.96, whereas that of ordinary commercial nitroguanidine is about 0.25 and that of the product rapidly crystallized from methanol is about 0.40. 

The solubility of nitroguanidine in organic solvents is limited. Desvergnes [31] determined its solubility in various solvents water, acetone, methyl and ethyl alcohols, ethyl acetate, ether, benzene, toluene, pyridine, chloroform, carbon tetrachloride and carbon sulphide. In all these liquids the solubility of nitroguanidine is negligible, the highest value—for pyridine—being 1.75 g/100 ml at 19°C. 

From left to right lamp black (mean primary particle diameter 95 nm, BET surface area 21 m2/g), furnace black (27 nm, 90m2/g), finely divided gas black (13 nm, 320 m2/g) 

The carbon layers of carbon black rearrange to a graphitic order, beginning at the particle surface at temperatures above 1200 °C. At 3000 °C, graphite crystallites are formed and the carbon black particles assume polyhedral shape. 

Specific Surface Area. The specific surface area of industrial carbon blacks varies widely. While coarse thermal blacks have specific surface areas as small as 8 m2/g, the finest pigment grades can have specific surface areas as large as 1000 m2/g. The specific surface areas of carbon blacks used as reinforcing fillers in tire treads lie between 80 and 150 m2/g. In general, carbon blacks with specific surface areas 150 m2/g are porous with pore diameters of less than 1.0 nm. The area within the pores of high-surface-area carbon blacks can exceed the outer (geometrical) surface area of the particles. 

Adsorption Properties. Due to their large specific surface areas, carbon blacks have a remarkable adsorption capacity for water, solvents, binders, and polymers, depending on their surface chemistry. Adsorption capacity increases with a higher specific surface area and porosity. Chemical and physical adsorption not only determine wettability and dispersibility to a great extent, but are also most important factors in the use of carbon blacks as fillers in rubber as well as in their use as pigments. Carbon blacks with high specific surface areas can adsorb up to 20 wt% of water when exposed to humid air. In some cases, the adsorption of stabilizers or accelerators can pose a problem in polymer systems. 

Density. Density measurements using the helium displacement method yield values between 1.8 and 2.1 g/cm3 for different types of carbon black. A mean density value of 1.86 g/cm3 is commonly used for the calculation of electron microscopic surface areas. Graphitization raises the density to 2.18 g/cm3. The lower density with respect to graphite (2.266 g/cm3) is due to slightly greater layer distances. 

Boiling points of alcohols, esters and nitro compounds, °C 

Alkyl Alcohol Nitric ester Nitrous ester Nitro compound 

According to de Kreuk the difference between the viscosity values of similar compounds (e.g. 1,3- and 1,2-propanediol dinitrates, 1,3- and 2,3-butanediol dinitrates) may be attributed to rotational isomerism. Free rotation makes possible the formation of trans isomers which according to this author should possess a higher viscosity. This would explain the relatively high viscosities of 1,3-propanediol and 1,3-butanediol dinitrates. 

Boileau and Thomas [3] have determined certain physical constants for nitroglycerine and a few glycol dinitrates of practical importance (Table 3). 

Dipole moments of alkyl nitrates were determined by Cowley and Partington [4]. They found the value n = 2.73 D for methyl nitrate. The values of n in the instance of longer chain alkyls do not differ essentially from this figure. 

No quantum mechanical calculation or similar theoretical treatment seems to have been dedicated to chrom-3-ene7 or to its simple derivatives. Interatomic distances and angles of two bromo derivatives of natural chromenos have been obtained by X-ray analysis,8,9 The UV absorption,10 emission,11 fluorescence, and fluorescence excitation spectra12 of some 2,2-dialkylchromenes have been studied in connection with their photochromic behaviour. 

The nuclear magnetic resonance (NMR) spectrum of chrom-3-ene (1) has been measured13 and the sign of coupling constants between protons on the hetero ring obtained from a study of double quantum transitions.13 An inter-ring coupling (J4 8) has been detected.14-16 In 

Mechoulam and Y. Gaoni, Fortschr. Chem. Org. Naturstoffe 25, 175 (1967) Ciba Foundation Symposium on the Chemistry and Botany of Cannabis, (C. R. B. Joyce and S. H. Curry, eds.). Churchill, London, 1970 Abstract of Symposium on the Chemistry and Biological Activity of Cannabis, Apotheker Societaten, Stockholm, 1971 It. K. Razdan, in Progress in Organic Chemistry (J. Cook and W. Carruthers, eds.), Vol. 8, Butterworth, London, 1973. 

7 For the sake of brevity, the numbering of the double bond will be omitted when not necessary. 

Arnone, G. Cardillo, L. Merlini, and It. Mondelli, Tetrahedron Lett., 4201 (1967). 

The parent naphthyridines are crystalline (see Table I) and some X-ray crystallographic work14,15 has been reported for the 1,5- and the 2,6-naphthyridines. 

The bond lengths (see Table II) and the bond angles of these two compounds (7 and 8) have been determined as their dihydrates. The 1,5-naphthyridine can be obtained in two crystalline forms, rhombic and monoclinic, by sublimation at 30° and 35°, respectively. Both forms lose water at 38°-40°. 

Brufani, D. Duranti, and G. Giacomello, Gazz. Chim. Ital. 89,2328 (1959) Chem. Abstr. 55, 5081 (1961). 

Naphthyridine Melting point (°C) Ref. Melting point of picrate (°C) Ref. 

Compound Bond Naphthalene Pyridine 1,5 -Nap ht hyridine 2,6-Naphthyridine 

Okamura and Katz have determined the pKa of 3H-pyrrolizine by measuring the rate of exchange of its protons with 5 M D20 in dimethyl-formamide containing 1 M triethylamine.115 The value of 29 seems surprisingly high compared with those of indene (18.2), cyclopentadiene (15), and fluorene (22.8). 

To remember that alkanes have low density, think of an oil spill where alkanes float on water. 

Alkanes have the lowest density of all groups of organic compounds. Density increases with molecular weight. 

Alkanes are almost totally insoluble in water. They are soluble in benzene, carbon tetrachloride, chloroform, and other hydrocarbons. If an alkane contains a polar functional group, the polarity of the entire molecule, and thus its solubility, decreases as tlie carbon chain is lengthened. 

Cyclohexane exists as three conformers the chair the fwisf and the boat All three conformers exist at room temperature however, the chair predominates almost completely because it is at the lowest energy. Although the boat configuration is often discussed, the twist-boat is usually intended, 

Hydrogens reverse orientation upon conformations) change of cyclohexane. 

The systematic name of indigo, also known as indigotin, is 2-(l,3-dihydro-3-oxo-2 //-indol-2-ylidcnc)-1,2-dihydro-3//-indol-3-onc or 2,2 -biindolinylidene-3.3 -dionc. C.I. Vat Blue 1. 73000 4H2-H9-3. It exists as blue-violet needles or prisms with a pronounced coppery luster. It sublimes above 170 °C as a red-violet vapor that condenses on cooling to form dark violet needles. The melting point is 390-392°C. 

Indigo is practically insoluble in water, dilute acids, and dilute alkalis, but slightly soluble in polar, high-boiling solvents such as aniline, nitrobenzene, phenol, phthalic anhydride, and dimethyl sulfoxide. Some polar solvents destroy indigo when it is dissolved in them at the boil. 

The dye is positively solvatochromic, the absorption maximum in a polar solvent such as dimethyl sulfoxide being 620 nm, that is, 12 rnn higher than in a nonpolar solvent such as carbon tetrachloride [5],Characteristic of indigo is the unusually deep shade compared with other conjugated systems of similar size [6], This is explicable in terms of the special arrangement of the atoms in the basic 

Bond orders and charge densities in the indigo molecule have been calculated [7] and compared with the results of X-ray analysis [8], These studies confirm the structural formula 1 and answer questions about the basic chromophore of the dye (see Section 2.4). 

The gases radon (222Rn) and thoron (220Rn) are formed as progeny of uranium and thorium in rocks and soil. They are emitted from the ground into the atmosphere, where they decay and form daughter products, isotopes of polonium, bismuth and lead, which either remain airborne till they decay, or are deposited in rain and by diffusion to the ground. 

Radon and thoron and their decay products are the most important sources of radiation exposure to the general public, contributing on average about half of the total effective dose equivalent received from natural and man-made radioactivity (Clarke Southwood, 1989). 

The emanation of a radioactive gas from radium was observed by Madame Curie. In the atmosphere, radon diffuses and mixes with air like any other gas. Rutherford Brooks (1901) obtained a value 8 x 10-6 m2 s-1 for the diffusivity of radon. Recent determinations are in the range 1.0 to 1.2 x 10-5 m2 s-1 at N.T.P. (Jost, 1960). 

Radon is slightly soluble in water, and obeys Henry s Law. At 20°C the partition coefficient (amount of radon per litre of water at equilibrium divided by the amount per litre of air) is 0.26. Despite the low solubility, water supplies derived locally from granite and metamorphic rocks can be an important source of airborne radon in dwellings (Nero Nazaroff, 1984 Hess etal., 1987). Radon is more soluble in fats and organic liquids, and the partition coefficient between air and human fat is about unity at 37°C. 

The radioactive decay schemes of radon and thoron are shown in Fig. 1.1. The old generic nomenclature (RaA, ThB etc.) is now superseded by the isotopic designation (218Po, 212Pb etc.), but where necessary for clarity the old designation will be added. 

PEA=poly(ethylene adipate) PBS=poly(butylene succinate), D=octyl branches and B=ethyl branches the numerals indicate mol % of branches in the copolymer Data adapted from [172] 

Poly(L-LA) is a semicrystalline polymer with a Tg of 61 °C and Tm of 174 °C. The crystal structure of PLLA is pseudo-orthorhombic [ 173]. It is a white fibrous material. 

Poly( -PL) has aTgof-15 °CandaTmof83 °C [ 174]. The degree of crystallinity depends on the method of preparation and ranges from 40-60%. Proper drying of the sample leads to an increase in Tg to -4 °C [ 175]. A tensile strength of 103 MPa and a tensile modulus of 1.59 GPa have been reported for unoriented strips. 

Aliphatic poly(ether-ester)s are more flexible because of the presence of ether linkages. Poly(l,4-dioxan-2-one) is a crystalline polymer with a tensile strength and elasticity similar to those of human tissue. Poly(e-CL) and poly(DXO) resemble each other in their chemical architecture, but poly(e-CL) is semicrystalline while poly(DXO) is an amorphous polymer with a Tg of about -37 °C. 

The Tg of copolymers of e-CL and DXO was in the range from -64 to -39 °C [131]. Both crystallinity and Tm decrease with increasing amount of DXO and about 40% of DXO comonomer units of poly(e-CL-co-DXO) are incorporated into the poly(e-CL) crystals. Some inclusion of DXO in the crystalline lattice of poly(S-VL) was also indicated on the basis of crystallinity data [138]. 

Dipole Moments, Molecular Geometry, and Electronic Structure 

/3 = 100°, and 2 == 2.220 The information available is not sufficiently accurate for bond length and bond angle determination and an accurate crystallographic analysis of phenanthridine itself is needed. 

Zahradnik and C. Parkanyi, Collect. Czech. Chem. Commun. 30, 355 (1965). 

Calculated reactivity indices are at one with qualitative electronic theory in accounting for ready nucleophilic attack at C-6 in the phenanthridine molecule. However, the limited data available on positional reactivities in electrophilic substitutions is not accounted for satisfactorily by any of the available treatments (see later) and it has been pointed out that the simple Hiickel treatment used by some authors,223, 220 is generally inapplicable in heteroaromatic systems.228 

Coppens, C. Gillet, J. Nasielski, and E. Vander Donckt, Spectrochim. Acta 18, 1441 (1962). 

Pure anhydrous nitric acid (100%) is a colorless liquid that solidifies at a temperature of -41.6°C to form white crystals. It boils at 84.1°C. When it boils in light, a partial decomposition occurs with the formation of NO2 via the reaction shown in Eq. (9.1)  

This means that anhydrous nitric acid should be stored below 0°C to avoid decomposition. The nitrogen dioxide remains dissolved in the nitric acid and creates a yellow color at room temperature and a red color at higher temperatures. While the pure acid tends to give off white fumes when exposed to air, acid with dissolved nitrogen dioxide gives off reddish-brown vapors which leads to the common name red fuming acid 53. 

Nitric acid is miscible with water and distillation gives an azeotrope with a concentration of 68.4% HN03 and a boiling temperature of 121.9°C at atmospheric temperature. Two solid hydrates are known - the monohydrate (HN0j H20) and the trihydrate (HNO, 3H20)53. 

The TLV for nitric acid has been set at 2 ppm as an 8 hour time-weighted average (TWA) with a short-term exposure limit (STEL) of4 ppm. 

Some properties of nitric acid are given in Table 9.1, Table 9.2 and Table 9.3. 

To estimate the Maxwell-Stefan and effective diffusion coefficients, diffusion data for binary mixtures is necessary. For gas systems under low pressure, the model of Fuller et al. is used most frequently [51]. The method of Wilke and Lee [40] is also valid for low pressures. Both of these methods generally agree with experimental data with an accuracy of up to 10 %, although discrepancies of about 20 % cannot be excluded [40], 

For diffusion coefficients in systems under high pressure, the method of Dawson-Khoury-Kobayashi (see Ref. [52]) suggests a relevant pressure correction factor. To estimate the molar volumes, some reliable equations of state should be applied, whereas the necessary binary diffusivities at 1 atm can be determined with one of the methods described above. 

Since reactive absorption systems often contain electrolyte species, the calculation of relevant diffusion coefficients is crucial. The effective diffusion coefficients for electrolyte components can be obtained from the Nernst-Hartley equation (see 

but this equation is valid only for dilute solutions. At higher electrolyte concentrations, another, empirical equation by Gordon (see Ref. [44]) should be applied, which takes the influence of the liquid phase viscosity into account 

Due to the lack of a reliable description, the diffusion of an ionic species in a molecular species is usually represented by the effective ionic diffusivity in the liquid phase [52]. The calculation of the diffusion coefficient for an ionic component in another ionic species is reduced to the arithmetical mean of both effective ionic diffusivities [52]. 

Crystallization from absolute alcohol gives anhydrous D-fructose as small, colorless prisms, m. p. 102-104°.15 This is the usual form in which the crystalline sugar is obtained, and is, almost certainly 0-D-fructo-pyranose1 (lb). In aqueous solution the sugar has [a] 0 —132.2° —  

The sugar is extremely soluble in cold water, but sparingly soluble in absolute alcohol. 

Solvent Md Solu g./lOO m Initial bility. solution Final 

Vosburgh19 gives tables of the specific rotations of aqueous solutions of fructose at different temperatures and concentrations. He deduced the following formulas 1, 2 and 3 which are useful for calculating the fructose content of invert sugar of known specific rotation  

Tsuzuki, Yamazaki and Kagami20 have also studied such rotations and give the equation 

Nitrobenzene is a highly toxic, pale, yellow liquid, having a specific smell of bitter almonds. It melts at +5.7°C, and boils at 210.9°C. It was first obtained by Mitscherlich [1] in 1834. The compound is widely used in organic industry as a starting material for the preparation of aniline, benzidine and other intermediates 

SOLUBILITY OF NITROBENZENE IN SULPHURIC ACID ALONE, AND IN THE PRESENCE OF HN03, AT 43°C 

H2SO4 concentration % C6H5N02 content in the solution, % Concentration of H2S04, containing 0.2% HN03, % C6H5N02 content in the solution, % 

The solubility of nitrobenzene in water and in spent nitrating acid is its most important property, which should be borne in mind in its manufacture on account of the possible loss of the product and the toxicity of the waste water. 

The relevant data, reported by Groggins [2] are tabulated above (Table 29). 

Liquid HF is miscible with H20 in all proportions. The other hydrogen halides are very soluble and form constant boiling mixtures with water. Therefore, constant boiling HC1 has been used as a primary standard for analytical purposes. At 760 torr, the compositions and boiling points of the constant boiling mixtures are as follows  

Although the hydrogen halides all dissolve in water to give acidic solutions, there is a great difference in the acidity. Hydrogen fluoride is a weak acid, whereas all the others are strong. The pKa values are 2.92, -7, -9, and -9.5 for HF, HC1, HBr, and HI, respectively. The weakly acidic character of HF is due in part to the fact that F is a hard base and competes effectively with H20 for the protons (see Chapter 5). Consequently, the reaction 

These types of processes are not, of course, of any consequence for the other hydrogen halides but rather are the result of the stability of the HF2 ion. The most important chemical property of the hydrogen halides is, nevertheless, their acidity. 

The preparation of the hydrogen halides can be carried out by several methods. Not all of these methods will work for all of the compounds, however. Because of their volatility, the usual method for preparing HF, HC1, or HBr is by heating a halide salt with a nonvolatile acid such as H2SO4 or H3PO4  

As a result of the ease with which the iodide compound dissociates at elevated temperature, this method is not applicable to the preparation of HI. Also, if an acid is used that can behave as an oxidizing agent, the reducing power of HI leads to a redox reaction producing the halogen  

When the ring has no polar substituents the dipole moments of imidazole and its derivatives are of the order of 3.8-4.0 D.163-165 A nitro substituent in a condensed ring increases this value by 2.0-2.5 D,166 whereas A-arylation lowers the dipole moment due to conjugation of the imidazole and aryl rings.167 Further measurements168 (from dielectric data in benzene at 25°C) have shown that in N-arylimidazoles, the phenyl ring is out of the plane of the imidazole 

Osipov, A. M. Simonov, V. I. Minkin, and A. D. Garnovskii, Tr. Soveshch. po Piz. Metodam lssled. Org. Soedin. i Khim. Protsessov, Akad. Nauk Kirg. SSR Inst. Organ. Khim., Frunze, 1962 61 (1964) Chem. Abstr. 62, 3494 (1965). 

The magnitude of the dipole moment for imidazole indicates considerable polarization of the ring, although the extent of polarization is much less than that required to yield an ionic structure. 

Syrkin and E. Shott-L vova, Acta Physicochim. URSS 20, 397 (1945) Chem. Abstr. 40, 5310 (1946). 

Methane is a colorless and odorless gas. It is insoluble in water, but soluble in benzene and gasoline. It is less dense than air and has a boiling point of-l6l,5°C. 

A 10-15% mixture of methane in air may cause an explosion. Explosions in mines are known as firedamp explosions . Also, huge garbage dumps in cities can cause dangerous explosions due to the production of methane. Methane burns with a light blue flame and is decomposed when it is heated strongly. 

The heterocyclic oxygen atom of the phenoxazine nucleus places certain restrictions on the aromaticity of this ring system, which appears to be somewhat less aromatic than the phenazine system, for 

The phenoxazines are crystalline, colorless to yellow solids, the nitrophenoxazines being colored in different shades of red. It is interesting that phenoxazine and its derivatives do not form hydrochlorides. Most phenoxazines have melting points below 200° and are stable, excepting those substituted in the position para to the bridging 

Malrieu and B. Pullmann, Theoret. Chim. Acta 2, 293 (1964) J. P. Malrieu, J. Chim. Phys. 62, 485 (1965) see also B. Pullmann and A. Pullmann, in Les Theories Electroniques de la Chimie Organique p. 446. Masson, Paris, 1952. 

Polarographic,35 chromatographic, and electrophoretic 36 investigations on phenoxazine derivatives have been reported for naturally occurring phenoxazones (actinomycins). 

The ultraviolet spectra of phenoxazine and of several 2-substituted phenoxazines, recorded in Table I, exhibit two bands at 224-247 m/i (log e 4.30-4.73) and 318-328 mfi (log e 3.84-4.01), while the acetyl-substituted phenoxazines present a third absorption band at about 270 m(i (aromatic ketone band). It can be seen from this table that A-alkylation has only a slight influence upon the position and intensity of these bands, and merely produces small bathochromic shifts. 

Amicyanin is a type I copper protein in which two histidines, one cysteine and one methionine provide the four ligands for the redox-active copper. The P. denitrificans protein is composed of 105 amino acid residues. Its primary sequence is known (Van Spanning et al., 1990) and its crystal stmcture has been determined (Durley et al., 1993 Cunane et al., 1996). 

The redox properties of amicyanin are dependent on pH and also are affected by its association with MADH (Gray et al., 1988 Zhu et al., 1998). The pH dependence of the EmValue of amicyanin free in solution correlates with that of a single protonated ligand having a pK of 7.5. The crystal stmctures of oxidized amicyanin at pH 4.8 and reduced amicyanin at pH 4.4 show that the Hiscopper ligand is doubly protonated in the reduced 

Molybdenum disulphide is a dark blue-grey or black solid which feels slippery, or greasy, to the touch. Because of its ready transfer to almost any solid surface, and the difficulty in removing it, it is a dirty material to handle. It exists in two crystal forms, hexagonal and rhombohedral, and the crystal structure is discussed in detail later. By far the most common form is the hexagonal, and the following data refer to this form. 

The easy transfer to surfaces is probably the reason for the early names plumbago and molybdaena , meaning lead-like, since lead also produces dark marks on paper and fabric. Lead rods were used in ancient times for marking out parchments, and this has led to the expressions lead pencil and black-lead which have been common until the twentieth century. Both terms now commonly refer to graphite, which resembles molybdenum disulphide in many ways, but the latter was almost certainly used in the same way until the late eighteenth century. The two materials can be easily distinguished by the lower density of graphite. 

Molybdenum disulphide can be cleaved like mica, and thin sheets several centimetres square can be separated from a large crystal. These thin plates resemble lead foil in appearance, but are less malleable. 

Some of the most important physical properties are listed in Table 4.1. 

The crystal structure of natural molybdenite has been shown to be hexagonal, with six-fold symmetry, two molecules per unit cell, and a laminar, or layer-lattice 

Of the three modifications ofTi02, rutile is the thermodynamically most stable one. Nevertheless, the lattice energies of the other phases are similar and hence are stable over long periods. Above 700 °C, the monotropic conversion of anatase to rutile takes place rapidly. Brookite is difficult to produce, and therefore has no value in the Ti02 pigment industry. 

Industrial Inorganic Pigments. Edited by G. Buxbaum and G. Pfaff Copyright 2005 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-30363-4 

Year Sulfate process Chloride process Total 10001 a-1 

Phase CAS r istry no. Crystal system Lattice constants, nm a b c Density, g/cm  

Titanium dioxide is a light-sensitive semiconductor, and absorbs electromagnetic radiation in the near-UV region. The energy difference between the valence and the conductivity bands in the solid state is 3.05 eV for rutile and 3.29 eV for anatase, corresponding to an absorption band at 415 nm for rutile and 385 nm for anatase. 

FIGURE 8-1 Electrical Resistivities of the Main Group Elements. Dashed lines indicate estimated values. (Data from J. Emsley, The Elements, Oxford University Press, New York, 1989.) 

Elements along a rough diagonal from boron to polonium are intermediate in behavior, in some cases having both metallic and nonmetallic allotropes (elemental forms) these elements are designated as metalloids or semimetals. As described in Chapter 7, some elements, such as silicon and germanium, are capable of having their conductivity finely tuned by the addition of small amounts of impurities and are consequently of enormous importance in the manufacture of semiconductors in the computer industry. 

Some of the columns of main group elements have long been designated by common names (e.g., the halogens) names for others have been suggested, and some have been used more frequently in recent years  

Hydrogen, although usually classified with Group 1 (lA), is quite dissimilar Irom the alkali metals in its electronegativity, as well as in many other properties, both chemical and physical. Hydrogen s chemistry is distinctive from all the groups, so this element will be discussed separately in this chapter. 

FIGURE 8-2 Electronegativities of the Main Group Elements. (Data from J. B. Mann, T. L. Meek, and L. C. Allen, J. Am. Chem. Soc., 2000, 122,2780.) 

Water is transported across cell membranes in one of two ways  

by the action of membrane-spanning transport proteins known as aquaporins. 

Water is an excellent solvent for both ionic compounds (e.g., NaCl) and low-molecular-weight nonionic polar 

Methyl alcohol is colorless, flammable and has a characteristic odor. Its taste is similar to ethanol but it is highly toxic. Ingestion of even small quantities of methyl alcohol can cause blindness, large quantities cause death. Methyl alcohol poisoning may also occur by inhalation of the vapors or by prolonged exposure to the skin. Since methyl alcohol can be deadly, pyridin, which has a bad odor, or dyes are added to it to prevent its use as a drink. As methyl alcohol has a low freezing point (-97 °C), it has been used as antifreeze in radiators. 

To distinguish between ethanol and methyl alcohol the borax test is used. When boric acid reacts with methanol, a pale green flame is observed. 

However, its boiling point (64.7 °C) is lower than that of water, and so usage of methyl alcohol has decreased in this area. Methyl alcohol can be dissolved in all proportions in water and organic solvents and can also dissolve fats and resins. Methyl alcohol can be converted into formaldehyde and this is the raw material for industrial products such as plastics, paints and solvents. 

Methyl alcohol is the most active and the most acidic member of the monohy-dric alcohols. 

In some countries, methyl alcohol is used as fuel. Compared with gasoline, methyl alcohol causes more wear to the engine, this is a disadvantage of methyl alcohol. 

Crystallization of D-fructose is usually effected at ice-box temperature from an ethanol solution, and further purification and recrystallization is performed at room temperature. The spherulitic aggregates of fine needles obtained by this technique are those of the hemihydrate, as shown by Young and coworkers. This possibility had been put forward by Honig and. lesser, but sufficient proof was lacking at that time. The anomalous x-ray diffraction data reported by Wolfrom and Thompson for their preparation of i fructose, in comparison with those of the normal form of D-fructose, may be explained by hemihydrate formation. Indeed, purification with ethanol at 25° results in dehydration, with formation of the 

Gel formation was observed during the phase-diagram studies of Yoimg and coworkers this occurred between —20° (62.5% of D-fructose) and -f 10° (78% of D-fructose). Another translucent gel formed dining crystallization from a cold solution in absolute methanol containing some calcium chloride.  

Changes in Optical Rotation of D-Fructose Caused by Different Solvents 

The observation that mutarotation of monosaccharides is retarded significantly by such solvents as l r,i f-dimethylformamide and methyl sulfoxide induced Kuhn and coworkers to investigate the pyranose-furanose interconversion more closely. Indeed, the rrii mechanism (normal a-/3 interconversion) is completely suppressed in these solvents, and the Isbell conversion (the rri2 mechanism) can be followed according to the equation  

The initial specific rotation in iV,iV-dimethylformamide was —129.5°, and the final value (at equilibrium) of —22.4° was only attained after 24 hours. According to methylation studies in the same solvent, 80% of this equilibrium mixture is in the furanose form. In methyl sulfoxide, changed from —140° to a value of —21.2° after 180 hours. A more fimdamental. 

Hydrated manganese in acidic aqueous solution exists in two oxidation states, Mn11 and Mnm, with a potential of +1.51 volts separating them (339). Therefore, Mn 1 in solution is a strong oxidant. This 

Mononuclear metal-ligand complexes with the Mnn-Mnv oxidation states are all known provided suitable chelating ligands are provided, and polynuclear complexes with MnII-MnIV are known as well. Consequently, to understand the spectroscopy of polynuclear complexes, it is necessary to begin by examination of the electronic properties of 

UV-vis spectroscopy proved particularly enlightening with respect to the catalase system (23, 30, 132). The spectra of model complexes bridged by carboxylate and oxo bridges were quite similar to those observed for the catalase. This led researchers to the proposal that such a motif might also be present, a hypothesis that has been borne out by the crystal structure of the catalase (125). 

Mononuclear Mn11 and Mn complexes exhibit characteristic EPR spectra that are, for the most part, insensitive to the ligand environment around the metal. However, the EPR spectra of polynuclear complexes are strongly dependent on the metal ligation environment, the nature of bridging ligands, and the degree to which the metal 

Several factors unique to polynuclear systems make the interpretation of their spectra more complicated than for the binuclear cases. One such factor is that a given manganese ion may couple to two or more other ions with different exchange magnitudes, Ji and J2. The interpretation of such spectra is often simplified by assuming that J2 

In addition to the examples given in this chapter, important applications of non-aqueous solvents include the separation of uranium and plutonium in nuclear technology (see Box 

and the analytical separation of many metals. Supercritical CO2 is a non-aqueous solvent for which applications are rapidly increasing in number, and we discuss this solvent and other supercritical fluids in Section 8.13. 

Liquid ammonia has been widely studied, and in this section we discuss its properties and the types of reactions that occur in it, making comparisons between liquid ammonia and water. 

Selected properties of NH3 are listed in Table 8.4 and are compared with those of water it has a liquid range of 

Coefficients of linear combination, charge density, bond order, free valency, N-H valency vibration, and atom localization energy were calculated for 1 (RL-R6 = H) by the use of the simple Hilckel LCAO-MO pattern. The data suggest that there is a strong localization of -electrons of nitrogen and of double bonds in the seven-membered ring.189 Dewar and Trinajstic carried out calculations of ground states of 1 (R1-R6 = H), 2, and 3 (R -R6 = H) by a semiempirical SCF-MO method. The results 

The conformation of the seven-membered ring of 7 (R1, R2 = H, Me) has been suggested to be in the chair form.66 

The pK (5.50) of 1 (R -R6 = H) in water at 18.6° was determined and compared with those of other amines on the basis of the different extent of conjugation of nitrogen with the aromatic ring due to steric effects.191 

X-Ray diffraction study and molecular parameters for 162 (R1 = R2 = H) have been described.166 

It has been claimed that IR spectra are useful in distinguishing 

Optical rotations have been recorded for most preparations of sugar sulfates but may be of little diagnostic value, since the values for isomeric sugar sulfates are often rather close to one another. In some cases, the values recorded in the literature are too numerous to mention individually, and some arbitrary choice of values for inclusion in Table IV has been necessary. 

For the paper chromatography of sugar sulfates, many of the solvent systems used for sugars have been tried, with varied success. Systems containing pyridine generally cause streaking of sulfates and are of little use. Neutral and acidic solvents will often give separations, but the R / values 

Solvent Systems Used for Paper Chromatography of Sugar Sulfates 

Solvent System and Proportions by Volume Separations Achieved References 

Ethyl acetate. acetic acid water isomeric monosulfates and 24, 30, 42 

Electron paramagnetic resonance spectroscopy is one of the primary tools in studying the electronic structure of polynuclear complexes (341). Whereas magnetic susceptibility studies are capable of detecting electronic interactions as small as a wavenumber (discussed earlier), the EPR spectrum of a polynuclear complex may be sensitive to intramolecular exchange couplings as small as 0.001 cm even at room temperature. Additionally, the °Mn nucleus has a nuclear spin 

The distinction between light and dark micas became almost synonymous with potassium micas and ferro-magnesium micas . 

Subsequently, another distinction was made for the biaxial micas, once it was clarified (see below) that they belong to the monoclinic system with the plane of symmetry normal to the cleavage lamina as started by Rensch in 1869. The plane of the optic axes could be normal or parallel to the plane of symmetry observed in crystals having the lateral pinacoid 010 well developed. These micas were called, respectively, type I and type II. Actually, this different behavior had been observed by Silliman in as early 1850. He wrote of a short and long diagonal of the basal face. 

Tschermak (1878) first observed that in the species of the first type (corresponding to the so-called light or white micas), the dispersion of the angle was p V, whereas for the second type (dark or black micas) the dispersion was p v, except for zinnwaldite. 

By contrast the measurements on muscovite revealed its clear biaxial nature, with values of 2E variable from 55° to76° but with a maximal incidence around 70°. There was also a similar large variation of 2V, although this is practically impossible to assess on account of the lack of data concerning the refraction indices but estimated to be 

As for other physical properties, mica appeared as term 3 on a 12-term scale of hardness proposed by Breithaupt (1836). This scale was not very different from the preceding one of Mohs. Indeed, there were only two differences, namely mica between gypsum and calcite and sodalite between apatite and adularia. 

Three determinations of the melting point of technetium metal are in reasonably good agreement 2140 20 °C [13, 2200 50 °C [14], and 2162 40°C (15). The average melting point of 2167 °C is near those of neighboring elements in the same period —molybdenum (2610 °C) and ruthenium (2310 °C) —but almost 1000 °C lower than that of rhenium [14]. Ilic boiling point of technetium metal was estimated as 4900 K [16] no experimental value seems to be available. 

For an ingot of arc-melted technetium metal, weighing approximately 70 g, the immersion density was found to be 11.47 g/cm [7]. An electron-beam melted sample showed a density of 11.492 g/cm [17], The X-ray density, calculated with the lattice parameters a=2.7407 A, c=4.3980 A [18] and the nuclide mass of 98.906 g, yields 

481 g/cm-, which is just a little higher than that of lead. 

The electrical resistivity of arc-melted technetium metal was determined from its superconducting transition temperature of 7.5 K to 1700 K. Above 77 K the resistivity can be described by p (in pQ-cm)= -3.191 -i-7,844-10 T - 2.816-10 T -t- 4.038-10 T-. From the electrical resistivity data a Debye temperature for technetium was calculated to be 411 K [7]. 

Some physical property data of technetium metal are summarized in Table 9.2. A. 

There was better agreement with calculations made on the basis of Klyne s rules, except for ,a-trehalose octaacetate. It was assumed that both parts of the trehalose molecule are identical. Moreover, the calculated values agreed more closely with the less positive values reported for a,/3-trehalose octaacetate (see Tables VII and VIII). 

Derivative Metting point, °C. C ]d, degrees/ Rotation solvent References 

Esterification of the trehaloses proceeds readily. The trehaloses form many crystalline esters (and ethers). Crystallization is facihtated by the absence of a free reducing group and the consequent absence of anomeric forms of the products. Derivatives are listed in Tables XII and XIII. A 

It has been discovered that rare-earth catalysts are highly specific for the dephosphorylation of sugar phosphates with a phosphatase. At 37°, for instance, a, a-trehalose 6-phosphate is completely unhydrolyzed by phosphatase in the absence of rare-earth catalysts, even after 144 hours. However, in the presence of cerium nitrate, over 20% hydrolysis occurs in this period of time. 

The tetrahedral structure of methane has been verified by electron diffraction (Fig. 2.1c), which shows beyond question the arrangement of atoms in such siihple molecules. Later on, we shall examine some of the evidence that led chemists to accept this tetrahedral structure long before quantum mechanics or electron diffraction was known. 

We shall ordinarily write methane with a dash to represent each pair of electrons shared by carbon and hydrogen (I). To focus our attention on individual electrons, we may sometimes indicate a pair of electrons by a pair of dots (II). Finally, when we wish to consider the actual shape of the molecule, we shall use a simple three-dimensional picture (III). 

As we discussed in the previous chapter (Sec. 1.18), the unit of such a non-ionic compound, whether solid, liquid, or gas, is the molecule. Because the methane molecule is highly symmetrical, the polarities of the individual carbon-hydrogen bonds cancel out as a result, the molecule itself is non-polar. 

Attraction between such non-polar molecules is limited to van der Waals forces for such small molecules, these attractive forces must be tiny compared with the enormous forces between, say, sodium and chloride ions. It is not surprising, then, that these attractive forces are easily overcome by thermal energy, so that melting and boiling occur at very low temperatures m.p -183 , b.p. — lcl.5 . (Compare these values with the corresponding ones for sodium chloride m.p. 80r. b.p. 1413 .) As a consequence, methane is a gas at ordinary temperatures. 

Methane is colorless and, when liquefied, is less dense than water (sp.gr. 0.4). In agreement with the rule of thumb that lil e dissolves like, it is only slightly soluble in water, but very soluble in organic liquids such as gasoline, ether, and alcohol. In its physical properties methane sets the pattern for the other members of the alkane family. 

Knowledge of the saturation concentrations of the organic condensable species remains incomplete. These concentrations are expected to vary significantly with temperature. The few available relevant measurements include the saturation vapor concentrations of mono-carboxylic and dicarboxylic acids (Tao and McMurry, 1989) and the )3-pinene aerosol products (Pandis et al., 1991). Saturation vapor concentrations of condensable products from the oxidation of some aromatic hydrocarbons (toluene, m-xylene, and 1,3,5-trimethylbenzene) were estimated to lie in the range of 3 to 30 ppt (Seinfeld et al., 1987). 

TABLE 13.13 Vapor Pressures of Selected Secondary Organic Aerosol Compounds 

Compound Saturation Mixing Ratio (Ppb) Temperature (K) Reference 

Magnesium hydroxide decomposes at much lower temperatures its vapour pressure reaches 1 atmosphere at about 190 °C. 

Reaction with chlorine. Dry hydrated limes readily react with chlorine forming bleaching powder — see section 31.3. Milks of lime also react with chlorine to produce bleach (a solution of calcium hypochlorite — equation 19.3). 

Phenanthridine, m.p. 106°-107°, crystallizes readily from petroleum and aqueous ethanol. The long-known mercuric chloride complex (B, HCl, HgClo) provides a convenient means of purification. 

An early value for the dipole moment (1.5 D) differs markedly from that obtained more recently (2.93 The higher figure is more 

The geometry of the phenanthridine molecule has not been determined accurately, but there seems no reason to doubt that the parent system is planar. The simplest derivative for which data are available is bis(6-phenanthridinyl)methane (193a l93b). The red tautomer is planar and isomorphous with tetrabenz[a,c,, y,]anthracene, consistent with the hydrogen-bonded structure(193b) the crystals are monoclinic, space group P2 jc °- with a = 9.52, 6 = 1.54, c = 6.66 

Early calculations by Longuet-Higgins and Coulson have been followed by a number of attempts to employ more refined theoretical treatments to predict bond parameters and 77-electron densities and to calculate reactivity indices which accord 

Soil bulk density. The mass of dry soil per unit bulk volume, including any air-filled spaces. The bulk volume is determined before drying to a constant weight. 

Bulk density values range from 0.5 g cm in organic soils to 1.8 g cm in mineral soils. Bulk density values are needed to calculate the total storage of a given nutrient per unit area in a given depth of soil. 

Soil particle density. The density of the soil particle, which is the dry mass of the particles expressed on volume of soil solids (not the bulk volume of the particles). 

Soil porosity. Refers to the volume fractions of pores in soil. Total porosity does not reflect the pore size distribution. 

Pure quartz occurs as transparent, hexagonal crystals, and at 20°C has a specific gravity of 2.65. 

Under the microscope, in thin sections of fired siliceous material tridymite usually appears as wedge-shaped crystals occasionally it has been found in volcanic lava. In tridymite the atoms are packed less densely than in quartz, and therefore the 

Cristobalite, like tridymite, is rarely found in Nature, but under the microscope in thin sections of certain ceramics it is frequently observed as a mass of small crystals. In cristobalite the packing of the atoms is also less dense than in quartz, the specific gravity of cristobalite at 20°C being 2.33. 

At the inversion temperatures there is clearly a marked increase in the rate of expansion for each mineral, particularly for the a-p quartz change at 573°C and for the a p cristobalite change at 220°-260 C. These sudden expansions are the cause of spalling in silica refractories. 

Since the linear expansion of silica at lOOO C is about twice that of clay, the expansion of a pottery body is often purposely increased by the addition of flint, which on being fired transforms to cristobalite. Of all the forms of silica referred to, vitreous silica expands the least (0.05% linear between 20° and 1000°C) and on this account it withstands sudden changes of temperature without shattering. Vitreous silica is therefore useful for making laboratory ware such as crucibles and tubes. 

1 Key design elements influorous/organic liquid biphasic reactions 

The (CH2)m spacers provide tuning elements that can be adjusted to insulate the active site from the electron-withdrawing perfluoroalkyl or Rf segments (higher m values) or enhance Lewis acidity (lower m values). These electronic effects have 

Ponytails with integral (permanent) fluorinated domains 

Protecting groups/tags with removable (temporary) fluorinated domains 

In contrast, light fluorous molecules may be distributed between both phases, and fluorous chromatography is the standard method of separating these molecules. 

TABLE 8.1 Top 20 Industrial Chemicals Produced in the United States, 2010  

Sources Data from Chem. Eng. News, July 4, 2011, pp. 55-63 U. S. D artment of the Interior, U.S. Geological Survey, Mineral Commodity Summaries 2011. 

FIGURE 8.1 Electrical Resistivities of the Main Group Elements. Dashed lines indicate estimated values. 

The highest purity extent of commercial-grade sodium is 99.8%, this value corresponding to the purity of sodium that passed through the cold or hot traps [3.1, 3.2]. However, sodium of 99.995% purity can be obtained using distillation. 

Sodium has one stable isotope, namely Na. Characteristics of other isotopes of sodium are presented in Table 3.1. The main isotopes result from the following reactions  

It is just Na isotope that determines the main contribution to the radioactivity of the coolant flowing in the circuit. 

The main thermophysical properties of sodium, lead, bismuth and lead-bismuth eutectic alloy (44.5% Pb-55.5% Bi) are presented in the Table 3.4. [3.3] 

Other thermophysical properties of these materials vs temperature are given in Tables 3.5-3.7 [3.3 3.4]. 

Pure aSiC is colorless while the cubic p modification is yellow. The only other elements that can be included in the SiC crystal lattice in amounts Ip.p.m. are N, Al, and B. Nitrogen gives a green color to 3C and 6H, and a yellow color to 4H and 15R. The presence of the trivalent elements boron and aluminum gives all the modifications and polytypes a blue-black color [176]. 

For a ceramic material, silicon carbide has an unusually high thermal conductivity 150 WmK- at 20°C and 54 WraK at 1400°C [180], The high thermal conductivity and low thermal expansion (4.7 x 10 K for 20-1400°C) explain why the material has such good resistance to thermal shock. 

The specific heat capacity of SiC is 0.67Jg K at room temperature, and 1.27Jg K at 1000°C. The standard enthalpy of formation A//298K 

Silicon carbide is noted for its extreme hardness [182-184], its high abrasive power, high modulus of elasticity (450 GPa), high temperature resistance up to above 1500°C, as well as high resistance to abrasion. The industrial importance of silicon carbide is mainly due to its extreme hardness of 9.5-9.75 on the Mohs scale. Only diamond, cubic boron nitride, and boron carbide are harder. The Knoop microhardness number HK-0.1, that is the hardness measured with a load of 0.1 kp (w0.98N), is 2600 (2000 for aAl203, 3000 for B4C, 4700 for cubic BN, and 7000-8000 for diamond). Silicon carbide is very brittle, and can therefore be crushed comparatively easily in spite of its great hardness. Table 8 summarizes some typical physical properties of the SiC ceramics. 

Since the microstructural grain size (Fig. 12a-h), pore content, and chemical composition of the various ceramic products differ considerably, it follows that the properties are also different. 

Ab initio calculations (multireference Cl) gave the adiabatic ionization potential E =18.0 eV [14]. 

Ab initio calculations on PHJ (X A ) gave the following values for the internuclear distance re, bond angle ae (HPH) or angle pe (angle between the P-H bond and the plane perpendicular to the C3 axis passing through the P atom) and inversion barrier B (PTCI second-order perturbation Cl, CAS complete active space)  

From the vibrational structure in the photoelectron spectrum of the PH3 frequencies of the symmetric out-of-plane (inversion) vibration of the ion, V2=450 [16], 500 20 [17, 18], and 530 80 cm [5], were obtained. The so-called frequency halving (compared to V2 900 cm for PH3) can be explained by a double minimum potential with a low inversion barrier which allows the left and right vibrational energy levels to interact and to split into equally spaced doublets see e.g. [18]. Ab initio calculated harmonic vibrational frequencies were reported [7]. 

The bond dissociation energies D(PHJ-H)=337.6 [19] and 308.8 kJ/mol [20] were obtained from electron impact studies on PH3. The proton detachment energy, D(PH2-H+) = 709 kJ/mol, was reported [21]. 

Selected-ion flow tube (SIFT) [21,25] and ion cyclotron resonance (ICR) [25, 26] investigations showed that no measurable reaction occurs at 80 K with H2 and CO2 [25] and at room temperature with H2 [21, 26], O2, H2O, CO2, CO [19], and CH4 [19, 21]. SIFT experiments yielded rate constants k29e (in cm -molecule s ) for the protonation of the following compounds by reaction with PHJ (for CH3C=CH an additional minor channel to PCHJ was found) [21]  

Bromide trifluoride -Dinitrogen tetraoxide -Fluorosulfonic acid -Hydrogen fluoride -Sulfuric acid -Sulfur dioxide -Ammonia -Water - 

Apparently all organopolysilanes are stable to spontaneous decomposition, and the majority of them melt without decomposition. In the cyclosilane series, octaphenylcyclotetrasilane 14), octa-/ -tolylcyclotetra-silane 14), decaphenylcyclopentasilane 14, 58), and dodecaphenylcyclo-hexasilane 14,58,101) all decompose to some extent at their melting points. Although dodecamethylcyclohexasilane 14) appears to be stable toward decomposition, it is reported 102) to undergo an irreversible change in crystalline form when heated to temperatures greater than 74° C. 

Hexamethyl-2//-2-phenyltrisilane has been observed to decompose slowly in air and to inflame when heated in the presence of air 21). 

Little infrared work has been reported concerning the higher polysilanes. A study of the infrared spectra of a,co-dihaloperphenylated polysilanes, Cl[(C6Hs)2Si] Cl, in the 400-800 cm region has been carried out (95), and a dependence of the band frequencies on chain length is indicated. 

A study of the infrared spectra of octaphenylcyclotetrasilane, decaphenyl-cyclopentasilane, dodecaphenylcyclohexasilane, and l,5-di- -butyldeca-phenylpentasilane has been carried out (58). While the spectra of the three cyclosilanes are almost identical in the 5000-700 cm range, significant differences are evident in the 700-200 cm region. The infrared and Raman spectra of octamethyltrisilane (107), decamethyltetrasilane (107), dodecamethylpentasilane (107), and dodecamethylcyclohexasilane (107), and a number of methylated polysilanyl cyanides (108) have been determined. 

3 The terms primary, secondary, etc., designate the degree of silyl substitution of a specific silicon atom, analogous to the use of these terms in carbon chemistry. 

Pioneering work in the field of luminescence by lanthanidomesogens in the liquid-crystal state has been done by Btinzli and coworkers. In a seminal paper, they monitored the luminescence intensity and the excited state 

FIGURE 62 Luminescence spectra of [Eu(tta)3l.2] (gray curve) and [Eu(bta)3 L2 ] (black curve) as a thin film in the mesophase at 25 °C. The excitation wavelength was 370 nm. All transitions start from the Dq level and end at the different J levels of the F term (J=0-4 in this spectrum). 

FIGURE 63 Luminescence decay time of the Dq level of the [Eu(tta)3L2]complex as a function of the temperature. The luminescence was monitored at 613 nm ( Dq— p2 line) and the excitation wavelength was 370 nm. The measurements were made during cooling of the sample. The transition SmA l (clearing point) can be observed as a jump in the curve at about 60 °C. Adapted from Yang et al. (2006). 

FIGURE 64 Polarization effects in the room-temperature luminescence spectra of an aligned supercooled thin film of the europium(lll) complex of the type shown in Fig. 44. The polarizer is either parallel (gray fine) or perpendicular (black line) to the alignment layers in the liquid-crystal cell Adapted from Galyametdinov et al. (2008). 

FIGURE 65 Structures of the nematic liquid-crystal host matrices MBBA and 5CB, and structure of the europium(lll) complex [Eu(tta)3(phen)]. 

Ge(CH3)4 is a colorless liquid at room temperature and has a sweetish odor somewhat resembling that of chloroform [1]. Experimental values of the density in the 0 to 25 C range [20, 28, 39, 48] are represented graphically in Fig. 1. The data can be expressed by the equations 

The cohesion energy of liquid Ge(CH3)4, Ec = AH —RT = RT(2.303 BT/(C + t) —1), has been calculated [48], using the vapor pressure data from [39] for evaluating the constants B and C of the Antoine equation. Selected values of Ec and the solubility parameter 6 = (Ec/V ) (Vrn = molar volume obtained from line dg in Fig. 1) are [48]  

Vapor pressures over a values are given below wide range of temperatures are listed in [1,28,36] selected 

Serious discrepancies are apparent for measurements between 20 and 40°C [24, 39]. Calculated vapor pressures based on equation (3) below are given with values from [48] (in parentheses)  

The following equations for p = f(T) have been derived from the vapor pressure measurements (range in parentheses)  

Thermal and Calorific Properties For a ceramic material, SiC has an unusually high 

20-1400 °C) explain why the material has such good resistance to thermal shock. 

Recrystallized SiC is much stronger than ceramically bonded material, but its high residual porosity imposes limits as far as mechanical strength is concerned [458]. 

The molecular weight of the purified poly(ADP-ribose) synthetase from rat liver has been reported to be 50,000-60,000 (159) and from pig thymus 63,500 (220, 221). All other reports place the molecular weight in the range of 108,000-130,000 (43, 59, 60, 93,100,105,117, 125, 148, 158, 233) regardless of the source of enzyme (Table III). 

The physical properties of the calf thymus enzyme are perhaps the best characterized this synthetase is reported to have a sedimentation coefficient of 5.8 S, an f f of 1.39, and a partial specific volume of 0.735 ml/g. Data for other synthetases are similar (105, 158). The calf thymus enzyme is believed to have an a-helical content of 30% (100) (refer to Table III). 

The isoelectric point (pi) of the calf thymus synthetase has been reported variously as 9.8 (100, 125) or 6.5 (125,148). The amino acid compositions of synthetases from Ehrlich ascites cells, pig, and calf thymus (Table IV) indicate that the protein is lysine-rich. The N-terminus of enzyme from all three sources is blocked (219). 

Effect of fiber treatments Alkali treatment on OPFs significantly improved its interfacial shear strength in polyester matrix [14]. Alkali treatment washed out the outer skin, better exposing fiber to the polyester matrix, leading to proper interaction between their surfaces. In addition, the fine holes created on alkali treatment allowed the polyester to penetrate into the fiber bundles in a better way. Acetylation treatment to the fibers improved impact strength of OPF-polyester composites due to improved fiber wettability and resulting fewer void spaces [71]. The tensile stress of OPF-polyester composites increased slightly upon both acetylation and silane treatments on fibers and decreased upon titanate treatment [14]. The flexural modulus of OPF-PP composites also increased considerably upon acetylation treatment on fibers. Similarly the abrasion resistance of OPF-polyester composites was enhanced upon alkali treatment to fibers [13]. Treated fibers enhanced the adhesion resistance of polyester resin by 75-85%, while untreated fibers enhanced the abrasion resistance only by 50-60%. 

Diborane is colorless in all its phases. There are at least two solid modifications, a low-teifiperature 

Useful tabulations of thermodynamic data have been published (165, 262), but the most comprehensive for the liquid and saturated vapor, as well as for the 

The solubility of hydrogen in liquid diborane has been measured (153), and that of diborane in a number of solvents has been extensively investigated. Of particular importance because of the practical significance of the system involved are the studies with the polyether diglyme as solvent (127, 332), but solubility measurements have also been conducted in simple hydrocarbons (213, 258), ditertiary-butyl sulfide (332), furfural (66), nitrobenzene (66), and tetraethoxysi-lane (66), among other substances. 

It is again emphasized that an optimal pore-size and volume distribution are critical for hydroprocessing of the high-metal-content feeds, particularly those 

The hydrogen activation and transfer by carbon-supported catalysts may involve both the support and catalytically active metals. These contributions can be decoupled by testing carbons alone in comparison with the corresponding carbon-supported catalyst under identical conditions. The involvement of various carbons during hydroprocessing reactions could not be evident without their ability to adsorb, activate and transfer active hydrogen to reactant molecules. 

Little experimental data is available on the role of surface properties of carbons during hydrogen activation, although one would expect that the involvement of CB will differ from that of AC. It is believed that for CB, the external surface will play an important role because of the nanosize particles. 

Carbons and Carbon-Supported Catalysts in Hydroprocessing By Edward Furimsky Edward Furimsky, 2008 

Thermochemistry of the hydrogen activation on carbons requires that the sum of bond energy (BE) of two C-H bonds in the reactions below is at least equal to or greater than the bond energy of H-H bond (436 kJ/mol), i.e. it must fulfill the following conditions 2 BEc h BEh h- This requirement is fulfilled even for one of the weakest C-H bond, i.e. 337kJ/mol.  

Palladium is well suited for the study of magnetic behavior. Bulk palladium is often described by a two-band model with an almost filled d-band and a partially filled s-band (d V). Whereas the s-band is considered to contain almost free electrons, the d-holes move in a narrow band. Palladium has a temperature dependent spin susceptibility and the free spin susceptibility, Xo is sensitive to 

The similarities between both images are evident. A chlorine atom is positioned in the center of the images (see also color plates). 

If carbon monoxide is chemisorbed on the surface of small jdatinum particles, the Pt NMR spectra indicate that the local density of states, D (r), decreases in an exponential manner ftom the bulk towards the surface. [61] The so-called Knight shift, K, as measured by NMR, consists of a K for the s-electrons and a K for the d-electrons. K is proportional to the local susceptibility, /p(r), on the nucleus. This local d-susceptitnlity is porportional to the local density of states, D r). In our model, atoms at different distances from the surface have different D r) and hence different Knight shifts. In the magnetic experiments described here, the susceptibilities of a macroscopic sample have been determined. This, of course, gives less detailed information than an NMR experiment, and so the NMR model must be somewhat amfriified. 

One can assume that at the surface of the cluster partides, the local density of states is reduced by a relative amount A compared to the bulk  

Due to the low number of data points, the values for A and X which give a best fit to X 3te charged with large uncertainty. The relation between the susceptibility and the density of states is given by 

The crystal structure of graphite and amorphous carbon is illustrated by the schematic representations given in Fig. 1. 

The lattice plane images of carbonaceous materials, which were obtained by high- 

A terminology to identify carbons that are graphitizable or those that are none graphitizable by heat treatment has been adopted. Hard carbons are those carbons that are nongraphitizable and are mechani- 

A variety of amorphous carbons such as carbon black, active carbon, and glassy carbon is available. With the exception of glassy carbon, these amorphous carbons generally have high surface area, high porosity, and small particle size. Carbon blacks, for example, are available with surface areas that are 1000 g , particle 

Both covalent carbides have high melting points which are slightly lower than the titanium compounds but higher than silicon and boron. Under most conditions, the thermal decomposition of SiC may occur well below its intrinsic melting poind l and decomposition can become significant at approximately 1700°C (see Sec. 3.7 and Fig. 7.8 of Ch. 7). The density of SiC is closer to that of diamond than it is to graphite, which can be expected since SiC has the structure of diamond. 

Boron carbide does not appear to decompose up to its melting point. It vaporizes by the preferential loss of gaseous boron. 

Liquids are very hard to compress because their molecules are very close together. Gases are much less dense than liquids and solids. A gas occupies all parts of any vessel in which it is confined. Gases are capable of indefinite expansion and are highly compressible. We conclude that gases consist primarily of empty space, meaning that the individual particles are quite far apart. 

To distinguish among samples of different kinds of matter, we determine and compare their properties. We recognize different kinds of matter by their properties. We can broadly classify these into chemical properties and physical properties. 

Unless otheiwise noted, all content on this page is Cengage Learning. 

Properties of matter can be further classified according to whether they depend on the amount of substance present. The volume and the mass of a sample depend on (and are directly proportional to) the amount of matter in that sample. Such properties, which depend on the amount of material examined, are called extensive properties. By contrast, the color and the melting point of a substance are the same for a small sample as for a large one. Properties such as these are independent of the amount of material examined they are called intensive properties. All chemical properties are intensive properties. 

Copyriglt 2013 Cengi eL amii All Riglts Reserved. not be copied, scanned, or duplicated, in whole or n part Due to elecinnic riglts, some fliird pai content maiy be suppressed from the ook andfor eChapter(s). 

O3F2 was investigated spectroscopically in order to elucidate its molecular structure, but no definite conclusion could be drawn about the molecular entity, as shown in the following short summary. 

For critical remarks, see [4]. Cryogenic mass spectrometry of O3F2 led to the assumption that O3F2 consists of loosely bound O2F and OF radicals [5], see [4]. Studies of the ESR spectrum that is identical with that of O2F2 and caused by O2F radicals also did not lead to a reasonable model of the O3F2 molecule [6, 7]. 

The molar extinction coefficient between 350 and 750 nm is claimed to have been measured with a solution of O3F2 in a CCIF3-CCI2F2 mixture at 77 K [18], see also a comparison with the data of other oxygen fluorides [19]. 

The structure of Th(N03)4, which is a white solid, is unknown. The melting point is reported to be ca. 55°C [3]. The enthalpy of solution of anhydrous thorium tetranitrate at a dilution of Th N03)4-2500H20 is reported to be -34.7 kcal/mol [5]. After making allowance for the effect of hydrolysis on the enthalpy of formation of Th in such a solution the recommended enthalpy of formation of crystalline Th(N03)4, AHf 298(Th(N03)4,c), is -345.5 3.0 kcal/mol [6. 7]. 

The infrared spectrum recorded by Ferraro, Walker [8] for anhydrous thorium tetranitrate is compared in Table 19 with those reported at the same time for the tetra- and penta-hydrate (see also [3] for information on Th(N03)4). The ultraviolet spectrum of a diethyl ether solution of the anhydrous tetranitrate (illustrated in [1]) is quite different from those of the hydrates. 

The chemical properties of thorium tetranitrate have not been extensively investigated. 

Addition of dimethylsulfoxide to a solution produced by electrochemical oxidation of thorium in nitric acid-tributylphosphate yields Th(N03)4-6dmso whilst addition of 2,2 -bipyri-dine or 1,10-phenanthroUne in ethanol yields, respectively, [(bpyH)3N03][Th(N03)6] and [(phenH)3N03][Th(N03)e]. The hexanitrato complex [N(C2H5)4]2[Th(N03)6] is obtained by addition of a solution of tetraethylammonium nitrate in ethanol [3]. 

Templeton [1 ] studied the Th(N03)4-H20 system over the temperature range 20 to 160°C and reported the formation of Th(N03)4-5.5H20 below 122°C and Th(N03)4 4H20 above this temperature. 

GSH is a colorless crystalline compound melting at 195°C. without decomposition. Specific rotation [a]J = —21.0 deg. (7), —18.5 deg. (5), — 16.0 deg. (12), —17.4 deg. (14). The disulfide has [a] —108 deg. in aqueous solution. The pK values have been measured by Pirie and Pin-hey (4) the isoelectric point p7 = 2.83. The SH-compound is relatively easily soluble in water, liquid NH3, and dimethylformamide, and rather soluble in alcohol-water mixtures. For the ultraviolet spectrum see Calvin s paper in this volume. So far no exact values of the redox potential have been obtained 

As for a, no comment seems necessary. There results from the second property, b, that evolution of 1 mole CO2 and NH3 takes place on treatment with ninhydrin. The divalent Cu ion forms a blue water-soluble complex. 

As for c, the peptide natiue of GSH is proved by a positive biuret reaction. In paper electrophoresis the substance migrates to the anode about half as fast as the somewhat isoelectrically similar aspartic acid, thus showing a higher molecular weight. Acid hydrolysis yields the three building stones in the normal fashion. In neutral or alkaline solution reactions occur resulting from the reasons given under d and e. 

Hydrogen fluoride attacks silica glass (eq. 9.36) thereby corroding glass reaction vessels, and it is only relatively recently that HF has found applications as a non-aqueous solvent It can be handled in polytetrafluoroethene (PTFE) containers, or, if absolutely free of water, in Cu or Monel metal (a nickel alloy) equipment. 

Polycarbonate was developed by the chemist Hermann Schnell in 1953 for Bayer AG. It is a basic polymer for a whole class of polymers with a widespread field of application. Polycarbonate is a mainly amorphous thermoplastic polymer with a very high optical transparency in the visible spectrum. Its crystalline portion is mostly less than 5%. Polycarbonates are resistant against weather and radiation, they are flammable but self-extinguishing if the ignition source is removed. They can be colored and are good electrical insulators. 

Polycarbonates can be processed with common plastic manufacturing processes. Technologies like injection molding, extrusion and casting bear good shaping opportunities. In comparison to transparent polymers like PMMA or PET, polycarbonates show extraordinary transparency, strength and endurance. 

The electronic and H n.m.r. spectra of monothiobiuret and dithiobiuret have been determined, and the results of quantum-mechanical calculations were used in a discussion of the electronic structures, p.e. and electronic spectra, and conformational stability. The structures of some (trimethylsilyl)thioureas were determined 

Mullen, G. Heger, and W. Treutmann, Z. Kristallogr., Kristallgeom., Kristallphvs., Kristall-chem., 1979, 148, 95 (Ghent. Abstr., 1979, 90, 178 467). 

X-Kay diffraction analysis of the 1 1 complex of thiourea with bis-[2-(o-methoxyphenoxy)ethoxyethyl] ether showed that the hydrogen atoms of the amino-groups are hydrogen-bonded to all the oxygen atoms, showing bifurcated hydrogen bonds.  

Reactions.—Oxidation. Thioureas and alkyl derivatives are oxidized very rapidly by ICl in the presence of NaHCOj [reaction (1)]. Titration of the liberated iodine 

6-Tetraazido-l,4-benzoquinone forms dark blue crystals with metallic luster [165] or nice brownish yellow prismatic crystals with a blue-black gloss [164]. It is soluble in acetone, slightly soluble in ethanol, and insoluble in water. The main 

TeAzQ yields white 2,3,5,6-tetraazido-l,4-hydroquinone oti reduction, but this is unstable and reoxidizes back to blue quinone while standing in air [165]. It decomposes under the action of sulfuric acid or sodium hydroxide liberating nitrogen [164]. 

The impact sensitivity of 2,3,5,6-tetraazido-l,4-benzoquinone is high significantly higher than for LA. Values published in scientific papers are summarized in Table 4.21. 

6-Tetraazido-l,4-benzoquinone can be easily prepared by the action over several hours of sodium azide on 2,3,5,6-tetrachloro-l,4-benzoquinone p-chloranil) in an ethanol suspension [165] or by the action of aqueous sodium azide on a methylene chloride solution of p-chloranil [166]. 

6-Tetraazido-l,4-benzoquinone has never been used due to its low thermal stability. 

Crude oil, as it comes from the oil well, is a black, odorous, syrupy liquid mixture. Gasoline, a mixture of organic compounds derived from crude oil, is a yellowish, odorous, volatile, and highly flammable liquid mixture. It should not be too surprising to realize that many organic compounds are liquids at ordinary temperatures and pressures, that many have an odor, that 

FIGURE 14.6 Ball-and-stick models of ethene (a, c) and propene (b) Flexible springs are used to show a double bond. From the angle in (c) we can see that the geometry is planar around carbons where there is a double bond attached. Notice that the third carbon on propene (b) has the tetrahedral geometry, since it has only single bonds attached. 

FIGURE 14.7 Ball-and-stick model of ethyne. Notice the linear geometry (right) around the carbons. This is characteristic of carbons that have a triple bond attached. 

Strained bone develops electrical potential differences. These used to be attributed to piezoelectric effects. However, the size of the piezoelectric effects is small compared with those produced by streaming potentials [10]. Furthermore, there were various anomalies with the potentials 

Along with solubility in solvents, the pigment should also be checked for water-soluble content. Water-soluble components are restricted to a few parts per million. Pigments prepared by precipitation or 

Tolerance to an individual solvent is tested by enclosing a certain amount of pigment powder in a piece of filter paper, which is then immersed in the organic solvent for a given amount of time. The extent of coloration of the test solvent indicates the solvent fastness of the pigment. 

The water-soluble matter can be determined by extraction of a known amount of pigment sample with water followed by filtration and evaporation of the filtrate to dryness in order to gravimetrically determine water-soluble. 

E/CO is produced commercially by the high-pressure copolymerization of ethylene and carbon monoxide using techniques similar to those used to make high-pressure, low-density polyethylene homopolymer (LDPE). The monomers undergo random copolymerization under well-controlled temperatures and pressures in either tubular or stirred autoclave reactors  

Wide ranges of average molecular weight and of CO incorporation can be achieved by varying the reaction conditions and monomer concentrations. Typical E/CO resins for extrusion contain 0.5-4.0 weight per cent CO and are 0.5 to 1.5 g/10 minutes in melt index. Densities from 0.928 to 0.936 g ml can result for a CO range of 0.5 to 1.6 weight per cent. 

Additives typically used to modify the properties of extruded and moulded LDPE products can be used to advantage with E/CO. Due to its polar nature, E/CO appears to have greater affinity for certain additives, such as fatty acid amide slip promoters. In some cases, slightly higher concentrations of additives may be needed to achieve the desired surface properties, especially in the higher CO copolymers. 

Typical plaque and film data, shown in Tables 8.1 and 8.2 for an E/CO and a corresponding LDPE homopolymer, demonstrate the similarities between the two resins. In appearance, as film or extruded items, they are also seemingly identical. 

E/CO density increases with increases in CO content. It has been noted that at around 16 per cent CO, E/CO will not float in fresh water, and at about 20 

ASTM D 1488-86 Test Method for Amylaceous Matter in Adhesives. 

ASTM D 1489-87 Test Method for Non-volatile Content of Aqueous Adhesives. 

ASTM D 1579-86 Test Method for Filler Content of Phenol, Resorcinol, and Melamine Adhesives. 

There are compounds containing two long chain lateral substituents that are ne- 

Whereas compounds with large flexible lateral substituents, assuming that the lateral chains are oriented nearly parallel to the basic molecule, may be considered as variants of the classical rod-like molecules, compounds with lateral ring-containing substituents lead to completely new concepts of mesogens. 

The first examples of mesogens with lateral aromatic substituents were synthesized already in Vorlander s group [18, 186]. 

Mauerhoff prepared the nematic compound 6 [186]. This field of liquid crystal chemistry, which was for a long time forgotten, has been re-activated by Cox et al. [188], Gallardo and Muller [189] and Weissflog et al. [190-192]. 

In the series represented by compound 7 [188] which have monotropic nematic properties, the lateral phenyl group is attached without a spacer. It is not easy to understand, why compounds with very bulky substituents are mesogenic. Hoffmann et al. [193] investigated compound 8 in the solid state by X-ray analysis. As was already 

CO—CH— NH... CO—CH—NH—CO—CHj-CHs CH—NH. a-Peptide chain (peptide links stable to acid) 1. CO—CHj-CHa-CH—NH—. 7-Peptide chain (peptide links easily hydro lyzed by acid) 

HOiC—CH—NH,. . CO—CH—NH, + HO2C—CHrCHrCH—NHj.. . HO2C—GHj-CH CH—NHj a-Peptide of n-glutamic acid D-Glutamic acid 

subtilis is homogeneous by electrophoresis measurements and has a mobility of 19.5 X 10 cm.yv.-sec. in phosphate buffer, 0.1 at pH 8.1 (335,336). The infrared spectrum of the silver salt of DGP of B. anthrads is very close to that of the synthetic a-polyglutamic peptide (252,252a). 

Fraenkel-Conrat et al. (200) prepared the polyamide of the peptide by treating the methyl ester of DGP with liquid ammonia and FeClj as catalyst. This treatment converts about 80% of the ester groups into amide groups. The action of o-chlorophenylisocyanate (199), of diverse agents of sulfatation (493), and phosphorylation (194) on DGP were also studied. 

According to Watson et al. (618) the chemical properties, absorption spectrum, and electrophoretic behavior of the inflammatory factor isolated from anthrax lesions, and the DGP isolated from B. anthrads 

The structure of chlorosulfonic acid 1 was proved by Dharmatti who showed by magnetic susceptibility measurements that the chlorine atom was directly 

GdSe is of the cubic NaCl type, space group Fm3m-0 (No. 225), with a = 5.758 A Z = 4. The calculated density is 8.2 g/cm . Each Se is surrounded by six Gd at the vertices of a regular octahedron. The Se-Gd distance of 2.879 A is somewhat less than the sum of the Ionic radii due to some covalent bonding character. The Gd atoms are also surrounded by six Se atoms with no contact between the Gd atoms, Vickery, Muir [6, 7]. The following lattice constants were 

Holtzberg et al. [3]. A later plot of a vs. composition in [10], in contrast to Fig. 131, shows a maximum at the stoichiometric composition. 

As noted above, varies with the conformational distributions of the polygermane. Thus in solution polydihexylgermane has a X ax of 327 nm while the 

Branched oligogermanes with alkyl or aryl substituents have formd applications in micro-patterning as a result of their UV light sensitivity  

Amorphous polygermynes (GeR) (16) formed by Wurtz coupling of organ-otrichlorogermanes are hght brown and display weak photoluminescence at 560 run.  

Cotton is a relatively stiff fiber however, wetting of the fiber with water plasticizes the cellulose structure, and the cotton becomes more pi iable and soft. The resi liency of dry and wet cotton is poor, and many 

Cotton is one of the more dense fibers and has a specific gravity of 

The hydroxyl groups of cotton possess great affinity for water, and the moisture regain of cotton is 7%-9% under standard conditions. At 100% relative humidity, cotton has 25%-30 moisture absorbency. 

The heat conductivity of cotton is high, and cotton fabrics feel cool to the touch. Cotton has excellent heat characteristics, and its physical properties are unchanged by heating at 120°C for moderate periods. The electrical resistivity of cotton is low at moderate relative humidities, and the fiber has low static electricity buildup characteristics. 

Cotton is not dissolved by common organic solvents. Cotton is swollen slightly by water because of its hydrophilic nature, but it is soluble only in solvents capable of breaking down the associative forces within the crystalline areas of cotton. Aqueous cupianunonium hydroxide and cupri-ethylenediamine are such solvents. 

1 Melting Point. Boiling Point. Density. Refractive index. Molar Refraction. 

Tetramethyllead is a colorless liquid (mobile at room temperature) having a relatively high vapor pressure. It volatilizes in air about as fast as benzene and is very volatile with ether vapor [6]. Its smell is sweetish and resembles that of raspberries [3,6]. Careful and cautious handling of the pure compound is necessary. 

Pb(CH3)4 can be distilled at normal pressure without decomposition in the presence of air [3] or advisably in an inert atmosphere [1, 2]. It decomposes explosively when overheated [11, 19, 20]. When distilling Pb(CH3)4, the bath temperature should be kept below 150 to 160°C [19]. Explosive decompositions have been reported during distillation [19] and shortly before the end of a distillation over sodium [23]. 

The boiling point was estimated to be 110°C [3, 4, pressure (probably 760 Torr). Boiling points (b.p. in corrected values from [16, 29] are collected below  

The zero point density was calculated to be 2.514 g/cm [13]. An equation to calculate the liquid and the vapor density based on a variant of the lattice theory of liquids was derived. Values of the vapor density dg (in mg/cm ) are given below [38]  

Handbook of Battery Materials, Second Edition. Edited by Claus Daniel and Jurgen O. Besenhard. 

Lead-acid Bipolar current collector, electrode additive 

Redox flow Positive electrode, negative electrode substrate, electrocatalyst support, current collector, bipolar separator 

Hydrogen/NiOOH Electrode additive, electrocatalyst support 

Zinc/carbon (Leclanche cell) Electrode additive, current collector 

Nucleoprotamine dissolves in aqueous solution of NaCl (1—2 M) or ammonium sulfate to give a viscous solution. In such solutions it largely dissociates into DNA and protamine, but upon dilution (e.g., to 0.14 M NaCl) they combine to form white fibrous precipitates [Watanabe and Suzuki, 1951 (3)]. 

The dissociation into DNA and protamine can be demonstrated by the fact that protamines can be dialyzed from such solutions [Akinrimisi et aL, 1965 Watanabe and Suzuki, 1951 (1, 2)] and that DNA alone can be precipitated by addition of alcohol (Hammarsten, 1924). Although the binding of protamine to DNA decreases sharply over the NaCl concentration range 0.3 to 0.7 M, the fact that protamine has an affinity for DNA even in 1.0 M NaCl indicates that interactions other than the main electrostatic one contribute to such binding. Protamine binds more strongly to native DNA than to denatured DNA. The affinity of protamine for native DNA is greater than that of histone and polylysine, as shown in Table X-1 (Akinrimisi et al. 1965). 

The isoelectric point of most protamines is about twelve (Miyake, 1927). The values of specific rotation ([ ]d) fot clupeine and salmine are — 83.07° or — 84.0°, 

The purification procedure of choice is vacuum distillation. Additionally, the melting point of 10.5°C allows a very efficient low temperature recrystallization from solvents like methanol, ethanol or mixtures thereof.  

El-Mass spectrum of EDOT (minor peaks deleted). 

The mechanical strength increases with increased Fe(II) content [86]. 

The heat capacity of an unreduced (Fe,Ca)-oxide sample displays a second order phase transition at 718 K [87]. 

The electrical conductivity of the unreduced catalyst has been studied [88]. 

The onset temperature is 188°C and the enthalpy ranges from 129 to 138 J/g for the two samples. The broader peak and lower temperature at the start of heat absorption for the 

Abbreviations 7g and Cg, the glass transition temperature and concentration (in %w/w) of the maximally freezeconcentrated soiution 7g and 7m, the glass transition (usually a mid-point determination) and melting temperatures of the dry materiai n, number of water molecules in the unit cell ACp, the change in heat capacity at the glass transition  

These vaiues have been taken from references cited throughout this article and are illustrative only. Some values are subject to debate, notably 7g and Cg, whilst others (7g) have a tendency to increase in value in more recent references as the remaining water is more effectively removed. There can be an alarming variation in values. For instance, values for the extrapoiated 7g for anhydrous starch have been reported from 150 to 330°C. 

An HPLC method was used to estimate the surviving sugar. 

The members of this class are typically mobile liquids except for methyl chloride and vinyl chloride, which are gases at normal temperatures and hexachloroethane, which is a solid. 

Some relevant physical properties are shown in Table 2. In any series formed by successive chlorination of a hydrocarbon molecule, the properties normally vary directly with the amount of chlorine present in the compound. The percentage of chlorine by weight in most of the compounds listed is higher than that in typical PCB and chlorinated insecticides by contrast, they are very much more volatile, and more soluble in water. 

The most widely used method of detection and quantification of halocarbons is Gas Chromatography, normally with an electron capture detector [12,40]. In some cases, air or water samples can be injected directly into the instrument where initial levels are low, a concentration step consisting either of adsorption onto active carbon, or solvent extraction, may be necessary. In the case of very volatile compounds like vinyl chloride or methyl chloride, special techniques are needed to prevent loss from the sample, and to obtain good resolution. 

Trivial name Formula Molecular weight % Chlorine % Bromine No.Cl atoms M.P. °C 

Where analysis of sediments, foods or biological tissues is required, it is necessary to carry out a solvent extraction, followed by clean-up of the extract to remove non halogenated fatty material. Great care in operation, and the use of highly purified solvents, are needed, as many of the compounds under discussion are widely used in and around laboratories, or in the construction and maintenance of apparatus and equipment. 

The Sun and the solar system is located at a distance of about 30 000 Ly from the center of the galaxy. The density of the interstellar medium in the solar neighborhood is about 0.25 particles per cm. Approximately 99% of the interstellar medium is composed of interstellar gas, and of its mass, about 75% is in the form of hydrogen (either molecular or atomic), with the remaining 25% as helium. The interstellar gas consists partly of neutral atoms and molecules, as well as charged particles, such as ions and electrons. 

Hanslmeier, Water in the Universe, Astrophysics and Space Science Library 368, DOI 10.1007/978-90-481-9984-6 7, Springer Science+Business Media B.V. 2011 

Such regions are also called H-I regions. The temperature is below 100 K. 

Generally, the interstellar medium is very dilute, even in clouds densities range from a few hundred up to about 10 particles cm . In total the interstellar medium contributes about 15% percent to the visible mass of a typical galaxy. 

The cold clouds of neutral or molecular hydrogen are important for the formation of new stars. They can become gravitationally unstable as soon as their density is above some critical value, the so called Jeans mass. Then a coUapse of the cloud and subsequent fragmentation starts and new stars are bom in a cluster. 

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Compilation of physical properties for 321 heavy hydrocarbons. Vapor pressures at low pressures. ... 

Compilation of azeotropic data as well as other physical properties including melting and boiling points. 

By assuming a reasonable fluid velocity, together with fluid physical properties, standard heat transfer correlations can be used. 

Although isotopes have similar chemical properties, their slight difference in mass causes slight differences in physical properties. Use of this is made in isotopic separation pro cesses using techniques such as fractional distillation, exchange reactions, diffusion, electrolysis and electromagnetic methods. 

Isoparaffins have boiling points lower than normal paraffins witTilHe same number of carbon atoms. Table 1.1 presents some physical properties of selected paraffins... 

Table 1.4 gives the physical properties of selected olefins. 

Normally absent or in trace amounts in crude oil, products of conversion processes such as diolefins, acetylenes, etc., are encountered. Table 1.4 gives the physical properties of some of them. Noteworthy is 1-3 butadienerC ( l)... 

Characterization of Crude Oils According to Dominant Characteristics Based on Overall Physical Properties... 

Experience has shown that certain carefully selected physical properties could be correlated with the dominant composition of a petroleum cut or crude oil. 

The analyst now has available the complete details of the chemical composition of a gasoline all components are identified and quantified. From these analyses, the sample s physical properties can be calculated by using linear or non-linear models density, vapor pressure, calorific value, octane numbers, carbon and hydrogen content. 

Knowledge of physical properties of fluids is essential to the process engineer because it enables him to specify, size or verify the operation of equipment in a production unit. The objective of this chapter is to present a collection of methods used in the calculation of physical properties of mixtures encountered in the petroleum industry, different kinds of hydrocarbon components, and some pure compounds. 

Chapter 4. METHODS FOR THE CaLCULA WN OF HYDROCARBON PHYSICAL PROPERTIES... 

Characteristics are the experimental data necessary for calculating the physical properties of pure components and their mixtures. We shall distinguish several categories ... 

These are necessary for precise determination of certain physical properties they include following items ... 

In the absence of a single accurate theory representing the physical reality of liquids and gases and, consequently, all their physical properties, a property can be calculated in various ways. 

The values obtained for the acentric factor differ significantly from one another. As shown in Figure 4.3, this factor depends on the temperature, the physical property being considered, and the method used. 

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