Properties, chemical and physical

At atmospheric pressure and room temperature, nitrogen is a colourless, odourless and non-flammable gas. At 0 °C and 1.013 bar, 1 L of nitrogen weighs 1.2505 g. N2 condenses at -195.8 °C to a colourless liquid with a density of 0.812 kg that gets solid at -209.86 °C in the form of white crystals. The solubility of N2 in water amounts to 23.2 mL per kilogram of water at 0 °C and 1 bar, at 25 °C it is only 13.8 mL kg . Consequently, N2 is less soluble in water than O2. 

The inversion temperature of Nj is 850 K. Inversion temperature is the temperature below which a gas cools down by adiabatic expansion (Joule-Thomson-Effect). Therefore, Nj can be liquefied from room temperature by means ofcounter ooling of previously expanded cold gas, in contrast to Hj und He. 

The nitrogen atom in compounds is often threefold coordinated and has a tetragonal structure with the free electron pair in one comer of the tetrahedron. Nitrogen occurs in varied forms in organic molecules, e.g. in amines (R-NH2), amides (R-C(=0)-NH2), nitriles (R-C=N), oximes (R2C=N-OH) and nitrogen-heterocycles (e.g. pyridine) [2.3]. 

Because of the sensitivity and selectivity of the ESR approach, it is a powerful method for studying free radicals in low concentrations in complex systems. ESR can be helpful in two ways to characterize and structurally identify radical intermediates and to obtain information on the kinetics and mechanisms of their reactions. These reactions can be very fast one of the main differences between ESR of biological free radicals and ESR of spin labels and metal ions is that in the former case one generally is dealing with transient paramagnetic species. 

Although in principle all free radical species are detectable by ESR spectroscopy, in practice detection may be difficult or impossible under a given set of experimental conditions. Problems with detection of a particular species will reflect m netic and/or kinetic factors. For example, oxygen-centered species such as OH, Oj, and RO [75] and sulfur-centered species such as thiyl radicals (RS ) [76] cannot be detected directly in fluid solution because of extreme anisotropy in their magnetic parameters which makes their ESR signal amplitudes vanishingly small. To detect radicals such as these, it is necessary to immobilize them in frozen solutions or to resort to indirect methods of detection (see below). The same applies to radicals that have a short lifetime. 

As noted, the transient nature of most free radical species is a major consideration in ESR studies of free radicals. Free radical chemistry [77] involves an initiation step in which the free radicals are formed, often followed by one or more propagation (chain) reactions before termination. Because most radical-radical termination reactions are fast, the majority of free radicals decay rapidly by self reaction, i.e., they are transient even in the absence of another species. (In non-transient, i.e., persistent, radicals the radical center is sterically hindered, thereby inhibiting self-reaction.) A comment on terminology may be appropriate at this point many transient radicals are frequently described as stable or unreactive, which can lead to some confusion. The source of this confusion is that reactivity and stability are often used to denote 

Although a radical must be reactive in order to damage other components of a system, there is not necessarily a simple correlation between reactivity and the ability to cause irreversible damage to a complex structure. For example, the activity of certain enzymes is found to be inhibited more effectively by radicals of relatively low reactivity than by the reactive hydroxyl radical. This is because reactive radicals are not very selective in their reactions, having a tendency to react at many different sites in a molecule. Less reactive radicals are more selective and can be more effective at damaging a specific site. If this site happens to be essential for activity, then the less reactive radical will be more damaging. 

The ways of getting around this problem involve increasing the lifetime of the radicals by some physical or chemical means. One such approach involves stabilizing the radicals by immobilization, for example, by freeze-quenching a reaction mixture [80]. The disadvantage of this method is that an immobilized radical is generally much harder to characterize and identify than one in fluid solution. Other approaches make use of the chemical reactivity of radicals, for example, their ability to add to the double bonds in nitrones and nitroso compounds. This has led to the development of the spin-trapping procedure [81,82], in which a transient radical is reacted with the 

Physical and Chemical Properties.—It has been shown that charge-transfer complexes of 1,2-dithiolium cations with TCNQ have conductivities comparable with, but smaller than, those of analogous 1,3-dithiolium salts. 

9-dithiaphenalenyl radical (128) is a stable, monomeric, coplanar species its e.s.r. spectrum and other spectroscopic properties have been described.  

It has been pointed out that n.m.r. spectroscopy indicates clearly that 

3-dithiolium cations, e.g. (129), are carbenium ions that are stabilized by heteroatoms, and are not delocalized systems that involve the double bond. The same is probably true of 1,3-dioxolium and 1,3-diselenolium ions and analogous mixed systems. 

The cularine group is the largest representative class and presently consists of 14 alkaloids. Alkaloids of this group, with three oxygenated substitutents at 

Other differences among this class of alkaloids resides in the type of substituent (hydroxy, methoxy, or methylenedioxy) and in the presence or absence of a methyl group at the nitrogen. They show an absorption maximum at about 283 nm in the UV spectrum, in common with many isoquinoline alkaloids. For those cularines with a phenolic group, under basic conditions, this band shifts to 294 nm. 

Alkaloid name Molecular formula (mol. wt.) Melting point °C (solvent) (Ref.) Optical rotation, ° (cone, solvent) (Ref.) Additional data (Ref.) 

The UV spectrum of the monophenolic base (+)-norcularicine (1) exhibits a bathochromic shift in alkaline solution (9). The presence of a methylenedioxy group (5.98 ppm) and two aromatic protons as singlets (6.63 and 6.68 ppm) in the H-NMR spectrum readily establishes the 3, 4 -substituJion pattern of the D ring, leaving position 7 for the hydroxy function. The MS peak at m/e 147 (32a) confirms the substitution of ring A. Eschweiler-Clarke methylation of 1 gives (+)-cularicine (6). Synthesis of ( )-norcularicine has been achieved as an intermediate step in the total synthesis of 6 (26). 

There are two types of mustard agents, sulfur mustards and nitrogen mustards the general structural formula of these compounds is as follows  

Agent HD [bis(2-chloroethyl)sulfide sulfur mustard CAS no. 505-60-2] is a colorless, odorless, oily liquid with a molecular weight of 159.08 and a water solubility of 0.092 g per 100 g at 22 °C (DA 1974 MacNaughton and Brewer 1994) (see Table 4). Agent HD is also referred to as distilled mustard, with laboratory samples having a purity range of 95%-100% (DA 1974). Its chemical structure is 

Commercial production of sulfur mustard results in the formation of a mixture containing about 70% bis(2-chloroethyl)sulfide and about 30% high molecular weight polysulfides. This mixture, referred to as agent H or Levinstein mustard, varies considerably in chemical composition and is not evaluated in this review. 

Agent HT is a product of a reaction that yields about 60% agent HD [bis(2-chloroethyl)sulfide] and less than 40% agent T [bis-[2-(2-chloroethylthio)-ethyl] ether], plus a variety of sulfur contaminants and impurities. The composition of this mixture may change with time as the result of degradation reactions. The chemical structures of the two major components are 

Agent T [bis-(2-(2-chloroethylthio)-ethyl) ether CAS no. 63918-89-8], a component of agent HT, is added to lower the freezing point and increase the stability. Agent T is practically insoluble in water. The molecular formula is 

Some physical and chemical properties of the lead oxides are compiled in Table 2. 

The specific resistance of the oxides depends on pressure (cf. 5], Table 2.3). 

In alkaline soils, the major components of the soil solution are Ni and Ni(OH)+ in acidic soils, the main solution species are Ni +, NiS04, and NiHP04. Atmospheric nickel exists mostly in the form of fine respirable particles less than 2 im in diameter, usually suspended onto particulate matter. 

Nickel carbonyl (Ni(CO)4) is a volatile, colorless liquid readily formed when nickel reacts with carbon monoxide it boils at 43°C and decomposes at more than 50°C this compound is unstable in air and is usually not measurable after 30 min. The intact molecule is absorbed by the lung and is insoluble in water but soluble in most organic solvents. 

Analytical methods for detection of nickel in biological materials and water include various spectrometric, photometric, chromatographic, polarographic, and voltammetric procedures. Detection limits for the most sensitive procedures - depending on sample pretreatment, and extraction and enrichment procedures - were 0.7-1.0 ng/L in liquids, 0.01-0.2 ttg/m in air. 

During occupational exposure, respiratory absorption of soluble and insoluble nickel compounds is the major route of entry, with 

Nickel retention in the body of mammals is low. The half-time residence of soluble forms of nickel is several days, with little evidence for tissue accumulation except in the lung. Radionickel-63 ( Ni) injected into rats and rabbits cleared rapidly most (75%) of the injected dose was excreted within 24-72 h. Nickel clears at different rates from various tissues. In mammals, clearance was fastest from serum, followed by kidney, muscle, stomach, and uterus relatively slow clearance was evident in skin, brain, and especially lung. The half-time persistence in human lung for insoluble forms of nickel is 330 days. 

FIGURE 3.23. 0 Si ratio as a function of water content (at a current density of 13mA/cm ) and current density (at a water content of 1.5% H2O). After Duffek et at.  

FIGURE 3.24. Relation between phosphorus incorporation and moiar ratio DEP N02 in the solution. Solution temperature 25°C current density 6mA/cm=. After Schmidt et (Reproduced by permission of The Electrochemical Society, Inc.) 

Anodic films can be densified by annealing in inert gases at high temperatures. A reduction of 10 to 30% in oxide thickness has been found to result from anneal- 

The hydride SiH groups in as-formed anodic oxide films can be reduced 

The properties of anodic oxide films depend on the mode of polarization particularly at the initial stage of anodization. For example, the number of hydroxyls in as-grown oxide formed in KNOa-containing tetrahydrofurfuryl at a constant current density of lOmAfcm is about 8 x This is reduced to 2.2 x lO /cm by 

Physical State at 15° C and 1 atm — The statement indicates whether the chemical is a solid, liquid, or gas after it has reached equilibrium with its surroundings at ordinary conditions of temperature and pressure. 

Boiling Point at 1 atm — The value is the temperature of a liquid when its vapor pressure is 1 atm. For example, when water is heated to 100 °C (212 °F) its vapor pressure rises to 1 atm and 

Fire and Explosion Hazards Handbook of Industrial Chemicals 

Freezing Point — The freezing point is the temperature at which a liquid changes to a solid. For example, liquid water changes to solid ice at 0°C (32°F). Some liquids solidify very slowly even when cooled below their freezing point. When liquids are not pure (for example, salt water) then-freezing points are lowered slightly. 

Specific Gravity — The specific gravity of a chemical is the ratio of the weight of the solid or liquid to the weight of an equal volume of water at 4°C (or at some other specified temperature). If the specific gravity is less than 1.0 (or less than 1.03 in seawater) the chemical will float if higher, it will sink. 

Lead azide forms white or yellowish crystals. It is known to form four allotropic modificatimis a, p, y, and 8 (older literature refers only to the first two of them). The orthorhombic a-form with crystal density reported from 4.68 to 4.716 g cm [12-14] is the main product of precipitation, with traces of other forms present, and is the only form acceptable for technical applications [15]. A variety of crystal 

Structure modifiers was tested for modification of the crystal form of precipitated LA. The most commonly noted ones include dextrin, carboxymethyl cellulose, and PVA. The presence of dextrin promotes formation of the ot-form [16] while the presence of organic dyes (eosin, erythrosin, or neutral red) at precipitation time enhances the formation of the p-form [15]. The crystals of p lead azide are formed in the shape of long needles (Fig. 4.1). 

The dry monoclinic p-form has a crystal density reported from 4.87 to 4.93 g cm [12, 13] and is stable. In older literature, the p-form is referred to as extremely sensitive to mechanical stimuli with the formation of long needles that may explode simply by the breaking of a single crystal [11]. Crystals 1 mm in length were reported liable to explode spontaneously because of the internal stresses within them [17]. This extreme sensitivity of the p-form was, however, later disproved and shown to be a common myth (more in part on sensitivity of LA). 

The other two allotropic forms can be obtained from pure reagents by maintaining the pH in the range 3.5-7.0 for monoclinic y and 3.5-5.5 for triclinic 5. They usually precipitate from the solution simultaneously [8]. The y-form is also created in presence of polyvinyl alcohol [18]. A method of exclusive preparation of a particular polymorph (y, ) was not known to Fair who recommended hand selection under the microscope as the only possible way, since the crystals differ in shape and size [15]. y-LA may be prepared reproducibly by using PVA (degree of polymerization does not play a role) which is free from unhydrolyzed polyvinyl acetate [19]. 

The a-form is the most stable of all four versions. For example, the enthalpy of formation of the y-form is higher by 1.25 kJ mol than the a-form [3]. Thermal decomposition of both the a-form and p-form has been studied and various results were reported. At temperatures around 160 °C, the p-form transforms irreversibly to the a-form [20]. 

The initial application of quantum mechanics to the electronic states of a perfect linear conjugated chain, as in the Htickel model discussed in Section 4.2.5 and above, led to a model of a one-dimensional semiconductor with well-defined valence and conduction bands. This labelling of the electronic states is widespread in the literature. On the other hand, when electron correlation is included, the electronic states are more localised and an exciton description is more appropriate. The disorder present in all but a few exceptional cases inevitably leads to the conclusion that the electronic states must be localised by chain defects. The extent to which the electronic states of conjugated polymers are localised, i.e. deviate from the band model, has been a matter of debate. There is a growing body of experimental and theoretical evidence, discussed in Sections 9.4.2 and 9.4.3 below, that suggests that the exciton description is closer to the truth. 

While most conjugated polymers display partial crystallinity, see Section 1.2.7, examples are known of extended-chain single crystals and amorphous isotropic solids. The extent of regions in the polymer backbone with uninterrupted overlap of the 7i-electron wavefunctions will obviously be much greater in an extended chain than in one that is randomly folded. Since physical properties, 

In view of the diversity in the morphology of conjugated polymers, it is essential that physical measurements be made on samples that are not only chemically pure but where the morphology has been established by thorough characterisation. 

D-Mannitol hexanitrate crystallizes from ethyl alcohol in the form of needles melting at 112-113°C. Its specific gravity is 1.604. It is immiscible with water, dissolves readily in ether and hot ethanol and with difficulty in cold ethyl alcohol. With aromatic mononitro compounds, e.g. nitrobenzene, p-nitrotoluene, p-nitroanisole, a-nitronaphthalene, mannitol hexanitrate forms addition compounds melting in a non-homogeneous way, as shown by T. Urbanski [5, 6, 7, 17]. 

The thermal analysis of these systems can be represented by a general curve — Fig. 69, v- 

Nitromannitol and nitrobenzene system melting points (T. UrbaAski [17]). 

Heated in a test tube, nitromannitol explodes at a temperature of 160-170°C. There is a divergence of opinion concerning its chemical stability. The stability of a very carefully purified, repeatedly crystallized sample is high, resembling that of nitroglycerine (Guastalla and Racciu [18]). However, a product crystallized only once or twice withstands heating at 75°C for only a few hours, after which brown fumes start to develop. 

According to a report of Tikhanovich [19] nitromannitol in contact with an ethereal solution of ammonia undergoes a partial denitration to form D-mannitol penta-nitrate (m.p. 8l-82°C) together with derivatives of an ether-alcohol mannitane C6H8(OH)4, namely mannitane tetranitrate C6Hg0(0N02)4 (an oily liquid) and crystalline mannitane tetramine C6HgO(NH2)4. 

Ordinary eutectics are formed by nitromannitol with higher nitrated aromatic compounds (Table 27). 

The solubility of gases in liquids varies within wide limits. It decreases rapidly with rising temperature, reaching zero when the liquid reaches its boiling point. Very high gas solubilities may be due to the influence of chemical processes. Examples are aqueous solutions of ammonia or carbon dioxide. 

The solubility of gases in liquids generally follows Henry s law, which states that, at equilibrium, the partial pressure of a gas lying above a solution is proportional to the concentration of the gas in the solution (see Table 3-5)  

The proportionality constant for a given gas and a given solvent, is dependent solely on the temperature. In general, Henry s law applies only to highly diluted solutions and is therefore not applicable to systems such as ammonia-water, carbon dioxide-water, and acetylene-acetone. 

If concentration is expressed in cubic meters of gas (0 C, 101.3 kPa) (32 F, 1 atm) per cubic meter of solvent, and the partial pressure is measured in atmospheres, the proportionality constant is termed the bunsen coefficient. The relationship between 

Under high pressure, many gases, including the noble gases, form aqueous solutions, in relatively fixed concentrations, that can take on solid form. Such solutions are called cla-thrates. Example argon clathrate 7.99 Ar46H20. 

The properties of canola oil are governed by components present in the oil and described by the general parameters for vegetable fats and oils. Selected physical properties for canola oil in comparison to HEAR oil are shown in Table 4.13. 

Cadmium is a transition metal in group IIB of the periodic table of elements. The metal is bluish-white to silver-white. At room temperature, it has a hexagonal close-packed crystal structure. Eight stable isotopes are known to be present in natui . The atomic weight of cadmium is 112.4 and the atomic number 48. The density at 25°C is 8.6 g/cm the melting point 321°C and the boiling point 765°C. The most common oxidation state is +2. The most important compounds are cadmium acetate, cadmium sulfide, cadmium sulfoselenide, cadmium stearate, cadmium oxide, cadmium carbonate, cadmium sulfate, and cadmium chloride. The acetate, chloride, and sulfate are soluble in water, whereas the oxide and sulfide are almost insoluble.  

When cadmium is oxidized by air, a thin greyish-white film is formed that protects the metal from further attack. In air, the powdered metal bums with a red flame. Cadmium is not lffected by alkalis, whereas dilute mineral acids dissolve the metal, with evolution of hydrogen.  

In nature cadmium is found together with zinc and is obtained as a byproduct in extraction processes for zinc and other metals. The cadmium zinc ratio is between 0.01 and 0.001 in most minerals and soils. The average content of cadmium in the earth s cmst has been estimated at 0.1-0.2 ppm. In 1977, the total production in the world was about 18,000 tons.  

Cadmium is used industriadly as a protective coating for iron, steel, and copper by electroplating. Cadmium sulfide and sulfoselenide are used as pigments in plastics, enamels, and paint. It may also serve as an alloy with copper for coating telephone cables, trolley wires, and welding electrodes. The stearate is used as a stabilizer in plastics, and cadmium electrodes are found in alka- 

Human beings are exposed to cadmium in food, water, and air. Of these routes of exposure, food is considered to be the major one. In contaminated areas, cadmium is accumulated in certain kinds of food, especially liver and kidney from animals and shellfish High concentrations may also be found in oysters and crabs. Rice and wheat in exposed areas may contain high levels of cadmium The daily intake of cadmium from food in uncontaminated areas has been estimated at 25-60 xg for a 70 kg person.  

Lithium is a fascinating example of an element, that was originally considered a chemical laboratory curiosity, but finally found to be an ultratrace element which in all probability is essential to humans. Moreover, it became a potent and safe drug, with specific effects mainly in the treatment of manic-depressive illness, and also a valuable versatile industrial material with a well-established broad spectrum of applications and possibilities for further developments. The importance of lithium will increase, for example by the discovery of lithium-dependent enzymes, proteins or hormones, the resolution of its biochemical mechanism in affective disorders, and progress in the battery sector, in the nuclear technology, or with the aluminum electrolysis (Schafer 1995, 2000). 

Physical and Chemical Properties As the first member of Group I of the Periodic Table of elements, lithium has the 

The first step in the development of a new dissolution test is to evaluate the relevant physical and chemical data for the drug substance. Knowledge of the drug compound s physical-chemical properties will facilitate the selection of dissolution medium and determination of medium volume. 

Some of the physicochemical properties of the active pharmaceutical ingredient (API) that influence the dissolution characteristics are  

N-Hydroxyamino acids are colourless, solid, crystalline compounds only stable in the solid state. When heated they melt above 200 °C with decomposition (79). However the melting point is not a good criterion of purity (80). They are usually purified by recrystallization from hot water in which they are less soluble than amino acids. However, recrystallization in this case is accompanied by great losses due to decomposition (80). N-Hydroxyamino acids are slightly soluble in alcohol and sparingly soluble in ether, acetone and other organic solvents (f, 79, 82, 31). They are soluble in both acid and basic aqueous solution and form the corresponding salts (79, 81). Stable solid hydrochlorides are obtained in this way (1, 82). 

A molecule of an a-N-hydroxyamino acid is a dipolar ion (27) (79, 81) as confirmed by the IR spectra which contain characteristic COO and -NHJ -OH group bands. The isoelectric point of these compounds lies within the 6-7 pH range. pKi constants have values between 2.1 and 2.3, while pK2 lies between 5.7 and 5.9 (81). 

In contrast to a-amino acids, N-hydroxyglycine (28) and N-hydroxy-alanine (29) form copper complexes (1 1 and 1 2) at pH as low as 1.5-2.5 (86). In such complexes the cation is coordinated with the carboxylic group with participation of the nitrogen atom of the hydroxyl-amine group, with = 620-630 nm. The structure of N-hydroxy- 

It should be emphasized that the first naturally-occurring compound containing vanadium, with unspecified biological activity was the blue substance amavadine (16) isolated from a mushroom (Amanita muscaria) (75). ESR studies showed that it was a complex of N-hy- 

N-Hydroxyamino acids, just like N-hydroxyamines, are strong reducing agents. At room temperature they reduce solutions of salts of such metals as silver, copper, mercury and lead (1). They also reduce Fehling s reagent (1) and decolorize iodine solutions in neutral or alkaline but not acidic media (36). As the result of the above reactions compounds of type (1) are oxidized to the oximes of a-keto acids (31). Esters of N-hydroxyamino acids (90), like N-alkylhydroxylamines, undergo oxidation to dimers of cw-nitroso compounds with a characteristic absorbance at 264 nm, this being analytically important (91). 

Several books have been published during the years, dealing with detailed explanations about the physical and chemical characterization of petroleum (Speight, 1999, 2001) as well as methods and correlations for prediction of petroleum properties (Riazi, 2004). Therefore, this section will not describe in detail all the properties of heavy crude oils, but only those relevant issues that need to be taken into consideration when processing these heavy materials. First, a general overview of the most common physical and chemical properties is summarized. And later, more details are given on those properties and how to calculate them that are crucial for heavy petroleum. 

Heavy crude oil is a thick, black, gooey fluid, harder to handle and more expensive to refine to produce the most valuable petroleum products. Heavy oil is a type of crude oil that is very viscous, meaning that it does not flow easily. The common characteristic properties of heavy oil are the following  

Because heavy oil is deficient in hydrogen compared with conventional crude oil, either hydrogen must be added to the molecules or carbon removed to render it useful as a feedstock for a conventional refinery. 

Heavy oil was originally conventional oil that migrated from deep reservoirs to the near surface, where it was biologically degraded and weathered by water. Bacteria feeding on the migrated conventional oil removed hydrogen and produced 

Elastomers are another large group of polymers classified by their ability to stretch (within limits) and return to their original shape. Rubber is an example of an elastomer. As described in Historical Evidence 13.1, rubber was one of the first raw materials used in early polymer research. Because of its elasticity, imtreated rubber flows when hot and becomes brittle when cold. It also will pull completely apart with little applied force. All of these properties are undesirable for 

Finally, many polymers tend to be hard and brittle. When these properties are undesirable, plasticizers are added to increase softness and pliability. Most such polymers are phthalates, and with the advent of mass-produced plastics, they have become ubiquitous. New-car smell results from the volatilization of plasticizers from synthetic upholstery and simileir materials when enough of the plasticizer is gone, the material becomes brittle and can crack. Plasticizers have recently been identified for further study as a possible health concern for children, who tend to put soft plastic toys in U eir mouth. 

PBT is a semi-crystalline polymer with a typical degree of crystallinity of about 35-40 % [56]. It has a glass-transition (T ) range of 30-50°C, while the melting temperature TJ is usually between 222 and 232 °C. The general characteristics of PBT lie between polyamides and PET. The lower production costs and the outstanding physical properties, as well as excellent chemical resistance, are the reasons why PBT is considered as the main competitor for polyamides [14,15]. 

The specific gravity of the unfilled, well-crystalline polymer is 1.320 g/cml Quenching of the melt leads to a fully amorphous polymer with the density of 1.256 g/cm Typical recrystallization occurs when PBT heats above its T. The crystalline portion of the polymers can be raised up to 60 % by annealing [57-59]. The faster crystallization of PBT in comparison with that of either polyamides or PET is of great importance, since it leads to low mould temperatures and short cycle times, and therefore, to economical processing. Slow cooling of the melt causes crystallization to large spherulitic forms [17]. 

PBT often displays multiple melting peaks in DSC measurements [60-63]. The DSC scans of PBT are influenced both by the heating and cooling rate, as well as by the thermal history of the sample and require very careful interpretation of the obtained results. This phenomenon of double melting behavior may be due to the formation of crystals of different sizes and distribution as well as because of repeated fusion/recrystallization processes during DSC measurement [63, 64]. 

The crystalline structure of PBT, studied by wide-angle x-ray scattering (WAXS), is characterized by a triclinic elementary cell. Two reversible triclinic modifications are possible an a- and a P-form [65]. The transition between the two modifications occurs reversibly by mechanical deformations from the a-form to the P-form by elongation and inversely by relaxation. The primary modification is the a-form with unit cell parameters a = 4.83 A, b = 94 A, c (fiber axis) = 11.59 A, a = 99.7°, P = 115.2°, and y = 110.8°, while the parameters for the unit cell of the P-form are a = 4.95 A, b = 5.67 A, c (fiber axis) = 12.95 A, a = 101.7°, P = 121.8°, and y = 99.9°. The unit cell is occupied by one repeating unit. As a result of reversible transitions in PBT, oriented fibers and monofilaments have outstanding release and toughness, which are important and useful characteristics for applications such as tooth- and paintbrush bristles and filler fabrics [17]. 

Other remarkable properties of crystalline PBT are high surface hardness and stiffness and a low friction coefficient. The surface of PBT is glossy and abrasion resistant. All these properties are of particular importance in the field of engineering polymers. 

Chloride-Containing Ionic Liquids. The melting points of some typical [AMIMJCl compounds are shown in Table I. Except for dimethylimidazolium chloride, which has a melting point above 120°C, the higher-alkyl [AMIM]C1 ionic liquids melt at temperatures below 100°C. 

Melting Points of Some Typical [AMIMJCl Ionic Liquids 

N-alkylpyridinium-Containing Ionic Liquids. The melting point of N-alkylpyridinium chloride increases from 70 to 80°C when the alkyl chain is lengthened from Ci2 to Cig. The melting point of iV-alkylpyridinium [NiCl4]J changes only from 80 to 86°C as the substituent changes from C12 to Cig 62). 

The compound with the lowest melting point among the N,N-dialkylpyrrolidinium tetrafluoroborate family is [(CH3)(K-C3H7)C4HgN]BF4, which has a melting point of 64°C, as does A -methyl-A -propylpyrrolidinium tetrafluoroborate. The melting point is sufficiently low to enable the application of this compound in syntheses at temperatures above 70°C (64). 

Melting Point of [EMIMJ-Containing Ionic Liquids with Corresponding Anions 

Finally, it should be noted that basicity of the nitrogen at the a-position decreases in the series of annelated pyridines as the angular strain of the fused ring increases [118]. This is in harmony with the interpretation of the MN effect presented in Section 5.1. More work on this topic is highly desirable. 

The free base (anhydrous) has m.p. 38.1° the hemihydrate, m.p. 40°. With 1.5% water, a eutectic mixture, ephedrine-ephedrine hydrate, with m.p. 32.1°, is obtained. The b.p. of anhydrous ephedrine is 225° 

Ephedrine shows [a]n — 6.3° (hemihydrate in alcohol) or [M]n + 18.5° (water). It is soluble in water, alcohol, ether, chloroform, and oils (239). The solution in water is strongly alkaline to litmus paper. The hydrochloride, CioHuON HCl, is in the form of white, prismatic needles of bitter taste, m.p. 220-221° [ ] — 34° (H2O) soluble in 2 parts of water and in 15 parts of alcohol (95°). The hydrobromide has m.p. 205°. The hydrobromide and the hydrochloride, unlike the corresponding -ephedrine salts, are very sparingly soluble in chloroform (30). The hydriodide, from acetone, has m.p. 165° (43). The sulfate is in the form of hexagonal plates, m.p. 247° [ ] — 32°, soluble in four parts of water, sparingly soluble in alcohol. The phosphate is in the form of long silky needles, m.p. 178° (165) the aurichloride, yellow crystals, m.p. 130-131° the platinichloride, m.p. 186° (240) Z-ephedrine-d-bitartrate, m.p. 69° (71) the oxalate, prismatic needles, m.p. 249°, sparingly soluble in cold water. The A -p-nitrobenzoyl derivative has m.p. 187-188 nitrosamine, m.p. 92°. A -Carbethoxy derivative has b.p. 169-171° (1-2 mm.)  

4-dimethyl-5-phenyl-2-oxazolidone from ephedrine, m.p. 57-58° (249). Methylephedrine methiodide has m.p. 212-213° (244). 

Ephedrine and Z -ephedrine are quite stable compounds. Heating at 100° for 24 hours causes no decomposition (42, 28). No alteration is observed by heating the bases with 5% sodium hydroxide on the water bath (21). Unsuccessful attempts were made to racemize ephedrine and Z -ephedrine with barium hydroxide or alcoholic potassium hydroxide 

On heating ephedrine hydrochloride with 5% hydrochloric acid, under pressure, at 170-180° (248) or with 25% acid, at 100°, the compound is partially converted to iZ -ephedrine (20, 32,40). The conversion is reversible and an equilibrium is established. According to Emde (39), the rearrangement takes place by replacement of the hydroxyl group by chlorine, followed by hydrolysis. Oxidation of ephedrine or Ephedrine, gives benzaldehyde or benzoic acid. 

3) The higher evaporation rate may have a negative effect on the paint surface 

4) Paint flow may be poor because the azeotropic mixture constantly evaporates 

Systems Containing More Than Two Components. As in binary systems, the behavior of systems containing more than two components can be understood on the basis of intermolecular forces and solubility parameters. Water and tetrachloromethane have widely differing solubility and hydrogen bond parameters, and are therefore immiscible. Added acetone dissolves partly in the aqueous phase due to hydrogen bond formation, and partly in the tetrachloromethane phase due to dispersion and induction forces. Twice as much acetone dissolves in the aqueous phase as in tetrachloromethane. On increasing the acetone concentration a homogeneous solution is obtained. The added solvent thus acts as a solubilizer for the two immiscible solvents. 

Addition of solvents as solubilizers is important in the dissolution of polymers. Poly(vinyl acetate) is insoluble in pure ethanol, but dissolves fairly readily in ethanol containing 3% water. Cellulose triacetate is sparingly soluble in pure trichloromethane, but is readily soluble in trichloromethane containing 3% methanol. Many paint resins dissolve more readily in aromatic-containing naphtha fractions than in pure naphtha. Poly(vinyl chloride) is sparingly soluble in acetone and carbon disulfide, but is more readily soluble in a mixture of the two solvents. 

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Overall Physical and Chemical Properties of Crude Oils Related to Transport, Storage And Price... 

Crude oils present a wide variety of physical and chemical properties. Among the more important characteristics are the following ... 

Another method by which metals can be protected from corrosion is called alloying. An alloy is a multicomponent solid solution whose physical and chemical properties can be tailored by varying the alloy composition. 

Another example of epitaxy is tin growdi on the (100) surfaces of InSb or CdTe a = 6.49 A) [14]. At room temperature, elemental tin is metallic and adopts a bet crystal structure ( white tin ) with a lattice constant of 5.83 A. However, upon deposition on either of the two above-mentioned surfaces, tin is transfonned into the diamond structure ( grey tin ) with a = 6.49 A and essentially no misfit at the interface. Furtliennore, since grey tin is a semiconductor, then a novel heterojunction material can be fabricated. It is evident that epitaxial growth can be exploited to synthesize materials with novel physical and chemical properties. 

The scope of tire following article is to survey the physical and chemical properties of tire tliird modification of carbon, namely [60]fullerene and its higher analogues. The entluisiasm tliat was triggered by tliese spherical carbon allotropes resulted in an epidemic-like number of publications in tire early to mid-1990s. In more recent years tire field of fullerene chemistry is, however, dominated by tire organic functionalization of tire highly reactive fullerene... 

Characterization of zeolites is primarily carried out to assess tire quality of materials obtained from syntliesis and postsyntlietic modifications. Secondly, it facilitates tire understanding of tire relation between physical and chemical properties of zeolites and tlieir behaviour in certain applications. For tliis task, especially, in situ characterization metliods have become increasingly more important, tliat is, techniques which probe tire zeolite under actual process conditions. 

Among the non-metals, nitrogen and chlorine, for example, are gases, but phosphorus, which resembles nitrogen chemically, is a solid, as is iodine which chemically resembles chlorine. Clearly we have to consider the physical and chemical properties of the elements and their compounds if we are to establish a meaningful classification. 

What are the principal differences in physical and chemical properties between any one metal from Group I and any one metal from Group IV and any one transition metal How far can you explain these differences in terms of their different atomic structures ... 

Rings have a profound influence on many properties of a molecule small rings introduce. strain into a molecule, aromatic rings dramatically change its physical and chemical properties, rings present particular problems in syntheses, etc. Thus, a knowledge of the I ings contained in a molecule is important in many applications in chemoinformatics. 

Prediction of Physical and Chemical Properties (Chapter X, Section 1) in Handbook of Chemoinformatics - From Data to Knowledge, J. Gasteiger (Ed.), Whey-VCH, Weinheim, 2003. 

Chemistry produces many materials, other than drugs, that have to be optimized in their properties and preparation. Chemoinformatics methods will be used more and more for the elucidation and modeling of the relationships between chemical structure, or chemical composition, and many physical and chemical properties, be they nonlinear optical properties, adhesive power, conversion of light into electrical energy, detergent properties, hair-coloring suitabHty, or whatever. 

Metal salts of A-4-thiazoline-2-thione are used in the rubber industry Zn salts (123, 152), Pb and Mg salts (54). Cd salts (151, 324), Cu salts (325), in photographic processes (146). and in analysis (328). Zn, Ni, Co and Cd salts are used as germicides (329). Despite their wide range of application, little is known about their physical and chemical properties. 

Because diastereomers are not mirror images of each other they can have quite different physical and chemical properties For example the (2R 3R) stereoisomer of 3 ammo 2 butanol is a liquid but the (2R 3S) diastereomer is a crystalline solid... 

Stereochemistry (Chapter 7) Chemistry in three dimensions the relationship of physical and chemical properties to the spatial arrangement of the atoms in a molecule Stereoelectron ic effect (Section 5 16) An electronic effect that depends on the spatial arrangement between the or bitals of the electron donor and acceptor Stereoisomers (Section 3 11) Isomers with the same constitu tion but that differ in respect to the arrangement of their atoms in space Stereoisomers may be either enantiomers or diastereomers... 

Multiple Chiral Centers. The number of stereoisomers increases rapidly with an increase in the number of chiral centers in a molecule. A molecule possessing two chiral atoms should have four optical isomers, that is, four structures consisting of two pairs of enantiomers. However, if a compound has two chiral centers but both centers have the same four substituents attached, the total number of isomers is three rather than four. One isomer of such a compound is not chiral because it is identical with its mirror image it has an internal mirror plane. This is an example of a diaster-eomer. The achiral structure is denoted as a meso compound. Diastereomers have different physical and chemical properties from the optically active enantiomers. Recognition of a plane of symmetry is usually the easiest way to detect a meso compound. The stereoisomers of tartaric acid are examples of compounds with multiple chiral centers (see Fig. 1.14), and one of its isomers is a meso compound. 

The subsequent literature shows the rule to be generally valid, within a few pet cent, amongst systems which give Typje IV isotherms in the typical example of Table 3.1, the data refer to adsorptives differing widely in their physical and chemical properties, yet the deviation of the saturation volume y, from the mean is within 6 per cent. 

Another important area of analytical chemistry, which receives some attention in this text, is the development of new methods for characterizing physical and chemical properties. Determinations of chemical structure, equilibrium constants, particle size, and surface structure are examples of a characterization analysis. 

Traditionally, chiral separations have been considered among the most difficult of all separations. Conventional separation techniques, such as distillation, Hquid—Hquid extraction, or even some forms of chromatography, are usually based on differences in analyte solubiUties or vapor pressures. However, in an achiral environment, enantiomers or optical isomers have identical physical and chemical properties. The general approach, then, is to create a "chiral environment" to achieve the desired chiral separation and requires chiral analyte—chiral selector interactions with more specificity than is obtainable with conventional techniques. 

The physical and chemical properties of acrolein are given in Table 1. 

Table 1. Physical and Chemical Properties of Adipic Acid...

The constants a and y depend on the physical and chemical properties of the system, the scmbbing device, and the particle-size distribution in the entering gas stream. 

J. T. Rogers, Physical and Chemical Properties ofEDX and HMX, Control Rpt. 20-P-26A, Holston Defense Corp., Kingsport, Tex., 1962. 

D. Hotovitz,H Keview of the Physical and Chemical Properties of Fluorine and Certain of Its Compounds, Report No. RMI-293-83, Reaction Motors, Inc., Rockaway, N.J., 1950. 

The physical and chemical properties are less well known for transition metals than for the alkaU metal fluoroborates (Table 4). Most transition-metal fluoroborates are strongly hydrated coordination compounds and are difficult to dry without decomposition. Decomposition frequently occurs during the concentration of solutions for crysta11i2ation. The stabiUty of the metal fluorides accentuates this problem. Loss of HF because of hydrolysis makes the reaction proceed even more rapidly. Even with low temperature vacuum drying to partially solve the decomposition, the dry salt readily absorbs water. The crystalline soflds are generally soluble in water, alcohols, and ketones but only poorly soluble in hydrocarbons and halocarbons. 

As a result of the development of electronic applications for NF, higher purities of NF have been required, and considerable work has been done to improve the existing manufacturing and purification processes (29). N2F2 is removed by pyrolysis over heated metal (30) or metal fluoride (31). This purification step is carried out at temperatures between 200—300°C which is below the temperature at which NF is converted to N2F4. Moisture, N2O, and CO2 are removed by adsorption on 2eohtes (29,32). The removal of CF from NF, a particularly difficult separation owing to the similar physical and chemical properties of these two compounds, has been described (33,34). 

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