Other methods

Other ways of improving the efficiency of distillation columns in general may include the following  

State-of-the-art control to ensure operation at the specified design conditions. Proper control can allow for operation with a smaller safety margin.  

Preheat the feed using waste heat instead of adding extra heat to the reboiler that operates at a higher temperature level, or use heat pumps.1 

Reduce the pressure drop in the column by using packings instead of trays, if possible. 

Separate to lower purity, and continue separation with other separation techniques. 

Other powerful approximative many-body techniques which are more 

Another possibility of constructing a chiral membrane system is to prepare a solution of the chiral selector which is retained between two porous membranes, acting as an enantioselective liquid carrier for the transport of one of the enantiomers from the feed solution of the racemate to the receiving side (Fig. 1-5). This system is often referred to as membrane-assisted separation. The selector should not be soluble in the solvent used for the elution of the enantiomers, whose transport is driven by a gradient in concentration or pH between the feed and receiving phases. As a drawback common to all these systems, it should be mentioned that the transport of one enantiomer usually decreases when the enantiomer ratio in the permeate diminishes. Nevertheless, this can be overcome by designing a system where two opposite selectors are used to transport the two enantiomers of a racemic solution simultaneously, as it was already applied in W-tube experiments [171]. 

Most of the chiral membrane-assisted applications can be considered as a modality of liquid-liquid extraction, and will be discussed in the next section. However, it is worth mentioning here a device developed by Keurentjes et al., in which two miscible chiral liquids with opposing enantiomers of the chiral selector flow counter-currently through a column, separated by a nonmiscible liquid membrane [179]. In this case the selector molecules are located out of the liquid membrane and both enantiomers are needed. The system allows recovery of the two enantiomers of the racemic mixture to be separated. Thus, using dihexyltartrate and poly(lactic acid), the authors described the resolution of different drugs, such as norephedrine, salbu-tamol, terbutaline, ibuprofen or propranolol. 

Another useful technique is mercury pycnometry which can be used to determine the geometrical volume of the dry gel (pores and solid), hence giving complementary data to helium pycnometry which measures only the pore volume. In this characterization method, a volume-calibrated chamber containing the sample is filled with mercury the mercury volume (or weight) is measured to compute the sample volume. Unlike mercury porosimetry, no pressure is exerted so that mercury neither enters the pores nor crushes the sample. 

Besides the determination of the porosity, pore size distribution and surface area, the (surface or mass) fractal dimension of dry gels may be of interest. To this purpose, small-angle X-ray scattering can be used nitrogen sorption and mercury porosimetry also offer possibilities to extract this structural information (see, for example, Blacher et al. (2000)). 

Electron microscopy is mostly used qualitatively (some examples will be given in Section 5.5) for SEM, because oflimited resolution and restriction to sample surface and for TEM, because of the difficulty in separating information in the third dimension. Quantitative analysis of TEM data obtained from dry gels allows determination of the size distributions of primary particles, for example, in silica-alumina and silica aerogels, for which Sinko et al. (2008) have measured particle diameters in the range 3-14 nm. 

Other Methods.—Last year it was shown that the equilibrium  

Using R = Ph, Y = S02CeH4Me or PS(OPh)2, the aminophosphine form was detected. A second mole of chlorophosphine was added and in all cases P-phosphinophosphazenes were obtained  

There was no evidence for the alternative diphosphinoamines, R2P-N(Y)-PR2, in the P n.m.r. spectra, which revealed relatively large P-P spin-spin coupling constants (225—300 Hz), characteristic of directly-bonded phosphorus atoms. It is interesting to note that the two groups of compounds gave different types of sulphide on reaction with sulphur  

Apparently, the second product did not react further with sulphur, by a reaction which might be possible if any R2P-NY-R2PS were present. 

In view of the above findings, it is not surprising that no evidence was obtained for the presence of a phosphazene in aminodifluorophosphine, which was recently obtained by the reactions  

Other Methods.—Only one new example of a phospha(m)azene has been reported 31 

and other derivatives containing both Me and Ph R-substituents, are susceptible to hydrolysis and oxidation for example, reaction with sulphur gave the phosphinothioyl-derivatives RaP(S)PRa=NY. The and 31P n.m.r. spectra were discussed, particularly with reference to J(PP) and/(PNP), and the former coupling increases with increasing basicity of Y. 

The conversion of aminophosphites into monophosphazenes has been a subject of particular interest. Compounds (20),34 (21),35 (22),38 and (23)37 have been prepared. 

It seems probable that these reactions proceed by nucleophilic attack of the phosphorus atom on the carbonyl group or activated olefin with the formation of a dipolar ion intermediate, which rearranges to a phosphazene by migration of a hydrogen atom or silyl group. 

Oxidation of phosphites to phosphazenes can also be achieved by reactions with diazo-compounds 38 

Other Methods.—No new phosph(m)azenes have been reported, but several unusual routes to phosph(v)azenes have appeared. In one case, migration of the silyl group from nitrogen to carbon in a Wittig reagent results in the formation of the phosph-azene (28). Descriptions of further conventional examples of deprotonation of 

The reactions of amino-phosphites with activated olefins, and with activated ketones, provide a route to phosphazenes (31) and (32), respectively. 

Other Methods.—The stabilizing influence of the trimethylsilyl group has been nicely demonstrated in the synthesis of the first phosph(m)azane  

The same product has since been obtained by a somewhat simpler route  

This phosphazene is characterized by fairly ready reactions with nucleophiles, e.g. 

The reaction of hexamethyldisilazane with chloro-phosphites provides a 

The synthesis of phosphazenes by the reactions of nitriles with chloro-phosphoranes continues to receive attention. Thus methanecarbonitrile gives iV-vinylphosphazenes, whose structures were assigned by C1 n.q.r. measurements  

Other methods have been reviewed by Reich [36]. 

Other Methods.—In an extension of a recently developed synthesis of phosphazenes it has been shown that tertiary phosphines react with carbon tetrachloride and methylene diamines to give diaminophosphonium salts  

With bis(diphenylphosphino)-ethane and -propane, diphosphazenes RS02N=PPh2(CH2)2,3PPh2=N-S0aR (R included NMea, Ph, and C6H4-/7-Me) were formed, but only a monophosphazene was obtained from bis(diphenylphosphino)methane  

In a related series of reactions, monophosphazenes were prepared from phosphorus(iii) amides and carbon tetrachloride in the presence of a base  

Other Methods. - One of the most important and flexible approaches to ketone synthesis involves the manipulation of 6-keto-esters. Tsuji et al. have reported that the use of allyl keto-esters, which are prepared from ketones and diallyl carbonate or allyl chloroformate, offer advantages over more common esters in that the ester hydrolysis/decarboxylation step 

The isomerisation of a variety of primary allylic alcohols by treatment with N-lithio-ethylenediamine or -lithio-aminopropylamine in the amine as solvent have been reported. 

The reaction is somewhat capricious but in favourable cases very 

A convenient and high yielding carbonyl homologation involves the reaction of excess sodium phenylselenide with a phenyl-sulphinyl epoxide. The required epoxides are most easily prepared by the reaction of the anion of an a-chloro-sulphoxide with a ketone and ring closure of the resulting chlorohydrin with potassium hydroxide (equation 12). 

Reports on the insertion of acyl carbenes into benzene for 

Other methods that can be effectively employed in MCRs are infrared (IR) and photochemical irradiations. These approaches are useful in specific circumstances where reactants 

SCHEME U MCR using either conventional heating or microwave irradiation and the results observed by Hasaninejad and coworkers [48]. 

SCHEME 14 Synthesis of dihydropyrano[2,3-c]pyrazoles under ultrasound irradiation [49]. 

Other methods The method of successive substitution (SS), and the full Newton method for solving the system of nonlinear algebraic equations of flash have certain limitations. They have also certain desirable 

The classical Newton method has quadratic convergence properties whereas the successive substitution method has linear rate of convergence. However, because of the overshoot, the Newton iteration may fail to converge when the initial estimate is not a good estimate of the solution of the system of nonlinear equations. 

A very large array of methods have been proposed to accelerate the convergence rate of successive substitution. These include the use of the Dominant Eigenvalue Method of Crowe and Nishio (1975). In spite of significant increase in the rate of convergence, such methods may cause the loss of basic stability of successive substitution. 

In Newton s method, various approaches have been suggested to adjust the step length to alleviate the overshoot problem. These adjustments do not guarantee convergence of the Newton s method in early iterations. 

The combination of successive substitution and Newton s method is a good choice and has the desirable features of both. In this approach, the successive substitution comprises the first few iterations and later, when a switching criterion is met, Newton s method is used. To our knowledge, some commercial reservoir simulation models have adopted the combined successive substitution-New ton approach after the experience with various methods of solving nonlinear flash calculation including Powell s method (1970). The application of a reduction method to phase equilibrium calculations has also been proposed (Michelsen, 1986 Hendriks, and Van Bergen, 1992). In this approach, the dimensionality of phase equilibrium problems for multicomponent mixtures can be drastically reduced. The application of reduction methods and its implementation in reservoir compositional models is under evaluation. 

Other Methods. Rates of hydrolysis of pyro- and tripoly-phosphates are greater in aqueous dioxan, and smaller in aqueous formic or acetic acids, than in water. As water molecules are more easily available for incorporation into the transition state in aqueous dioxan than in water, but less available in the strongly intermolecularly hydrogen-bonded aqueous carboxylic acids, the observed rate trends are consistent with a bimolecular mechanism for hydrolysis of these phosphates.  

Rate constants for bromide exchange with the c r-[Ru(NH3)4Bra]+ cation vary little with solvent composition in methanol-water mixtures. There is a shallow minimum at a mole fraction of ca. 0.08 water. It is claimed that at higher mole fractions of water the mechanism involves rate-determining 5 n2 attack by water, but that at lower mole fractions of water the mechanism is dissociative. This is not the only recent example of a suggestion of a change of mechanism in going from water-rich to water-poor solvent mixtures. Another such example is afforded by the aquation of the c/r-[Co(en)2(py)Br] + cation (see above).  

Formation of ternary complexes from the [Ni(phenXOH2)J cation is unusually rapid when the incoming ligand can associate itself with the co-ordinated phen molecule and still retain a free nitrogen atom in a suitable place for bonding to the 

Ohyoshi, T. Shinohara, Y. Hosoyamada, T. Yamada, and Y. Hiroshima, Bull. Chem. Soc. 

Other Methods.— The isoteniscope is a form of apparatus for making static experiments, but it has an affinity with ebulliometry in that the sample is repeatedly degassed by boiling. If two isoteniscopes, one of which contains water and each of which is in a separately controlled bath, are both balanced against the same pressure by adjustment of the temperatures of the baths, measurements may be made in the comparative manner. The Reporter has used this method but did not succeed in making its precision approach that easily attainable by comparative ebulliometry. It does, however, have the advantage that no more than 2 cm of each liquid are 

The transpiration method is adequately discussed by Thomson, but there has been one recent development the use of a flame-ionization 

Goncharov and M. Kh. Karapet yants, Trudy Mask. Khim.-Tekhnol. Inst., 1969, No. 62, 17. 

Application of the ebulliometric method at elevated pressures has already been discussed. The method has been used only occasionally, and most vapour-pressure measurements in the range now considered have been made by the static method in apparatus which is, in principle, the same as that used by Andrews for his work on the isotherms of carbon dioxide, and subsequently developed by Hannay and by Ramsay and Young. The sample is confined over mercury in a thick-walled glass tube sealed at its upper end, and the tube is attached to a steel U-tube containing mercury the pressure is transmitted through the mercury to the pressure gauge and a piston on a screw allows the level of the mercury, and hence the volume occupied by the sample, to be adjusted. The experimental tube is heated by means of a vapour jacket. (Alternatively, the glass tube itself may be bent into the form of a U, often then known as a Cailletet tube, and the apparatus is heated by immersion in a normal thermostat bath. ) 

Another apparatus for static measurements is that originally developed for determination of the p, V, T behaviour of water, but later used for other 

Other Methods.—The synthesis of aldehydes and ketones from lower carbonyl compounds by C—C coupling reactions has been reviewed (273 references) the review is sectionalized by the number of bonds between the new carbonyl group and the original electrophilic centre.  

Hydroacylation of olefins to yield ketones can be achieved by the addition of an aldehyde in the presence of a silver salt or by the addition of an aldimine (29) in the presence of a rhodium(i) catalyst [equation (5)].  

Reagents i, hv ii, m-CPBA iii, HOCH2CH2OH-TSOH iv, hydrolysis v, MeLi vi, HjO vii. Base 

The high-pressure Diels-Alder reaction of ketones with 1-methoxybutadiene yields the masked a,/3-unsaturated aldehyde (30). ° Under similar conditions, the highly functionalized cyclohexene (31) may be obtained [equation (6)]. ° 

Vinyl azides, which can be obtained from olefins, are converted in high yield into the corresponding carbonyl compounds by sodium sulphide in methanol. The mercury(ii)-catalysed hydrolysis of the vinyl chloride (32) shows an interesting solvent dependence in dichloromethane, acetic acid, benzene, or acetonitrile the yield of (33) is almost quantitative and no trace of (34) is observed, whereas in methanol 83% (34) and 6% (33) are obtained [equation (7)].  

Other Methods.—Semicarbazide on silica gel and Girard-T on silica gel have been recommended as reagents for the isolation of aldehydes and ketones.  

Although this may find its major application in the separation of carbonyl compounds from natural mixtures occasional use may be found with synthetic mixtures. Regeneration of the aldehyde or ketone was highly effective using aqueous oxalic acid and toluene-heptane mixtures. 

Aryl- and alkyl-carboxylic dihalophosphoric anhydrides acylate activated arenes without the need for a conventional Friedel-Crafts catalyst. The anhydrides are prepared in situ, and the low temperatures required (20 C) allow reasonable yields of ketones to be obtained from mixed anhydrides of low stability, for example those derived from acetic and pivalic acids [equation (8)]. 

Aromatic palladocycles react regiospecihcally with acyl halides to give aryl ketones in good yield [equation (9)]. Unfortunately, at present the method requires the preparation of the palladocycle prior to acylation, and so is not catalytic in palladium. 

Potassium peroxydisulphate in the presence of cupric ions has been shown to be a convenient reagent for the conversion of electron-rich benzylic hydrocarbons into carbonyl compounds.  

Other Methods.— The palladium-catalysed oxidation of terminal olefins to methyl ketones is very efficient using 30% hydrogen peroxide in acetic acid or t-butyl alcohol. The method offers advantages in that conversions are usually high, aldehyde production is very low, and the method requires only very low concentrations of palladium [20—40p.p.m, as palladium(li) acetate], fi-Hydroxy-o-nitrophenylselenides, or their O-acyl derivatives, on oxidation with hydrogen peroxide undergo elimination to form ketones or enol esters [equation (10)]. The starting materials can be prepared easily from alkenes via their epoxides. 

The exceptional selectivity exhibited by disiamylborane in the hydroboration of terminal olefins enables the efficient conversion of such olefins into aldehydes, since disiamylboranes have been shown to be oxidized readily by pyridinium chlorochromate. Thexylalkylchloroboranes, reduced in the presence of an alkene, produce mixed thexyldialkylboranes, which can be transformed into ketones by carbonylation or cyanidation. This advance in the preparation of trialkylboranes bearing three different alkyl groups removes limitations previously imposed on ketones available by carbonylation of boranes [equation (11)]. 

Reagents i, PhMejSiCCljLi ii, H2O2—NaOH iii, Jones reagent 

Aspects of the rhodium-catalysed hydroformylation of olefins have been reviewed. Copper(ii) acetate catalyses the highly stereoselective solvolysis of -alkenylpentafluorosilicates to -alkenyl ethers under an atmosphere of air. Since the pentafluorosilicates can be obtained via hydrosilylation of acetylenes, the sequence represents a regio- and stereo-selective transformation of acetylenes into carbonyl precursors in moderate yield. The reaction of vinylmercurials and mercury carboxylates catalysed by palladium(ii) acetate provides a stereospecific route to enol carboxylates, which are valuable precursors of specific enolates.  

Isomerization of allylic alcohols to ketones is possible under mild, basic conditions using the chlorodicarbonylrhodium(l) dimer [Rh(CO)2Cl]2. Some cases benefit from the addition of a phase-transfer catalyst. Raney nickel has 

Other methods include end group analysis (Mn), ultracentrifugation (Mw) and, indirectly by determining glass transition temperatures, DSC/DTA. 

A review of the determination of the molecular weight of polymers has been produced by Holding and Meehan (396). 

There are other lumping techniques for linear kinetics, such as cluster analysis observer theory , singular perturbation , and intrinsic lowdimensional manifolds. Recently, Androulakis treated kinetic mechanism reduction as an integer optimization problem with binary variables denoting the existence and nonexistence of reactions and species. The technique is amenable to uncertainty analysis. 

Different methods were developed and applied for the structure analysis and characterization of the polyesters properties. The morphology of the imsatu-rated polyester and vinyl ester networks was studied using the ArF excimer laser (A. = 193 nm, pulse duration time 16 ns, in air under atmospheric pressure) smface treatment, followed by SEM observations [157]. Samples were analyzed, after laser treatment, by profilometry to determine the ablation threshold. The differences between the thresholds at which ablation of various consistent phases of the materials occurs were used. That method enabled the determination of the two-phase structure of the vinyl ester matrices and the organized structme network of UPs. SEM analysis was also used for investigation of the compatibihty of imcured fluorinated UPR systems. The results were in good agreement with the macroscopic results obtained by visual inspection [72]. 

Structure-property relationships in crosslinked polyester-clay nanocomposites, prepared by dispersing methyl tallow bis-2-hydroxyethyl quaternary ammonium chloride-modified montmorillonite in prepromoted polyester resin and subsequently crosslinking using the methylethylketone peroxide initiator at room temperature and at several clay concentrations, were analyzed by X-ray diffraction combined with Transmission Electron Microscopy (TEM), thermal (TGA) and dynamic mechanical analyses as well as by the determination of mechanical and optical properties [158]. In all cases the formation of a nanocomposite and the morphology of a dispersion of intercalated/exfoHated aggregates of clay sheets in the resin matrix were confirmed (Fig. 17). hi the absence of reflection irrespective of clay concentration in the scattering curves for all the polyester-clay nanocomposites was ascertained. 

Dynamic mechanical analysis is the most widely used technique for the investigation of mechanical properties and the structure-property relationships in polymeric materials. The dynamic mechanical results expressed as storage modulus ( ), loss modulus ( ) and loss tangent (tan S) in the function of temperature demonstrate for example the phase composition, phase transition with glass transition temperature and the structural relaxation processes. The phase segregation in the cured UPRs with an increase in styrene concentration and the dependence of glass transition temperature of UPRs 

Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) followed by dynamic mechanical parameter tests were used for the investigation of the morphology of unsaturated polyester/diol-polyurethane hybrid polymer networks (UP/PU HPNs). The effect of phase separation on mechanical properties was described [142]. 

The results of DC-electrical conductivity, confirmed by DSC measurements, were used for the monitoring of radiation and thermally initiated crosslinking of UPRs [159]. Interpretation using conductivity data itself instead of the commonly used logarithmic data form (Fig. 18), as proposed by the authors, showed the influence of the upper liquid-liquid transition on the rate of radiation induced reaction, as well as two reaction rate maxima of thermally initiated crosslinking with the rate increase caused by heat release in the first part of the process. 

A number of other techniques have been used to determine pore size, but they are not accurate enough to be used as standard characterization tools. 

Alternative methods of sialic acid determination have been described, but remain largely unused due to their poor sensitivity or difficulty in application relative to the assays described in these sections. These include the sulpho/phospho/vanillin method, originally used with gangliosides (Saifer and Feldman 1971), and the 1,10-phenanthroline method of Dimitrov (1973), which was subsequently refuted as a valid method by Snyder et al (1974). Of the remaining methods, already detailed at the beginning of section II, only the direct Ehrlich reaction has occasionally been employed where great sensitivity was of secondary importance (Werner and Odin 1952, Onodera et al 1965), or in cases where an additional colorimetric assay for identification of sialic acid was required (Onodera et al 1965, Cabezas 1973, Schauer 1978). 

Other physical methods are also useful for asymmetric transformation. Enantioselective photochemical sensitization has been noted in stereo- 

ASYMMETRIC CATALYSIS WITH PURELY ORGANIC COMPOUNDS 

Detailed mechanism H. Buschmann, H -D. Scharf, N. Hoffmann, and P. Esser, Angew. Chem., Int. Ed. Engl., 30, 477 (1991). 

Reviews H. Wynberg, Selectivity in Organic Synthesis, in W Bartmann and B. M. Trost, eds, Selectivity—A Goal for Synthetic Efficiency, p. 365, Verlag Chemie, Weinheim, 1984. 

First example B. LSngstrom and G. Bergson, Acta Chem. Scand., 27, 3118 (1973). 

Many other methods can be useful for the characterization of metal complexes, and we will briefly discuss some of them here. Microanalysis of the products is standard practice, and the values found for C and H are normally acceptable if they fall within 0.03% of the calculated figure. Solvent of crystallization can be present in the lattice and can alter the percentages 

Conductivity measurements in solution are useful for telling whether a given complex is ionic, and the measurements can also give the electrolyte type (A B , etc.). 

The UV-visible spectrum of an organometallic complex is most commonly obtained when photochemical experiments are carried out, to help decide at which wavelength to irradiate (see Section 4.7). A detailed interpretation of the spectrum has been carried out for few organometallic complexes, a situation that contrasts with that in coordination chemistry, where UV-visible spectroscopy and the ligand field interpretation of the results has always been a major focus of attention.  

One other diffraction method that has proved useful for sufficiently volatile organometallic compounds is electron diffraction. In this technique the organometallic compound is introduced into a vacuum chamber through a nozzle, and an electron beam is passed through the stream of molecules. The resulting diffraction pattern contains much less information than does an X-ray diffraction pattern, but by making simple assumptions about the structure of the molecule, valuable data can be obtained. A useful feature of the results is that they refer to the molecule in an isolated state in a vacuum, so solvation or crystal packing effects are absent. 

Computational Methods Molecular orbital theory, at both the extended Hiickel and ab initio levels, has played an indispensable role in clarifying the structure and reactivity of a wide range of organometallic compounds. Such studies are particularly useful when they are interpreted so that the important interactions are explicitly identified. The results of some of these studies are incorporated into the discussion in other chapters of this book. 

Once rate, these are much more commonly studied today. The magnetic moment is most conveniently determined by Evans s method. This involves measuring the chemical shift of a solvent resonance on going from the pure solvent (often present in the form of a sealed capillary tube placed in the sanqile) 

Molecular orbital (MO) theory includes a series of quantum mechanical methods for describing the behavior of electrons in molecules by combining the familiar s, p, d, and / atomic orbitals (AOs) of the individual atoms to form MOs that extend over the molecule as a whole. The accuracy of the calculations critically depends on the way the interactions between the electrons (electron correlation) are handled. More exact treatments generally require more computer time, so the problem is to find methods that give acceptable accuracy for systems of chemical interest without excessive use of computer time. For many years, the extended Hiickel (EH) method was widely used in organometallic chemistry, largely thanks to the exceptionally insightful contributions of Roald Hoffmann. The EH method allowed structural and reactivity trends to be discussed in terms of the interactions of specific molecular orbitals. Fenske-Hall methods also proved very useful in this period.  

There are many more methods for estimating the surface tension. Two useful methods are those based on the corresponding-states principle (CSP) and on solubility parameters. 

The CSP method has been proposed by Brock-Bird-Miller (Reid, Prausnitz and Poling, 1987) and the surface tension (mN m ) is given by the equation  

Finally, we mention a method based on solubility parameters. As both solubility parameters and the 

The solubility parameter introduced by Hildebrand (Hildebrand and Scott, 1964) is a widely used concept in thermodynamics and physical chemistry in general. Several handbooks and reference books provide extensive lists of solubUily parameters of numerous chemicals. The solubility parameter is defined as  

Traditionally, solubility parameters are given in (cal cm ) = Hild(ebrands), in honour of the founder of the regular solution theory, Joel Hildebrand. The solubility parameters were originally defined in conjunction with the regular solution theory. Now, they are more commonly listed in (MPa) (= (J cm ) ). In the absence of experimental data, the solubility parameters of both solvents and polymers can be estimated via group contribution methods, as discussed by van Krevelen and Hoftyzer (1972). 

Several other methods have been employed for the preparation of carbon-supported catalysts, although to a lesser extent that impregnation methods. Nakamura et al. [38] prepared molybdenum catalysts for ethene homologation by physical deposition of gaseous [Mo(CO)6]. Their supports were commercial activated carbons that were subjected to different treatments to modify then-surface. The authors compared these supports with oxidic supports and concluded that the interaction between the metal carbonyl and the carbon supports were weaker. Furthermore, they observed that oxidation of the carbon surface was effective in enhancing the catalytic activity of Mo/C, and they ascribed this effect to the contribution of the surface oxygen groups to the partial oxidation of decomposed [Mo(CO)6]. 

Serp et al. [39] prepared activated carbon-supported platinum catalysts by chemical vapor deposition of organometallic compounds. They contacted carbon rods with a gas mixture containing He, 3% H2, and a 10 molar ratio of [Pt(CH3)2(COD)] (COD ri -l,5-cyclooctadiene) for 12 minutes at 383 K and 50 torr. They concluded that preoxidation of the carbon support with HNO3 was a very important factor in obtaining well-dispersed platinum particles, as the oxygen surface complexes acted as anchoring centers for the platinum precursor. 

Precipitation or coprecipitation methods are also often used. Suh et al. [40] analyzed the effect of the oxygen surface functionalities of carbon supports on the properties of Pd/C catalysts prepared by the alkali-assisted precipitation of palladium chloride on carbon supports, followed by liquid-phase reduction of the hydrolyzed salt with a saturated solution of formaldehyde. They observed that the metal dispersion increased with increasing amount of oxygen surface groups. Nitta et al. [41] also used a deposition-precipitation method, with sodium carbonate and cobalt chloride or nitrate, to prepare carbon-supported Co catalysts for the selective hydrogenation of acrolein. 

Harada et al. [42] prepared nanosized palladium particles supported on activated carbons using a simple liquid-phase reduction of aqueous Pd complexes with KBH4. They found that the addition of appropriate amounts of NaOH into aqueous solutions of Na2PdCLt, followed by reduction with KBH4, produced highly dispersed Pd particles (less of 5 nm in diameter), irrespective of the carbon support used. The prepared catalysts were used efficiently in the liquid-phase oxidation of benzyl alcohol to benzaldehyde and in the liquid-phase hydrogenation of cinnamaldehyde to obtain the saturated aldehyde. 

Similar methods for the preparation of noble metal nanoparticles on carbon materials are being used extensively for the synthesis of electrocatalysts. 

In addition to the above methods, which are of general application in structural polysaccharide chemistry, a number of procedures should be mentioned which either give more limited information or can be applied only in special cases. 

Hudson s rules of isorotation are used for the determination of the configuration at the anomeric centers in oligo- and poly-saccharides and Korytnyk has discussed some extensions of these rules. Reeves has demonstrated that studies of the optical rotation in cuprammonia solution can give valuable information on the types of linkages and also on the conformation of sugar residues in a polysaccharide. Bourne and coworkers have shown that some o- and /S-D-glycosidic linkages display characteristic absorptions in the infrared at 844 and 891 cm, respectively. 

Mention should also be made of the specific precipitation of certain polysaccharides with antisera, a procedure which has been extensively studied by Heidelberger and his group. These precipitations can often be correlated with the presence of special groupings in the polysaccharides, and it is therefore possible to use antisera reactions for the investigations of the presence of such groups in polysaccharides of unknown structure. 

For many years, the carbohydrate esters of carbonic acid and thiocar-bonic acid have found important application as intermediates in the synthesis of otherwise difficultly accessible derivatives. A review of these esters is particularly opportune, because both their preparation and properties are considerably influenced by stereochemical factors which require interpretation in the light of modem concepts of reaction mechanisms and conformational analysis. Although the historical development of the chemistry of the carbonic and thiocarbonic esters of carbohydrates has been independent, it is appropriate to give a comparative treatment of their closely related structures and properties. 

Nemirowsky, in 1883, reported the preparation of the cyclic carbonate ester I from ethylene glycol and phosgene, and, in 1909, Siegfried and 

There are other methods which are either some substantial variations of the above techniques or new processes that arc not well studied. 

A number of other methods are available to elucidate the thermodynamic relationship between polymorphs. Solution calorimetry, for example, can be used to determine the enthalpy difference of two forms (H gijj(A ) — H5gijj(A ), since the enthalpy difference is equal to the difference of the heats of dissolution. 

For transition metal systems, DFT methods generally lead to more accurate structures and vibrational energies than single determinant HF methods[22,28], and often they are similar in quality to high-level post-HF methods. Since, in addition, DFT calculations are less computationally expensive (approximate scaling factor N3) they have become the method of choice for routine applications in the area of transition metal compounds[22,28 30]. 

Following the reports by McCullough and Rieke, other groups have found that specific oxidative conditions with a limited number of thiophene monomers can 

There are a number of other methods which have been used for the study of monolayer properties, but not appUed at present to the study of reaction kinetics. 

These methods are discussed briefly further information is obtainable from the references 2ilready mentioned  

Surface viscosity can be measured with a canal viscometer or with a torsion viscometer. The former instrument measures the flow of the film through a slit in a beurier on a film balance the latter, the damping caused by the presence of a film on a body moving in the surface of the liquid. Interpretation of measurements on films with a constant viscosity is difficult and would be more so in the presence of viscosity changes caused by reaction. 

Adamson, Physical Chemistry of Surfaces, Interscience, New York, 1960, p. 457. 

Catalysis by Metals, Academic Press, London, 1962, p. 49. 

Synthesis by Miscellaneous Other Methods. An 5 2 reaction with inversion at the cyclpropyl carbon in (103) has been demonstrated unambiguously. 

The tosylates (104) could not be isolated but cyclized spontaneously to (105). Two approaches have been described to the oxabicyclo-octene moiety (106) that is present in certain antibiotics and nucleophilic addition of the hydroxyl function to the C=C bond in systems such as (107) has been ascribed to the relief of strain in the ground state.An intramolecular Michael addition converts (108) into (109).  

Gunther, and A. Waldner, Helv. Chim. Acta, 1981,64, 2709. 

Sudani, Y. Takeuchi, E. Yoshii, and T. Kometani, Tetrahedron Lett., 1981, 22, 4253. 

Descriptions of a variety of routes to a-multistriatin (110) and related compounds have been published. Two reported syntheses of sarracenin 

In addition to the methods described above, some other methods have been developed to prepare supported gold clusters [62-65]. Huang et al. [62] have 

Exterior surface of as-prepared TS-1 or alkaline-treated TS-1 Surface defects or small mesopores clusters ( 2.0 nm) 

Three techniques have been mainly utilized to characterize gold clusters, namely mass spectroscopy, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and extended X-ray absorption fine structure spectroscopy (EXAFS). For unsupported gold clusters, electrospray ionization (ESI) mass spectrometry and matrix-assisted laser desorption ionization (MALDI) mass 

HAADF-STEM is also widely used to characterize supported gold clusters. Recent research shows that tiny gold clusters (even a single gold atom) can be observed by aberration-corrected HAADF-STEM, when supported on iron oxides 

The foregoing methods are certainly not exclusive, and many other techniques such as cloud chambers (e.g., see Miller et al., 1987) and fluidized bed reactors have also been applied to following the kinetics of heterogeneous reactions relevant to the atmosphere. However, due to space limitations, these will not be treated in detail here. 

Fortunately, there are several compendia of kinetic data applicable for atmospheric reactions that are 

FIGURE 5.30 Schematic diagram of XPS apparatus used for gas-solid reactions (adapted from Laux et al., 1994). 

FIGURE 5.31 Change in surface concentrations of N(ls), OUs), and Cl(2p) as a function of exposure time of an NaCl(lOO) single crystal to gaseous HNO, (adapted from Laux et al., 1996). 

NASA also carries out kinetic evaluations for reactions of interest in the stratosphere (although many of them are also important in the troposphere) (DeMore et al., 1997). This document can be obtained from the Jet Propulsion Laboratory (California Institute of Technology, Document Distribution, MS 512-110, 4800 Oak Grove Drive, Pasadena, CA 91109) or through the Internet (see Appendix IV). 

Besides the methods described in the foregoing chapters, several other methods have been proposed that have not received greater attention as they are either more inaccurate or they only allow the determination of a few Leslie coefficients or shear viscosities. These methods are mainly based on  

Shear viscosities under flow alignment can be studied using commercial viscosimeters. 

In addition to the experiments briefly discussed above, two further equitibrium methods and two nonequilibrium procedures are sometimes employed to obtain thermodynamic information. 

The most frequently used additional method is the evaluation of data for liquid/ liquid phase separation, i.e., of critical points and of binodal curves [21]. This information is normally obtained by means of cloud point measurements (either visually or turbidimetrically) and the analysis of the composition of coexisting phases. Critical data give access to the system-specific parameters via the critical conditions, as formulated in (36) and (37) for the present approach or by means of equivalent expressions of other theories. If the critical data (temperature, pressure, and composition) are known for a sufficiently large number of polymer samples with different molar mass, and the number of parameters required for a quantitative description of g(v ) is not too high, this method yields reliable information. Similar consideration also hold true for the evaluation of binodal curves. In both cases it is very helpful to formulate a theoretically justified temperature dependence of the system-specific parameters. 

Liquid/solid equilibria also offer access to thermodynamic information. In this case, it is the differential interaction parameter of the polymer that is obtained according to (38) from the known molar mass of the polymer, its melting temperature in the pure state, and the corresponding heat of melting plus the polymer concentration in the solution that is in equilibrium with the pure polymer crystals. Because of the well-known problems in obtaining perfect crystals in the case of macromolecules, special care must be taken with the evaluation of such data. 

Vapor pressure osmometry [34 36] constitutes a very helpful nonequilibrium method for obtaining thermodynamic information for solutions of oligomers and polymers of low molar mass, for which osmometry and light scattering experiments do no longer yield reliable data. Such experiments are based on the establishment of stationary states for the transport of solvent via the gas phase from a drop of pure solvent fixed on one thermistor to the drop of oligomer solution positioned on another thermistor. Because of the heats of vaporization and of condensation, respectively, this transport process causes a time-independent temperature difference from which the required information is available after calibrating the equipment. 

Inverse gas chromatography (IGC) represents another nonequilibrium method it yields valuable information on polymer solvent interactions in the limit of vanishing solvent content [37, 38]. In experiments of this t)q)e, a plug of solvent vapor is transported in a column over a stationary phase consisting of the pure polymer melt. The more favorable the solvent interaction with the polymer, the longer it takes 

The preceding sections outline the three most commonly implemented and currently practical methods for computing nonlinear optical properties. But, as discussed, each of those methods has drawbacks, and a great deal of effort is being expended in the quantum chemistry community to develop alternate methods that are more accurate and more efficient. This section briefly introduces a few of the approaches that currently look most promising. We introduce the reader to these methods but do not provide a detailed discussion. 

Another way to view the nonlinear optical properties is via the time-de-pendent response functions  

When the perturbing potential V is an external electric field and the property of interest A is the dipole moment, the coefficients, indicated in the expansion above by the double angle brackets, are referred to as polarization propagators. These functions are equivalent to the tensor components 

Two major approximations must be made to obtain the response functions a choice of a reference function and a choice of an operator manifold. For the linear response function, the choices of a Hartree-Fock reference state and simple particle-hole excitation operators (in the second quantization sense) lead to an approximation known as the random phase approximation (RPA) and is equivalent to the TDFiF method discussed earlier. 

The quadratic response functions have been calculated within the RPA approximation by Parkinson and Oddershede. Cubic response functions have been calculated within the random phase approximation (RPA) and within the multiconfiguration RPA (MCRPA).  

As in a certain number of our experiments, some investigators used primary toxic solutions of DNCB others employed primary non-toxic solutions of DNCB, as we did in some of our experiments. There are many technical differences (concentration, number of applications) in addition to numerous variations in the results obtained by experimentation on guinea pigs in different laboratories as well as in the same laboratory. 

The success of sensitization does not depend only upon the quantity of the allergen applied, but also upon the concentration of the substance per surface unit (ScHNiTZER, 1941 Miescher, 1941 Frey and Wenk, 1956). 

By intradermal administration. Landsteiner and Jacobs (1935) practiced repeated injections of 0.0025 mg of DNCB in an alcoholic solution mixed with physiological serum this procedure regularly induced a sensitization. The guinea pigs thus treated react to the patch test in 0.1% concentration of DNCB in olive oil (Skog, 1955) and even in 0.04% (Chase, 1941). 

Other authors confirmed this means of sensitization (Ginsberg and coll., 1939 Rosten-BERG, 1947 Rockwell, 1955 Maibach and Maguire, 1963 Rebello and Suskind, 1963). 

By sub-cutaneous or intramuscular administration. Landsteiner and Jacobs (1935) and See-berg (1951) obtained a weak and irregular sensitization. Whereas Miescher (1941), then ScHNiTZER (1942), regularly obtained a sensitization by intramuscular administration of DNCB. 

In addition to the techniques outlined above, many other methods have been developed for droplet sizing. These include, for example, intensity ratio method, phase optical-microwave method, and dual-cylindrical wave laser technique)1(n etc. 

An acoustical particle counter for counting and sizing fog droplets has been evaluated by Singh and Reist.161 Fog droplets, mostly in the size range of 5-30 pm, were measured by the acoustical particle counter as well as an optical and an electron microscope for comparison. The mean droplet diameters estimated from the acoustical particle counter were in agreement with the microscope values. A Rich 100 condensation nuclei monitor was also operated simultaneously during the fog droplet counting to monitor condensation nuclei counts. 

Korobochka and Pavlenko 705 proposed a simple model and nozzle design for the determination of exact droplet size distribution generated by an air-assist nozzle. The approach enables the direct measurements of droplet size and allows generation of a very narrow range of droplet size distribution. 

Other techniques for mass measurement are available, but they are not as popular as those outlined above. These other methods include mass measurements on a standard substance to calibrate the instrument. The standard is then withdrawn, and the unknown is let into the instrument to obtain a new spectrum that is compared with that of the standard. It is assumed that there are no instrumental variations during this changeover. Generally, this technique is less reliable than when the standard and unknown are in the instrument together. Fourier-transform techniques are used with ion cyclotron mass spectrometers and give excellent mass accuracy at lower mass but not at higher. 

By high-resolution mass spectrometry, ions of known mass from a standard substance can be separated from ions of unknown mass derived from a sample substance. By measuring the unknown mass relative to the known ones through interpolation or peak matching, the unknown can be measured. An accurate mass can be used to obtain an elemental composition for an ion. If the latter is the molecular ion, the composition is the molecular formula. 

Note that many of the terms mentioned in this chapter are discussed in detail elsewhere in this book. For example, the theory and practical uses of electron ionization (El) are fully discussed in Chapter 3. 

All these methods and the methods of the preceding section have one characteristic in common an object may be part of only one cluster. Fuzzy clustering applies other principles. It permits objects to be part of more than one cluster. This leads to results such as those illustrated by Fig. 30.16. Each object i is given a value 

The assignment of the membership values is done by an optimization procedure. Of the many criteria that have been described, probably the best known is that of Ruspini [32]  

As described in the Introduction to this volume (Chapter 28), neural networks can be used to carry out certain tasks of supervised or unsupervised learning. In particular, Kohonen mapping is related to clustering. It will be explained in more detail in Chapter 44. 

There have been a few studies that do not seem to fit into any of the categories thus far identified. Moss [70] has made a number of high-precision nonadiabatic calculations on hJ both by variational methods that specifically include vibrational wavefunctions and by methods based on scattering theory. The same system has also been studied by Ackermann and Shertzer [71] using finite-element methods. Finally, we mention the very precise variational Monte Carlo studies of Ps2 and its generalization to four-charge systems of type M m M m by Bressanini et al. [72]. 

While the radioisotopic labelling method described above has some tmquestionable advantages, the fluorescence labelling method has its outstanding features as well the sensitivity of quantitative assays is at least comparable with isotopic methods. An amount of about 10 ng of polymer tagged with one mole of fluorochrome per thousand moles of monomer units can be quantitatively determined in biological 

Autoradiography can directly identify and localize radiolabelled polymers in tissues Autoradiograms have very impressively shown the overall topography of polymer distribution in whole-body or organ sections . Similar techniques have been adopted for fluorescence-labelled polymers.  

Although the tables presented by Parks and Huffman [1] are based on older data, they are often more convenient to use, because they are simpler and because they have been worked out for the liquid and the solid states as well as for the gaseous phase. A complete survey and analysis of methods of estimating thermodynamic properties is available in Janz s monograph [5], and in the work by Reid et al. [6]. Thermodynamicists should have a general acquaintance with more than one method of estimating entropies so they can choose the best method for a particular application. 

Poling et al. [6] also describe methods for estimation of additional properties, such as critical properties, P-V-T properties, and phase equilibria. 

In 1933, Brattain and Becker [259] measured the thermionic emission from a polycrystalline tungsten ribbon and its variation with adsorbate coverage to investigate thorium diffusion. Thorium was evaporated on to one side of the ribbon and they measured the thermionic emission (at 1274 K) from the other side after periods of holding the ribbon at an even higher temperature. As the thorium diffused to the reverse side, the thermionic emission from that side increased (since the work function is decreased) and from the rate of diffusion the diffusion activation energy was estimated. 

Renard and Deloche [261] examined the surface diffusion of physi-sorbed tritium on a single crystal Ni lll] surface. The gas was deposited as a patch with the crystal held at 4K and the concentration profile across the surface was determined by collection of the radiation emitted from tritium in a channeltron electron multiplier. For the diffusion experiments, the collector was positioned so as to collect radiation from a point well outside the original patch area and the sample was then heated to temperatures in the range 13—20 K. Desorption was also appreciable from, the physisorbed layer and so they derived the coverage-time relation (at fixed temperature) 

The linear methods have no provisions for bounds on 6(x). In principle, solutions are free to assume any value, as long as they satisfy the data i(x). We have shown that a problem of uniqueness results. Many functions are thus possible candidates—they all satisfy the data, or nearly so. Noise, which is always present in measurements, unfortunately provides the basis by which a linear method prefers one solution over another. 

It has been demonstrated both theoretically and computationally that a simple bound of positivity produces superior solutions, by eliminating many of the undesired solutions from the selection of possible solutions. Another 

Since the value of bounds has come to be widely accepted, numerous other effective bounded methods have appeared. Linear programming has provided the basis for a method presented by Mammone and Eichmann (1982a, 1982b). In a method loosely related to linear programming, MacAdam (1970) exploited the relationship between polynomial multiplication and convolution. His method is particularly suited to human interactive adjustment of constraints. 

In general, problems having solutions that vary radically or discon-tinuously for small input changes are said to be ill-posed. Deconvolution is an example of such a problem. Tikhonov was one of the earliest workers to deal with ill-posed problems in a mathematically precise way. He developed the approach of regularization (Tikhonov, 1963 Tikhonov and Arsenin, 1977) that has been applied to deconvolution by a number of workers. See, for example, papers by Abbiss et al (1983), Chambless and Broadway (1981), Nashed (1981), and Bertero et al. (1978). Some of the methods that we have previously described fall within the context of regularization (e.g., the method of Phillips and Twomey, discussed in Section V of Chapter 3). Amplitude bounds, such as positivity, are frequently used as key elements of regularization methods. 

In this chapter, we have detailed Frieden s maximum-likelihood approach. Other probability-based methods based on Bayes theorem have been explored by Richardson (1972), Lucy (1974), Hunt (1975, 1977), Mendes and DePolignac (1975), Mendes et al (1975), Trussed (1976), Kennett et al (1978a, 1978b, 1978c), Hunt and Trussed (1976), and Trussed and Hunt (1979). 

Although modern VB theory is by now well established, in various forms, it should be remembered that the foundations were all laid in the Pauling era. The first true multi-configuration theory was, in fact, that proposed by Serber [29] it was capable in principle of ab initio implementation and wets the precursor of severed group theoretical approaches, mostly betsed on the use of BD functions, which we mention before indicating the connection with Slater methods. 

The difference between (56) and (55) is important (56) requires explicit knowledge of N matrices, whose evaluation involves non-trivial algorithms [32] (see Ch.7 of 

As in the discussion above, let us use the operator (25) to extract, from an arbitrary Cl a component behaving like namely 

The fundamental result (18) may now be used to construct a totally antisymmetric wavefunction with spin included. This will be, for any choice of A, 

Unfortunately, the use of Slater determinants does not lead to any great reduction in computational problems, because (i) the numbers involved may be rather large and 

Some surface characterization techniques, such as Raman and infrared reflectance spectroscopies (see Appendix 3), have been used extensively in corrosion experiments in some laboratories, but the techniques are not considered sufficiently universal to be discussed here. Moreover, instrument operation and data interpretation are, at the moment, sufficiently complex and specialized that production of a series of protocols to suit most corrosion situations would be difficult. Other techniques such as XRD have been used frequently for routine characterization of thick corrosion layers (often after mechanical separation from the substrate). However, XRD has not been used on films much thinner than 2-3 pm, and, where it is used, a major problem has been the inability to determine the precise location of the various phases whose XRD patterns were reflected from the surface. Grazing-incidence XRD may provide some of this depth resolution in the future. Another technique on the horizon is SPM, which is described within the major corrosion application below. 

As part of the same application, the uses of electrochemistry are discussed. Electrochemical investigations can range from generalized studies aimed at understanding the mechanisms of corrosion of a metal in a particular medium to measurements of defect areas of failed specimens from the field. For the latter, defect areas can be masked off from noncorroded areas on the metal surface and numerous electrochemical procedures can then be applied in order to dc-tennine the film porosity and the chemical activity of the region. The studies on Monel 400 alloy corrosion described below represent a comprehensive approach to a corrosion problem. While, by itself, the work cannot claim to have solved the problem at hand, it has helped to develop confidence in the mechanisms proposed earlier, which were based on much less solid evidence. The experimental approach followed is based on some of the most practical choices facing a scientist or engineer who wishes to employ the techniques of modern surface science and electrochemistry to solve a practical problem. 

A strategy that seems feasible If the number of patterns Is lower than three times the number of dimensions uses cluster analysis of the features C1893- For this purpose, the data set Is Inverted features are treated as objects and the objects are treated as features. A cluster analysis (Chapter 7) shows whether there are groups of features with similar behaviour. One can then take one feature from each group and proceed with other feature selection methods. 

The SIMCA method (Chapter 6.3) can be used to delete features which have low modelling and discriminating power C81, 1893. 

The KNN-method (Chapter 3) C2283 and the progressive filter network (Chapter 5.5) C1703 have been proposed for feature selection. 

If only a small number of features Is retained after application of feature selection, then a trial-and-error method may be useful for the next step C2973. Individual features are preliminarily and randomly deleted. A feature Is definitively deleted If thereby the classification accuracy Is Improved. 

Number of Intrinsic Dimensions and Nuniber of Patterns (n/d - Problem) 

An approximate idea of the degree of swelling (the swelling index) experienced by a coal on carbonization may be obtained from the coke button left after the determination of volatile matter, but in many cases this measure of the swelling power is not sufficiently discriminating, principally because this is not the main function of the test. 

For this reason, a standard crucible test has been devised in which the chief features, compared with other tests, are the use of a leveled coal surface, a crucible of special shape and unidirectional heating by a gas flame. As a result, regularly shaped coke buttons are obtained and the degree of swelling is assessed by comparison with profiles of standard buttons. 

The conditions for obtaining the correct heating should be checked by means of a fine wire thermocouple inserted through a pierced lid having its unprotected junction in contact with the center of the base of the empty crucible. The end of the couple should be formed into a flattened loop so that the junction and a portion of each wire rests on the bottom of the crucible during a temperature measurement. The couple should be made of wires not heavier than 34-gauge platinum or 26-gauge base metal. 

As an extension of the proximate analysis or coal assay, it is worthy of note that new methods continued to be developed. For example, thermogravimetric analysis has been extended to cover determinations of volatile matter (as well as determination of moisture and ash) in coal and coke. These constituents can be measured by pyrolyzing the samples in oxygen and air, and the weight loss at prescribed temperatures was measured by using a thermobalance. 

Although in many laboratories the methods described above remain the methods of choice for determining the proximate analysis of coal, there is also a test method for the proximate analysis of coal by instrumental procedures, assuming that calibration is an integral part of the procedure (ASTM D-5142). This method covers the determination of moisture, volatile matter, and ash and the calculation of fixed carbon in the analysis of coal and coke samples prepared in accordance with standard protocols (ASTM D-2013). The results may require a correction for bias or be corrected for instrument calibration using samples of known proximate 

The reaction of hydroxylamine with an a,/3-unsaturated pyruvic acid (533) produced (534) (76TL1825). Hydroxylamines reacted with the nonconjugated ketoalkene (535) to produce (536) (73T2683). 

Azetidine N-oxides produce isoxazolidines by a thermal ring expansion (77AHC(21)207, 75GEP2365391), and nitrosobenzenes react with alkenes to provide isoxazolidines (77AHC(21)207, 79IZV1059). 

The reduction of 3,5-diphenylisoxazoline with sodium cyanoborohydride produced a mixture of isomeric 3,5-diphenylisoxazolidines. The H and NMR spectra were utilized to distinguish the isomers SOLAIOI). Sodium borohydride reductions likewise reduce isoxazolines to isoxazolidines (equation 56) (80JA4265). 

Treatment of (537) with acid chloride (538) in the presence of triethylamine produced isoxazolidine (539) in 45% yield (80IZV1694). 

This is a very selective survey of additional techniques Caldin, Hammes, and Hague give more complete treatments. 

The study of relative rates by the competitive method can be useful. The principle was discussed in Section 3.1 in the context of parallel reactions, for which the ratio of the product concentrations is equal to the ratio of rate constants (provided the concentrations are under kinetic control). 

In principle, MALDI-TOF (MALDI-Time Of Flight) analysis allows for the determination of the complete polymer mass distributions and, from that, the calculation of various molecular weight averages like Mn and Mw and the 

It needs to be pointed out, that the investigation of some technically important polymers like polyolefines has not been very successful so far. Owing to their inert nature they are difficult to dissolve and also difficult to ionize. Typically one needs for the ionization process some heterogeneities or double bonds in the polymer. For some insoluble substances a solvent-free sample preparation method has been developed that allows a characterization by MALDI-TOF mass spectrometry [93]. 

NMR allows the determination of molecular weight by near end [97] or end groups [98]. The method is limited to rather low molecular weights below 3 x 104 g / mol, because for higher molecular weight the number of end groups eventually 

In very few cases solid-state NMR has been used to determine molecular weights for polyethylene [99]. In general solid-state NMR is not so suitable due to the long relaxation times of the end groups, which lead to long measurement times. The strength of NMR is in chemical structure characterization and also the possibility to determine the chain branching, tacticity or to obtain further details of the microstructure. 

Capillary electrophoresis has also been combined with other analytical methods like mass spectrometry, NMR, Raman, and infrared spectroscopy in order to combine the separation speed, high resolving power and minimum sample consumption of capillary electrophoresis with the selectivity and structural information provided by the other techniques [6]. 

Recently, a flow-injection method has been reported in which pKa values are measured by UV absorbance after injection into a flowing phosphoric acid buffer [40], 

No mention of throughput was made. Measurement of pKa by UV after separation by CE has been described for acids [41] and bases [42], and while this method only requires small sample quantities, the rate of throughput is currently about 20 samples per day [23, 43], A rate-limiting step in the CE method is the need to make separate experimental runs at different buffered pH values in order to determine the relative concentration of ionized species at each pH. 

The linear buffer is created by mixing several weak acids and bases in varying concentrations such that the titration curve is linear in terms of pH, and the ionic 

240 nm. (B) Experiments to demonstrate the linearity of the pH gradient. Aliquots of acidic and basic buffers were mixed and the pH measured. pH results are the mean of two readings. Average SD of pH measurements between pH 3.0 and 11.6 was +0.004 pH. 

TFA is used for samples with weak absorbance changes or overlapping pKas. In TFA, absorbance (A) with respect to wavelength and pH is expressed as a matrix A. Two other matrices are set up. The C matrix shows the concentration (C) of each 

provide a waste water collection drum to collect all waste water that might contain substantial amounts of toluene from upset conditions. 

Additional changes were made in the operating and emergency procedure. They included 

checking the room air periodically with colorimetric tubes to determine whether any toluene vapors are present and 

The formal safety review can be used almost immediately, is relatively easy to apply, and is known to provide good results. However, the committee participants must be experienced in identifying safety problems. For less experienced committees, a more formal HAZOP study may be more effective in identifying the hazards. 

Other methods that are available for identifying hazards are the following  

Preparation of heteroatom-substituted carbene complexes by olefin metathesis. 

Donor-substituted alkynes can insert into the C-M double bond of alkoxycarbene complexes, yielding donor-substituted vinylcarbene complexes [191,192]. In addition to this, photolysis or thermolysis of a-alkoxycyclopropyl carbonyl complexes or a-alkoxycyclobutanoyl complexes can lead to rearrangement to metallacyclic carbene complexes (Table 2.11). This methodology has not been used as extensively for the preparation of carbene complexes as the other methods described above. 

Photolysis of cationic alkoxycarbene iron complexes [193] or alkoxycarbene manganese complexes [194] has been used to replace carbonyl groups by other ligands. The alkylidene ligand can also be transferred from one complex to another by photolysis [195], Transfer of alkylidene ligands occurs particularly easily from diaminocarbene complexes, and has become a powerful synthetic method for the preparation of imidazoline-2-ylidene complexes [155,196]. 

The reaction of alkoxy(aryl)carbene iron complexes with two equivalents of an isonitrile leads to the formation of azetidin-2-ylidene complexes [197]. For other reactions of Fischer-type carbene complexes with isonitriles see [198]. 

2 Synthetic Applications of Heteroatom-Substituted Carbene Complexes 

Davis studied the dehydration of urea nitrates as a route to iV-nitroureas. The nitrate salt of iV-methylurea undergoes dehydration-rearrangement on treatment with concentrated sulfuric acid to give Af-nitro-A -methylurea in 42 % yield. In this compound the nitro and methyl groups are attached to the same nitrogen and so its hydrolysis can provide a route to methylnitramine. In contrast, the nitrate salts of ethyl, n-propyl, n-butyl and n-amyl ureas, give iV-nitro-A -ethylurea (49 %), A -nitro-A -propylurea (60 %), iV-nitro-iV -butylurea (67 %) and iV-nitro-A -amylurea (67 %), respectively, on treatment with concentrated sulfuric acid. 

Bachman and co-workers reported the synthesis of 3,3 -dinitro-l,T-ethylenebisurea (179) by treating the dinitrate salt of ethylenebisurea (178) with cold concentrated sulfuric acid or by heating with acetic anhydride. 

Thermal decomposition of iron pentacarbonyl NB this is poisonous. 

A full range of ferrihydrites varying in crystallinity and with between 2 and 6 XRD lines (Schwertmann et ah, 1999) may be produced by  

02 M solution. Heat the solution at 98 °C for 7 d. A compact, bright red precipitate forms. Centrifuge, wash and dry the precipitate. This method gives ca. 3 g of fairly uniform, rhombohedral crystals. 

Hydrothermal transformation of ferrihydrite in a teflon bomb at 180 °C for several days yields platy crystals up to several pm in size (Schwertmann and Cornell, 2000). 

Decomposition of iron chelates (e. g. Fe-EDTA or a solution of Fe salt in the presence of triethanol amine) in alkaline media (pH 12) in an autoclave for one hour (Sapieszko and Matijevic, 1980). 

Very much less useful are the various kinds of simplified measuring devices found in many industrial plants and even in their technical support laboratories. Such devices may not be capable of determining shear stresses for known shear rates or may not be capable of operation at shear rates that are appropriate to the process under consideration. Instruments that are capable of absolute viscosity measurements provide the most useful information. 

There have now been attempts to determine rheological properties on the nanoscale. The nano-rheological properties (surface viscoelasticity) of emulsion droplets have been estimated through modelling based on data from atomic force microscope measurements [371]. 

Chromatography in hydroxylapatite gel is particularly suitable for application after the gel-permeation chromatography steps. The adsorption of proteins to the matrix is affected specifically by the pres- 

41) [96], and the resultant acyl oxyl radical XXXIII rapidly loses C02, leading to the carbamoyl radical XXXIV. The latter intermediate undergoes cyclization to yield the bicyclic radical XXXV. Subsequent reaction with oxygen and toluene (used as a solvent) finally leads to the bicyclic [3-lactame 100. The two diastereoisomers were isolated in a ratio of 5 1. Upon UV irradiation, the bridged tricyclic ketone 101 

Particles within the colloidal size range can also be made by breaking down massive gold by the input of the necessary energy.16 When this is mechanical, the process is termed attrition, but more useful is metal vapour synthesis 

In CVD, a volatile gold compound, usually Me2Au(acac) is caused to decompose on or near a supporting surface, with the formation of small particles that can be used as a model or conventional catalyst58-60 (Section 4.3.4). 

We should also note the availability of cluster compounds that contain assemblies of gold atoms numbering 13, 39 or 55 7,16,19 they are stabilised by phosphine or other ligands and are quite readily prepared. Some remarks on the physical properties of the AU55 cluster will be made later (Section 3.4). 

Gold nanotubes have been made by electroless plating within the 220 nm diameter pores of a polycarbonate membrane.66 

The purpose of this section is to introduce the main methods that are used to study the physical properties of small gold particles, to give their acronyms for subsequent use, and where necessary to add a few explanatory or cautionary words. These methods are already well described in the literature, so only brief treatments are necessary. A small selection of references to their use in studying gold catalysts will be included as an introduction to the relevant literature. 

The chemistry of pyrrolopyrroles has not been explored because of synthetic barriers. The synthesis of 1,4-dimethyl and 3,6-di-(-butyl-1 f/,4/f-pyrrolo[3,2-6]pyrrole has been described 

For self-propagation, the IMO burning rate test(p,121 in book M ) is suitable. In addition, the dust explosion test (p.223 in book 1 1 ) is recommended when combustible dusts are evaluated. 

Perturbation theory provides a clearly defined order parameter in the expansion for expectation values giving a least-biased indication of the importance of various terms. To quote Brandow 107 

The relationship between the coupled-electron pair approximation (c.e.p.a.) and the many-body perturbation theory has been discussed in detail by Ahl-richs.149 All of the methods denoted by c.e.p.a. (x) (x=0, 1, 2, 3) may be related to the summation of certain classes of diagrams in the many-body perturbation theory to infinite order. For example, c.e.p.a. (0), which is Cizek s linear approximation or Hurley s c.p.a. (0) ansatz150 is equivalent to the summation of all double-excitation linked diagrams in the perturbation series. This is also denoted d.e.m.b.p.t. (double excitation many-body perturbation theory) by some workers.151 168 

The method of single- and double-excitation configuration mixing is not size-consistent. The method remains size-inconsistent even if a multi-configurational reference function is used. For a configuration mixing calculation, with 

Hurley, Electron Correlation in Small Molecules , Academic Press, 1976. 

Bensted (B38) described the use of TG in the study of clinkers or unhydrated cements. At 4°Cmin in Nj with cements, losses normally occur at I00-200 C from gypsum or hemihydrate, 400-500°C from CH and 500-800°C from CaCOj. If a normal, open sample cup is used, the losses from conversion of gypsum to hemihydrate and from dehydration of hemihydrate are poorly resolved, making interpretation difficult. Better separation can be achieved by using a sample cup with a top that is closed except for a narrow exit (S32). 

Syngenite, if present, decomposes at 250-300°C. Small amounts of CH can occur due to hydration, and of CaCOj due to carbonation during i milling or storage, impurity in the gypsum, or, where specification allows it, deliberate addition. The increasing tendency to allow additions of sub-1 stances other than calcium sulphate may lead to the presence of other phases  

Applications of IR and Raman spectroscopy to the study of clinkers and unhydrated cements have been reviewed (B39,B40). The laser Raman microprobe, with which regions of micrometre dimensions on a polished surface may be examined, has been used to investigate structure and crystallinity, especially of the alite and belite (Cl9). Spectroscopic methods for studying the surface structures and compositions of cements are considered in Section 5.6.2. 

This is a good route to compounds that are functionally. substituted at silicon (entries 6-10). 

Alkanes can also be formed by the interaction of M-alkyl and Si-H species. 

This method was unsuccessful when R was the bulky CHjSiMes group (entry 11). A six-coordinate M(IV) adduct is probable intermediate in entries 12-15, and elimination of groups other than R + H from this adduct provides a reasonable explanation for the volatile products observed in entry 12 and the formation of cis-R3SiPt(H)L2 in entry 15. 

Elimination of hydrogen halide occurs both from M-H and Si-halogen (entry 18) and from M-halogen and Si-H systems (entries 17 and 19) a Lewis base must normally be added to drive the reaction from left to right (entries 17 and 18). 

By contrast, elimination of an amine to yield Si-M bonds has been achieved only between M-H and Si-N compounds (entries 20 and 21). 

Chiral separation using MIPs can also be achieved by bubble fractionation [63] and with MIP membranes [64-68], MIP particles selective for an amino acid derivative were used as collectors for enantiomeric enrichment by bubble fractionation. The method is envisaged to be a potentially powerful approach to process-scale separations [63]. 

Molecular imprinting is a technique with great potential. MIPs have found many applications and many more are likely to be developed. One of the first applications investigated was their use as CSPs, the subject of this chapter. A number of polymer systems has been developed and these have been used for the imprinting of different classes of chiral compounds. 

One of the advantages of MIP CSPs, in comparison with other CSPs, is that the material is designed directly for a specific molecule or class of molecules and that the elution order of the enantiomers is therefore known. 

To be able to attribute the binding of an MIP to an imprinting effect it is of utmost importance to show that specific recognition sites have been formed due to the presence of the print molecules during the polymerisation. This is usually done by comparisons with appropriate reference polymers. Polymers prepared without print molecules are not always the best choice, since the physical properties (surface area, porosity, etc.) of these polymers often differ from those of imprinted polymers. Reference polymers prepared with the optical antipode or a racemic mixture as the print species are preferred. The selectivity will be reversed when using the optical antipode and a racemic mixture will give a polymer incapable of separating the two enantiomers (unless the monomer(s) is/are chiral). 

The goal of any endeavour involving chromatographic separations is to achieve 

Monodomainic lath-like crystals up to 0,5-1 j,m long were synthesized by air oxidation (0.5 L/min) of a 0.2 M FeCl2 solution in a NH3/NH4CI-buffer at 50 °C and pH 6 (see Fig. 3-11) (Giovanoli and Briitseh, 1974). The pH was held constant by adding 0.1 M NH3 from a burette. The sample surface area was 15 m /g. 

Tabular lepidocrocite has been obtained by holding metallie iron particles in 0.25 M HNO3 at 70 °C and aerating for 6 hr at 1.5 L/hr (Kiyama etal. 1972). 

6- anhydro-D-altropyranose. The anhydro-epiglucosamine of Levene and Meyer is a 3-amino-D-altrose and probably has the 1,6-anhydro ring. 

A number of dihydro-1,2,4-triazines were prepared by alkylation of the corresponding 1,2,4-triazinones.230 235 

If t is not too small, the higher-order terms can be neglected and the reaction rate constant is given by 

2-Pyrone itself can be prepared via Prins alkylation of but-3-enoic acid with subsequent lactonisation, giving 5,6-dihydro-2-pyrone, which, via allylic bromination and then dehydrobromination, is converted into 2-pyrone. Alternative manipulation of the dihydropyrone affords a convenient synthesis of a separable mixture of the important 3- and 5-bromo-2-pyrones (see 11.2.2.4). 

Phosphine-catalysed addition of ethyl allene carboxylate to aldehydes also involves the construction of the 5,6-bond.  

The esterihcation of a 1,3-ketoaldehyde enol with a diethoxyphosphinyl-alkanoic acid, forming the ester linkage of the final molecule first, allows ring closure involving C-3-C-4 bond formation via an intramolecular Homer-Emmons reaction.  

The palladium-catalysed coupling of alkynes with a 3-iodo-a,P-unsaturated ester, or with the enol triflate of a P-keto-ester as illustrated below, must surely be one of the shortest and most direct routes to 2-pyrones.  

6-Chloro-2-pyrone is easily available by reaction of iran -glutaconic acid with phosphorus pentachloride.  

Information on the hydrolytic activity in marine sediments has been obtained from the use of model substrates labeled with fluorescent dyes such as methylumbelliferone (MUF) or fluorescein. These substrates may be small dimeric molecules, the hydrolytic cleavage of which releases the fluorescence signal, which is then indicative of the activity of specific enzymes such as glucosidase, chitobiase, lipase, ami-nopeptidase or esterase (Chrost 1991). Also large fluorescently labeled polymers such as the polysaccharides laminarin or pullulan have been used in experiments to demonstrate the mechanism and kinetics of bacterial degradation (Amosti 1996). 

This is contribution No 0331 of the Research Center Ocean Margins (RCOM) which is financed by the Deutsche Forschungsgemeinschaft (DFG) at Bremen University, Germatty. 

Following the last glaciation, the salinity of the oceans decreased due to melting of the polar ice caps. This decrease in chloride and sodium and other major ions of sea water has led to a lowered concentration in the pore water of the upper seabed. By using the equation for diffusion distance versus time (ca. 10,000 years), calculate how deep this concentration decrease has diffused into the seabed. Diffusion coefficients are given in Chapter 

Make sure that similar units are being used. 

Which of the following processes are energetically feasible (exergonic)  

Tsuda et al. have continued their studies on the palladium(0) catalysed decarboxylative allylation of 0-keto esters and 0-keto 

A pinacol-type rearrangement of epoxy silyl ethers has been used to prepare 0-hydroxy ketones, the migratory aptitudes observed 

Reagents i, Et30+BF,T ii, EtSH, NaOMe, MeOH iii, NalO, MeOH iv, CaCOj, PhH, v, H3POA, HC02H. vi. HCl, BunOH 

Cyclic Ketones. - Several interesting papers have appeared directed 

The annelation of cyclopentenone rings has also received some 

Troensgaard (1947) has used reduction with sodium and amyl alcohol to split proteins and has isolated a number of piperazines and pyrrole derivatives. The relationship of these products to structures in the original protein is not clear at present. 

Sol-gel techniques have also been used for film preparation. Magnetite has been prepared from sols formed from tris(acetylacetonate, CH3COCHCOCH3)FeIII, or Fe(acac)3 and a mixture of CH3COOH as 

Chemical vapour deposition (CVD), or more specifically, organo-metallic CVD can also be used to prepare ferrite thin films (Itoh, Takeda Naka, 1986). A mixture of acetylacetonate complexes of the desired metal is evaporated in a quartz boat (number 1 in Fig. 3.27) and is reacted with O2, which is introduced directly in the deposition zone. By adding a second furnace (B), an additional component evaporating at a different temperature can be transported to the substrate. Glass or MgO single crystals can be used as the substrates an annealing up to 1(X)0°C is performed on the film to improve its crystallisation. Spinel thin films (Ni, Ni-Zn) have been prepared by this method. 

Arc plasma has been used to deposit polycrystalline Ni-Zn, Mg-Mn spinels and garnets onto diverse substrates (Harris et ah, 1970). The arc gases are passed between concentric electrodes and rapidly heated by a dc arc. Fig. 3.29. The material to be deposited is injected as a fine powder with a carrier gas into the plasma. The film thickness is typically 1 pm with deposition rates of 2 pm/min. 

Plasmas are also used to provide a more reactive Oj atmosphere during molecular beam epitaxy of magnetite (Lind et al., 1991). In this technique, electrons are accelerated to impinge on a metallic target (Fe) to release metal atoms and deposit them on a substrate (the (001) face of MgO single crystals). Instead of flooding the deposition chamber with diatomic O2 gas, an oxygen plasma provides a reactive mixture of O and O which 

Single crystals are essential for certain applications as well as for fundamental studies. Magnetic properties such as anisotropy and magnetostriction (see next chapter) are not the same for all the crystal orientations. Investigation of basic magnetic phenomena is also simplified if single crystals are available. 

Second harmonic generation (SHG) sjjectroscopy is based on the same principles (two photons of frequency v are converted to one photon of frequency 2v). SFG has appeared to be the more successful and versatile technique to date. 

Jerome et al. demonstrated that a single PPY nanowire with a diameter of a few hundred nanometers could be prepared from a polyethylacrylate (PEA)-coated conducting 

A single PANl nanowire of 100 nm diameter was produced by electrochemical growth on gold electrodes modified with SAMs of thiolated cyclodextrins or 4-aminothiophenol (molecular templates) in alkanethiol [73,74]. Monomers were seeded to the surface within the isolated hydrophobic cyclodextrin cavities and initiated polymerization. While in these studies, the shape and directionality of the nanowires were not well controlled, they have demonstrated the possibility of growing individual CPNWs in selected locations using molecular templates. 

Wire growth by PPy polymerization from the foot of the channel 

4 Template-Free Controlled Electrochemical Growth between Electrodes 

It has been reported that the size and direetionality of the nanowire is very sensitive to synthetie eonditions sueh as eleetrode size, the gap between the electrodes, and magnitude and fiequency of the voltage/current, as weU as the concentrations of the monomers and electrolyte, etc. However, even if precautions are taken, control over the dimensions and directionahty of the grown single nanowire is limited. Variation of the wire size is common, and the wires can be knobbly. 

The theory of singular perturbations, arising from problems of limiting layers in fluid mechanics, also applies to kinetics, where the equivalent of the limiting layer is the true induction period, i.e. the period needed to establish the quasi-stationary state. The following differential system is considered  

The external solutions x(t) and y(t) constitute a satisfactory approximation when the following is true  

The following asymptotic conditions result from this  

The simplest external approximation of the system (71) is obtained by putting e = 0 the following system is then obtained  

This is a mixed system of differential and algebraic equations which possesses exactly the same structure as the system (35)-(36) resulting from the application of the QSSA. The same conclusions can be drawn as in the corresponding paragraph 2.1.a with respect to the interest this approximation has from a numerical point of view. 

We have mentioned previously that it is possible to reduce the Verlet method to a scheme involving positions only  

This is a type of a multistep method. Such methods may be studied using a generalization of the techniques used to understand one-step methods [167]. There are a variety of muitistep methods which could in principle be used for molecular dynamics, however, we regard the benefits as unproven in particular, such methods neglect the phase space structure such as the symplectic property. 

Another scheme which is sometimes used in molecular dynamics is Beeman s Algorithm [30, 331], 

Example 2.8 (Beeman s Algorithm) The method treats the positions and momenta differently, updating these from the formulas 

This method requires that the positions (and forces) be known at two successive points h apart in time in order to initialize the iteration. These might be generated by using the Verlet method or some other self-starting scheme. Beeman s algorithm is explicit since, given q , q - andp , one directly obtains q + and then, q i, and thus p +i, with only one new force evaluation. Because it is a partitioned multistep method, its analysis is more involved than for the one-step methods, and, in particular its qualitative features are difficult to relate to those of the flow map. The order of accuracy of the scheme above can be shown to be three. 

One of the challenges faced in both the laboratory- and large-scale water treatment plants is the fact that the samples have to be removed from the reactor vessel and the catalyst separated before the analysis. The use of a novel compact FL sensor for the in situ monitoring of the photocatalytic destruction of MB dye effluents was described by Robertson et al. [62]. The results showed that the instrument provides an effective method for in situ monitoring of the photocatalytic destruction of fluorescent dyes, hence allowing more accurate measurement because of the minimization of sample loss and cross contamination. Furthermore, a method for real time monitoring of the dye pollutant destruction in large-scale photocatalytic reactors was provided. 

Dip coating is a technique which provides uniaxial planar aligned columnar films onto substrate surfaces from solutions of compound 45 [179]. During the dip 

For most geochemical modeling purposes, only the pressure effect on G is required. The effect of pressure on S is  

Therefore the effect of pressure on H and S using the constant molar volume assumption ((9Vyd7)p = 0) is particularly simple. Equation (5.39) shows that there is no effect on 5, and integration of Equation (5.40) with (3V/97)p = 0 shows that the pressure effect on H is the same as that on G, that is, V P — 1). 

Equations (5.39) and (5.40) result in particularly simple expressions for an ideal gas, which are often useful. Substituting RT/P for V in Equation (5.39) leads to 

These results should make intuitive sense. Changing the pressure on an ideal gas does not change the fact that there are no interparticle forces, so there should be no effect of pressure on energy terms. However, it does change the ordering or arrangement of the particles, and hence the entropy. 

Up to here in this chapter we have discussed getting data only for solid phases. We have seen that the goal is to determine over a wide range of T and P (and that A G°= A G° at 25 °C, 1 bar for one widely used convention, but 

El Guebely and Sikkeland report an interesting method for preparation of extremely thin Pu sources. The basis of the method is adsorption of Pu(IV) onto glass or 

The method is not quantitative. Samartseva reports that adsorption of Pu(IV) is 97- 

Carswell and Milstead made thin sources of U and Pu by electrostatically focussing a jet of the material to be plated which was dissolved in a volatile solvent. 

The subject of the determination of the amount of alpha radioactivity has been re- 

The ratios of the isotopes of Pu can be determined by making use of the difference in the energies of the alpha particles in alpha pulse analysis. 

The signs are such that first, S(G) is antisymmetric second, if for an embedding of G in the plane one follows the edges of S around any even face (i.e. minimal ring) of this embedding, then the number of times a minus sign is encountered is odd. That is, if one proceeds around a ring of sites zj, 12,. .., i then 

Kasteleyn describes how this odd orientation is readily achievable for any planar graph. For instance, if one inserts arrows on edges of G so that an arrow from a 

Thus Ising-type graph enumeration on is equivalent to Kekule-structure enumeration on and indeed such correspondences have sometimes been used. But again correspondences between different types of enumerations seem to be quite frequent. The correspondence of Kekule structures to sets of mutually self-avoiding walks as noted in passing in Section 2.2 in connection with the John-Sachs method of enumeration provides yet another example of such a correspondence. 

The use of reactive magnetron sputtering allows more control of the structure and properties of the films due to the ease of adjusting deposition conditions [105]. 

High enantiomeric excess (after several cycles) 

These and other processes are not by any means widespread or generalizable, and they have not yet had an impact on the industrial preparation of enantiopure compounds, but are included as suggestions of where the vibrant and important field of the synthetic separation of enantiomers might go next Some of these methods also remind us of the prototypical synthetic separation of enantiomers that may have played a role in the origin of life. 

I thank Paul A Bartlett (UC Berkeley) and Craig Williams (University of Queensland) for helpful comments. 

(a) Jacques, J., Collet, A., and Wilen, S.H. (1981) Enantiomers, Race-mates and Resolutions, Chapter 4, Jon Wiley Sons, Inc., New York (b) 

and Wilen, S.H. (1994) Stereochemistry of Organic Compounds, Chapter 7, Wiley-Interscience, New York. 

If CS2 and cyanolysis are used with subsequent reaction with iron(///), the S concentration is determined from a standard additions curve (at 460 nm) by adding different amounts of sulphur using different volumes of the standard solution (Section 6.3.2.3). For procedure see Section 6.3.4. 

The seawater sample may contain substances that are extracted with chloroform and absorb light at 270 nm (method A). There are several ways to deal with this problem. One way is to use a less polar solvent, e.g., petroleum ether or hexane. Another method is to evaporate the solvent and bind the sulphur by cyanolysis and then determine SCN by com-plexation with iron(III) (see Section 6.3.4, method B). Standard additions to the sample will not solve the problem, but running a full spectrum on both the standard solution and the sample extract might disclose what the interfering substance is. 

In method B with CSa. solvent corrections have to be made for blank absorption due to reagent colour (FeCb) and chlorophyll, and other pigments extracted from the sample. The last can be removed by passing the extract through a filter column packed with a few cm of Florisil (Troelsen and J0rgensen, 1982 Chen etal., 1973). 

If the methods suggested here are not sensitive enough, one of the following methods 

Sulphite and thiosulphate have been determined by liquid chromatography after derivati-zation with 2,2 -dithiobis(5)nitropyridine (Vairavanmurthy and Mapper, 1990). At high levels of H2S sulphide should be precipitated with ZnCl2 Millero, 1991). 

The Laplace-space method of Rizzo and Shippy (1971) and Coen et al (1986) was, in fact applied by Coen et al to a two-dimensional simulation and appeared to be a success. As mentioned in Chapt. 5, the method has the decided disadvantage of being mathematically demanding. 

Orthogonal collocation in two dimensions has been used to simulate microdisk edge effects. The first paper in a series (5 up till now), by Speiser and Pons (1982) is a formidable tour de force. A two-dimensional set of polynomials is fitted to the grid and it leads, as in one dimension, to an easily solved set of ordinary differential equations. In the fifth part of this series of papers, Cassidy et al (1985), applied the method to electrode ensembles. This is obviously not for the occasional simulator, who is advised to use a simple technique and put up with the long computational times or use someone else s program but the method undoubtedly makes two-dimensional simulations efficient and accurate. 

Though conceptually simple, photochemical E to Z isomerization of double bonds is not an efficient approach for accessing geometrically pure alkenylboronic esters [253, 258]. Alkynylboronic esters, however, can be selectively hydrogenated over Lindlar s catalyst [276]. 1,4-Dioxane was found to be the optimal solvent for providing (Z)-l- 

The NF31/DMAP test described above also detects alcohols and phenols. 

An ethanol solution of commercial phenol formaldehyde resin (PFR) was sprayed on a stainless-steel plate [16]. The resin was cross-hnked at 150°C and caibonized at 800°C under N2 environment and further activated at 800°C in CO2 stream. 

Strano MS, Zydney AL, Barth H, Wooler G, Agarwal H, Foley HC (2002) Ultrafiltrabon membrane synthesis by nanoscale templating of porous carbon. J MembrSci 198(2) 173-186 

Strano MS, Agarwal H, Pedrick J, Redman D, Foley HC (2003) Templated pyrolytic carbon The effect of poly(ethylene glycol) molecular weight on the pore size distribution of poly(fufuryl alcoholyderived carbon. Carbon 41 (13) 2501-2508 

Rajagopalan R, Merritt A, Tseytlin A, Foley HC (2006) Modifieation of maeroporous stainless steel supports with silica sub-micron particles for size seleetive earbon membranes with improved flux. Carbon 44 (10) 2051-2058 

Merritt A, Rajagopalan R, Foley HC (2007) High performanee nanoporous earbon membranes for air separation. Carbon 45 (6) 1267-1278 

Reagents i, Bu Li ii. R COR (chiral, racemic) iii. separate diastereoisomers (chromatography) fv, heat 

Cross-coupling of aryl or benzyl halides with 2-ethoxyvinylboranes to give enol ethers can be achieved with catalysis by palladium salts under basic conditions [equation (9)].  

Acetone cyanhydrin and aluminium chloride may be used in place of hydrogen cyanide in the Gattermann formylation of aromatic compounds. Yields and substrate reactivities are comparable to those observed with the Gattermann procedure. The trimethylstannyl groups in stannyl-pyridines and -quinolines may be replaced regiospecifically by acyl groups by reaction with acyl chlorides. When the tin substituent is not at the 2-position, palladium catalysis is necessary, but this also leads to a small amount of formation of a bipyridyl [equation (10)1. 

Palladium salts also catalyse the formation of aryl ketones from organotin compounds, carbon monoxide, and arenediazonium salts. The method is applicable to the preparation of nitro-acetophenones, which are difficult to prepare under classical Friedel-Crafts conditions. 

Conditions have been defined for the preparation of acylsilanes by trapping acyl anions, formed from alkyl-lithium reagents and carbon monoxide, at low temperature with trimethylsilyl chloride. Acylsilanes have found use as hindered aldehydes, improving selectivity in the addition of ambident nucleophiles.  

As mentioned in 2.1.1.C, the catalytic activity for dehydration of isopropyl alcohol to propylene (rp) is proportional to the acidity of a catalyst. 

On the other hand, the activity for dehydrogenation of isopropyl alcohol to acetone (ra) is assumed to be proportional to the acidity and basicity of a catalyst, since the dehydrogenation is considered to proceed by a concerted mechanism, for example -  

ta/tp can be used as a measure of the basicity of a catalyst. In fact, a good correlation is found between rjrp and the amount of carbon dioxide irreversibly ad-sorbed.  

This method can be applied well to the basicity measurement of some oxidation catalysts such as V2O5 — K2SO4 — H2SO4 whose surface area is so small (about 0.7 m g that the accurate measurement of the eunount of carbon dioxide irreversible adsorbed is not easy.  

The other reactions which can be used to estimate the basic property of a solid are the decomposition of 4-hydroxyl — 4-methyl — 2-pentanone (diacetone alcohol) and the isomerizaiton of 1-butene.In the latter reaction, use of isotope tracer gives information regarding the activity of basic sites. 

This first initial report stimulated much interest in this type of chemistry. In 2007, Wng and co-workers reported the synthesis of core-shell structures that were dispersible in water through the use of several functionalized silanes. The key feature of this work was that the particles were directly protected with functionalized silanes (Fig. 7.5). The most important contribution of this approach is that different types of particles (oxides, metals, semiconductors) can be at the center of these core-shell structures. 

Because alkoxides of less electronegative metals are more susceptible to hydrolysis and therefore more difficult to functionalize, we chose to follow a different approach to obtain Pd ceria coreshell structures. A schematic showing the basic procedure is given in Fig. 7.6.  

In the first step, we synthesized Pd nanoparticles protected by 11-mercaptoundecanoic acid (MUA), referred to here as 

Rgure 7.6 Procedure to obtain dispersible Pd CeOz core sheU nanostructures by self-assembly of a cerium(IV) alkoxide around preformed Pd particles protected by 11-mercaptoundecanoic acid. Reprinted from Cargnello et Copyright 2010 the American Chemical Society. 

Current core-shell structures have the advantage of being dispersible in organic solvents, without any sign of agglomeration after several months. Therefore, they could be easily adsorbed onto supports and used for different applications, as we will demonstrate later in this chapter. 

Kinetic isotope effects come from the measurement of the WIcd rate ratio for a given reaction where an X-(H,D) bond is present in the substrate. The types of experiment involved and the intepretations that are permitted by the data have been discussed in detail in an important paper by Simmons and Hartwig.  

Care always needs to be taken with interpreting physical data because Nature has a thousand ways to mislead. An approach to test your conclusion is to ask if there is any combination of events that could falsify it. Devising good control experiments is critical for testing alternate explanations of the data. 

Girolami, T. B. Rauchfuss, and R. J. Angelica, Synthesis and Technique in Inorganic Chemistry, University Science Books, Mill Valley, CA, 1999 D. F. Shriver, The Handling of Air-Sensitive Compounds, McGraw-Hill, New York, 1969. 

Ebsworth, D. W. H. Rankin, and S. Cradock, Structural Methods in Inorganic Chemistry, Blackwell, Oxford, 1987. 

A variety of alternative synthetic strategies has been created for the generation of metal nanoparticles, aU of which make use of different ligands as stabilizers, reverse micelles, microemulsions, membranes, polyelectrolytes, and so on. 

Schiffrin approach [148-152], the method has certain limitations with regards to the compatibihty of the stabilizing thiol ligands with the other reagents. 

A number of other reports have been made relating to the use of surfactants, reverse micelles, microemulsions, membranes and polyelectrolytes for the synthesis of noble metal nanoparticles [157-159]. This type of synthetic method generally involves a two-phase system with a surfactant causing the formation of a microemulsion or micelle, and maintains a favorable microenvironment together with extraction of metal ions from aqueous phase to organic phase. In such cases, the surfactant not only acts as a stabilizer but also plays an important role in controlling crystal growth. 

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When there is significant random error in all the variables, as in this example, the maximum-likelihood method can lead to better parameter estimates than those obtained by other methods. When Barker s method was used to estimate the van Laar parameters for the acetone-methanol system from these data, it was estimated that = 0.960 and A j = 0.633, compared with A 2 0.857 and A2- = 0.681 using the method of maximum likelihood. Barker s method uses only the P-T-x data and assumes that the T and x measurements are error free. 

The most widely used reactions are those of electrophilic substitution, and under controlled conditions a maximum of three substituting groups, e.g. -NO2 (in the 1,3,5 positions) can be introduced by a nitric acid/sul-phuric acid mixture. Hot cone, sulphuric acid gives sulphonalion whilst halogens and a Lewis acid catalyst allow, e.g., chlorination or brom-ination. Other methods are required for introducing fluorine and iodine atoms. Benzene undergoes the Friedel-Crafts reaction. ... 

Finally, other methods are used to obtain simulated distillation by gas phase chromatography for atmospheric or vacuum residues. For these cases, some of the sample components can not elute and an internal standard is added to the sample in order to obtain this quantity with precision. 

Other methods for analyzing combustion products can be substituted for chromatography. Gravimetry can be used, for example, after a series of absorption on different beds, as in the case of water absorption in magnesium perchlorate or CO2 in soda lime infra-red spectrometry can be used for the detection of CO2 and water. 

The choice between X-ray fluorescence and the two other methods will be guided by the concentration levels and by the duration of the analytical procedure X-ray fluorescence is usually less sensitive than atomic absorption, but, at least for petroleum products, it requires less preparation after obtaining the calibration curve. Table 2.4 shows the detectable limits and accuracies of the three methods given above for the most commonly analyzed metals in petroleum products. For atomic absorption and plasma, the figures are given for analysis in an organic medium without mineralization. 

This method is applicable for mineral oil fractions whose molecular weight is between 290 and 500 and for < 60% and 40% < Cp< 70%. The analysis is fast, approximately 10 minutes, and the correlation with other methods is satisfactory. 

The other method is to employ the principle of corresponding states and calculate the Cp/ of the mixture in the liquid phase starting from the mixture in the ideal gas state and applying an appropriate correction ... 

Certain calibrated orifice instruments (Engler-type) provide viscosity measurements at temperature lower than pour point. This is possible because the apparatus agitates the material to the point where large crystals are prevented from forming whereas in other methods, the sample pour point is measured without agitation. 

When comparing the magnetic particle- and penetrant inspection with other visual methods it appears that our viewing eonditions are not so bad, compared with other methods. In radio-graphie the contrast on the film is mueh lower. In ultrasonies and eddy current the presentation times on the screen is shorter and the contrast is lower. 

The capillary rise method is generally considered to be the most accurate means to measure 7, partly because the theory has been worked out with considerable exactitude and partly because the experimental variables can be closely controlled. This is to some extent a historical accident, and other methods now rival or surpass the capillary rise one in value. 

The specific surface area of a solid is one of the first things that must be determined if any detailed physical chemical interpretation of its behavior as an adsorbent is to be possible. Such a determination can be made through adsorption studies themselves, and this aspect is taken up in the next chapter there are a number of other methods, however, that are summarized in the following material. Space does not permit a full discussion, and, in particular, the methods that really amount to a particle or pore size determination, such as optical and electron microscopy, x-ray or neutron diffraction, and permeability studies are largely omitted. 

Other methods for detennining the energy band structure include cellular methods. Green fiinction approaches and augmented plane waves [2, 3]. The choice of which method to use is often dictated by die particular system of interest. Details in applying these methods to condensed matter phases can be found elsewhere (see section B3.2). 

Once a sample is properly oriented and polished, it is placed into a UHV chamber for the final preparation steps. Samples are processed in situ by a variety of methods in order to produce an atomically clean and flat surface. Ion bombardment and aimealing (IBA) is the most conunon method used. Other methods include cleaving and film growth. 

Vibrational spectroscopy provides detailed infonnation on both structure and dynamics of molecular species. Infrared (IR) and Raman spectroscopy are the most connnonly used methods, and will be covered in detail in this chapter. There exist other methods to obtain vibrational spectra, but those are somewhat more specialized and used less often. They are discussed in other chapters, and include inelastic neutron scattering (INS), helium atom scattering, electron energy loss spectroscopy (EELS), photoelectron spectroscopy, among others. 

Other methods of sample introduction that are commonly coupled to TOP mass spectrometers are MALDI, SIMS/PAB and molecular beams (see section (Bl.7.2)). In many ways, the ablation of sample from a surface simplifies the TOP mass spectrometer since all ions originate in a narrow space above the sample surface. 

One of the most attractive features of the CIDNP multiplet effect is that it allows detennination of the sign of the J coupling, which is often difficult to do by other methods. 

In tenns of individual techniques, table B1.2T1 lists tlie breakdown totalled over time, counting from the inception of surface stmctural detennination in the early 1970s. It is seen that LEED has contributed altogether about 67% of all stmctural detenninations included in the database. The annual share of LEED was 100% until 1978, and has generally remained over 50% since then. In 1979 other methods started to produce stmctural detenninations, especially PD, ion scattering (IS) and SEXAFS. XRD and then XSW started to contribute results in the period 1981-3. 

The pump-probe concept can be extended, of course, to other methods for detection. Zewail and co-workers [16,18, 19 and 2Q, 93] have used the probe pulse to drive population from a reactive state to a state that emits fluorescence [94, 95, 96, 97 and 98] or photodissociates, the latter situation allowing the use of mass spectrometry as a sensitive and selective detection method [99, 100]. 

The method of Ishida et al [84] includes a minimization in the direction in which the path curves, i.e. along (g/ g -g / gj), where g and g are the gradient at the begiiming and the end of an Euler step. This teclmique, called the stabilized Euler method, perfomis much better than the simple Euler method but may become numerically unstable for very small steps. Several other methods, based on higher-order integrators for differential equations, have been proposed [85, 86]. 

Apart from the techniques described in this chapter other methods of organic film fonnation are vacuum deposition or film fonnation by allowing a melt or a solution of the material to spread on the substrate and subsequently to solidify. Vacuum deposition is limited to molecules with a sufficiently high vapour pressure while a prerequisite for the latter is an even spreading of the solution or melt over the substrate, which depends on the nature of the intennolecular forces. This subject is of general relevance to the fonnation of organic films. 

This makes it desirable to define other representations in addition to the electronically adiabatic one [Eqs. (9)-(12)], in which the adiabatic electronic wave function basis set used in the Bom-Huang expansion (12) is replaced by another basis set of functions of the electronic coordinates. Such a different electronic basis set can be chosen so as to minimize the above mentioned gradient term. This term can initially be neglected in the solution of the / -electionic-state nuclear motion Schrodinger equation and reintroduced later using perturbative or other methods, if desired. This new basis set of electronic wave functions can also be made to depend parametrically, like their adiabatic counterparts, on the internal nuclear coordinates q that were defined after Eq. (8). This new electronic basis set is henceforth refened to as diabatic and, as is obvious, leads to an electronically diabatic representation that is not unique unlike the adiabatic one, which is unique by definition. 

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