Organosulphur compounds

Andreae [89] has described a gas chromatographic method for the determination of nanogram quantities of dimethyl sulphoxide in non saline waters, sea water and phytoplankton culture waters. The method involves a chemical reduction to dimethyl sulphide, which is then determined gas chromatographicedly using a flame photometric detector. 

Andreae [89] investigated two different apparatus configurations. One consisted of a reaction-trapping apparatus connected by a six-way valve to a gas chromatograph equipped with a flame ionisation detector the other apparatus combined the trapping and separation functions in one column, which was attached to a flame photometric detector. The gas chromatographic flame ionisation detector system was identical to that described by Andreae [89] for analysis of methylarsenicals, with the 

Source Reproduced by permission from the American Chemical Society [89] 

Other applications to the determination of organic sulphur compounds in non saline waters are discussed in Table 15.9. 

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Chiral sulphoxides are the most important group of compounds among a vast number of various types of chiral organosulphur compounds. In the first period of the development of sulphur stereochemistry, optically active sulphoxides were mainly used as model compounds in stereochemical studies2 5 6. At present, chiral sulphoxides play an important role in asymmetric synthesis, especially in an asymmetric C—C bond formation257. Therefore, much effort has been devoted to elaboration of convenient methods for their synthesis. Until now, optically active sulphoxides have been obtained in the following ways optical resolution, asymmetric synthesis, kinetic resolution and stereospecific synthesis. These methods are briefly discussed below. 

A great achievement of the stereochemistry of organosulphur compounds was the stereoselective synthesis of optically active sulphoxides developed by Andersen in 1962342. This approach to sulphoxides of high optical purity, still most important and widely used,... 

Aliphatic hydrocarbons, triazine, substituted urea type and phenoxyacetic acid types of herbicides, Fluazifop and Fluazifop-butyl herbicides, ethylene diamine tetracetic acid salts in soil, aliphatic and polyaromatic hydrocarbons, phthalate esters, various organosulphur compounds, triazine herbicides, optical whiteners, mixtures of organic compounds and organotin compounds in non-saline sediments, aromatic hydrocarbons, humic and fulvic acids and mixtures of organic compounds in saline sediments and non-ionic surfactants and cobalamin in sludges. 

In non-saline sediments aliphatic and polyaromatic hydrocarbons, phthalate esters carboxylic acids, uronic acid aldoses chloroaliphatics haloaromatics chlorophenols chloroanisoles polychlorobiphenyls polychlorodibenzo-p-dioxins poychlorodibenzofurans various organosulphur compounds, chlorinated insecticides, organophosphorus insecticides mixtures of organic compounds triazine herbicides arsenic and organic compounds of mercury and tin. 

The analysis of organosulphur compounds has been greatly facilitated by the flame photometric detector [2], Volatile compounds can be separated by a glass capillary chromatographic column and the effluent split to a flame ionization detector and a flame photometric detector. The flame photometric detector response is proportional to [S2] [3-6]. The selectivity and enhanced sensitivity of the flame photometric detector for sulphur permits quantitation of organosulphur compounds at relatively low concentrations in complex organic mixtures. The flame ionization detector trace allows the organosulphur compounds to be referenced to the more abundant aliphatic and/or polynuclear aromatic hydrocarbons. 

Reliable flame photometric detector quantification of organosulphur compounds requires careful optimization of the gas chromatograph parameters. Although the relative response of the flame photometric detector to various sulphur compounds remains somewhat controversial [7], analysis of organosulphur compounds by flame photometric detector is now relatively straightforward. 

In a method described by Bates and Carpenter [8] for the characterization of organosulphur compounds in the lipophilic extracts of marine sediments these workers showed that the main interference is elemental sulphur (S8). Techniques for its elimination are discussed. Saponification of the initial extract is shown to create organosulphur compounds. Activated copper removes S8 from an extract and appears neither to create nor to alter organosulphur compounds. However, mercaptans and most disulphides are removed by the copper column. The extraction efficiency of several other classes of sulphur compounds is 80-90%. Extracts are analyzed with a glass capillary gas chromatograph equipped with a flame photometric detector. Detection limit is lg S and precision 10%. 

Jensen et al. [45, 46] also discuss complications in analysis due to the presence of elementary sulphur and organosulphur compounds in the gas chromatographic determination of DDT and polychlorobiphenyls in sediments and sewage sludges. 

Przyjazny, A., Janicki, W., Chrzanowski, and Staszewki, R. Headspace gas chromatographic determination of distribution coefficients of selected organosulphur compounds and their dependence of some parameters, J. Chromatogr. A, 280 249-260, 1983. 

While the sulphur values associated with gas, oil and bitumens are either in the form of H2S or organosulphur compounds coals can have significant inorganic sulphur values. This introduces the possibility of desulphurisation by chemical methods different from that required for removal of organic sulphur values. Nonetheless, the desulphurisation problems associated... 

Less easily accomplished under readily accessible surface conditions, however, is the high temperature and pressure hydrolysis of organosulphur compounds, eg. 

Recent work ( ) with model organosulphur compounds has shown that at temperatures above 350 C and pressures in excess of 100 atm (1500 psig), the hydrolytic desulphurisation reaction occurs readily with thioethers, mercaptans and other non-thio-phenic types of organosulphur compounds. Thiophene itself is more resistant to this type of reaction but desulphurisation is significant in the 450 - 500 C range. More complex fused ring sulphur containing aromatic structures, can, however, be more reactive. 

Much remains to be learned about the reactions of organosulphur compounds at the elevated temperatures and pressures that can be readily achieved in in situ recovery processes. The use of the natural formation as the chemical reactor permits the attainment of reaction conditions that have previously been out... 

J. F. Liebman, K. S. K. Crawford and S. W. Slayden, Thermochemistry of Organosulphur Compounds , Chap. 4 in The Chemistry of Groups, Supplement S The Chemistry of Sulphur-containing Functional Groups (Eds. S. Patai and Z. Rappoport), Wiley, Chichester, 1993. 

Reduced organosulphur compounds Flame photometric Cryogenic trapping used to minimise losses, sulphur compounds then revolatilised by controlled heating and injected into GLC column [343]... 

Organosulphur compounds Purge and trap analysis GC- microwave induced atomic emission spectrometry ppt [348]... 

Organosulphur compounds — Open tabular column Chemiluminescence 1 ppb [504, 505]... 

Table 15.10 presents a summary of the applications of gas chromatography to the determinations of other organic compounds, including chlorofluoroparalfins, carboxylic acids, monosaccharides, organosulphur compounds, polychlorobiphenols and azine herbicides in seawater. 

Sulphonic acids (-S03H) and sulphonates (—SOf). Sulphonic acids and sulphonates are the most studied organosulphur compounds, due to the quite narrow line widths of their 33S resonances (Table A.5). 33 35 38 37 63... 

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