Organosulfur compounds production

Multiple reactors achieve 95-96% conversion and recovery, and stringent air pollution legislation has now pushed this to 99%. A similar sequence of reactions is used for sulfur production from crude oil except that the organosulfur compounds must first be removed from the refinery feed and converted to H2S by a hydrogenation process before the sulfur can be recovered. 

Organosulfur chemistry is presently a particularly dynamic subject area. The stereochemical aspects of this field are surveyed by M. Mikojajczyk and J. Drabowicz. in the fifth chapter, entitled Qural Organosulfur Compounds. The synthesis, resolution, and application of a wide range of chiral sulfur compounds are described as are the determination of absolute configuration and of enantiomeric purity of these substances. A discussion of the dynamic stereochemistry of chiral sulfur compounds including racemization processes follows. Finally, nucleophilic substitution on and reaction of such compounds with electrophiles, their use in asymmetric synthesis, and asymmetric induction in the transfer of chirality from sulfur to other centers is discussed in a chapter that should be of interest to chemists in several disciplines, in particular synthetic and natural product chemistry. 

In most experiments the sulfur removed from the Mequinenza lignite appeared in two products, hydrogen sulfide and liquid organosulfur compounds (LOG) present in the THF-soluble extract There are three mechanisms by which these two sulfur-containing products could be produced from the lignite ... 

Many organosulfur compounds undergo biological oxidation at the sulfur atom to yield products which have pronounced physiological activity or serve as intermediates in generating bioactive compounds. Three examples are the lachrymating agent in onions ( ) (1), the oxo intermediate ( ) in metabolic desulfuration of phosphorothionate insecticides to form potent cholinesterase inhibitors (2), and the sulfoxides QJ produced on metabolism of thiocarbamate herbicides (3). 

The atmospheric sources and sinks of CS2 and COS are reviewed by Chin and Davis (1993). Oxidation of CS2 generates COS (discussed in the following section). COS is also generated by natural emissions, including photochemical production from organosulfur compounds in seawater (e.g., see Zepp and Andreae, 1994). 

Photoelectrochemical oxidation products can be obtained from organosulfur compounds. Thioethers can be cleanly converted to the corresponding sulfoxides,... 

Dimethyl sulfoxide, (DMSO) and dimethyl sulfone, (DMSO2) have been reported in rain water samples (lg). As is the case for MSA, the vapour pressures of these compounds are such that they are much more likely to be partitioned into heterogenous (aqueous) phases than to remain in the gas phase. A second aim of this work was to observe possible reaction pathways of these organosulfur compounds, which are also potentially stable oxidation products of dimethyl sulfide. 

Other Organosulfur Compounds. There have been reports of the microbial metabolism of other OSC. However, few of these studies have given the identities of intermediates or organic endproducts of the OSC. For example, aerobic cultures have been reported to remove sulfur from phenyl sulfide (62). Thioxanthene and thianthrene were transformed to water-soluble products by a dibenzothiophene-oxidizing bacterium (48). In addition, thianthrene and thioxanthene served as sole carbon sources for the aerobic thermophile S. acidocaldarius (69) which released sulfate from these compounds. 

Iron Post. The Iron Post coal is a high sulfur coal (Table I) from the northeastern Oklahoma shelf, which is associated with pyritic shales. FPD chromatograms of the pyrolysis products of two Iron Post coals of similar rank show that the distributions of organosulfur compounds produced by pyrolysis of these two coals are quite similar (Figure 7). This supports the idea of a relationship between rank and organosulfur compound distribution in the pyrolysates of coals. 

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