Alkyl Sulfur Compounds

The term naphthenic acid, as commonly used in the petroleum industry, refers collectively to all of the carboxyUc acids present in cmde oil. Naphthenic acids [1338-24-5] are classified as monobasic carboxyUc acids of the general formula RCOOH, where R represents the naphthene moiety consisting of cyclopentane and cyclohexane derivatives. Naphthenic acids are composed predorninandy of aLkyl-substituted cycloaUphatic carboxyUc acids, with smaller amounts of acycHc aUphatic (paraffinic or fatty) acids. Aromatic, olefinic, hydroxy, and dibasic acids are considered to be minor components. Commercial naphthenic acids also contain varying amounts of unsaponifiable hydrocarbons, phenoHc compounds, sulfur compounds, and water. The complex mixture of acids is derived from straight-mn distillates of petroleum, mosdy from kerosene and diesel fractions (see Petroleum). 

A problem associated with the use of abrasive metal poHshes is that the fresh metal, which has been exposed by the cleaning, rapidly oxidizes or tarnishes. Thus, many modem poHshes contain inhibitors. Sulfur compounds, eg, alkyl benzyl thiols, commonly are used, as are mercapto esters such as lauryl thioglycolate [3746-39-2] and dialkyldisulfides (52—54). 

Organosulfur Adsorbates on Metal and Semiconductor Surfaces. Sulfur compounds (qv) and selenium compounds (qv) have a strong affinity for transition metal surfaces (206—211). The number of reported surface-active organosulfur compounds that form monolayers on gold includes di- -alkyl sulfide (212,213), di- -alkyl disulfides (108), thiophenols (214,215), mercaptopyridines (216), mercaptoanilines (217), thiophenes (217), cysteines (218,219), xanthates (220), thiocarbaminates (220), thiocarbamates (221), thioureas (222), mercaptoimidazoles (223—225), and alkaneselenoles (226) (Fig. 11). However, the most studied, and probably most understood, SAM is that of alkanethiolates on Au(lll) surfaces. 

As seen in Figure 1, the organo sulfur compounds are methylated at the boiling point (90°C) of dimethyl carbonate, whereas methylation (or alkylation with other alkyl groups) of other functional groups requites higher temperatures. This has resulted in the selective methylation of sulfhydryl groups of compounds that contain other substituents that can be alkylated. The other substituents can then be alkylated at elevated temperatures (63). 

The overhead product is totally liquefied in the overhead condensers. A portion of the overhead liquid is pumped and returned to the tower as reflux. The remainder is sent to a treating unit to remove H2S and other sulfur compounds. The mixed Cj s and C s stream can then be fed to an ether or an alkylation unit. It can be fed to a depropanizer tower where the Cj s are separated from C4 s. The Cj s are processed for petrochemical feedstock and the C4 s are alkylated. 

Sulfoxides (R1—SO—R2), which are tricoordinate sulfur compounds, are chiral when R1 and R2 are different, and a-sulfmyl carbanions derived from optically active sulfoxides are known to retain the chirality. Therefore, these chiral carbanions usually give products which are rich in one diastereomer upon treatment with some prochiral reagents. Thus, optically active sulfoxides have been used as versatile reagents for asymmetric syntheses of many naturally occurring products116, since optically active a-sulfinyl carbanions can cause asymmetric induction in the C—C bond formation due to their close vicinity. In the following four subsections various reactions of a-sulfinyl carbanions are described (A) alkylation and acylation, (B) addition to unsaturated bonds such as C=0, C=N or C= N, (C) nucleophilic addition to a, /5-unsaturated sulfoxides, and (D) reactions of allylic sulfoxides. 

Ohta and coworkers used a bacterium, Corynebacterium equi IFO 3730, rather than a fungus, to oxidize eight alkyl phenyl and p-tolyl sulfides to their respective sulfoxides (119, 120) of configuration R. Virtually all of the sulfur compounds were accounted for as the sum of uncreacted sulfide, sulfoxide and sulfone. The enantiomeric purities of the sulfoxides obtained were quite good and are shown below in parentheses. The formation of the allyl sulfoxides in high optical purity is noteworthy. The authors believe that the sulfoxides were formed by enantioselective oxidation of the sulfides rather than by enantioselective oxidation of racemic sulfoxides, since the yield of sulfoxides was greater than 50% in five of the ten oxidations reported (see also Reference 34). 

Sulfur compounds are useful as nucleophilic acyl equivalents. The most common reagents of this type are 1,3-dithianes, which on lithiation provide a nucleophilic acyl equivalent. In dithianes an umpolung is achieved on the basis of the carbanion-stabilizing ability of the sulfur substituents. The lithio derivative is a reactive nucleophile toward alkyl halides and carbonyl compounds. 11... 

Further development in the area of alternate value-added products for improving economics included other oxygenated sulfur compounds [246,247], This invention included alkylated 2-(2-hydroxyphenyl) benzenesulfinic acid and 2-(2-hydroxyphenyl)-benzenesulfonic acid compounds and compositions which consist essentially of 2-(2-hydroxyphenyl) benzenesulfinic acid, 2-(2-hydroxyphenyl)-benzenesulfonic acid and/or substituted derivatives. The compositions are useful as hydrotropes and are also of use as, or as starting materials for, surfactants, and as starting materials for the synthesis of other useful chemicals such as, polymers and resins, solvents, adhesives, and biocides. 

Ishii, Y. Okumura, K. Kobayashi, M., and Suzuki, M., Microorganism capable of degrading alkylated heterocyclic sulfur compound Patent No. JP11009293. 1999, Jan. 19. 

Microorganism capable of degrading alkylated heterocyclic sulfur compound [155],... 

The researchers from Waseda University have been following the most recent GE strategy for developing improved biocatalysts with desulfurization activity. They hold two patents, the first concerns with the use of Mycobacterium frei WU-0103 strain in a method for decomposing heterocyclic sulfur compounds [169], This bacterium has the ability for desulfurizing DBTs, benzothiophenes, naphthothiophene, and their alkyl derivatives, at 50°C. Details about this strain and the method can be found in Section 2.2.3 in Chapter 3. 

The oxidation of thiophene and its derivatives with H202 was studied using a Ti-Beta molecular sieve. The oxidation product is very dependent from the aromaticity of model compounds. The thiophene oxidation product was mostly sulfates and the benzothiophene oxidation product was benzothiophene sulfone. Oxidation of mono and di-alkyl thiophenes also produced sulfates and sulfones. The diffusivity and aromaticity of the relevant sulfur compounds, intermediates and stable product, as well as the proposed new mechanism of oxidation will be discussed. This proposed new reaction pathway is different from current literature, which reports the formation of sulfones as a stable oxidation product. 

Used industrially as a chemical intermediate for alkyl carbonates and organic sulfur compounds. 

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