Ethyl thiobenzoates, preparation

The preparation of thioesters by Fischer esterification is not very effective, however, because the equilibrium is normally unfavorable. Under conditions in which ethanol is converted to ethyl benzoate to the extent of 68%, ethanethiol gives only 15% ethyl thiobenzoate. 

Sulfhydryl compounds are oxidized with ease to disulfides. It is necessary to employ mild oxidizing agents that do not attack the product. Oxidation of an alkaline solution of n-amyl mercaptan by iodine is described for -amyl disulfide (68%). A mixed disulfide, ethyl /-butyl disulfide, is obtained in 63% yield by treatment of an equimolecular mixture of ethyl and /-butyl mercaptans with iodine in ethanol. Hydrogen peroxide is probably the best reagent for the oxidation. " Halo and amino groups in the molecule are unaffected. Benzoyl disulfide, CtHsCOSSCOCjH, is conveniently prepared by the iodine oxidation of the potassium salt of thiobenzoic acid, C4H5COSK. ... 

Analogous to the synthesis of l,4-benzodioxepin-5-ones, the benzoxathiepinones (166) were prepared by the reaction of ethyl 2-thiobenzoates with chlorohydrin and glycerol chlorohydrin and cyclization of intermediate (165) (Scheme 17) <75BSF277>. The sodium borohydride reduction of bienzoxathiepinone (167) has also been studied <82NJC149>. 

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