Thioethers mercaptals

Citral diphenyl mercaptal refluxed 0.5 hr. with 0.5 equivalent BFg in benzene -> product. Y 80%. Also cycloisomerization of thioethers and sulfones with BFg or H2SO4 s. S. Torii, K. Uneyama, and M. Ishihara, Chem. Lett. 1975, 479. 

A soln. of tert-dimy alcohol in DME added to a suspension of Ni(II)-acetate, 2,2 -bi-pyridyl, and NaH in the same solvent at 63° under N2, the mixture stirred for 2 h, a soln. of dibenzothiophene in DME added over 2-3 min, and worked up after 5 h - biphenyl. Y 98%. The reagent efficiently desulfurizes S-heteroaromatics, ar. thioethers, sulfoxides, sulfones and mercaptals (although the efficiency of the last depends on the nature of the substituents on the S atom). F.e.s. S. Becker et al.. Tetrahedron Letters 29, 2963-6 (1988). 

Zinc iodide Mixed mercaptals from aldehydes and mercaptans via l-(acylthio)thioethers... 

Controlled reductive desulfuration Thioethers from mercaptals C(SR)2 -> CH(SR)... 

Hydrocarbons from alcohols via bromides s. 18, 125 Replacement of hydroxyl by hydrogen via mesylates and iodides s. 19, 114 via mesylates and benzyl thioethers s. 16, 107 via ketones and cyclic mercaptals s. 16, 138 OH H... 

However, more recent experiments of V. Macho [135,136] and L. Marko et al, [137-144, 829, 913, 953-955] showed that these assumptions have to be corrected. They proved that some sulfur compounds (e.g. saturated thioethers and thiophene) are practically of no harm to the hydroformylation, but that other compounds (e. g. COS, HgS, unsaturated thioethers, mercaptans, mercaptals, disulfides, CSg and elementary sulfur) inhibit the 0X0 reaction by forming sulfur-containing cobalt carbonyls which are inactive as oxo catalysts and less soluble than carbonyls. In the course... 

Controlled reductive desulfuration Thioethers from mercaptals... 

Bdhme prepared chloromethyl ethyl thioether (or chloromethyl ethyl sulfide) in 60 i>e.r cent yield Iry saturating an ice-cold mixture of alpha-polyoxymethylene and ethyl mercaptan with hydrogen chloride until a clear liquid was obtained. After treatment with calcium chloride, the product separated as a separate phase with loss of unreacted hydrogen chloride, and was purified by dtstillation. It is a colorless liquid with an unpleasant odor which boils at 128-131°C. It is quite stable when pure. On treatment with water, it- forms methylene diethyl mercaptal mth liberation of formaldehyde and hydrogen chloride. 

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