1,1-Dithiols mercaptans

The polysulfide then reacts by a condensation polymerization with the difunctional and trifunctional chloro compounds. It is also possible to react cyclic S8 with a mercaptan-capped molecule or dithiol in a condensation reaction in the presence of a basic catalyst. An example is the reaction with ethanedithiol (reaction (10)) 56... 

Dithiols. Thiols and mercaptans (RSH) are similar to alcohols, as oxidizable reductants, but ate much stronger nucleophiles and usually couple to form disulfides ... 

The hydrolysis of thiol esters is achieved in either acidic or basic media. Alcoholic solutions of hydrogen chloride or potassium hydroxide are the most common reagents. Dithiols, hydroxy mercaptans/ and mercapto ethers, ketones, and acids have been prepared by this method. The corresponding thiol esters are obtained by the addition of thioacetic acid to oxides and olefinic acids or by the action of its potassium salt on halo ketones or sulfonic esters. ... 

The addition of other sulfur nucleophiles was reported by Jacobsen to be catalyzed by the same Cr(salen) complex 1 initially reported for the ARO with TMSNj. Benzyl mercaptan afforded the ring-opened hydroxy sulfides in excellent yield and 59-70% ee [17]. The moderate levels of enantioselectivity were improved by use of the dithiol 5, which afforded mixtures of bishydroxy sulfides in which the ee of the chiral product 6 was substantially enriched (Scheme 5). The sulfide products could be easily elaborated into the free thiols by reductive de-benzylation, providing access to the jl-silyloxy thiol 8 in optically pure form. 

Although the action of POClaF on an alcohol cannot compete with the hydrogen phosphite method for large-scale work, the (vmer was found extremely valuable for exploratory purposes. In particular, it was found possible to prepare diaryl phosphoro-fluoridates (e.g. (C,H50)aPOF) and diethyl phosphorofluorido-dithiolate (diethyl dithiofluorophosphonate, (CaH5S)aPOF) by the action of phosphorus oxydichlorofluoride on the appropriate phenol or mercaptan. 

Braun and Muijahn [75] reported that attempts to distill allyl mercaptan gave the pure product and a nondistillable residue. Braun and Plate [76] later reported that several other unsaturated mercaptans gave liquid polymers. Vaughan and Rust [77] obtained low-molecular-weight (less than 300) poly(alkylene sulfide) by the reaction of hydrogen sulfide and diallyl or diallyl ether. Coffinan [78] reported that polymeric alkylene sulfide of molecular weights to about 1300 were obtained by the reaction of dithiols with diolefins. 

Thiol group, sulfkydryl group, metcapto gro -SH, the functional group of thiols (mercaptans), i.e. the functional group of RSH, where R is the remainder of the molecule. T.g. may be structurally important as in Thiol enzymes (see), or functionally important as in Coenzyme A (see), Pantetheine-4 -phosphate (see), Lipoic acid (see), Thioredoxin (see), etc. The functional form of lipoic and thioredoxin is a dithiol. 

Polymers (XLIII-XLV) containing vicinal mercaptan groups were also synthesized from polyfvinyl alcohol) (56,57). The bromoacetal was elaborated with sodium allyloxide, and the allyl ether formed was converted to a dithiol by addition of bromine followed by substitution with KSH. The incorporation of free mercaptan groups was low ( 25 %) (Scheme VIII). These materials are polymeric analogs of 2,3-dithiol-1-propanol (BAL) and would probably be very efficient heavy metal scavengers. 

Reactions of Formaldehyde with Mercaptans. Reactions of formalde-ifvde with thio-alcohols or mercaptans are similar in many respects to those encountered with alcohols. According to Posner ", mercaptals or methylene dithiols are formed in a two-step lection, as indicated by the equations shown below in which the R of RSH stands for an alkyl, aralkyl or aryl radical. 

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