Direct conversion to disulphide

The direct conversion of thioethers to unsymmetrical disulphides with thiocyanogen or sulphenyl thiocyanates has been studied in some detail. Early invest ations established that the S-trityl thioethers could be selectively oxidized in the presence of S-benzhydryl or S-benzyl thioethers [95] as well as in the presence of one or more disulfide bonds [100]. Molecules containing two 5-trityl thioethers can also be cyclized [104, 105] in good yield. The reaction of thiocyanogen with thiols... 

Polymerization is carried out at 40°C and is allowed to continue until a 90% conversion is reached. The latex is cooled to 20°C and tetraethylthiuram disulphide is added the product is then allowed to stand for about 8 hours until the desired molecular weight is reached. The latex is then acidified with acetic acid just short of coagulation, which is ultimately accomplished by freezing on the surface of a cooled (about — 15°C) rotating drum partially immersed in the latex. The resulting film of polymer is stripped from the roll, washed, dried in air at 120°C and cut into small pieces. This method of isolation is used because polychloroprene is tacky and it is difficult to coagulate the latex directly to crumb. 

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