Acyl thiocyanates—III: The synthesis of stable Aroyl thiocyanates

Two methods are devised for the synthesis of aroyl thiocyanates. One method is based on the thermal breakdown of 5-aroylthio-1,2,3,4-thiatriazoles to aroyl thiocyanates, nitrogen and sulfur. The other method is based on the reaction between thioacid salts and cyanogen halides. The latter synthesis also gives rise to diacyldisulfides. A hypothesis for the disulfide formation is advanced. These investigations have revealed that 2,4,6-tribromobenzoyl- and 2,4,6-tridobenzoyl thiocyanate are stable compounds which can be kept at room temperature for prolonged periods without decomposition, while 2,6-dimethyl-4-nitrobenzoyl and 3,4,5-trimethoxybenzoyl thiocyanate are of intermediate stability. The former thiocyanates are the first examples of stable acyl thiocyanates.