The same benzyl-γ-butyrolactone was synthesized from reductivehydrogenolys is of methyl thiolbenzyl diester of benzylsuccinic acid (5) or methyl thiolethyl diester of benzylsuccinic acid (10) synthesized from benzylsuccinic anhydride. Also, reductive hydrogenolysis of ethyl thiolbenzyl diester of benzylsuccinic acid (15) synthesized from β-benzilidenesuccinic acid monoethyl ester (12) of known structure gave β-benzyl-γ-butyrolactone and it was found that this was identical with the lactone prepared in the above method. Accordingly, the position of benzyl group in the above lactone must be in β-position.
Catalytic hydrogenation of mercaptans with molybdenum sulfide was carried out with pressure.Either aliphatic or aromatic mercaptan was reduced to hydrocarbon with an initial hydrogen pressure at around 100 atmospheres and at a temperature below 300°C, and the reduction of benzyl mercaptan was effected at a temperature below 200°C. The product of this reaction was composed of corresponding hydrocarbon only and there was no formation of raductive condensation product;therefore, it is considered to be a simple reduction process. Also, the reaction of mercaptans was proceeded at a temperature slightly lower than the corresponding alcohols, indicating that the reduction of >C-SH bonding was more easily destroyed than that of >C-OH.