Herbicidal (S)-benzyl-thiocarbomate(s) prodn. - from (O)-alkyl thiocarbamate(s) and benzyl chloride(s)

摘要

Prepn. of S-benzylthiocarbamates of formula (I) comprises reacting an O-alkyl ester of formula R1R2N.CSOR5 (II) with a benzyl chloride (III) opt. in presence of a bivalent metal halide catalyst and of an inert organic solvent. In the formulae, R1 is 1-4C alkyl, R2 is 1-4C alkyl or cyclohexyl or R1+R2 together are 4-6C polymethylene; R3 and R4 are each H, Cl or 1-4C alkyl, alkoxy or alkylthio; and R5 is 1-3C alkyl. (I) are know herbicides, e.g. S-(5-(4-chlorobenzyl)N,N-diethylthiocarbamate. (Ia) which is useful in rice crosp. Reactants such as COCl2 and COS are not required. Typically (Ia) is obtd. with a yield of 88% as a crude prod. of purity 97% c.f. a yield of 78-79.5% in previous processes.