Process for the preparation of isothiazolinones

摘要

Compounds of the general formula <IMAGE> are cyclised to the corresponding isothiazolinone using a carbonyl halide of the formula RCOX where R is halogen or alkyl and X is halogen. R3 and R4 are preferably such as to form a 5 or 6 membered ring. Useful carbonyl halides are phosgene and propionyl chloride. Using acyl halides such as propionyl chloride, a mixture of the isothiazolinone and a salt of the carboxylic acid can be obtained, for example an essentially equimolar mixture of 2-methyl-4,5-trimethyl-4-isothiazolin-3-one and sodium propionate