GB984811A - Process for the production of isothiazole and substituted isothiazole compounds - Google Patents

Abstract

The invention comprises 4-methyl, 5-methyl, 4-cyano, 4-phenyl- and 5-phenyl isothiazoles. These and other isothiazoles are prepared by reacting compounds of the general formulae R1-CH2-CR2 = CHR3 and R1-CH2-C ­ CR3, in which R1, R2 and R3 are like or different and represent hydrogen, alkyl, aryl, aralkyl, alkaryl, acyl, nitrile or alkoxy groups, with sulphur dioxide and ammonia in the presence of solid dehydrating, cracking or dehydrogenating catalysts. The preferred temperature range is 200-500 DEG C. Propylene is converted to isothiazole by the process of the invention. Instead of propylene isopropyl alcohol, which is converted to propylene under the reaction conditions may be used as starting material. Similarly tertiary butanol and n-butyl acetate may be used instead of the corresponding butylenes. Compounds which give sulphur dioxide, e.g. sulphurous acid, and ammonia, e.g. ammonium carbonate and ammonium carbamate, under the reaction conditions, may be used instead of sulphur dioxide and ammonia respectively. Examples are given of the conversion of (a) propylene to isothiazole; (b) isobutylene to 4-methyl isothiazole which on oxidation with permanganate gives isothiazole-4 carboxylic acid; (c) butene-2 to 3- and 5-methyl isothiazole; (d) allyl cyanide to isothiazole nitrile; (e) methacrylonitrile to 4-cyanoisothiazole; (f) a -methyl styrene to 4-phenyl isothiazole; (g) b -methyl styrene to 5-phenyl isothiazole; (h) tertiary butanol to 4-methyl iso thiazole; and (j) methyl acetylene to isothiazole.