GB769827A - Improvements in or relating to the production of hydrochlorides of 2-aminothiazoles - Google Patents

Abstract

A process for the production of a 2-aminothiazole hydrochloride comprises reacting a compound of formula <FORM:0769827/IV(b)/1> wherein n is 1 to 3 inclusive, with thiourea or an N-substituted thiourea having one of its amino groups unsubstituted at an elevated temperature in the presence of an acid catalyst. N-substituted thioureas include those substituted with alkyl, aryl, cycloalkyl and aralkyl groups, e.g. methyl, ethyl, unsym.-dimethyl, unsym.-diethyl, tertiary-butyl, n-butyl, phenyl, unsym-. methylphenyl, para-methoxyphenyl and para-bromophenyl thioureas. The acid catalyst may comprise an aqueous solution of a strong mineral acid present in an amount between 0.1 and 5 per cent based on the weight of the reactants, and is preferably aqueous hydrochloric acid of 5-37 per cent strength. The 2-aminothiazole hydrochlorides are preferably isolated by adding to the reaction mixture (before or after completion of the reaction) a glycol-miscible organic liquid that is substantially a non-solvent for the resulting 2-aminothiazole hydrochloride, cooling the reaction mixture to a temperature of 0 DEG to -50 DEG C. and separating the solid product which precipitates. The glycol-immiscible organic liquid is preferably added in an amount equal to half to twice the volume of the reaction mixture and is preferably acetone, methylethyl ketone or methyl, ethyl, propyl or isopropyl alcohol. The 2-aminothiazole hydrochlorides may be neutralized to give the corresponding free bases. The glycol by-products may be isolated and reacted with a : b -dichloroethyl ethers to give chloromethylated cyclic glycol ether starting materials according to the process of Specification 758,425. In examples, thiourea is reacted with (1) 2-chloromethyl-1 : 3-dioxolane and (2) 2-chloromethyl-1 : 3 : 6-trioxocane to give in both cases 2-aminothiazole hydrochloride.