Continuous process for making a dialkyltin thiocarboxylic acid ester

摘要

A method for reducing fifty-fold the size of equipment required for making a given volume of alkyltin thioglycolic acid esters. An alkyltin thiocarboxylic acid ester is made from the corresponding alkyltin halide and thiocarboxylic ester in a continuous process that requires but one agitated reaction vessel. The organic reactants and an acid acceptor are added simultaneously to a reaction vessel equipped with agitator impellers and containing a sufficient level of water to provide an agitatable medium. Extremely vigorous agitation (at least 75, preferably at least 90, turnovers per minute, which is sufficient to achieve a fluid velocity across the impeller(s) of at least 15.2m or 50 feet per minute) is employed to avoid side reactions which often cause the formation of a tenacious, stringy emulsion, the breaking of which requires a rather difficult and wasteful filtration. Continuous withdrawal of the reaction mixture from said reactor is commenced promptly after commencement of the additions and said mixture is continuously separated into an aqueous phase and an organic phase as it is withdrawn without the need of demulsification means. The pH of the reaction mixture is greater than 7 but the maximum is 8.2 and the temperature is from 40 to 80 DEG C.