Vilsmeier adducts of dimethylformamide

Abstract

The reactions of dimethylformamide with cyanogen chloride and with thionyl chloride have been studied, and several of the products identified by spectroscopic methods. As in the case of a previously reported reaction between dimethylformamide and cyanuric chloride, Vilsmeier adducts are formed. For the cyanogen chloride reaction a mechanism is put forward that accounts for the products more satisfactorily than would the cyanuric chloride mechanism. Among the products, those identified are 3-dimethylamino-2-azaprop-2-enylidenedimethylammonium chloride, 3-(NN-dimethylcarbamoyl)-1,1-dimethylformamidine, 1,1-dimethylformamidine hydrochloride, 1,1-dimethylurea, 1,1-dimethylbiuret, dimethylamine-hydrochloride, and cyanuric acid. The cyanogen chloride adduct reacts with diphenylamine to form diphenylformamide. The adduct formed between dimethylformamide and thionyl chloride is fairly stable, but it does decompose slowly in air in a complex manner. Several of the products were identified. The adduct reacts with aniline to form 1,3-diphenylformamidine in addition to the expected 1,1-dimethyl-3-phenylformamidine.