Pyridazines. Part II. Reaction of polychloropyridazines with trimethylamine

Polychloropyridazines with trimethylamine give trimethylpyridazinylammonium chlorides, and these, with the exception of 5,6-dichloropyridazin-3-ylammonium chloride, undergo demethylation in the reaction mixture at room temperature, affording dimethylaminopyridazine derivatives. The position of substitution is governed by the steric requirements of the quaternary salt. Chloropyrimidines and cyanuric chloride are also dimethylaminated by trimethylamine. The structures of the products were established by reaction with nucleophiles and by hydrogenolysis.