AbstractRing‐chlorination of 6‐trifluoromethyluracil in phosphorus oxychloride in the presence of triethyl, tri‐n‐propyl, and tri‐n‐butylamines was studied with respect to by‐product formation. Comparisons were made with the results obtained by treating the preformed chlorinated pyrimidine with triethyl amine in boiling toluene.Amination of chloropyrimidines by tertiary amines takes place by a Hofmann type reaction with substituent orientation generally in the 2 position of the ring. Yields of products depended on the base and reaction time. The rate of substitution in the 2 position is significantly enhanced by the presence of the trifluoromethyl group in the 6 position as compared with a methyl group.Heating preformed chloropyrimidines with tertiary amines in toluene, offers a satisfactory approach for the preparation of 2‐N,N‐disubstituted aminopyrimidines. For the formation of ring‐chlorinated pyrimidines in phosphorus oxychloride with a minimum of by‐products, tri‐n‐propylamine, after a short ref