Pyrimidine reactions. XXIV. The dehalogenation of 2-halogenopyrimidines by hydriodic acid

Abstract

2-Halogenopyrimidines underwent dehalogenation conveniently on treatment with hot hydriodic acid; 4,6-dimethyl-, 4,6-diphenyl-, 5- methyl-, 4-methyl-, and 4-amino-pyrimidine were so prepared from their respective 2-chloro derivatives, of which the second and third were made by improved methods; unsubstituted pyrimidine was obtained similarly from its 2-chloro, 2-bromo, or 2-iodo derivative, of which the last was made in a pure state for the first time. In contrast, 4- chloro-2,6-dimethylpyrimidine underwent hydrolysis in hot hydriodic acid and transhalogenation to give its 4-iodo analogue at lower temperatures; both 2-chloro-4-methoxy-pyrimidine and 5-chlorouracil gave uracil with hot hydriodic acid; and 4-chloro- 2,6- dimethoxypyrimidine gave 6-iodouracil under similar conditions.