Structure and reactivity of nitrosocimetidine.

The major product of reaction of cimetidine in 2 M hydrochloric acid in the prescence of excess sodium nitrite is a mono-nitroso derivative, the structure of which has been determined by the application of field desorption mass and proton magnetic resonance spectrometry. The methylating ability of nitrosocimetidine in phosphate buffer at pH 7 towards 3,4-dichlorobenzenethiol is comparable to that of the known gastric carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine.