The Nitration of Brominated Pyrazoles in Aqueous Sulfuric Acid

Abstract

Nitration in 80% sulfuric acid of 4-bromopyrazoles gives rise to considerable nitrodebromination. Compounds with no alkyl or aryl substituent on nitrogen give only the 4-nitro products (except 4-bromo-3-phenylpyrazole which gives the p-nitrophenyl compound). N-Alkyl-4-bromopyrazoles give products of nitrodebromination as well as those arising from nitration in the 3- and/or 5-positions. N-Aryl-4-bromopyrazoles can also undergo nitration of the aryl substituent.