NUCLEOPHILIC SUBSTITUTION REACTIONS OF 1-METHYL-4,5-DINITROIMIDAZOLE WITH AQUEOUS AMMONIA OR SODIUM AZIDE

Abstract

In this work, 5-amino-1-methyl-4-nitroimidazole was synthesized by amination reaction of 1-methyl-4,5-dinitroimidazole with aqueous ammonia in 95% yield. Meanwhile, one of its isomers, 4-amino-1-methyl-5-nitroimidazole as byproduct was obtained from the filtrate. Furthermore, nucleophilic substitution reaction of 1-methyl-4,5-dinitroimidazole with sodium azide gave 5-azido-1-methyl-4-nitroimidazole in 98% yield. The three compounds were characterized by IR, ¹H and ¹³C NMR spectra, melting points, and elemental analysis. The structure of 4-amino-1-methyl-5-nitroimidazole was further confirmed by single crystal X-ray diffraction. These reactions indicate that the nitro group at position 5 of 1-methyl-4,5-dinitroimidazole is quite unstable, as well as partial substitution of nitro group at position 4 also occured in aqueous ammonia. Only one nitro group of the two is involved in nucleophilic substitution reaction in each case.