GB1411476A - Production of 4-nitroimidazoles - Google Patents

Abstract

1411476 4-Nitroimidazoles BADISCHE ANILIN- & SODA-FABRIK AG 23 Feb 1973 [25 Feb 1972] 8939/73 Heading C2C 4-Nitroimidazoles of general Formula I wherein the individual radicals R are identical or different and are each hydrogen or an optionally substituted aliphatic, araliphatic or aromatic radical, are obtained by nitration of the imidazole of Formula II with HN0 3 in the presence of H 2 SO 4 and urea at >200‹ C. (e.g. up to 260‹ C.). The nitric acid may be produced in situ in the reaction mixture and a gas inert under the reaction conditions (e.g. N 2 ) may be passed through the reaction zone during the reaction. Nitric acid of density 1.38-1.52 and sulphuric acid of density 1.82-1.87 are preferred and the molar ratio of HNO 3 /H 2 SO 4 , is generally from 0.2/1 to 2/1. The nitration may be carried out batchwise or continuously using 1-5 moles HNO 3 per mole of starting imidazole II and 10-100% by weight of urea based on II. Specified apparatus for carrying out the nitration are a vertical, coiled tube having heating means and a falling film evaporator. The examples describe the nitration of (1) 2 - methylimidazole, (2) 2 - p - nitrophenylimidazole, (3) 2,5 - dimethylimidazole, (4) imidazole, (5) 2 - ethylimidazole and (6) 2- isopropylimidazole, the 4-nitroimidazoles being used as polymerization catalysts. Other specified starting materials are 2- benzylimidazole, 2 - phenylimidazole, 2 - otolylimidazole, 2 - n - propylimidazole, 2 - nbutylimidazole, 2,4 - dimethylimidazole, 2- neopentyl - 4 - ethylimidazole, 2 - tolyl - 4- phenylimidazole, 2,4 - diethylimidazole, 2,4- dibenzylimidazole and 2,4-diphenylimidazole.