Nitric Acid → 2-Methyl-5-nitroimidazole

Participants

Reaction Steps

Into a glass bottle of 750 ml, provided with a reflux condenser, 50 g of 2-methylimidazole was placed and while constantly stirring and cooling, 10 ml of sulphuric acid of 1.84 density were carefully and gradually introduced in such a way, that the temperature did not exceed 120° (2-methylimidazole is a free base and its transformation into the sulphate of 2-methylimidazole is a highly exothermic reaction). Then there was slowly introduced 20 ml of sulphuric acid and after lowering the temperature to about 50°, 100 ml of nitric acid with a density of 1.50 was poured in, and, if a too violent course of the reaction in the first stage was detected, the reaction could be inhibited by addition of several ml of nitric acid of 1.50 density. Then, after several minutes, as the intensity of the reaction and of the exothermic effect began to diminish sulphuric acid was added up to exhaustion of the entire quantity of 50 ml. After the sulphuric acid was added, the reflux condenser was removed and the temperature raised to 130°-150°. The solution remained for complete cooling and in a known manner, by means of neutralization with ammonia water, 4.5 g of 2-methyl-5-nitroimidazole were isolated corresponding to a yield of about 60% of theoretical.

Provenance & Evidence