S(=O)(=O)(O)O.[CH3:6][C:7]1[NH:8][CH:9]=[CH:10][N:11]=1.NC(N)=O.[N+:16]([O-])([OH:18])=[O:17]>O>[CH3:6][C:7]1[NH:8][CH:9]=[C:10]([N+:16]([O-:18])=[O:17])[N:11]=1A mixture of 3,735 parts of sulfuric acid (35.5 percent by weight), 1,135 parts of 2-methylimidazole, 565 parts of urea, 3,495 parts of nitric acid (33 percent by weight) and 1,625 parts of water is reacted continuously in a three-stage cascade (consisting of 3 reactors each with a distillation column and reflux condenser) for 6 hours at from 125° to 130° C. During the reaction, 2,088 parts of 33 percent strength by weight nitric acid distil off. The reaction mixture is then diluted with a 3.5-fold volume of water whilst cooling and is neutralized to pH 3-4 with ammonia solution. The 2-methyl-4-nitroimidazole which separates out is centrifuged off, washed, dried and recrystallized from water. 1,475 parts of 2-methyl-4-nitroimidazole (83.5% of theory) of melting point 145°-146° C. are obtained.
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