Low temperature nitration of 2-methylimidazole gave 2-(dinitromethylene)-4,5-imidazolidine-dione (1) in 33.9% yield (16.8% in literature). Ring cleavage of 1 to FOX-7 was achieved by liquid alcohols for the first time and reaction conditions were optimized. The effect of methanol, formic acid and aqueous ammonia as nucleophiles on the ring cleavage of 1 was investigated. It was found that methanol was a better nucleophile than other alcohols with 94.6% yield of FOX-7 (87.4% in literature). Methanol adduct 2, the first adduct of 1, was synthesized and characterized. The reaction mechanisms of ring cleavage and parabanic acid formation were discussed.

Key words: methanol, 1,1-diamino-2,2-dinitroethylene (FOX-7), reaction mechanism, ring cleavage, 2-(dinitrome-
thylene)-4,5-imidazolidinedione, adduct