64736-53-4

A mixture of 137 g (1 mol) of 4,5-dichloroimidazole, 414 g (3 mol) of K2CO3 and 1,000 ml of carbon dioxide was stirred in an autoclave at 200° C. under autogenous pressure for 10 hours. The solid output was pulverized, suspended in 2 1 of water and brought to pH 3-4 with concentrated hydrochloric acid while being cooled with ice. The resulting precipitate was filtered off and recrystallized from water to give 136 g (75%) of 4,5-dichloroimidazole-2-carboxylic acid; mp. 240° C. (dec.).