Nitric Acid → 4-nitro-1H-pyrazole-3,5-dicarboxylic acid

Participants

Reaction Conditions

Reaction Steps

Fuming sulphuric acid (105 ml) was added dropwise over 45 minutes to ice-cooled finning nitric acid (88 ml), so as to maintain the internal temperature below 20° C. Once addition was complete the mixture was warmed to 40° C., pyrazole-3,5-dicarboxylic acid (125 g, 0.80 mol) added portionwise over 75 minutes, so as to maintain the reaction temperature below 50° C., and the reaction then stirred at 60° C. for 18 hours. The cooled mixture was poured onto ice (1 kg), and flaked potassium hydroxide carefully added with stirring, until the solution pH was 2. The resulting precipitate was filtered, and triturated with boiling water (500 ml), to afford the title compound (123 g, 76%) as a white solid. m.p. 325-327° C.

Provenance & Evidence