Nitric Acid → HCID 178526877, compound

Participants

Reaction Conditions

Reaction Steps

6-Trifluoromethyl-pyridine-2,4-diol (56 g, 310 mmol) was added in 3-5 gm portions to concentrated sulphuric acid (140 mL) with stirring to give a pale brown solution. The temperature increased to −50° C. during the addition. Nitric acid (21.1 mL 328 mmol, 70% HNO3 d=1.4 gm/ml) was added drop wise at such a rate as to maintain a reaction temperature of between 45° and 50° C. which took approximately 90 minutes. Once all the nitric acid had been added the reaction was allowed to cool to ambient temperature over 3 hours. Poured into ice/water (˜1.3 kg) with stirring, after a few minutes a pale yellow precipitate formed which was filtered off, dissolved in ethyl acetate and dried over sodium sulphate, filtered and evaporated. A second crop of material was obtained by extraction of the aqueous filtrate with ethyl acetate. Combined batches and purified by crystallization from ethyl acetate/n-heptane gave 3-nitro-6-trifluoromethyl-pyridine-2,4-diol as a white ‘fluffy’ solid (49.5 gm 71% yield).

Provenance & Evidence