Hydrochloric Acid → 5-Chloropyrazinoic acid

Participants

Reaction Conditions

Reaction Steps

A solution of methyl 5-chloropyrazine-2-carboxylate (30.00 g, 0.17 mol) in tetrahydrofuran (87 mL) was treated with a solution of potassium carbonate (72.08 g, 0.52 mol) in water (261 mL). The resulting reaction mixture stirred at 25° C. for 42 h. The reaction mixture was then acidified to a pH=2 with concentrated hydrochloric acid, diluted with a saturated aqueous sodium chloride solution (300 mL), and was continuously extracted with ethyl acetate (4 L total) until no product was present in the aqueous layer. The combined organic layers were dried over sodium sulfate, filtered, and concentrated in vacuo to afford 5-chloro-pyrazine-2-carboxylic acid (26.54 g, 96%) as an off-white solid: mp 150–151° C.; EI-HRMS m/e calcd for C5H3ClN2O2 (M+) 157.9883, found 157.9877.

Provenance & Evidence