67-56-1

41110-28-5

41110-29-6

3-Methylpyrazine-2-carboxylic acid (19.95 g, 144 mmol) was suspended in methanol (500 mL) in a 2L round bottom flask. The suspension was cooled in an ice-water bath, followed by slow dropwise addition of concentrated sulfuric acid (27.3 mL, 506 mmol) over 5 min. The reaction mixture was heated to 80 °C and maintained at this temperature for 5 hours. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure and the residue was dissolved in dichloromethane (750 mL). Excess acid was neutralized in small amounts with 5 M aqueous sodium hydroxide solution (200 mL). The aqueous layer was separated and extracted with dichloromethane (250 mL). All organic layers were combined, dried with anhydrous magnesium sulfate, filtered and concentrated to give methyl 3-methylpyrazine-2-carboxylate (16.15 g, 106 mmol, 73% yield). Mass spectral analysis showed m/z = 153 [M + H]+.