5552-44-3

100-26-5

64-17-5

5552-44-3

Concentrated sulfuric acid (3.9 mL, 71.6 mmol) was slowly added dropwise to a stirred suspension of 2,5-pyridinedicarboxylic acid (3.0 g, 17.9 mmol) in anhydrous ethanol (10 mL) over 15 minutes. Subsequently, the reaction mixture was heated to reflux for 18 hours. Upon completion of the reaction, the solution was cooled to room temperature and the solvent was removed by evaporation under reduced pressure. Saturated sodium bicarbonate (NaHCO3) solution was added to the residue and the pH was adjusted to 7-8. Next, the aqueous phase was extracted with ethyl acetate (EtOAc, 4 x 50 mL). All organic extracts were combined and washed with brine (30 mL) and subsequently dried with anhydrous sodium sulfate (Na2SO4). Finally, the solvent was evaporated under reduced pressure to afford diethyl 2,5-pyridinedicarboxylate (3.0 g, 75% yield), which could be used for subsequent experiments without further purification.