PYRIDINE-3,4-DICARBOXYLIC ANHYDRIDE

490-11-9

4664-08-8

The general procedure for the synthesis of pyridine-3,4-dicarboxylic anhydride from 3,4-pyridinedicarboxylic acid is as follows: in a 1 L round-bottomed flask fitted with a drying tube, 3,4-pyridinedicarboxylic acid (160 g, 1 mol) and acetic anhydride (500 mL) were added. The reaction mixture was refluxed in an oil bath at 165°C for 2 hours. Upon completion of the reaction, decompression concentration was carried out to remove excess acetic anhydride. After cooling, a residual oily substance was obtained. Methyl tert-butyl ether (500 mL) was added to the residue and stirred overnight at room temperature. Subsequently, a dark brown solid precipitate precipitated and was separated by filtration. The filter cake was washed with 100 mL of methyl tert-butyl ether (MTBE) and dried under vacuum at 45°C to give 99 g of solid product in 76% yield.