Esterification of 2,6-Pyridinedicarboxylic Acid with n-Butanol Catalyzed by Heteropoly Acid H3PW12O40 or Its Ce(III) Salt
Journal of Molecular Catalysis A: Chemical
||Cerium, Esterification, Heteropoly acid, Pyridinedicarboxylic acid, Tungsten
Boreskov Institute of Catalysis
The liquid-phase esterification of 2,6-pyridinedicarboxylic acid (PA) with n-BuOH is efficiently catalyzed by heteropoly acid H3PW12O40 as a homogeneous catalyst and by its insoluble acidic Ce(III) salt, Ce0.87H0.4PW12O40, as a heterogeneous catalyst, yielding 100% of PA dibutyl ester. The Ce(III) salt has a lower activity than H3PW12O40 but can be easily recovered and reused. Insoluble NH+4, K+ and Cs+ salts also exhibit moderate activities. The activity of the salts decreases in the series: Ce0.87H0.4PW12O40 ⪢ Cs2.5H0.5PW12O40 ∼ Cs3PW12O40 ∼ Cs2HPW12O40 ∼ (NH4)3PW12O40 > K3PW12O40.