UCLA

Aldol condensations are one of the most important methods to form carbon-carbon bonds in organic chemistry and biochemistry. The kinetics of formation of the 2-methyl-2-pentenal in acid-catalyzed aldol condensation reaction of propionaldehyde were studied at ambient temperature and 175℃ in pure water and a mixture consisting of 80 vol% γ-valerolactone (GVL) and 20 vol% water using aqueous HCl and on various solid acid zeolites. The rate orders and rate constants were determined, showing that GVL as a co-solvent enhances the reaction rate via solvation of the aldol-condensation reaction transition state. In addition, the mechanism of propionaldehyde pathway was discussed. Propionaldehyde conversions and selectivities to 2-methyl-2-pentenal varied on the different zeolites tested (BEA, Y, MOR, MFI, FER) at 175℃ using both water and 80/20 GVL/H2O as solvents.