Aldol Condensations Catalyzed by Basic Anion‐Exchange Resins

The aldol condensations of various aldehydes with ketones in the presence of anionic (basic) ion-exchange resins have been investigated. Both batch and continuous modes were studied and compared for the reaction of citral (a mixture of geranial and neral) with acetone to give psi-ionone. Different reaction conditions were investigated, and the performances of five different ion-exchange resins were compared. The most stable resins could be used for 10 cycles in batch mode or 1000 min in continuous mode without a significant loss in activity or selectivity.