Liquid phase aldol condensation of formaldehyde and propionaldehyde catalyzed by L-proline functional polymers

Herein, an environmentally friendly and compositionally tunable proline-functional polymer was prepared by copolymerization of divinylbenzene (DVB) with L-proline functional monomer. The synthesized poly[DVB-(4-APCA)x]s were characterized by Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), solid state 13C cross-polarization/magic angle spinning NMR (solid state 13C CP/MAS NMR), thermogravimetry-Mass (TG-MS). The combined characterization results elucidated the skeletal structure of the polymer. The proline-functional polymer was used as catalyst in the preparation of methacrolein (MAL) by liquid phase condensation of formaldehyde (FA) and propionaldehyde (PA), in which the conversion of PA is 73.3%, the selectivity of MAL is 85.6% and the yield of MAL is 62.8% under 0.1 g poly[DVB-(APCA)]s at 75 degrees C for 4 h when dimethyl sulfoxide (DMSO) is used as the solvent. Its catalytic performance did not degrade markedly after five cycles. Moreover, the kinetics of the condensation reaction was also studied using the isolation method.