Cascade Knoevenagel condensation-chemoselective transfer hydrogenation catalyzed by Pd nanoparticles stabilized on amine-functionalized aromatic porous polymer

초록

An aromatic porous polymer incorporated with carbonyl functionality (APP) was prepared via a facile route of Friedel-Crafts reaction. Subsequent reaction with diethylenetriamine via Schiff-base chemistry produced the amine-functionalized porous polymer (DETA-APP), which was used as a solid backbone to stabilize Pd nanoparticles with sizes of 1-3 nm. The prepared multifunctional Pd/DETA-APP catalyst showed high catalytic activity and selectivity towards the cascade reaction of Knoevenagel condensation-transfer hydrogenation using HCOOH as a hydrogen source. The positive influence of the amine functionality on the Pd/DETA-APP in the hydrogenation step was established after comparing the catalytic performance with that of the Pd/APP. The catalyst could be reused without any loss in reaction efficiency and selectivity for at least 5 times. Finally, a plausible mechanistic pathway for the cascade reaction over Pd/DETA-APP catalyst was proposed.

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