Urea-functionalized mesoporous polymeric catalyst: a cooperative effect between support and secondary amine on water-medium Knoevenagel reactions

Urea-functionalized mesoporous polymers (urea-MPs) were synthesized through the surfactant-directed urea-phenol-formaldehyde oligomers self-assembly approach. The as-prepared urea-MPs material exhibited superior catalytic activity than parent urea in water-medium Knoevenagel condensation reactions and could be used repetitively for seven times. The excellent activity could be attributed to the synergic effect derived from the secondary amine with the surface phenolic groups in the mesoporous support, which generated the acid-base cooperative catalytic behavior. Meanwhile, the urea functional groups embedded in the mesopore wall could inhibit the leaching of active species and thus resulted in the relatively good durability.