Acid and base catalysed reactions in one pot with site-isolated polyHIPE catalysts

Abstract

The polyHIPE catalysts based on styrene, vinyl benzyl chloride, and divinylbenzene co-polymerisation were functionalised with carboxylic and tertiary amine groups. Catalyst characterisation showed covalent bonding of the graft polymers. The macroporous and highly interconnected structure of polyHIPEs allows isolation of the acid and base functional groups and allows the presence of these otherwise incompatible functionalities on the same catalyst. The functionalised polyHIPE catalysts were shown to perform two reactions; (i) acid-catalysed acetal hydrolysis and (ii) base-catalysed Knoevenagel condensation in one-pot with 97% yield. The yield obtained is substantially higher than that observed with the homogeneous or resin polymer type catalysts due to the compartmentalisation of the active sites and improved mass transfer through the open porous polyHIPE structure.