Ultra-high concentrations of amino group functionalized nanoporous polymeric solid bases: Preparation, characterization and catalytic applications

We report here that the amino-group functionalized nanoporous polydivinylbenzene (PDVB-2.0-NH2, PDVB-NH2), acts as an efficient solid base for catalyzing Knoevenagel condensation, which could be synthesized from nitration of nanoporous polydivinylbenzene (PDVB), reduction in the mixture containing SnCl2 and HCl, and activated with isopropylamine. The resultant solid bases of PDVB-2.0-NH2 and PDVB-NH2 have large BET surface areas, abundant nanopores, controlled hydrophobic network and ultra-high concentrations of the amino group. The above characteristics result in their excellent activities and good recyclability for catalyzing Knoevenagel condensation of various aldehydes with malononitrile, much better than those of commercially basic resin of Amberlite-400 and Amberlite-910, which was as comparable as that of the homogeneously strong base of CaO. This work develops efficient nanoporous polymeric solid bases with controllable surface characteristics and ultra high concentrations of basic sites. (C) 2015 Elsevier B.V. All rights reserved.