An ionic porous organic polymer gel with hydroxide anions as an efficient catalyst for N-formylation of amines and amides with carbon dioxide†
Abstract
The reduction and functionalization of greenhouse gas CO2 remain in line with the characteristics of green and sustainable development. In this work, an ionic porous organic polymer gel was prepared through a hydrazone condensation reaction between triaminoguanidine and 1,1′-(p-phenylenedimethylene)bis(4-formylpyridinium) cationic units under mild conditions. A metal ion-free triaminoguanidine- and pyridinium-incorporated porous organic polymer gel (PT-OH) with triple synergistic effects of hydroxide anions, multi-ion activation centers and a porous gel structure was obtained after ion exchange. PT-OH provides excellent functional group tolerance and high activity to achieve the N-formylation reaction of primary amines, secondary amines and amides using phenylsilane as the reducing agent under ambient conditions (room temperature and 1 atm CO2 pressure). Moreover, PT-OH has chemical stability, is easy to recycle and can be reused 5 times without loss of activity. The material represents an efficient, economical and environmentally friendly heterogeneous metal-free catalytic system, which conforms to the principle of green utilization of CO2.