Efficient DMF-assisted synthesis of formamides from amines using CO2 catalyzed by heterogeneous metal-free imidazolium-hypercrosslinked polymers

Abstract

CO2 emissions are constantly increasing, so it is necessary to continue working to mitigate the excess of CO2 in the atmosphere and reduce the effects it has on the environment. In this regard, we have developed novel catalysts by synthesizing ionic liquids based on imidazolium chloride, supported on hyper-crosslinked polymers (HCP-BzmimCl and HCP-Bis(BzmimCl)). These catalysts enable the highly selective N-formylation of secondary amines, utilizing CO2 as a carbon source, phenylsilane as a hydrogen donor, and DMF as a crucial polar additive. The reactions were carried out under mild conditions, with CO2 pressure at 5 bar and a temperature of 35ºC, yielding formamides in excellent yields. HCP-Bis(BzmimCl) has emerged as a particularly promising catalyst, boasting shorter reaction times, exceptional recyclability, and scalability for potential industrial applications.