Non-metal and non-halide enol PENDI catalysts for the cycloaddition of CO2 and epoxide

Abstract

A series of non-metal and high-efficiency PENDIs with hydrogen bond donor, which were prepared by condensation reaction of β-diketone and imine, are used for cycloaddition of CO2 and epoxides. The influences of different structure of catalysts and hydrogen bonds on catalytic performance were studied by experiments and density functional theory. The results showed that PENDIs which possess -OH of β-diketone and -NH- exhibit excellent catalytic performance for cycloaddition of CO2 and epichlorohydrin, and the record yield is 97.26 %. The single factor investigation and response surface methodology were used for obtaining optimal reaction conditions of PENDIs. A possible mechanism for CO2 cycloaddition that catalyzed by PENDIs is proposed, it includes epoxide adsorption, ring-opening of epoxide, CO2 insertion and the formation of cyclic carbonate. It is proved that the synergy between -OH of β-diketone and -NH- can promote the catalytic performance of PENDIs for CO2 cycloaddition.