A high-throughput study of cyclic and polymeric carbonates synthesized from CO2 and epoxides with iron(III) pyridylamino-bis(phenolate) catalysts

Abstract

The atom-efficient reaction of a nontoxic, inexpensive and renewable C1-feedstock as CO2 with a variety of epoxide substrates and oxetane was studied employing iron(III) pyridylamino- bis(phenolate) complexes as homogeneous catalysts. These complexes can act as bifunctional catalyst to promote the reaction between CO2 and epoxides, but the addition of a Lewis base co- catalyst allows to reduce significantly the amount of iron complex needed to achieve high epoxide conversion. The possibility to control the selectivity of the reaction towards each of the two possible products of the reaction, i.e. cyclic carbonate and polycarbonate, was evaluated. An efficient switch in selectivity could be achieved when cyclic epoxides as cyclohexene oxide and the seldom explored 1,2-epoxy-4-vinylcyclohexane were used as substrates. For the polycarbonate prepared with the latter epoxide, a post-synthetic cross-linking reaction was performed, leading to a substantial increase in the glass transition temperature and chemical resistance of the polymer.