Aromatic guanidines as highly active binary catalytic systems for the fixation of CO2 into cyclic carbonates under mild conditions

We have synthesised a set of aromatic mono- and bis(guanidines) which are highly effective binary catalytic systems (guanidine/cocatalyst) for the formation of cyclic carbonates. The presence of multiple N–H bonds causes a modification in the traditional mechanism proposed for the synthesis of cyclic carbonates catalysed by guanidines through the formation of hydrogen bonds between the oxygen atom of the epoxide and the N–H groups of the guanidines. This change allows a considerable reduction of the reaction temperature and CO2 pressure employed in this process.