Efficient coupling of CO2 and epoxides with bis(phenoxyiminato) cobalt(III)/Lewis base catalysts

Abstract A series of unbridged bis(phenoxyiminato) cobalt(III)complexes were synthesized and studied as catalysts for the coupling of CO 2 and epoxide. Dimethylamino pyridine (DMAP) and tetrabutyl ammonium bromide (Bu 4 NBr), were used as co-catalysts in the reaction. Both Co(III)/DMAP and Co(III)/Bu 4 NBr systems showed high catalytic activity and selectivity in the coupling of n -hexyl oxide and CO 2 , resulting in n -hexyl carbonate. Several mono- and di-substituted terminal epoxides were also tested. The reaction mechanism of the Co(III)/DMAP system was investigated in detail using ESI-MS revealing that in addition to the main product, cyclic carbonate, traces of oligomers are formed.

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