Transition metal coordination polymers MeX2(4,4′bipyridine) (Me = Co, Ni, Cu; X = Cl−, CH3OCO−, acetylacetonate) selective catalysts for cyclohexene epoxidation with molecular oxygen and isobutyraldehyde

This paper presents aspects concerning the catalytic activity of several transition metal coordination polymers with the general formula 2∞[Me(II)X2(4,4′bipyridine)] (Me(II) = Co, Ni, Cu; X = Cl−, CH3OCO−, and acetylacetonate) towards the epoxidation of cyclohexene with molecular oxygen in the presence of isobutyraldehyde as reductant. The obtained results proved that all the investigated catalysts showed a high selectivity for epoxidation (over 88%). The conversion of cyclohexene was found to depend on the nature of both the transition metal cation and the ligand X. The most active catalyst was found to be 2∞[Co(II)(CH3OCO)2(4,4′bipyridine)].

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► 2∞[Me(II)Cl2(4,4′bipyridine)] show selectivity for cyclohexene epoxidation above 88%
► 2∞[Co(II)Cl2(4,4′bipyridine)] has better activity than analogous Ni or Cu complexes
► The presence of CH3OCO− instead of Cl− in Co-complex increases the catalytic activity
► Replacement of Cl− by acetylacetonate decreases the catalytic activity of Co-complex.