Heterogeneous catalytic epoxidation of olefin over a hydrothermally synthesized 3D phosphate bridged copper(II) framework

Abstract

A 3D copper phosphate, [Cu-2(PO4)(OH)] (n) (1), has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction analysis. In [Cu-2(PO4)(OH)] (n) , there are two types of copper centers having distorted trigonal bipyramidal geometry and distorted octahedral geometry that are connected by the (2)-bridging of each phosphate oxygen ultimately forming a (8)-PO4 bridged 3D network. The compound exhibited excellent catalytic performance in olefin epoxidation. Epoxidation of styrene and substituted styrenes, as well as bulky olefins like cycloalkenes and long-chain alkenes, is efficiently catalyzed by [Cu-2(PO4)(OH)] (n) using tert-butylhydroperoxide in acetonitrile. The results obtained in the heterogeneous catalytic reactions show that the olefins are converted to the respective epoxides in good yield with high selectivity. [Cu-2(PO4)(OH)] (n) was catalytically more active and selective in comparison to simple copper(II) phosphate salt in heterogeneous medium. The catalyst can be recycled and reused several times without significant loss of activity.