Chemoselective Catalytic Oxidation of Olefin Derivatives with Co–Salen Immobilized SBA-15

Abstract

Chemoselective catalytic oxidation of olefin derivatives containing alcoholic and olefinic groups is important in organic synthesis. In the present study, Co–Salen immobilized on SBA-15 was synthesized and characterized to study its chemoselective catalytic activity towards the oxidation of cinnamyl alcohol and cinnamaldehyde, with tert-butyl hydroperoxide as the oxidant at 60, 70 and 80 oC. Cinnamyl alcohol selectively yielded cinnamaldehyde at the reactant ratio of cinnamyl alcohol tert-butyl hydroperoxide equal to 1:0.5. Cinnamaldehyde selectively yielded 2,3-epoxy-cinnamaldehyde at the ratio of cinnamaldehyde tert-butyl hydroperoxide equal to 1:0.5. The catalyst yielded epoxide with many styrene derivatives and benzaldehyde with benzyl alcohol, but only cinnamaldehyde with cinnamyl alcohol, thus proving its applicability for chemoselective catalytic oxidation of olefin derivatives. The cinnamaldehyde conversion and selectivity to 2,3-epoxy-cinnamaldehyde increased with the increase in the content of tert-butyl hydroperoxide. So, this study establishes that the catalyst can be applied to selective oxidation of primary alcoholic function without affecting olefinic double bonds. The conversion was maximum at 70 oC. The conversion and product selectivity remained the same for 5 cycles thus endorsing stability of the catalysts. Based on the activity and selectivity of the catalysts, it is inferred that the same catalyst can be exploited for selective oxidation of multifunctional olefin derivatives.