Novel pyridineSchiff base–manganese(ii) complexes: synthesis, characterization and catalytic reactivity of the epoxidation of cyclohexene

Abstract

Four novel pyridine Schiff bases derived from 2,6-pyridinedicarbaldehyde and substituted o-hydroxyl-aromatic amines and their manganese(II) complexes were synthesized and characterized by elemental analyses, ESI-MS analysis, thermal analysis (TGA), H-NMR, IR and UV-vis. The activity of these complexes as catalysts in cyclohexene autoxidation were investigated and the effects of various reaction conditions on the catalytic reaction were optimized to obtain as high as 99.6% conversion with 95.0% selectivity of epoxycyclohexane at 40 °C for 6 h using molecular oxygen as an oxidant in acetonitrile. The result presents excellent catalysts for epoxidation of cyclohexene under mild temperature and atmospheric oxygen (O₂) pressure.