Heterogeneous catalysts hold the edge over homogeneous systems: Zeolite-Y encapsulated complexes for Baeyer-Villiger oxidation of cyclohexanone

A series of heterogeneous catalysts [M(pamp)]-Y (Where, M = V, Mn, Fe or Cu; pamp = 2,2'-((1E,1'E)-(1,2-phenylenebis(azanylylidene))bis(methanylylidene))diphenol) was prepared by encapsulation of metal complexes within zeolite-Y. Synthesized materials were characterized by chemical, BET and thermogravimetric (TG) analysis, X-ray diffraction (XRD), UV-vis and infrared spectroscopies, and scanning electron microscopy (SEM). Zeolite-Y encapsulated complexes were tested in Baeyer-Villiger (B-V) oxidation of cyclohexanone beside neat complexes to check the aptitude of heterogeneous catalysis over the homogeneous system. The effect of experimental variables viz., solvents, catalysts amount, the mole ratio of substrate to an oxidant, temperature and reaction time on substrate conversion was also tested. Under the optimized reaction conditions, [VO(pamp)]-Y was found to be a potential candidate by providing 1500 TONs in cyclohexanone oxidation, and the selectivity towards epsilon-caprolactone was 85.2%. (C) 2016 Elsevier B.V. All rights reserved.