Heterogenization of three homogeneous catalysts: A comparative study as epoxidation catalyst

Three homogeneous catalysts, (MnLCl)-Cl-1 center dot 2H(2)O(1.2 H2O) (HmC-1), FeL1(NO3)center dot 3H(2)O (HmC-2) and CoL1(NO3)center dot 2H(2)O (HmC-3) [L-1 = N, N'-ethylenebis(3-formyl-5-methylsalicylaldimine)] have been synthesized and characterized. The catalytic activity of HmC-1, -2 and -3 for epoxidation of alkenes has been investigated in the presence of terminal oxidant tert-butyl hydrogen peroxide (TBHP), in two solvents CH3CN and CH2Cl2. Epoxidation of alkenes catalyzed by HmC-2 and HmC-3 in two solvents CH3CN and CH2Cl2, have also been investigated with of iodosylbenzene (PhIO) as terminal oxidant. The epoxidation study with HmC-1 as catalyst was reported earlier using PhIO as oxidant. Highly ordered 2D-hexagonal mesoporous silica has been functionalized with 3-aminopropyltriethoxysilane (3-APTES) and this has been used to heterogenize the three synthesized homogeneous catalysts and thereby obtained three new heterogeneous catalysts HtC-1, HtC-2 and HtC-3. The heterogeneous catalysts have been characterized by FT-IR, solid state UV-Vis spectroscopy, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The catalytic activity of these heterogeneous catalysts [HtC-(1-3)] for epoxidation of alkenes has been investigated in the presence of two terminal oxidants PhIO and TBHP, in two solvents CH3CN and CH2Cl2 under mild conditions and compared their activity with their homogeneous counterpart. (C) 2013 Elsevier B.V. All rights reserved.