Polymer Anchored Catalysts for Oxidation of Styrene Using TBHP and Molecular Oxygen

Abstract

Catalytic oxidation of styrene was investigated for polymer anchored Cu­(II) and Mn­(II) complexes prepared by Schiff base tridentate ligand. The effect of different oxidants, tert-butyl hydroperoxide (TBHP) under atmospheric pressure and molecular oxygen (O2) at high pressure in a batch reactor, were studied for maximum conversion of styrene and selectivity of styrene oxide product. The effect of various reaction parameters such as temperature, styrene to TBHP mole ratio, and catalyst amount were studied using TBHP as oxidant. The maximum conversion of styrene (87.3%) was obtained using Cu­(II) complex, with maximum selectivity to styrene oxide (76.2%) at styrene to TBHP mole ratio of 1:3, 70 °C, and 25 mg catalyst. The O2 oxidant showed maximum conversion of 45.5% at 80 °C and 0.5 MPa pressure, with a styrene oxide selectivity of 22.4%. The catalytic activity was improved to 70.0% by addition of TBHP as initiator during the use of O2 oxidant. The Cu­(II) catalyst showed better catalytic activity in comparison to Mn­(II) catalyst using both TBHP and O2 oxidant.

Liquid-phase catalytic oxidation of organic substrates by a recyclable polymer-supported copper(II) complex

“…We conclude that the catalyst is purely heterogeneous in nature. Comparison of the catalytic activity of PS-(PBIM) 2 Cu(II) with other reported systems (Table 4) Scheme 2 Plausible reaction mechanism for the oxidation of styrene reveals that the present catalyst exhibits higher conversion and selectivity compared to other systems [24][25][26][27][28][29][30][31][32][33].…”

Catalytic oxidation of styrene over Cu-doped hydrotalcites

“…The [17,18,20]. A small difference in the initial ratios of cations between starting materials and the copper-richer solids (x > 0.28) is probably due to the different solubility products of ionic solids at a constant pH during the precipitation course [28,30,[32][33][34][35].…”

“…In the latter case, the styrene conversion gradually decreases with increasing copper content, as consequence the selectivity to benzaldehyde shows a better value on the copper-richer catalysts. This indicates that Cu 2+ ions has not only shown a good ability to oxidize styrene to benzaldehyde, but also exhibited the parallel competitive catalytic destruction of H 2 O 2 [20,51,52].…”

“…12B). This may be suggested that the main product may be converted to secondary product due to the hydrolysis and opening of the oxirane ring [20,52,54].…”

“…Among these heterogeneous systems, titanium -containing catalysts are the most available systems reported in literature, but their activity is rather fluctuation and strongly dependent upon the preparation routes, chemical precursors, and laboratory skills ( Table 1, Entry # 2-6) [4][5][6][7][8]. Hence, many other transition metals have been recently tried in variable ways for the preparation of catalysts, including in the form of oxide film [7,8], nanoxides [9], metals supported catalysts [4,10,17], immobilized systems [2,[18][19][20]. The product selectivity is strongly dependent on the catalyst nature, oxidant behavior, solvent… (Table 1).…”