Studies of the autoxidation of phenols catalyzed by the cobalt(II) complex of disodium N,N′‐bis(salicylidene)‐ethylenediamine‐5,5′ ‐disulfonate bound to colloidal anion exchange resin

Abstract

To overcome mass transfer limitations which are usually encountered on immobilizing active catalysts, cationic latex particles were used as support for the cobalt(I1) complex of disodium N,hP-bis(salicylidene)ethylenediamine-5,5'-disulfonate (1). The cationic latex 2 was prepared by emulsion copolymerization of chloromethylstyrene (m/p-isomer mixture 60/40) and divinylbenzene (m/p-isomer mixture) followed by treatment with trimethylamine. The latexbound catalyst from 1 and 2 was found to considerably increase the reaction rate of the autoxidation of 2,6-di-tert-butylphenol in water as compared with the conventional polymer-free system. Reaction products were identified as the oxidative coupling product 3,3',5,5'-tetratert-butyldiphenoquinone (3,3',5,5'-tetra-ter~-butyl-4,4'-dioxo-l,l'-bicyclohexa-2,5-dieny~idene) and 2,6-di-tert-butyl-1,4-benzoquinone. All reactions showed an induction period before the start of dioxygen consumption. The rate of autoxidation in the three-phase mixtures of water, latex particles, and phenol droplets was not affected significantly by the method of mixing. The reaction rate increased as the concentration of 1 increased. Increasing the partial pressure of dioxygen in the range between 0,25 and 1,0 atm (2,53 . lo4 -1,Ol . 10' Pa) gave a small increase in rate. The colloidal latex catalyst from 1 and 2 showed some loss of activity after successive runs. 0 1993, Huthig & Wepf Verlag, Basel CCC 0025-1 16X/93/$05.00

Studies on the oxidation of 2,6-di-tert-butylphenol by molecular oxygen catalyzed by cobalt(II) tetraarylporphyrins bound to cationic latex

“…Comparing the results of the present work with that previously reported on the autoxidation of 2,6-di-tert-butylphenol catalyzed by latex-supported cobalt(II) sulfophthalocyanine [8,10] and latexsupported cobalt(II) complex of N,Nʼ-ethylene-bis-(salicylaldimine-5-sulfonate) [ 9,11]. These catalysts showed almost the same catalytic activities as L-5.…”

“…These catalysts showed almost the same catalytic activities as L-5. However the latex-supported cobalt(II) porphyrin catalysts L-2 and L-5 exhibited higher catalytic stabilites compared to the previously reported catalysts [8][9][10][11].…”

“…Colloidal polymer particles have the potential as catalyst supports because their <1 um sizes avoid mass transfer and intraparticle diffusional limitations to reaction kinetics [5,6]. Colloidal polymers have proven to be viable catalyst supports for a variety of oxidations, such as cobalt-catalyzed autoxidation of tetralin [7], cobalt(II) phthalocyanine and cobalt(II) Schiff-base -catalyzed autoxidation of 2,6-di-tertbutylphenol [8][9][10][11] and thiols [6, 12,13] and manganese(III) porphyrin bound to colloidal anion exchange resin catalyzed epoxidation of alkenes [14,15]. Despite the widespread interest in metalloporphyrin-catalyzed oxidations, there are few reports in the literature dealing with metalloporphyrin catalyzed oxidations of phenols [16][17][18][19][20][21][22][23][24][25].…”

Oxidation of 2,6-Di-tert-butylphenol by dioxygen catalyzed by tetrasodium phthalocyaninatocobalt(II) tetrasulfonate in aqueous micellar media

“…The monomeric CoPcTS-dioxygen adduct (Scheme 2) is therefore the active species in the oxidation reaction of 2,6-di-tert-butyl-phenol in the presence of cationic surfactant CTAB. In the literature, there is a general consensus that, the phenoxy radical is the first intermediate in the mechanism of the formation of coupled product 2 and the oxygen insertion product 3 in the oxidation of substituted phenols catalyzed by dioxygen-cobalt complexes [26][27][28]35]. The coupling product 2 in the oxidation reaction is formed by dimerization of the phenoxy radical (Scheme 3).…”

Synthesis of polymer‐supported metal‐ion complexes and evaluation of their catalytic activities

“…Schiff base complexes of transition‐metal ions have shown significant catalytic activities in various reactions such as oxidation,1, 2 epoxidation of olefins,3, 4 and polymerization of ethylenes,5, 6 but supported metal‐ion complexes have shown high catalytic activity7–9 and enantioselectivity10, 11 in comparison with homogeneous and unsupported catalysts. Cobalt(II) and manganese(II) ion complexes of salen on tailor‐made polymer supports have shown considerable increases in activity9, 12 and enantioselectivity12 due to a significant reduction in the mass‐transfer limitation for the reactants.…”