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

To overcome mass transfer limitations which are usually encountered on immobilizing active catalysts, cationic latex particles were used as support for the cobalt(II) complex of disodium N,N′-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′-tetra-tert-butyldiphenoquinone (3,3′,5,5′-tetra-tert-butyl-4,4′-dioxo-1,1′-bicyclohexa-2,5-dienylidene) 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. 10⁴ – 1,01. 10⁵ Pa) gave a small increase in rate. The colloidal latex catalyst from 1 and 2 showed some loss of activity after successive runs.