CATALYTIC ACTIVITY OF COPPER(II)COMPLEXES OF IMMOBILIZED POLYSTYRENE-BOUND 4-(N,N-DIMETHYLAMINO)PYRIDINE AND POLY(STYRENE-CO-4-(N-METHYL-N-P-VINYLBENZYLAMINO)PYRIDINE) FOR THE OXIDATIVE COUPLING OF 2,6-DISUBSTITUTED PHENOLS

'Polystyrene-bound 4-(N,N-dimethylamino)pyridine'-copper (PS-DMAP-Cu(II)) catalysts for the oxidation of 2,6-disubstituted phenols were immobilized by grafting or by partial adsorption on silica and by crosslinking with 2% divinylbenzene. The most active immobilized catalyst is the most flexible, i. e. the grafted one. The less extended conformation of the adsorbed polymeric catalyst exhibits a significantly lower activity. For the crosslinked catalyst, indications were obtained that diffusional limitations occur. Application of all three types of immobilized PS-DMAP based catalysts in a continuous stirred tank (CST) reactor was unsuccessful. The phenol conversion drastically decreased in time.