Oxidation of benzyl alcohols to benzaldehydes in water catalyzed by a Cu(II) complex with a zwitterionic calix[4]arene ligand

A water-soluble cationic mononuclear copper(II) complex [Cu(II)L(H2O)I-2 (1, H4L = 5,11,17,23 tetrakis(trimethylammonium)-25,26,27,28-tetrahydroxycalix[4]arene) was employed as a catalyst in the oxidation of benzyl alcohols to benzaldehydes in water. In the presence of TEMPO and H2O2, complex 1 exhibited good catalytic activity towards primary benzyl alcohols with a less catalyst loading (0.25 mol%) and a lower temperature (60 degrees C). The isolated yields of the aldehydes achieved 63-98% within 12 h. (C) 2015 Elsevier BY. All rights reserved.