Oxidation of alcohols with tert-butylhydroperoxide catalyzed by Co(II) complexes immobilized between silicate layers of bentonite

The oxidation of alcohols with tert-butylhydroperoxide (TBHP), in the presence of immobilized Co2+ complexes with ligands of 2,2′-bipyridine (bpy), ethylenediamine (en), acetylacetonate (acac), urea, N,N′-ethylenebis(salicylideneamine) (salen), N,N′-propylenebis(salicylideneamine) (salpn) and N,N′-phenylenebis(salicylideneamine) (salophen) were investigated. It was found that immobilized [Co(bpy)2]2+/bentonite is an efficient catalyst for the oxidation of alcohols such as cyclohexanol (91% conversion; 100% selectivity), benzyl alcohol (53% conversion; 100% selectivity) and hexanol (40% conversion; 100% selectivity). Effect of reaction time, effect of the amount of Co2+ in catalyst and the effect of type of substrates and oxidants in this catalysis systems were investigated. In the best conditions, TBHP is more efficient oxidant with respect to H2O2 and order has been observed for the percentage of conversions of alcohols: 2° > benzylic > 1°.