COMPOSITION CATALYSTS OF ETHYLBENZENE OXIDATION BASED ON BIS(ACETYLACETONATO)NICKEL(II) AND PHASE-TRANSFER CATALYSTS AS LIGANDS .1. MACROCYCLIC POLYETHERS

The addition of the macrocyclic polyether 18-Crown-6 (18C6) increases the selectivity of oxidation of ethylbenzene to alpha-phenylethylhydroperoxide (PEH) in the presence of Ni(acac)(2). The initial oxidation rate, selectivity and degree of conversion of ethylbenzene to PEH are greater than those catalyzed by Ni(acac)(2) only. The efficiency of the macrocyclic ligand as an activator of Ni(acac)2 exceeds that of monodentate donor ligands. The high selectivity of the process is due to both the ''primary'' Ni(acac)(2) . 18C6 complexes and the products of their transformation in the course of oxidation. The mechanism of ethylbenzene oxidation catalyzed by Ni(acac)(2) . 18C6 complexes is discussed.