New cumene-oxidation systems -: O2 activator effects and radical stabilizer effects

For the purpose of increasing the efficiency of cumene hydroperoxide (CHP) production, two approaches, (A) increasing CHP generation rate by the acceleration of rate-determining step vis-a-vis CHP formation using O-2 activators, and (B) increasing CHP selectivity by the mitigation of side reactions, were carried out. As for O-2 activators, we found that a new Cu(II) complex having a pyridine-imine chelate ligand (TRIP) increased CHP formation rate with no practical decrease in CHP selectivity. Thus, TRIP displayed higher CHP formation rate and selectivity than those for conventional auto-oxidation at 90 degreesC. Regarding the mitigation of side reactions, we focused on the reaction of CHP with a cumyl radical, resulting in a by-product formation. For suppressing this reaction, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was investigated as a radical stabilizer. As a result, TEMPO provided higher CHP selectivity compared to that of auto-oxidation at the same CHP formation rate. Therefore, two methods for increasing the efficiency of CHP production have been demonstrated. (C) 2001 Elsevier Science B.V. All rights reserved.