Efficient allylic oxidation of cyclohexene catalyzed by Ti-MCM-41 using H2O2 as oxidant

Abstract

2-cyclohexen-1-ol and 2-cyclohexen-1-one are very important chemical raw materials, and it is a challenge to develop an environmental and efficient synthesis route with titanium-containing catalyst to obtain high yield of allylic oxidation product. Herein, we present an intensive study on the allylic oxidation of cyclohexene over titanosilicates/H₂O₂ system. Ti-MCM-41 is found as an efficient catalyst. The reaction parameters, including cyclohexene/H₂O₂ molar ratios, solvent, catalyst amount, titanium content, reaction temperature and reaction time, were studied in detail. And a high cyclohexene conversion (∼20.2 %) and total selectivity of 2-cyclohexen-1-one and 2-cyclohexen-1-ol (∼90.0 %) was achieved under optimized reaction conditions. Further the allylic oxidation of cyclohexene proceeds a radical mechanism as demonstrated by the addition of radical scavenger BHT. This will make it possible for the highly selective green generation of enols and ketenes.