Catalytic oxidation of 1,3-diisopropylbenzene using imidazolium ionic liquid as catalyst

Peroxidation of alkylaromatics is the key step in the synthesis of phenols. Different imidazolium ionic liquids were investigated for the oxidation of cumene. The selectivity of cumene hydroperoxide (CHP) increased with different ionic liquids in the order [C 4 mim]Cl<[C 4 mim]Br<[C 4 mim]BF 4 <[C 4 mim]OH. This finding could be interpreted as being due to the partial decomposition of CHP by the acidic proton of the imidazolium cation. Thus [C 4 mim]OH was chosen as the catalyst for the oxidation of 1,3-diisopropylbenzene to corresponding hydroperoxides and its derivatives. The catalytic performance of [C 4 mim]OH was also better than that of the traditional catalyst NaOH. Furthermore, the effects of the operating variables were investigated and the mechanism was discussed.