Ethylene and Cyclohexene Oxidation by p-Benzoquinone, Hydrogen Peroxide, and Oxygen in the Solutions of Cationic Pd(II) Complexes in Acetonitrile–Water and Ionic Liquid–Water Binary Solvents

Abstract

Optimal conditions are selected for ethylene and cyclohexene oxidation reactions in the acetonitrile (AN)–water system in the presence of \({\text{Pd}}{{({\text{AN}})}_{x}}({{{\text{H}}}_{2}}{\text{O}})_{{4 - x}}^{{2 + }}\) complexes. It is shown that hydrogen peroxide oxidizes hydroquinone (QН₂) in acetonitrile solutions and in ionic liquids (\({\text{BMI}}{{{\text{M}}}^{ + }}{\text{BF}}_{4}^{ - },\)\({\text{BMI}}{{{\text{M}}}^{ + }}{\text{PF}}_{6}^{ - }\)), and the rates of ethylene oxidation in the \({\text{BMI}}{{{\text{M}}}^{ + }}{\text{PF}}_{6}^{ - }\) ionic liquid in the presence of p-benzoquinone (Q) and hydroquinone are the same. It is shown that solid and soluble phthalocyanine iron complexes catalyze oxidation of olefins by oxygen in acidic acetonitrile media by converting p-benzoquinone to the third catalyst of the process. The apparent first-order rate constants of hydroquinone oxidation by oxygen are determined. The use of the IL–Н₂О–Н₂SO₄ system is found to be inappropriate for cyclohexanone synthesis because of the formation of byproducts of cyclohexene conversion.