Keggin heteropolyacid as catalyst for olefin epoxidation: A multiphase approach

Keggin-type heteropolyacids have been used as catalyst for the selective oxidation of olefins to the corresponding epoxides in multiphase conditions (isooctane/Aliquat 336/water). Multiphase system allowed achieving a higher conversion (72%) and selectivity (70%) to epoxide than related homogeneous or biphasic systems. Optimization of the system has been conducted considering reaction time, temperature, amount of the catalysts and quantity of the oxidant. In addition, it was shown that, in the multiphase system, only an insignificant decomposition of hydrogen peroxide was observed. The best-found reaction conditions were then employed for the selective epoxidation of several substrates. An environmental assessment has been conducted comparing green metrics related to the homogenous, biphasic and multiphase systems herein investigated