Two-Phase Epoxidations with Micellar Catalysts: Insights, Limitations, and Perspectives.

Biphasic molecular catalysis is a promising strategy for combining catalyst recycling with the synthesis of advanced chemical products. The anchoring of catalysts to surfactants in water allows for both catalyst solubility in aqueous media and a simple separation from the organic product. In biphasic epoxidations, this approach allows the use of environmentally benign hydrogen peroxide as oxidant. However, challenges remain due to mass transport limitations between the aqueous and organic phase, incompatibilities in the multicomponent system, and side reactions in the acidic medium. Hence, the development of surface-active catalysts that enable controlled phase separation from all other components is highlighted in this concept article.