Biphasic epoxidation reaction in the absence of surfactants - integration of reaction and separation steps in microtubular reactors

This paper presents a paradigm shift with respect to the current direction of biphasic reactions in surfactant-free emulsions. Herein, the contact area between both phases is simply sustained by the reactor design (i.e., diameter of the tubular reactor) compared to the current trend of using reversible/switchable emulsions where the addition of an external agent (e.g., bistable surfactant, magnetic particles, etc.) is required. In this way, temporally stable phase dispersions using microtubular reactors facilitate the integration of reaction and separation steps in biphasic systems without the need for energy-intensive downstream separation steps. In this study, we demonstrate this innovative tool in the epoxidation reaction of sunflower oil with hydrogen peroxide. Using a combination of mechanistic and kinetic studies, we demonstrate that the poor solubility of the catalytic species in the oil phase may be used advantageously, allowing ready recyclability of catalyst (and oxidant) in consecutive runs.