Micrometer-scale mixing with Pickering emulsions: biphasic reactions without stirring.

A general strategy that avoids stirring for organic/aqueous reactions involving solid catalysts is reported. The strategy involves converting a conventional biphasic system into a Pickering emulsion phase with micrometer-scale droplets ensuring good mixing. In test reactions, nitrotoluene reduction and epoxidation of allylic alcohols, the reaction efficiency is comparable to conventional stirrer-driven biphasic catalysis reaction systems. Short diffusion distances, arising from the compartmentalization of densely packed droplets, play an important role in boosting the reaction efficiency.