Accelerated Chemical Reactions and Organic Synthesis in Leidenfrost Droplets

Leidenfrost levitated droplets can be used to accelerate chemical reactions in processes that appear similar to reaction acceleration in charged microdroplets produced by electrospray ionization. Reaction acceleration in Leidenfrost droplets is demonstrated for a base‐catalyzed Claisen–Schmidt condensation, hydrazone formation from precharged and neutral ketones, and for the Katritzky pyrylium into pyridinium conversion under various reaction conditions. Comparisons with bulk reactions gave intermediate acceleration factors (2–50). By keeping the volume of the Leidenfrost droplets constant, it was shown that interfacial effects contribute to acceleration; this was confirmed by decreased reaction rates in the presence of a surfactant. The ability to multiplex Leidenfrost microreactors, to extract product into an immiscible solvent during reaction, and to use Leidenfrost droplets as reaction vessels to synthesize milligram quantities of product is also demonstrated. Chemische Reaktionen können in schwebenden Leidenfrost‐Tröpfchen in Prozessen beschleunigt werden, die der Reaktionsbeschleunigung in durch Elektrospray‐Ionisierung generierten geladenen Mikrotröpfchen ähneln. Für mehrere organische Reaktionen wurden so Beschleunigungsfaktoren von 2 bis 50 relativ zu den entsprechenden Umsetzungen in der Volumenphase erzielt.