Lewis Acid Catalysis in Supercritical Carbon Dioxide. Use of Poly(ethylene glycol) Derivatives and Perfluoroalkylbenzenes as Surfactant Molecules Which Enable Efficient Catalysis in ScCO₂

Lewis acid catalysis in supercritical carbon dioxide (CO₂) was investigated. While solubility of most organic materials is low in scCO₂, poly(ethylene glycol) derivatives or perfluoroalkylbenzenes were found to work as surfactants to dissolve organic materials in scCO₂. In the presence of these molecules, Lewis acid catalyzed organic reactions such as aldol-, Mannich-, and Friedel−Crafts-type reactions proceeded smoothly in scCO₂. Formation of emulsions was observed in these reactions, and the systems were studied in detail.