Interfacial Mechanism and Kinetics of Phase-Transfer Catalysis

As the chemical reactants reside in immiscible phases, phase transfer (PT) catalysts have the ability to carry one of the reactants as a highly active species for penetrating the interface, into the other phase where the reaction takes place, and to give a high conversion and selectivity for the desired product under mild reaction conditions. This type of reaction was termed ‘‘phase-transfer catalysis’’ (PTC) by Starks in 1971 [1]. Since then, numerous efforts have been devoted to the investigation of the applications, reaction mechanisms, and kinetics of PTC. Nowadays, PTC becomes an important choice in organic synthesis and is widely applied in the manufacturing processes of specialty chemicals, such as pharmaceuticals, dyes, perfumes, additives for lubricants, pesticides, and monomers for polymer synthesis. The global usage of PT catalysts was estimated at over one million pounds in 1996, and PTC in industrial utilization is continuously growing at an annual rate of 10–20% [2]. PTC is a very effective tool in many types of reactions, e.g., alkylation, oxidation, reduction, addition, hydrolysis, etherification, esterification, carbene, and chiral reactions [2,3].