Phase-Transfer Catalysis

The passage of a reactant from one phase into another, where reaction takes place, is facilitated by a catalyst known as a phase-transfer catalyst, or PTC. One particular type of heterogeneous catalysis is phase-transfer catalysis. In the absence of the phase-transfer catalyst, ionic reactants frequently dissolve in an aqueous phase but are insoluble in an organic phase. In order to dissolve the salts into the organic phase, the catalyst acts as a detergent. Upon the inclusion of the phase-transfer catalyst, the process is said to have been catalysed by phase-transfer. By using a PTC process, one can speed up reactions, increase conversions or yields, produce fewer byproducts, avoid the need for costly or dangerous solvents that will dissolve all the reactants in one phase, do away with the need for pricey raw materials, and/or reduce waste issues. Phase-transfer catalysts are particularly helpful in green chemistry because they enable the use of water, thereby lowering the demand for organic solvents. PTC is not only applicable in systems with hydrophilic and hydrophobic reactants, as is frequently believed. When liquid/solid and liquid/gas reactions take place, PTC is occasionally used. As suggested by the name, one or more of the reactants are transferred into a second phase that also includes the other reactant.