Phasentransfer-Katalyse. Eine vielseitige, moderne Synthesetechnik mit potentieller Bedeutung für die Farbenchemie

Abstract

Phase transfer catalysis is a modern technique that permits reactions between substances that are dissolved in water or are present as solids and other compounds dissolved in organic media. These processes are catalyzed by onium salts or crown ethers in most cases. A brief survey of factors controlling the catalytic efficiency (choice of suitable catalyst, use of a good reagent/solvent combination etc.) is given based on some known extractabilities of ion pairs. Although this method is just 10 years old, almost 1300 references are known today. Thus, a limited number of applications are chosen arbitrarily to discuss applications of phase transfer catalysis. Special attention is given inter alia to vast changes in lipophilicities of dyes by the use of judiciously chosen counter ions, i. e. water soluble dyes can be transformed into toluene soluble ones. These then can be reacted further in organic media. Furthermore, unusual solubility properties and reactions of diazonium salts can be achieved with phase transfer catalysis.