General Overview, Fundamentals, and Definitions

Most organic substrates are hardly soluble in water, or miscible with it, whereas the appropriate reagents may be situated in an aqueous layer. Depending on their structure, organometallic catalysts can be present in either phase. The necessary transport often causes inefficient reaction rates. As detailed in other sections, the situation may be rectified by one of the following  

Aqueous-Phase Organometallic Catalysis, Second Edition 

Copyright 2004 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim 

This so-called liquid/liquid phase-transfer catalysis is what most chemists associate with the term the extraction of a vital anionic species from the aqueous phase to the organic one, either by an onium salt or with the help of a crown ether or cryptand. Its application to metal organic catalysis will be described below. First it should be stressed, however, that the concept of PTC is much wider in scope and comprises numerous variants  

A comprehensive introduction to PTC may be found in recent monographs [1-3] and these as well as a symposium volume contain specific chapters on organometallic applications [4, 5]. Other short reviews are also available [6-8]. 

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