ABSTRACT
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Organic synthesis is normally performed in a homogeneous liquid reaction medium, consisting either of one solvent or of a mixture of solvents. When the reaction involves reactants with widely different polarity, such as a lipophilic organic molecule and an inorganic salt – which is common, for instance in oxidation reactions and in nucleophilic substitution reactions – a two-phase system is often employed. The common practice is to accelerate such a two-phase reaction by addition of a phase transfer catalyst, which may be either a quaternary ammonium salt or a crown ether (1).
