Phase transfer catalysis
Catalysis at liquid-liquid interfaces

Consider the case of a substance added to a two-phase system (organic and aqueous phases, for example):

• or the substance is not soluble in the organic phase in which the reaction takes place, and can only pass through this phase thanks to a complexing agent which is soluble there and which acts as a transfer agent and catalyst;

• or the substance is soluble in the organic reaction phase, but requires the action of a reagent from the other phase in order to react, the reaction taking place at the interface; the catalyst then intervenes to return the modified product to the organic phase, where the reaction continues.

The behavior, mobility and reactivity of the substance will depend on the reaction medium (solvent for each phase) and the transfer agent or catalyst. We will...