Phase Transfer Catalysts
Quats are used as Phase Transfer Catalysts in chemical reactions.
Quaternary ammonium compounds (Quats) are soluble in both water and non-polar liquids. They are therefore used extensively as auxiliary reagents (phase transfer catalysts, also called PTC) in chemical reactions such as organic synthesis, in order to significantly improve the reaction rate.
The benefits of using
Quaternary ammonium compounds as phase transfer
catalysts include:
- No need to use expensive solvents
- Higher yield
- Purer end-product
- Milder reaction conditions
- Better and simpler separation
- Biodegradable process aid
Many inorganic salts are poorly soluble in various organic liquids, but very soluble in water. Contrary to this, many organic compounds are very soluble in organic solvents and poorly soluble in water. Chemical reactions can only proceed if the reactants are mixed intimately. This is rather difficult when the reactants are present in two non-miscible phases, such as oil and water. Phase transfer catalysts (PTC) act as carriers for the inorganic reactants, transferring them from the aqueous medium into the organic phase.
If we take for example a reaction between an alkyl chloride and an inorganic salt, using Benzalkonium Chloride (BKC) as a phase transfer catalyst will allow the reaction to occur by transferring the salt from the inorganic to the organic phase.
If bromides are involved instead of chlorides, Cetrimide or CTAB may be good catalysts.
