Phase Transfer Catalysis (PTC) generally means that the reaction between the two substances, located in totally different immiscible phases, in the presence of a catalyst. Phase Transfer Catalysis is mainly used for the synthesis of organics such as pharmaceuticals, dyes, chemicals, etc. In this process, one phase acts as a reservoir of the reacting anions. The second phase, which is the organic phase, contains the organic reactants and catalysts generating lipophilic cations. The reacting anions enter the organic phase in ion pairs with lipophilic cations of the catalyst.
The advantages of Phase Transfer catalysis can be summarized as:
- The elimination of organic solvents
- The elimination of dangerous, inconvenient and expensive reactants
- Having high reactivity and selectivity of the active species
- Having high yields and purity of products
- The simplicity of the procedure
- Having low investment cost
- Having low energy consumption
- Minimization of industrial wastes
- Mild reaction conditions.
In chemistry, a Phase-transfer catalyst or PTC is a catalyst that facilitates the migration of a reactant from one phase into another phase where the reaction occurs. Phase-transfer catalysis is one of the special forms of heterogeneous catalysis.
The phase transfer catalysis can be categorized as per its dependence on the number of phases included:
- Liquid-liquid phase transfer catalysis
- Solid-liquid phase transfer catalysis
- Third-liquid phase-transfer catalysis
Now let's introduce you the popular phase transfer catalyst, Quaternary ammonium salts which had given good results in phase transfer catalysis.
Quaternary Ammonium Salts (QAS) are those cationic compounds having alkyl groups in a chain length of C8–C18, which are generally water soluble compounds and can be used as in disinfectants in textile industries.
A quaternary ammonium salt is readily immobilized in a soluble poly(ethylene glycol) polymer support efficiently catalyzes different reactions carried out under phase-transfer catalysis conditions; the catalyst is easily recovered by precipitation and filtration which shows no appreciable loss of activity when recycled three times.
Let me mention you a few types of QAS:-
1) Tetra-alkyl-ammonium or phosphonium salts
Tetra-n-butyl ammonium bromide
Methyl- triethyl ammonium chloride
2) Tri-ethyl-benzyl-ammonium chloride.
Quaternary Ammonium Compounds are the nitrogenous organic compounds which are basically used as disinfectants in restaurants, hospitals, and homes. The basic chemical structure of ammonium includes a nitrogen atom consisting of four hydrogen atoms connected around it. Quaternary ammonium is created when each of those four hydrogen atoms is replaced with some combination of four other organic chains or rings. Due to the limitless count of possible combinations can take place, there are so many different modes of quaternary ammonium are in the markets already and new types of those are still constantly in development.
O-Alkyl N-anthracenylmethyl derivative compound of Cinchona alkaloids can work in the role of enantioselective phase-transfer catalysts. By employing these catalysts in the asymmetric alkylation of glycine imines, one can generate a range of α-amino acid derivatives with high levels of enantiomeric excess. It is also possible to generate the catalysts in situ from commercially available chiral amines, which offers the opportunity to evaluate libraries of related structures. This specific approach has been applied to many series of biphenyl quaternary salts deriving out in the development growth of a new highly selective catalyst and boosting up the potential for further expansion in the range of α-amino acid derivatives which can be prepared.
So by the above explanation, we came to the conclusion that Quaternary Ammonium Salts are one of the most important and common Phase-Transfer Catalysts. These chemicals and compounds are easily available at the “Tatva Chintan Pharma” which are one of the biggest chemical suppliers in India and are known for their high quality products.
This post first appeared on Cetrimide | Phase Transfer Catalyst | Tetraethylammonium Tetrafluoroborate, please read the originial post: here
