The use of ion exchange resins as catalysts in organic synthesis, such as esterification, alkylation, etherification, aldolization, isomerization and epoxidation. Compared with inorganic catalysts, the ion exchange resin catalysts show excellent catalytic performance and readily recyclability. The modern resins consist of a stable hydrocarbon matrix formed by co-polymerising unsaturated materials such as styrene and divinylbenzene. The reactive, functional groups may be introduced either before or after polymerisation.
Ion Exchange Resins:-
The basic polymeric structure (or the solid support) for ion exchange resins is called its Matrix.
- Functional Groups
The matrix is a 3 dimensional co – polymer on which acidic/basic sites are situated. These sites are called functional groups.
- Functional Polymer
The matrix along with functional groups is known as the Functional Polymer or Ion Exchange Resin.
Classification – Bases on Functionality:-
- Cation Resins
Strong Acid – Suphonic Acid
Weak Acid – Carboxylic Acid
- Anion Resins
Strong Base – Quaternary Ammonium
Weak Base – Tertiary Ammonium
Ion Exchange Resins as Catalyst
Sulphonic acid Cation Exchangers in Hydrogen form and Quaternary Ammonium Anion Exchangers in Hydroxyl form are used as substitutes to reactions catalysed by mineral acids and bases respectively.