Carbonyl addition elimination mechanism

This is a step growth polymerisation mechanism. This method is important for the preparation of condensation polymers. Here addition and elimination at the carbonyl double bond of carboxylic acids or it's derivative occurs.

Step growth polymerisation mechanism.

The species in the bracket is at metastable equilibrium and it can either return to it's original state by eliminating Y or it can proceed to its final state by eliminating X. Example of this reaction is interfacial condensation.

Interfacial condensation

The reaction of acid halide with a glycol or a diamine can be proceed rapidly to high molecular weight polymers, if carried at the interface between two liquids, each containing one of the reactants.

Typically an aqueous phase containing glycol or diamine and an acid acceptor is layered at room temperature over the organic phase containing acid chloride. The polymer formed at the interface can be pulled off as a continuous film or filament.

The polymers formed by interfacial condensation are polyureas, polyphenyl esters, polyamides, polyurethanes etc. Those polymers which are unstable at higher temperature are formed by interfacial condensation.

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Polymers

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