Solved Examples on Polymers

Question:1, The correct functional group X and the reagent/reaction conditions Y in the following scheme are  (IIT-JEE 2011)

(A) X = COOCH3, Y = H2/Ni/heat

(B) X = CONH2, Y = H2/Ni/heat

(C) X = CONH2, Y = Br2/NaOH

(D) X = CN, Y = H2/Ni/heat

Answer: A,B,C,D

Solution:

Condensation polymers are formed by condensation of diamine or diols with dicarboxylic acids.

So, X may be  -COR, -CONH₂, -CN

Question:2,

a) What is the structure of nylon-6, made by alkaline polymerisation of caprolactom?

b)  Suggest a mechanism for the process. Is polymerisation of the chain reaction or step reaction type?

Solution:

The reaction is anionic chain reaction polymerization, involving nucleophilic substitution at the acyl group of the cyclic amide. The base could be OH^– itself or the anion formed by abstraction of the –NH proton from a molecule of lactam.

Question:3, Identify the compound C

Solution: