Question

Arrange the following monomers in order of decreasing ability to undergo cationic polymerisation-
(I)`CH_2=CH-C_6H_4(NO_2)`
(II)`CH_2=CH-C_6H_4(CH_3)`
(III)`CH_2=CH-C_6H_4(OCH_3)`
A. I gt II gt III
B. II gt I gt III
C. III gt II gt I
D. I gt II gt III

Answer 1

Correct Answer - C
Electron releasing groups such a `-CH_3, -OCH_3` activate the monomer towards cationic polymerisation because these groups provide stability to the carbocation formed. On the other hand, `-NO_2` is a electron withdrawing group.So, it reduces the stability of carbocation formed. Thus , the correct order is `underset"(III)"(CH_2=CH-C_6H_4(OCH_3)) gt underset"(II)"(CH_2=CH-C_6H_4(CH_3)) gt underset"(I)"(CH_2=CH-C_6H_4(NO_2))`