Advices For Studying Organic Chemistry

A.1F CATIONIC POLYMERIZATION

1. Alkenes polymerize when they are treated with strong acids:

Step 1

H O O

H

+ BF 3 H

H

+ BF− 3

Step 2

H 3 CC

CH 3

CH 3

H O+

H

BF− 3 + H 2 CC

CH 3

CH 3

+

Step 3

H 3 CC

CH 3

CH 3

+ + H 2 CC

CH 3

CH 3

CC

CH 3

CH 3

+

H

H

C

CH 3

CH 3

H 3 C

Step 4

CC

CH 3

CH 3

+

H

H

C

CH 3

CH 3

H 3 C

H 2 CC

CH 3

CH 3

CC

CH 3

CH 3

+

H

H

C

CH 3

CH 3

C

H

H

C

CH 3

CH 3

H 3 C etc.

1) The catalysts used for cationic polymerizations are usually Lewis acids that

contain a small amount of water.

A.1G ANIONIC POLYMERIZATION

1. Alkenes containing electron-withdrawing groups polymerize in the presence of
   strong bases:

H 2 N + H 2 C CH

CN

NH (^3) CH
2 CH
CN
− H 2 N −
CH 2 CHCN CH
2 CH
CN
CH 2 CH −
CN
CH 2 CH H 2 N etc.
CN
H 2 N −

1. Anionic polymerization of acrylonitrile is less important in commercial
   production than the radical process.