Question

a. Draw three segments of the polymer that is formed from 1,4-polymerization of 1,3-butadiene in which all the double bonds are trans.

b. Draw three segments of the polymer that is formed from 1,2-polymerization of 1,3-butadiene.

Short answer

a. The three segments of polymer created by 1,4-polymerization of 1,3-butadiene are given below.

b. The three segments of polymer created from 1,2-polymerization of 1,3-butadiene is given below.

Step-by-step solution

Polymerization of dienes

The treatment of diene with strong acids leads to the creation of polymers. The polymerization of 1,3-butadiene at the C1 and C2 positions create polyethylene.

The polymerization at the C1 and C4 positions generate cis-polybutadiene, trans-polybutadiene, or a mixed polymer.

Drawing the three segments of the polymer formed from 1,4-polymerization of 1,3-butadiene and three segments of the polymer formed from 1,2-polymerization of 1,3-butadiene

a. In 1,4-polymerization of 1,3-butadiene, one C-1 of 1,3-butadiene connects to the fourth carbon of the other 1,3-butadiene. Hence, all the double bonds are trans.

The three segments of polymer created by 1,4-polymerization of 1,3-butadiene are given below.

Segments of polymer created by 1,4-polymerization of 1,3-butadiene

b. In 1,2-polymerization of 1,3-butadiene, the first carbon of 1,3-butadiene links to the second carbon of the other 1,3-butadiene.

The three segments of polymer created from 1,2-polymerization of 1,3-butadiene are given below.

Segments of polymer created from 1,2-polymerization of 1,3-butadiene

The three segments of the polymer formed from 1,4-polymerization of 1,3-butadiene and three segments formed from 1,2-polymerization of 1,3-butadiene are drawn.