Chemistry Reference
In-Depth Information
R
2
R
R
4
n
R
2
R
1
R
4
R
5
R
3
R
3
R
R
4
n
R
5
R
1
R
R
3
n
R
5
R
1
R
2
1,2 and 3,4 placements
The polymerizations and copolymerizations of various conjugated dienes are discussed in Chap.
6
.
3.4.5.1 Ring Forming Polymerization
Propagation reactions of unconjugated dienes can proceed by an intra-intermolecular process. This
usually results in ring formation or in
cyclopolymerization
. It can be illustrated as follows:
R
+
R
R
X
X
X
R
X
where, X can designate either a carbon or a heteroatom. An example of such a polymerization is a
free-radical polymerization of quaternary diethyldiallylamine [
98
]:
N
Br
N
Br
Another example is a polymerization of 2,6-disubstituted 1,6-heptadiene [
103
]:
RR
RR
I
+
I
3
3
RR
RR
I
n
