Chemistry Reference
In-Depth Information
Another example is a room temperature 1:1 copolymerization of vinylidene cyanide with sty-
rene [
185
]:
+
N
N
N
N
N
N
n
N
N
Still another example is a reaction of 1,3 dioxalene with maleic anhydride [
183
].
Examples of stable complexes are reactions of sulfur dioxide with styrene [
175
], or vinyl ethers
with maleic anhydride [
184
], also
a
-olefins with maleic anhydride [
179
-
181
]. Also, a reaction of
trans
-stilbene with maleic anhydride [
182
], In these reactions charge-transfer complexes form. They
are stable and their existence can be detected by spectroscopic means. Additional energy, such as heat
or a free-radical attack, converts them to diradicals and polymerizes them into alternating copolymers
[
175
,
185
-
191
].
Examples of intermediates between the two extremes in stability are reaction products of sulfur
dioxide with conjugated dienes [
192
]. In this case, the reaction results in formation of mixtures of
alternating copolymers and cyclic adducts:
O
O
O
+
S
S
+
O
O
O
S
+
n
S
O
O
The yield of the polymer increases at the expense of the cyclic structure when heat or radiation is
applied. A free-radical attack has the same effect [
192
].
