Chemistry Reference
In-Depth Information
Examples are hydrolyses of methyl and butyl acetates [
19
]. Another example is formation of eximers
and exiplexes in polyesters and methacrylate polymers that always favor large molecules over small
ones [
33
]. Proton transfer reaction of poly(vinyl quinoline) [
34
] can serve as a third example.
The emission, excitation, and absorption spectra of this polymer in a mixture of dioxane and water
can be compared to that of 2-methylquinoline. The emissions coming from the protonated heterocy-
clic rings in the polymer occur sooner than from the low molecular weight compound [
34
].
9.2 Addition Reactions
Polymers with double bonds in the backbones or in the pendant groups can undergo numerous
addition reactions. Some are discussed in this section.
9.2.1 Halogenation
Hydro chlorination
of natural rubber is often accompanied by cyclization [
35
,
36
]:
H
+
H
Cl
Cl
-1,4 and 1,2-Polybutadiene can be hydro halogenated under mild conditions with gaseous
HCl [
51
]. The same is true of copolymers of butadiene with piperylene and also of isotactic
trans
trans
-1,4-
piperylene. The addition of HCl to the asymmetric double bond is
trans
for polypiperylene and occurs
in a stereoselective way, judging from the
13
CNMR[
51
] spectra.
Polysilanes with alkene substituents add HCl and HBr in the presence of Lewis acids [
58
]. The
products are the corresponding chlorine and bromine containing polymers with little degradation of
the polysilane backbone:
R
R
HX
Si
Si
Si
Si
Lewis acid
X
