Chemistry Reference
In-Depth Information
-xylylene)s can also be prepared by other reactions. Among them is the condensation of
trimethyl(
Poly(
p
p
-methylbenzyl) ammonium halide in the presence of a base [
47
]:
NaOH
n
N
Br
n
-xylylenes with caustic.
It results in 1,6 elimination of HCl and formation of a chlorine-substituted poly(
A route to a halogen-substituted polymer is through a reaction of di halo-
p
p
-xylylene) [
47
]:
Cl
NaOH
Cl
Cl
n
n
Cl
n
With excess caustic, however, all chlorine is removed and presumably an all-conjugated poly
(phenylene vinylene) polymer forms [
47
]:
n
n
Cl
-Bis(trichloromethyl) benzene can be pyrolyzed over copper gauze at 300-600
C temperatures
to form
p
a
0
,
a
0
-tetrabromo-
a
,
a
,
p
-xylylene. This monomer polymerizes at temperatures just below
140
C[
107
]:
Cl
Cl
Cl
Cl
Cu
Cl
Cl
+
CuCl
2
Cl
Cl
Cl
Cl
Cl
Cl
Cl
C
l
n
Cl
Cl
n
Cl
Cl
-Xylylene polymers also form electrolytically [
88
] in dioxane-water solution with mercury or
lead cathodes and carbon rod anodes. During the reaction, a quinone dimethide intermediate probably
forms [
88
]. Many substituted polymers also form by this reaction [
88
]. Following is an example of
one of them:
p
F
F
F
F
Br
Br
n
F
F
F
F
Another interesting synthesis is through an equilibration reaction of suitably substituted styrenes to
p
-xylylenes that spontaneously polymerize to linear polymers [
108
]. A suitable substituent can be a
p
-cyanophenylmethyl group. Such compounds undergo complete ionization and rearrange in the
presence of a strong base:
