Chemistry Reference
In-Depth Information
of either of them, however, result not only in greater levels of chloromethylation, but also in higher
degrees of secondary cross-linkings and in uneven distributions of the chloromethyl groups [
188
].
Another technique of chloromethylating polystyrene is to react it with methylal and thionyl
chloride in the presence of zinc chloride [
189
]:
ZnCl
2
+
OO
+
SOCl
2
+
(CH
3
)
2
SO
3
CH
2
Cl
-methyl styrene)s by
treating them with aqueous sodium hypochlorite in the presence of a phase transfer catalysts, like
benzyltriethylammonium chloride [
190
]. The conversions of methyl to chloromethyl groups can be as
high as 20%without any detectable morphological changes [
187
]. If these reactions are carried out with
low levels of chloromethylating agents or catalysts, they occur more or less homogeneously. Larger
levels of either of them, however, result not only in greater levels of chloromethylation, but also in higher
degrees of secondary cross-linkings and in uneven distributions of the chloromethyl groups [
188
].
Another technique of chloromethylating polystyrene is to react it with methylal and thionyl
chloride in the presence of zinc chloride [
189
].
Techniques for chloromethylating polyarylether sulfones, polyphenylene oxide, phenolic resins, and
model compounds were described recently [
191
]. When the subsequent products are converted to quater-
nary amines, there is a decrease in the quaternization rate with increase in degree of substitution. This may
be due to steric effects imposed by restricted rotation of the polymeric chains [
191
]. This phenomenon was
not observed in quaternization of poly(chloromethyl styrene). The chloromethylation reaction of a
polysulfone with chloromethyl ether, catalyzed by stannic chloride, can be illustrated as follows:
Chloromethyl-substituted polystyrenes can also be prepared from poly(
p
O
O
S
O
O
S
O
O
CH
2
Cl
O
O
S
O
O
S
O
O
CH
2
Cl
Vinyl benzyl chloride monomer is available commercially. It is possible, therefore, to simply
prepare the chloromethylated polystyrene or copolymers
from the monomer without
the
chloromethylation reactions.
9.4.3.3 Reactions of Halomethylated Polymers
Many known reactions of the halomethyl groups on polymers are possible. One can, for instance,
convert poly(chloromethyl styrene) to poly(hydroxymethyl styrene) [
183
]. Also, iodomethylated
polystyrene can be treated with triethyl phosphite in order to carry out an
