Chemistry Reference
In-Depth Information
9.4.4.2 Nucleophilic and Electrophilic Substitutions
Many other conversions of functional groups of acrylic and methacrylic resins were reported. One of
them is a conversion of methyl acrylate to a hydrazide by a direct reaction with hydrazine [
244
]:
+
H
2
N
NH
2
H
2
O
O
O
O
N
H
NH
2
The above reaction requires a 10:1 ratio of hydrazine to the ester groups. In the laboratory, it can be
carried out on a steam bath over a period of 2-3 h. Approximately 60-80% of the ester groups convert
[
244
]. The hydrazides can form various hydrazones through reactions with aldehydes and ketones:
R
O
R'
O
O
or
RCHO
N
H
N
H
NH
2
N
R' (or H)
R
The hydrazide can also be converted to an azide [
244
]:
H
O
NaNO
2
+
O
N
H
N
3
NH
2
of the azide yields a cross-linked polymer [
244
]. Syndiotactic poly(methyl
methacrylate) converts to a hydrazide in a similar manner [
245
].
Nucleophilic substitution reactions
can be carried out on poly(methyl methacrylate) with hetero-
cyclic organolithium reagents [
246
]. The reactions are conducted in homogeneous solutions in
tetrahydrofuran or in benzene combined with hexamethyl-phosphoramide. Copolymers will form
with tautomeric keto-
A
Hoffman reaction
-heterocyclic structures. Following heterocyclic reagents are useful [
246
]:
2-picolinyllithium, [(4,4-dimethyl-2-oxazole-2-yl)methyl]lithium, quinaldinyllithium, and [2-thia-
zole-2-yl-methyl]lithium.
In attempts to carry out
b
reactions on poly(methacryloyl chloride), the polymer was
reacted with diazomethane in various molar ratios and at different temperatures [
247
]. Initially, acid
chloride groups do react with diazomethane as expected. The products, however, undergo subsequent
reactions with neighboring acid chloride groups and form cyclic structures [
247
]:
Arndt-Eister
