Chemistry Reference
In-Depth Information
Potassium and sodium cyanide catalyze the reaction. It can be carried out between
20 and
100
C. An example is the following preparation [
47
]:
O
KCN
n
O
N
O
n
O
The resultant polymer has a molecular weight of one million. When the methyl group is replaced
by butyl, the product is a tough film former, but depolymerizes in the presence of some catalysts.
Many other interesting high molecular weight polymers with various substitutions can be formed by
this reaction at low temperature.
Polymerization of
-amino acid anhydrides results in formations of
Nylon 2
.This
reaction is also discussed in Chap.
5
. These polymers are mainly of interest to protein chemists in
model studies of naturally occurring poly(
N
-carboxy-
a
-amino acids).
Nylon 3
can be synthesized by intramolecular hydrogen transfer polymerization of acrylamide
a
H
O
B
n
N
NH
2
n
O
The fibers from nylon 3 are reported to resemble natural silk [
50
]. They possess high water
absorbency and good light and oxygen stability. The polymer, however, is too high melting for melt
spinning, or for molding and extrusion [
46
]. Nylon 3 fibers can be spun, however, from special
solutions containing formic acid [
52
].
It is difficult to synthesize
b
-propiolactam. A synthetic route, however, was found for substituted
propiolactams like
-butyrolactams [
50
]. The compounds form by nucleophilic additions of
carbonylsulfamoyl chloride to olefins [
51
]:
b
+
ClO
2
S
N
O
N
O
NO
H
ClO
2
S
b
-butyrolactam polymerizes readily by anionic mechanism, yielding a very high
molecular weight polymer. This lactam preparation reaction is quite general. It can be carried out on
propene, 1-butene, 1-hexene, and styrene [
50
]. Although substituted lactams are harder to polymerize
[
53
], the four-membered lactams exhibit such a strong tendency toward ring opening that even
substituted
b
-propiolactams polymerize well [
50
]. The rate of polymerization, however, does tend
to decrease with the number of substituents.
Nylon 4
or polypyrrolidone is an attractive polymer for use in fibers. The original syntheses of
nylon 4 from 2-pyrrolidone were carried out by alkaline catalyzed ring opening polymerizations
promoted by
The above shown
-acylpyrrolidone [
49
]. The products from these reactions melt between 260 and 265
C.
N
