Chemistry Reference
In-Depth Information
O
H
Cl
Cl
Cl
H
NC
H
N
C
R
O
+
R
O
N
R
C
N
R
C
O
HCl
+
H
H
O
Cl
Cl
HCl
Cl
HCl
NC
R
O
+
HCl
NC
R
O
HN
C
NC
R
R
O
+
2 HCl
5.9.2 Anionic Polymerization of Lactams
The anionic polymerizations of lactams are initiated by strong bases [
128
] capable of forming lactam
anions:
N
O
C
O
C
H
+
BH
+
B
Such bases can be alkali metals, metal hydrides, organometallic compounds, and metal amides.
The initiation step of ring-opening amidation can be shown as follows:
2
O
C
H
O
C
N
2
+
2 Na
2 Na
+
H
2
+
O
C
N
O
C
O
C
H
N
C
O
H
+
The primary amine anions abstract protons very rapidly from other molecules of lactams to form
amino-acyllactams [
130
]:
O
O
O
O
O
O
C
N
C
H
HN
C
C
N
C
N
C
NH
2
+
+
In these reactions, the propagation centers are the cyclic amide linkages of the N-acylated terminal
lactam rings. Acylation of the amide nitrogens have the effect of increasing the electron deficiencies
of these groups. This in turn increases the reactivities of the cyclic amide carbonyls toward attacks by
the nucleophilic lactam anions [
115
]:
O
O
O
O
O
O
C
N
C
N
C
C
C
N
N
C
+
