Chemistry Reference
In-Depth Information
The reaction then proceeds by the
activated mechanism
. The initiation reaction was pictured by
Ballard and Bamford [
151
] as follows:
H
O
H
N
O
O
O
N
R
N
O
+
O
O
R
O
R
O
N
O
O
R
O
O
O
O
O
O
O
R
O
R
R
N
R
N
H
+
CO
2
+
NO
N
B
H
OH
O
Each propagation step consists of an addition of one unit of the anhydride and an accompanying
loss of carbon dioxide:
O
O
O
O
H
O
O
O
R
R
N
O
+
R
N
R
N
H
NH
2
N
2
O
R
O
O
H
+ CO
2
When the reaction is initiated by primary amines, the first step is a nucleophilic attack by the amine
on the C
3
of the anhydride [
151
-
153
]. The carbon dioxide that is released comes from the C
2
carbonyl
group. The propagation proceeds by addition of terminal amine groups to the C
3
carbonyl groups of
the monomers [
151
-
153
]:
H
O
O
H
N
N
O
+
H
2
NR'
R
R'NH
COOH
O
R
O
NH
2
R'NH
+
CO
2
R
