Chemistry Reference
In-Depth Information
-Caz-1, promote a difficult tosylamine ring-closing with
100% conversion, compared with about 60% achieved by existing catalysts. And a considerably smaller
amount of Caz-1 is needed to promote ring-closing metathesis of hindered dienes than is required for
current catalysts. The Caz-1 catalysts also showunusually good stability and longevity in reactions [
184
].
Wathier, Stoddart, and Grinstaff reported using the Grubs catalyst to form high molecular weight
polymers, poly(ethyl-5-norbomene-2-carboxylate) and poly(methyl-5-oxanorbomene-2-carboxylate)
carrying ester functions. The preparations were illustrated as follows [
185
]:
The catalysts, that they call
cis
-and
trans
O
n
OR
O
R
O
The authors point out that synthesizing high molecular weigh polymers with the aid of the Grubbs'
catalyst can be difficult. Small changes in the structure of the monomer (i.e., oxa-norbornene vs.
norbornene) can lead to drastic change in polymerization outcomes. On the other hand, the polymeri-
zation of norbornene with Grubbs' catalyst can lead to high molecular weight polymers with
relatively narrow molecular weight distribution [
185
].
5.12 Polymerization of Cyclic Amines
The cyclic amines or imines (aziridines) polymerize only with acidic catalysts [
186
]. This reaction
can be illustrated as follows:
H
2
H
N
A
N
+
HA
H
2
H
H
NH
2
N
A
A
N
N
+
H
H
N
H
N
NH
2
A
N
H
NH
2
NH
2
N
A
N
+
H
2
A
N
NH
2
N
N
H
