Chemistry Reference
In-Depth Information
(a)
H
3
C
CO O
CO
O
(CH
2
)
10
O
OAc
O
(CH
2
)
10
O
OAc
(b)
O
(CH
2
)
10
O
OAc
HO
2
C
O
(CH
2
)
3
O
(CH
2
)
10
O
OAc
(c)
HO
2
C
O
(CH
2
)
10
O
O
(CH
2
)
3
O
CO
2
H
HO
2
C
O
(CH
2
)
10
O
CO
2
X
(d)
O
(CH
2
CH
2
O) H
HOCH
2
CH
2
O
MeO
2
C
CO
2
X
(e)
O
(CH
2
CH
2
O) H
X = H, Me
Formula 11.3
However, side reactions, such as formation of ether groups or cyclization, were not
investigated. Turner et al. [
11
] reported on the Bu
2
Sn(OAc)
2
-catalyzed polycon-
densation of 5-(2
0
-hydroxyethoxy) isophthalic acid in bulk at 190 C. Dimethyl
isophthalate served as ''core monomer'' in several experiments. Polycondensation
promoted by bis(cyclohexyl)carbodiimide (DCC) were reported for the aromatic
monomer (f), Formula
11.1
[
35
]. The mild reaction conditions prevented transe-
sterification, but only low molar mass polyesters (Mw \ 17 kDa) were obtained.
Similar molar masses were achieved by Voit et al. [
36
] for carbodiimide promoted
polycondensations of the triazene monomers (b) and (c), Formula
11.4
. Some-
what more successful were DCC-activated polycondensations of trifunctional
oligo(e-caprolactone)s such as (d), Formula
11.4
, reported by Hedrick et al.
[
37
,
38
]. Syntheses of LC polyesters from monomers (e), Formula
11.4
, and
isomers were achieved by means of thionyl chloride and pyridine [
39
].
