Chemistry Reference
In-Depth Information
(a)
Me
O
CO
O
NH
2
HO
2
C
O
(b)
OH
O
NH
2
O
NH
2
.HCl
(c)
HO
2
C
OH
ClH.NH
2
O
CO
2
H
O
NH
2
.HCl
ClH.NH
2
Br
O
CO
2
H
NH
2
Br
H
2
N
R
CO
1) Pd(dppa)
3
2) RCO-Cl
N
Br
N
N
N
H
2
N
Formula 11.6
whereby Mw values in the range of 24-46 kDa were found. The hydrochloride of
the amine-terminated polyamides was even soluble in water.
With one exception, all the ab
n
-type amino acids outlined in Formulas
11.5
and
11.6
were polymerized by in situ activation with phosphorous reagents. Either
triphenylphosphite (TPP) ? pyridine were used in NMP at 100 C (Yamazaki
method) or diphenyl(2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate (DBOP) ?
triethylamine. This approach has the important advantage that monomers which are
stable on storage and insensitive to moisture may be used. The contributions came
from Russo et al. [
43
,
44
], Ueda et al. [
45
] and mainly from the research group of Jikei
and Kakimoto [
46
-
54
]. For the hb polyamide derived from monomer c, For-
mula
11.5
, a Mw of 98 kDa was determined by SEC-MALLS along with a DB of
0.48 [
45
]. From other synthese only viscosity data were reported. Kakimoto et al. [
46
]
studied the influence of the monomer structure on the DB. For the polycondensations
of 3,5-diamino benzoic acid an unexpectedly low DB of 0.32 was found and ascribed
to steric hindrance. The high DBs of 0-72 were measured for the polycondensate of
monomer (f) and 0.844 for (e), Formula
11.5
, these extraordinarily high values result
from the 100 % branching in the dendritic monomers themselves.
