FORMATION OF HUGE CYCLIC OLIGOMERS IN THE CONDENSATION POLYMERIZATIONOF BIS(9-HYDROXY-1,4,7-TRIOXANONYL) SUBSTITUTED NAPHTHALENE AND BENZENES WITH BOTH AROMATIC AND ALIPHATIC BIS-ACID CHLORIDES
Ija. Mertens et al., FORMATION OF HUGE CYCLIC OLIGOMERS IN THE CONDENSATION POLYMERIZATIONOF BIS(9-HYDROXY-1,4,7-TRIOXANONYL) SUBSTITUTED NAPHTHALENE AND BENZENES WITH BOTH AROMATIC AND ALIPHATIC BIS-ACID CHLORIDES, Perkin transactions. 2, (3), 1998, pp. 725-736
Without the use of high dilution techniques condensation polymerizatio
n of bis(9-hydroxy-1,4,7-trioxanonyl) substituted naphthalene and benz
enes (1a-d) with the bis-acid chlorides terephthaloyl dichloride (2),
adipoyl dichloride (5a) and isophthaloyl dichloride (5b) at 80 degrees
C, respectively, gives giant-size macrocycles, i.e. crownophanes 3a(n
) with n = 1-5, 3b-d(n) with n = 1-3 and 6a-b(n) with n = 1-2, respect
ively, in high overall yield (ca, 30% w/w, monomer cone. 0.033 M). The
crownophanes with 28-150 atom perimeters have been isolated using pre
parative column chromatography. Both in the melt and in solution; with
a ten-fold increase in monomer cone. (0.33 M), cyclic oligomer yields
remain considerable (melt, ca. 2% w/w, and solution ca. 10% w/w). H-1
NMR conformational analysis of the 9-hydroxy-1,4,7-trioxanonyl side c
hains of both 1a and 1d at 25 and 80 degrees C have shown that all HO-
[CH(I)(2)-CH(II)(2)-O](n)-units are almost exclusively present in thei
r gauche conformation at both temperatures. This is supported by semi-
empirical AM1 calculations, Hence, favourable pre-orientation of the s
ide chains is apparently an important factor in the formation of cycli
c oligomers, Single crystal X-ray structures of 3a(1), 3d(1) and 6a(1)
are reported; solid-state packing motifs are strongly affected by the
type of diol and bis-acid constituent.