Chemistry Reference
In-Depth Information
condensation, because the phenol hydroxyl possesses low reaction ability.
Usually more reactive chloranhydrides are used. The polycondensation
of
n
-oxybenzoic acid with blocked hydroxyl group (or of corresponding
chloranhydride) happens at temperature of 150 °C and greater. The
n
-
acetoxybenzoic acid [23, 24] or the
n
-oxybenzoic acid mixed with acyla-
tion agent Ac
2
O [25-27] at presence of standard catalyst (in two stages:
in solution at temperature 180-280 °C and in solid phase at temperature
300-400 °C) as well as chloranhydride of
n
-oxybenzoic acid [34], or the
reaction of
n
-oxybenzoic acid with acidic halogenating agent (e.g., SOCl
2
,
PCl
3
,
PCl
5
) [29] have been used at synthesis of high-molecular polymer
aiming to increase the reactivity.
Besides the
n
-oxybenzoic acid, it's replaced in core derivatives (with
F, Cl, Br, J, Me, Et etc. as replacers) can be used as initial materials in
polycondensation processes. However, the low-molecular polymer of log-
arithmic viscosity equal to 0,16 is formed at polycondensation of methyl-
replaced
n
-oxybenzoic aced in presence of triphenylphosphite [37] which
is associated to the elapsing of adverse reaction of intramolecular etherifi-
cation with triphenyl phosphite, resulting in termination of chain. This re-
action does not flow when using PCl
3
. High heat- and thermo-stable poly-
esters of
n
-oxybenzoic acid of given molecular weight containing no edge
СООН-groups can be obtained by heating of
n
-oxybenzoic acid mixed
with dialkylcarbonate at 230-400 °C [20].
The high-molecular polymer can be produced from phenyl ester of
n
-
oxybenzoic acid at presence of butyltitanate in perchloroligophenylene at
heating in current nitrogen during 4 h at temperatures 170-190 °C and
later after 10 h of exposure to 340-360 °C [20]. Usually [32], Ti, Sn, Pb,
Bi, Na, K, Zn or their oxides, salts of acetic, chlorohydratic or benzoic
acid are used as catalysts of polycondensation processes when producing
polyesters. The polycondensation of polymers of oxybenzoic acids and
their derivatives has been performed at absence of catalysts [33] in current
nitrogen at temperatures 180-250 °C and pressure during 5-6 h either. The
temperature of polycondensation can be lowered [34] if it is carried out in
polyphosphoric acid or using activating COOH- group of the substance.
Interesting investigation on study of structure characteristics of polyes-
ters and copolyesters of
n
-oxybenzoic acid have been performed in Refs.
[35, 36]. The introduction of links of
n
-oxybenzoic acid results in high-
molecular compounds of ordered packing of chains, similar to the struc-
ture of high-temperature hexagonal modification of homopolymer of
n
-
