Synthesis and properties of carbon-chain polymers with pendant 1,3,4-oxadiazole rings

Article abstract of DOI:10.1134/S107042720607024X

Carbon-chain polymers with 1,3,4-oxadiazole rings were prepared by radical polymerization and polymer-analogous transformations. The kinetic relationships of the polymerization of vinyl-1,3,4-oxadiazole monomers and some properties of the resulting polyme

Full text of DOI:10.1134/S107042720607024X

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 7, pp. 1167 1173. Pleiades Publishing, Inc., 2006.
Original Russian Text V.N. Kizhnyaev, A.F. Pokatilov, L.I. Vereshchagin, L.V. Adamova, A.P. Safronov, A.I. Smirnov, 2006, published in Zhurnal
Prikladnoi Khimii, 2006, Vol. 79, No. 7, pp. 1177 1184.
MACROMOLECULAR CHEMISTRY
AND POLYMERIC MATERIALS
Synthesis and Properties of Carbon-Chain Polymers
with Pendant 1,3,4-Oxadiazole Rings
V. N. Kizhnyaev, A. F. Pokatilov, L. I. Vereshchagin, L. V. Adamova,
A. P. Safronov, and A. I. Smirnov
Irkutsk State University, Irkutsk, Russia
Ural State University, Yekaterinburg, Russia
Received March 10, 2006
Abstract Carbon-chain polymers with 1,3,4-oxadiazole rings were prepared by radical polymerization and
polymer-analogous transformations. The kinetic relationships of the polymerization of vinyl-1,3,4-oxadiazole
monomers and some properties of the resulting polymers were studied. The thermodynamics of interaction of
poly-2-vinyl-5-methyl-1,3,4-oxadiazole, a nonionic water-soluble polymer, with water was examined.
DOI: 10.1134/S107042720607024X
Macromolecular compounds containing 1,3,4-oxa-
diazole rings in the backbone are widely used as
chemically stable and heat-resistant, semiconducting,
fiber-forming, and gas-separating materials [1, 2]. The
main routes to these polymers, including commercial
procedures, involve polycondensation of bifunctional
heterocyclic compounds or formation of the 1,3,4-oxa-
diazole ring in a macromolecule of a polymeric pre-
cursor. At the same time, available data on vinyl
derivatives of oxadiazoles, on their polymerization,
and on the properties of carbon-chain polymers with
pendant 1,3,4-oxadiazole rings are scarce and concern
the synthesis of vinyl-1,3,4- and vinyl-1,2,4-oxadi-
azoles, and also the use of polyvinyl-1,2,4-oxadiazoles
for preparing heat-resistant fibers [1, 3 5]. Recently
we studied the polymerization of vinyl monomers
with 1,3,4-oxadiazole rings [6].
chain polymers containing pendant 1,3,4-oxadiazole
rings.
EXPERIMENTAL
2-Vinyl-5-methyl-1,3,4-oxadiazole was prepared in
one step from 5-vinyltetrazole as described in [4];
yield 80%. 2-Vinyl-5-phenyl-1,3,4-oxadiazole was
prepared in two steps. First 5-vinyltetrazole was acy-
lated with benzoyl chloride in the water toluene sys-
tem at room temperature in the presence of a phase-
transfer catalyst. Then the organic phase was sepa-
rated and heated to 368 373 K to decompose the ben-
zoyl derivative of vinyltetrazole. After the gas evolu-
tion ceased, the solvent was removed and the residue
was subjected to fractional distillation. Yield of the
target product 70%. 2-Vinyl-5-trifluoromethyl-1,3,4-
oxadiazole was prepared by mixing equimolar
amounts of 5-vinyltetrazole and trifluoroacetic anhy-
dride in methylene chloride at room temperature.
After the reaction completion, the solvent was re-
moved and the product was isolated by vacuum distil-
lation (yield 95%). The constants of the synthesized
vinyl monomers purified by column chromatography
on alumina are given in Table 1. The purity of the
compounds was checked by NMR, IR, and UV spec-
troscopy. The kinetic relationships of the polymeriza-
tion of the vinyl monomers were studied by the pro-
cedure described in [6].
This paper deals with the synthesis of poly-2-vinyl-
5-R-1,3,4-oxadiazoles
(
CH2 CH )n
N
O
N
R
[
R = CH (I), Ph (II), CF (III), C H (IV)] by
3 3 9 19
radical polymerization of the corresponding vinyl
monomers and by polymer-analogous transformations
of the macromolecular precursor, poly-5-vinyltetrazole
The synthesis of poly-2-vinyl-5-R-1,3,4-oxadia-
(PVT), and with the properties of the resulting carbon-
zoles I IV by polymer-analogous transformations
1167

1168
KIZHNYAEV et al.
Table 1. Characteristics of 2-vinyl-5-R-1,3,4-oxadiazoles
95% according to 13C NMR and elemental analysis of
the resulting polymer.
2
0
d, g cm 3
R
bp, K (P, kPa)
n
D
Complexes of polyvinyloxadiazole I with metal
salts were prepared by combining the solutions of the
polymer and salt in appropriate solvent at room tem-
perature with stirring. The precipitates of the metal
complexes were washed with water, filtered off, and
vacuum-dried to constant weight. The compositions of
the products were determined by elemental analysis.
CH3
CF3
Ph
314 (1.33)
313 (20.0)
395 (1.33)
1.4905
1.3945
1.5885
1.12
1.32
1.17
involved the reaction of PVT with acetic anhydride,
trifluoroacetic anhydride, benzoyl chloride, and deca-
noyl chloride, respectively, in pyridine or dimethyl-
formamide (DMF) on heating. As in the case of the
monomers, the reaction completion was judged from
the cessation of evolution of gaseous nitrogen from
the reaction mixture. The resulting polyvinyloxadi-
azoles were precipitated with diethyl ether, washed
with the precipitant, and vacuum-dried to constant
weight. The degree of conversion of the tetrazole
fragments into oxadiazole fragments was calculated
from elemental analysis data (Table 2).
For thermodynamic studies of the interaction with
water, we used nonfractionated, thoroughly dried in
a vacuum, samples of polymer I prepared both by
5
radical polymerization (M = 6 10 ) and by polymer-
5
analogous transformations (M = 1.7 10 ). The iso-
thermal sorption of water vapor with the polymer
samples at 298 K was studied gravimetrically using
highly sensitive quartz spirals [7]. The sorption iso-
therms were expressed in the coordinates x/m =
f(p/p ), where x is the amount of water vapor ab-
s
sorbed by the polymer sample of weight m, and p/ps
is the relative water pressure. The Gibbs energies of
mixing gm were calculated from the sorption iso-
therms of water vapor [8]. The integral heat of solu-
tion of the polymers in water and the integral heat of
dilution of polymer solutions of given concentration
in a large amount of the solvent were determined with
a DAK-1-1-A microcalorimeter. The mean specific
enthalpies of mixing hm and the mean entropies of
mixing sm were calculated by the procedure sug-
gested in [9].
The reaction of polyvinyloxadiazole I with forma-
mide was performed by heating a solution of the
polymer in excess formamide at 348 K in an argon
flow for 5 h with continuous stirring. The resulting
poly-3-vinyl-5-methyl-1,2,4-triazole was precipitated
by pouring the reaction mixture into a mixture of
acetone and diethyl ether, washed with the precipitant,
and vacuum-dried to constant weight. The degree of
conversion of the oxadiazole fragments into triazole
fragments was about 97% according to 13C NMR and
elemental analysis of the resulting polymer.
The H and 13C NMR spectra were recorded on a
Varian VXR-500 spectrometer, and the IR spectra, on
a Specord M80 spectrometer. The molecular weights
of the polymer samples were determined by small-
angle light scattering with an FSR laser photometer
(Russia). The thermograms of the polymers were
recorded on an MOM derivatograph (Hungary) in the
1
The reaction of I with aniline was performed in
polyphosphoric acid at 358 363 K in an argon flow
for 7 8 h with continuous stirring. The resulting poly-
3
-vinyl-4-phenyl-5-methyl-1,2,4-triazole was precipi-
tated by pouring the reaction mixture into water, re-
precipitated from DMF into diethyl ether, and vacu-
um-dried to constant weight. The degree of conversion
of oxadiazole fragments into triazole fragments was
1
dynamic mode at a heating rate of 5 deg min . The
Table 2. Conditions and results of the synthesis of poly-2-vinyl-5-R-1,3,4-oxadiazoles I IV by the modification of poly-
5-vinyltetrazole (PVT). Molar ratio PVT : acylating agent = 1 : 5
Nitrogen content in reaction product, %
Polyvinyl-
oxadiazole
Acylating
agent
Conver-
sion, %
Solvent
, h
T, K
calculated
found
I
II
III
IV
(CH CO) O
PhC(O)Cl
Pyridine
2
2
1
0.5
373
393
373
318
28.07
17.01
13.42
18.81
25.45
16.28
12.61
17.07
91
97
96
93
3
2
C H C(O)Cl
9
19
(CF CO) O*
DMF
3
2
*
Molar ratio PVT : acylating agent = 1 : 1.5.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 7 2006

SYNTHESIS AND PROPERTIES OF CARBON-CHAIN POLYMERS
1169
Table 3. Kinetic parameters of the polymerization of 1-vinyl-5-R-1,3,4-oxadiazoles (acetonitrile, AIBN, 333 K)
Eapp
Ep
0.5E0
kp/k 00 .5 102,
l0.5 mol 0.5 s 0.5
k
105,
app
Ki 10 , s 1
5
R
l0 mol 0.5 s 1
.5
kJ mol 1
CH3
CF3
Ph
95.1
88.5
109.3
29.7
21.0
35.2
25.4
76.5
1.8
1.4
1.3
1.1
0.068
0.21
0.0055
viscosities of polymer solutions were measured with
an Ubbelohde viscometer at 273 K.
ator concentration is 0.5, and with respect to the
monomer concentration, 1.0. As expected, the highest
activity in the radical polymerization is exhibited by
the monomer containing in the 1,3,4-oxadiazole ring
an acceptor trifluoromethyl group. For 2-vinyl-5-tri-
The synthesis of the monomeric and polymeric
compounds containing 1,3,4-oxadiazole rings is based
on the recyclization at elevated temperatures of un-
stable acylated derivatives of tetrazole into the oxadi-
azole ring with the release of gaseous nitrogen:
0.5
p
fluoromethyl-1,3,4-oxadiazole, the parameter k /k0
used as a criterion of the monomer activity in radical
polymerization is by a factor of 3 higher than for
2-vinyl-5-methyl-1,3,4-oxadiazole (Table 3). In turn,
the latter monomer is by an order of magnitude more
active than the vinyloxadiazole with the phenyl sub-
stituent in the ring. The energy consumption in the
N N
H
N N
O
R C(O)X
C(O)R
R
O
N
N
R
N
N
N N
R
O
I
R ,
chain propagation step (the quantity Ep 0.5E ) regu-
N
0
2
larly increases with a decrease in the monomer activ-
ity parameter. The fact that 2-vinyl-5-trifluoromethyl-
where R = CH =CH , (CH CH ) ; X = Cl,
2
2
n
1,3,4-oxadiazole is the most active in the polymeriza-
O(O)CR .
tion among the compounds studied is well consistent
with the typical trend noted previously for vinylazoles
The starting compound can be 5-vinyltetrazole or
its polymer. In the first case, the reaction yields mono-
meric vinyl derivatives of substituted 1,3,4-oxadia-
zoles, and in the second case, carbon-chain polymers
with pendant 1,3,4-oxadiazole rings. A distinctive
feature of the reaction with trifluoroacetic anhydride
as acylating agent is that the transformation of the
tetrazole ring into the 1,3,4-oxadiazole ring occurs
virtually quantitatively at room temperature in the
case of the synthesis of the vinyl monomer and at
[14]: an increase in the activity of monomers in radi-
cal polymerization with an increease in the electron-
withdrawing power of the heterocyclic substituent at
the vinyl group.
The lower reactivity in polymerization of phenyl-
substituted vinyloxadiazole compared to the methyl-
substituted monomer is attributable to the steric effect
of the bulky phenyl substituent or to the lower reac-
tivity of the radical center due to additional delocali-
zation of the unpaired electron. Comparison of the
kinetic parameters of the polymerization of vinyl
1,3,4-oxadiazole derivatives (Table 3) with those re-
ported for another C-vinylazole, 2-methyl-5-vinyl-
3
13 318 K in the case of the modification of the poly-
meric precursor. In all the other cases, the similar
transformation of the azole ring requires heating to
3
73 393 K.
0.5
0.5
0.5 0.5
tetrazole (k /k0 = 0.31 l mol
s
[14]), shows
As shown in [6], vinyl derivatives of 1,3,4-oxadi-
p
that the oxadiazole monomers are less reactive in the
polymerization, which is consistent with the stronger
electron-withdrawing power of the tetrazolyl substitu-
ent compared to the oxadiazolyl substituent. 2-Vinyl-
azole are very active in radical polymerization and
form polymeric products of high molecular weights in
high yields. The kinetic relationships of the radical
polymerization of 2-vinyl-5-methyl-, 2-vinyl-5-phen-
yl-, and 2-vinyl-5-trifluoromethyl-1,3,4-oxadiazoles
do not differ from those found previously for vinyl
derivatives of azoles containing only nitrogen hetero-
atoms in the ring [10 13]. In the polymerization of
all the three monomers in acetonitrile under the action
of AIBN, the reaction order with respect to the initi-
5
-methyl-1,3,4-oxadiazole is a water-soluble mono-
mer, and water exerts a strong accelerating effect on
its polymerization. In aqueous solution, the activity
parameter of the monomer increases by a factor of 18
0.5
0.5
0.5 0.5
(k /k = 1.24 l mol
s
[6]) compared to the
p
0
polymerization in acetonitrile (Table 3), and the
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 7 2006

1170
KIZHNYAEV et al.
Table 4. Solubiity and decomposition points of polyvinyloxadiazoles
Polymer
Solvent
Softening point, K Decomposition onset point, K
I
DMF, DMSO, acetone, acetonitrile, ethanol, acetic acid,
478
622
1
,2-dichloroethane, water
II
III
IV
DMF, DMSO, CH Cl
DMF, DMSO, acetonitrile, acetic acid
1,2-Dichloroethane, benzene, dioxane
483
460
603
585
579
2
2
molecular weights of the resulting polymers increase.
Whereas the molecular weight of samples of poly-
of IV give four signals at 0.9 (CH ), 1.32, 2.02, and
3
13
3.25 ppm (CH ). The CF groups in the C NMR
2
3
vinyloxadiazole I prepared in acetonitrile is within
spectra of samples of III prepared by different pro-
5
(
1 7) 10 , in an aqueous solution it is possible to
cedures give a quartet at 113.0 119.5 ppm.
6
prepare polymer samples with M as high as 4 10 .
Polyvinyloxadiazoles I III, irrespective of the
synthesis procedure, are amorphous colorless powders
(polymer IV is rubber-like) with the softening and
decomposition points depending on the substituent in
the heteroring (Table 4, Fig. 1). On the whole, carbon-
chain polyvinyloxadiazoles can be regarded as rela-
tively heat-resistant polymers, despite the fact that
they are inferior to the known heterochain oxadiazole-
containing polymers by approximately 100 C [2].
Spectroscopic studies of the polymers show that
the polymer backbone is formed exclusively by open-
ing of the vinyl double bonds, without involvement of
the heterocyclic fragments. Polyvinyloxadiazoles I V
prepared by the polymer-analogous transformation
from PVT have a similar structure. The absorption
bands of the 1,3,4-oxadiazole ring at 1250, 1350,
1
530, and 1580 cm 1 remain unchanged in the spec-
trum of the polymers prepared by various procedures.
A minor distinctive feature of the spectra of the poly-
mers prepared by the modification to a conversion less
than 95% is the presence of a broad absorption band
at 2250 3700 cm 1 corresponding to the vibrations of
the residual N H groups in the unsubstituted tetrazole
The solubility of polyvinyloxadiazoles is character-
ized by the same trends as the solubility of vinylazole
polymers containing only the nitrogen heteroatoms in
the heterorings [16]. Polyvinyloxadiazole I whose
heterocyclic fragments contain a small alkyl substitu-
ent, CH group (Table 4), dissolve in the widest set
1
3
rings [15]. The H NMR spectra of polyvinyloxadi-
of solvents. An increase in the size of the alkyl group
azoles I and II prepared by various procedures are
similar in the shape and position of signals of the
methyl ( 2.4 ppm) and phenyl ( 7.2 7.6 ppm)
groups. Protons of the nonyl substituent in the spectra
(passing to nonyl-substituted polyvinyloxadiazole IV)
results in the loss of the solubility in polar solvents,
but makes the polymer more readily soluble in low-
polarity liquids such as benzene and dioxane. Poly-
vinyloxadiazoles are not polyelectrolytes; therefore,
solutions of polymers prepared by polymerization
show a linear concentration dependence of the reduced
viscosity (Fig. 2). However, the polymers prepared by
the modification and containing residual N H-unsub-
stituted tetrazole fragments (>5 mol %) behave in
solutions as typical polyelectrolytes: Their reduced
viscosity increases with the dilution.
m, %
In contrast to hydrophobized polyvinyloxadiazoles
with phenyl, nonyl, and trifluoromethyl substituents,
polymer I, similarly to polymers with the 1,2,4-tri-
azole ring, is a nonionic water-soluble macromolecu-
lar compound. Comparison of 1,2,4-oxadiazole- and
1
,2,4-triazole-containing polymers is interesting from
T, K
the viewpoint of the effect of the ring-forming hetero-
atoms (at their equal number) on the compatibility
with water. However, it was noted previously [16]
that polyvinylazoles containing sequences of two and
Fig. 1. Dynamic thermogravimetric analysis of polyvinyl-
oxadiazoles (1) I, (2) II, (3) III, and (4) IV. ( m) Weight
loss and (T) temperature.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 7 2006

SYNTHESIS AND PROPERTIES OF CARBON-CHAIN POLYMERS
1171
3
1
more nitrogen atoms in the ring are insoluble in water
e.g., poly-1-vinyl-1,2,3-triazole, poly-1-vinyl-1,3,4-
/c , cm g
p
sp
(
triazole, poly-1-vinyltetrazole). Polyvinylazoles con-
taining an isolated pyridine nirogen atom in the
heteroring are water-soluble (poly-1-vinylimidazole,
poly-1-vinyl-1,2,4-triazole). In the structure of the
1
,3,4-oxadiazole ring, there are two vicinal pyridine
nitrogen atoms which, by analogy with poly-1-vinyl-
,3,4-triazole, is unfavorable for the affinity of the
1
polymer for water, and an isolated oxygen atom of the
furan ring. Apparently, this oxygen atom is responsi-
ble for the solubility of I in water.
cp 10 , g cm 3
2
Fig. 2. Reduced viscosity /c of aqueous solutions as a
The thermodynamic parameters of the interaction
with water of polymer I prepared by polymerization
and modification were estimated from the sorption
and calorimetric data. For both samples of I, the iso-
therms of water vapor sorption asymptotically in-
sp p
function of polymer concentration c : polyvinyloxadiazole I
p
prepared by (1) polymerization and (2) polymer-analogous
transformation; (3) poly-3-vinyl-5-methyl-1,2,4-triazole.
crease at p/ps
1 (Fig. 3), which is typical of poly-
mers infinitely miscible with water. The concentration
dependences of the Gibbs energy of mixing ( g ) of
m
the polymers with water, calculated from the sorption
isotherms, are negative, and the second derivative
2
2
g / W > 0, i.e., the systems are thermodynami-
m
2
cally stable in the entire composition range. Poly-
vinyloxadiazole I prepared by the modification exhib-
its somewhat lower affinity for water because of the
presence of residual tetrazole fragments. Comparison
with the gm values obtained for mixing of poly-1-
vinyl-1,2,4-triazole with water shows that the oxadia-
zolyl substituent is substantially less hydrophilic than
the triazolyl substituent. This fact cannot be attributed
to the presence of the methyl substituent in the hetero-
ring of I, since the previous studies showed that elec-
tron-donor methyl substituents in azolyl fragments of
polyvinylazoles, as a rule, enhance the affinity of the
polymer for water [16].
p/ps
Fig. 3. Isotherms of water vapor sorption at 298 K for poly-
vinyloxadiazole I prepared by (1) polymerization and
(
2) polymer-analogous transformation. (x/m) Weight ratio
The weaker, compared to the 1,2,4-triazole-contain-
ing polymer, interaction of polyvinyloxadiazole I with
water also follows from the substantially smaller neg-
of water and the polymer; (p/p ) relative vapor pressure.
s
entropies of mixing T s (Fig. 4c), which indicates
that these polymers show a weaker tendency to form
joint ordered polymer water structures, compared to
the triazole-containing polymer. Thus, the difference
between the triazole and oxadiazole derivatives in the
kind of one of the three heteroatoms does not result in
the loss of the capability of the polymer with the
ative enthalpies of mixing ( h ) of I with water
m
(
Fig. 4b). The stronger exothermic effect of the
donor acceptor interaction with water and the shape
of the dependence hm = f(W ) for the sample of I
2
prepared by the polymer-analogous transformation are
attributable to the presence of the residual monomeric
units with N H-unsubstituted tetrazole rings [17].
1
,3,4-oxadiazole pendant group to dissolve in water
but appreciably decreases its thermodynamic affinity
for water.
The difference in the water affinity of oxadiazole-
and triazole-containing polymers is also manifested in
variation of the entropy parameters at formation of
the aqueous systems. Dissolution of oxadiazole poly-
mers is characterized by substantially smaller negative
As noted above, poly-2-vinyl-1,3,4-oxadiazoles can
be prepared by modification of PVT. In turn, oxadia-
zole polymers can act as precursors for preparing
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 7 2006

1172
KIZHNYAEV et al.
(
a)
Ph-NH
2
(
CH2 CH )n ,
N
N Ph
(
CH2 CH )n
N
N
O
N
CH3
(
CH2 CH )n .
HC(O)NH
2
CH3
N
NH
N
CH3
gm, J g 1
The reaction with formamide gave poly-3-vinyl-5-
methyl-1,2,4-triazole with a high conversion (up to
(
b)
13
9
7%); this was confirmed by the C NMR spectrum
13
of the final product. The C NMR spectrum of the
starting polymer I consists of the following signals
(
ppm): 11.7 ( CH ), 32.3 39.5 ( CH CH of poly-
3 2
2
5
mer chain), 167.5 (C of ring), and 169.5 (C of ring).
The chemical shifts in the spectrum of the triazole-
containing polymer are somewhat different (ppm):
1
2.9 ( CH ), 35.4 44.7 ( CH CH
of polymer
3
2
3
5
chain), 158.2 (C of ring), and 172.7 (C of ring).
Assignment of the latter two signals to the triazole
ring was based on the NMR data for model 3,5-disub-
stituted 1,2,4-triazoles. In contrast to the starting poly-
vinyloxadiazole, the triazole-containing polymer is
insoluble in organic solvents but remains soluble in
water. Because of weak acid properties of the 1,2,4-
triazole ring, poly-3-vinyl-5-methyl-1,2,4-triazole in
aqueous solutions exhibits no polyelectrolyte proper-
ties (linear concentration dependence of the reduced
viscosity, Table 2), in contrast to tetrazole-containing
polymeric NH acids [17].
hm, J g 1
(
c)
The reaction of polyvinyloxadiazole I with aniline
in polyphosphoric acid yields poly-3-vinyl-4-phenyl-
5
-methyl-1,2,4-triazole with a high degree of conver-
13
sion (up to 95%). The C NMR data confirm that the
final product contains the phenyl fragment (a set of
signals in the range 126.1 130.8 ppm). The resulting
triazole-containing polymer is soluble in DMF and
DMSO but, in contrast to the starting polymer, insolu-
ble in water.
1
T s , J g
m
Fig. 4. Mean specific thermodynamic quantities of mixing
with water at 298 K of polymer I prepared by (1) polymer-
ization and (2) polymer-analogous transformation, and
(
3) of poly-1-vinyl-1,2,4-triazole [9]: (a) Gibbs energy
g , (b) enthalpy h , and (c) T s. (W ) Weight fraction
m
m
2
of the polymer.
Similarly to other known polyvinylazoles [18],
polyvinyloxazole I forms complexes with metal ions.
2+
2+
2+
+
macromolecular compounds with other heterocyclic
fragments. Similarly to the known transformations of
heterochain polymers containing the 1,3,4-oxadiazole
ring into those containing the 1,2,4-triazole ring [2],
polyviyloxadiazole I reacts with formamide or aniline
to form the corresponding poly-C-vinyl-1,2,4-tria-
zoles, which are extremely difficult to prepare by
polymerization:
Complexes with Cu , Ni , Pd , and Ag salts are
formed just when solutions of the polymer and salt are
mixed at room temperature. The resulting complexes
of the composition L : MAn = 2 : 1 (Table 5) are
n
soluble neither in organic solvents nor in water and
separate out from the reaction mixtures as finely dis-
persed precipitates. In the IR spectra of the reaction
products, the absorption bands of the bending vibra-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 7 2006

SYNTHESIS AND PROPERTIES OF CARBON-CHAIN POLYMERS
1173
Table 5. Complexation of poly-2-vinyl-5-methyl-1,3,4-
2. Buhler, K.-U., Spezialplaste, Berlin: Akademie, 1978.
oxadiazole with metal salts MAn . L : MA = 2 : 1 (base
mole : g-equiv)
n
n
3. Matsuda, K. and Morin, L., J. Org. Chem., 1961,
vol. 26, no. 9, pp. 3783 3787.
4
. Arnold, C. and Thatcher, D., J. Org. Chem., 1969,
vol. 37, no. 4, pp. 1141 1143.
Found, %
N
Yield,
%
MAnn
Solvent
Ethanol
5. Macor, J., Ordway, T., Smith, R., et al., J. Org.
Chem., 1996, vol. 61, no. 10, pp. 3228 3229.
C
Cl
6
. Kizhnyaev, V.N., Pokatilov, F.A., Kotikov, P.V., and
Smirnov, A.I., Vysokomol. Soedin., Ser. B, 2005,
vol. 47, no. 6, pp. 1054 1057.
CuCl2
NiCl2
AgNO3
80
73
91
55
32.6
27.5
34.4
27.4
14.5
11.8
9.8
15.9
16.0
H O
2
Pd(CH COO)2 DMF
11.4
7. Tager, A.A., Adamova, L.V., Kryakunov, A.A., et al.,
Vysokomol. Soedin., Ser. B, 1985, vol. 27, no. 8,
pp. 593 596.
3
tions of the heteroring are shifted toward higher fre-
quencies by approximately 10 20 cm . In accord-
ance with the generally accepted views on the struc-
ture of metal azole complexes, it can be suggested that
the complexation with polyvinyloxadiazole is due to
the donor acceptor interaction of the ring nitrogen
atoms with the metal ion:
8
. Tager, A.A., Fizikokhimiya polimerov (Physical
Chemisatry of Polymers), Moscow: Khimiya, 1978,
3rd ed.
1
9
. Tager, A.A., Safronov, A.P., Lopyrev, V.A., et al.,
Vysokomol. Soedin., Ser. A, 1987, vol. 29, no. 11,
pp. 2421 2425.
1
1
0. Skushnikova, A.I., Domnina, E.S., and Skvortso-
va, G.G., Vysokomol. Soedin., Ser. B, 1977, vol. 19,
no. 5, pp. 372 374.
An
N
N
N
N
(
L ) O
O (L )
.
M
An
1. Skushnikova, A.I., Domnina, E.S., and Skvortso-
va, G.G., Vysokomol. Soedin., Ser. B, 1985, vol. 27,
no. 9, pp. 705 707.
CH3
CH3
Participation of the oxygen atom in the coordina-
tion is not confirmed.
12. Tsypina, N.A., Kizhnyaev, V.N., Pokatilov, F.A., and
Smirnov, A.I., Vysokomol. Soedin., Ser. B, 2003,
vol. 45, no. 2, pp. 358 362.
CONCLUSION
13. Kizhnyaev, V.N. and Vereshchagin, L.I., Usp. Khim.,
2
003, vol. 72, no. 2, pp. 159 182.
Previously unknown carbon-chain polymers with
pendant 1,3,4-oxadiazole fragments can be success-
fully prepared from low- and high-molecular-weight
precursors. The synthesized vinyl-1,3,4-oxadiazole
monomers are somewhat less active in radical poly-
merization than vinylazoles containing only nitrogen
heteroatoms in the ring. Polyvinyl-1,3,4-oxadiazoles
are nonionic, relatively heat-resistant polymers and
can act as starting compounds for further chemical
modification.
14. Kizhnyaev, V.N., Ratovskii, G.V., Bazhenov, D.N.,
and Pokatilov, F.A., Vysokomol. Soedin., Ser. A, 2005,
vol. 47, no. 10, pp. 802 1811.
15. Kruglova, V.A., Kizhnyaev, V.N., Ivanova, N.A.,
et al., Vysokomol. Soedin., Ser. B, 1987, vol. 29,
no. 6, pp. 416 420.
1
1
1
6. Tsypina, N.A., Kizhnyaev, V.N., and Adamova, L.V.,
Vysokomol. Soedin., Ser. A, 2003, vol. 45, no. 10,
pp. 1718 1723.
7. Kizhnyaev, V.N., Gorkovenko, O.P., Safronov, A.P.,
and Adamova, L.V., Vysokomol. Soedin., Ser. A,
1
997, vol. 39, no. 3, pp. 527 532.
REFERENCES
8. Pomogailo, A.D. and Savost’yanov, V.S., Metallso-
derzhashchie monomery i polimery na ikh osnove
(Metal-Containing Monomers and Polymers Derived
from Them), Moscow: Khimiya, 1988.
1
. Khimicheskaya entsiklopediya (Chemical Encyclo-
pedia), Moscow: Bol’shaya Ross. Entsiklopediya,
1
992, vol. 3, p. 673.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 7 2006