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Polym Int 48 :41–46 (1999)
Polymer International
Synthesis of aliphatic polyamides containing
4-phenylurazole linkages
Shadpour E Mallakpour*,¹ and Bahram Sheikholes lami
Organic Polymer Chemis try Res earch Laboratory , College of Chemis try , Is fahan Univers ity of Technology , Is fahan 84156 , Iran
Abstract : 4-Phenylurazole (1) was reacted with excess acetyl chloride in N,N-dimethylacetamide
(DMAc) solution at room temperature. The reaction occurred in quantitative yield with acetylation of
both of the NwH bonds of the urazole group. This compound was characterized by IR, 1H NMR and
elemental analysis, and was used as a model compound for the polymerization reaction. Solution
polymerization of monomer (1) with adipoyl chloride (AC) and suberoyl chloride (SC) was performed
in DMAc and chloroform in the presence of pyridine, and lead to the formation of a novel aliphatic
polyamide with an inherent viscosity in the range of 0.108–0.396 dl g—1. When interfacial polymerization of monomer (1) with suberoyl chloride was performed in DMAc/cyclohexane, a lower viscosity resulted. The resulting polymers are soluble in most organic solvents. Some structural
characterization and physical properties of these novel polymers are reported.
( 1999 Society of Chemical Industry
Keywords : 4-phenylurazole ; aliphatic acid chlorides ; polyamides ; adipoyl chloride ; suberoyl chloride ; solution polymerization ; interfacial polymerization
INTRODUCTION
4-Phenylurazole (1) is an important precursor for the
synthesis of 4-phenyl-1,2,4-triazoline-3,5-dione (2).
Compound (2) is an exceptionally strong electron
acceptor and is among the most powerful dienophiles
and enophiles as well as being an electrophile.1h4
Although compound (1) is a very stable molecule and
its shelf life is many years, it can be readily oxidized
to compound (2) with a wide variety of oxidizing
reagents.5 Compound (1) also has two NwH protons
which are acidic. The urazole derived from the ene
reaction of triazolinediones with alkenes and polydienes has one NwH proton which is very acidic. The
acidity of this proton has been measured and it has a
pK of 4.71 which is almost the same as that of acetic
a
acid.6 Compound (1) has the potential to undergo N-
acylation. 4-Substituted-urazoles have been converted
to 1-acyl derivatives by acylation with a series of carboxylic acid anhydrides.7 A simpliÐed procedure for
the N-acylation of oxazolidin-2-one chiral auxiliaries
has been reported.8
Recently we have been able to take advantage of the
acidic NwH bond in the formation of the compound
1-methyl-2,5-bis[1-(4-phenylurazolyl)]pyrrole and synthesise novel polymers via N-alkylation and Nacylation reactions.9,10 Polymerization of compound
(1) with phosgene, terephthaloyl chloride, and epichlorohydrin has been reported to give insoluble polymers.11 Triazolinedione ylides as reactive carbonyl
equivalents have also been reported.12 The modiÐcation of polydienes using urazole chemistry has been
studied by Butler and co-workers,13h15 and Stadler
and co-workers.16h21 We also reported the acylation
of polybutadiene containing the 4-phenylurazole
moiety and the preparation of optically active polybutadiene.22,23
The aim of this investigation was to examine the
reaction of 4-phenylurazole with acetyl chloride and
then aliphatic diacid chlorides for the synthesis of
soluble polyamides with urazole linkages. In the
* Corres pondence to : Shadpour E Mallakpour, Organic
Polymer Chemis try Res earch Laboratory, College of Chemis try,
Is fahan Univers ity of Technology, Is fahan 84156, Iran
¹ E-mail : MALLAK=CC.IUT.AC.IR
Contract/grant s pons or : Res earch Affairs Divis ion, Is fahan
Univers ity of Technology, Is fahan, Iran.
Contract/grant number : 1CHD 761.
Contract/grant s pons or : The Graduate School, Is fahan Univers ity
of Technology, Is fahan, Iran.
(Received 17 December 1997 , revis ed vers ion received 5 Augus t
1998 ; accepted 2 September 1998 )
( 1999 Society of Chemical Industry. Polym Int 0959–8103/99/$17.50
41
SE Mallakpour, B Sheikholeslami
present paper, we report the Ðrst successful polymerization where 4-phenylurazole is used as a novel
monomer for the synthesis of soluble polyamides.
EXPERIMENTAL
Materials and equipments
Reagents were purchased from Fluka Chemical
Co, Aldrich Chemical Co and Riedel-deHaen AG.
4-Phenylurazole was synthesized according to
published procedures.5,24h26 DMAc was dried over
BaO and then distilled under reduced pressure.
Chloroform was puriüed by washing with water,
drying with CaCl and subsequent distillation under
2
normal pressure. Proton nuclear magnetic resonance
(1H NMR, 90 MHz) spectra were recorded on a
Varian EM-390 instrument. Multiplicities of proton
resonances are designated as singlet (s), doublet (d),
triplet (t), multiplet (m) and broad (br). Tetramethylsilane (TMS) was used as an internal reference. IR spectra were recorded on a Shimadzu 435
IR spectrophotometer. Spectra of solids were measured using KBr pellets. Vibrational transition frequencies are reported in wavenumbers (cm~1). Band
intensities are assigned as weak (w), medium (m),
shoulder (sh), strong (s) and broad (br).
All melting points were taken with a Gallenkamp
melting point apparatus and are uncorrected. Inherent viscosities were measured by a standard procedure using a Cannon Fensk routine viscometer.
Diþerential scanning calorimetric (DSC) data for
polymers were taken on a DSC-PL-1200 instrument
under N atmosphere at a rate of 10¡C min~1. Ele2
mental analyses were performed by the Research
Institute of the Petroleum Industry, Tehran, Iran.
Reaction of compound (1) with excess acetyl
chloride
Into a 25 ml one-necked round-bottomed ýask,
which was equipped with a magnetic stirrer, 0.30 g
(1.69 ] 10~3 mol) of compound (1), 2 ml of DMAc
and 5 ml of acetyl chloride were added. The stirrer
was started and after 60 min a white solid was precipitated ; the mixture was then stirred for a further
24 h. The excess acetyl chloride was removed and the
resulting solid was added to 50 ml of distilled water,
ültered oþ and dried under vacuum for 14 h at 60¡C
to give 0.41 g (93%) of white solid (3). Recrystallization from chloroform–cyclohexane mixture
gave white crystals, mp 164¡C. IR (KBr): 3100(w),
2900(w), 1800(m,sh), 1750(s), 1730(s,sh), 1720(s,sh),
1680(m,sh), 1600(w), 1495(m), 1460(m), 1410(s),
1370(m), 1260(s), 1230(s,sh), 1210(m,sh), 1160(s),
1050(w), 1020(w), 970(m), 880(w), 800(w), 750(s),
690(w), 580(m), cm~1 ; 1H NMR (CDCl , TMS): d
3
2.65 (s,6H), 7.55 (s,5H).
Analysis. Calcd for C H O N : C, 55.17%, H,
12 11 4 3
4.24% ; N, 16.08%. Found : C, 55.20% ; H, 4.20% ;
N, 16.40%.
42
Polymerization of compound (1) with adipoyl
chloride (4) : solution polymerization
Method A
Into a 25 ml one-necked round-bottomed ýask were
placed 0.30 g (1.69 ] 10~3 mol) of monomer (1),
1.5 ml of DMAc and 0.10 ml of pyridine. The stirrer
was started and 0.246 ml (1.69 ] 10~3 mol) of
adipoyl chloride was added. The reaction mixture
was stirred for 24 h and 1.5 ml of DMAc was added ;
then, the viscous mixture was stirred for 36 h and
was precipitated in methanol to give 0.55 g (10%) of
white gummy solid polyamide (6A).
Method B
The above polyamidation reaction was repeated
using chloroform (3 ml) as a solvent, DMAc (1 ml) as
a co-solvent and pyridine (0.5 ml). The mixture was
reýuxed for 5 h and stirred for 43 h at room temperature ; the polymer was precipitated in methanol
to yield 0.44 g (92%) of white polymer, mp 150¡C.
IR (KBr): 3050(w), 2920(m), 1800(s,sh), 1740(s,br),
1600(w), 1500(s,br), 1320(s,br), 1170(s), 1050(s),
1020(s), 920(w), 880(w), 1060(m), 760(s), 690(m),
640(w), 620(w), cm~1 ; 1H NMR (DMSO-d ,
6
TMS): d 1.75 (m,br,4H), 2.90 (m,br,4H), 7.55 (s,
5H).
Analysis. Calcd for C H O N : C, 58.53% ; H,
14 13 4 3
4.56%, N, 14.63%. Found : C, 57.20% ; H, 5.00% ;
N, 13.30%.
Polymerization of compound (1) with suberoyl
chloride (5) : solution polymerization
Method A
Compound (1) (0.30 g, 1.69 ] 10~3 mol), 1.5 ml of
DMAc and 0.1 ml of pyridine were placed in a 25 ml
one-necked round-bottomed ýask. The stirrer was
started and a clear solution was formed. Suberoyl
chloride (0.305 ml, 1.69 ] 10~3 mol) was added. The
mixture was stirred for 24 h during which it turned
into a viscous liquid ; then 3.5 ml of DMAc was
added and stirred for 36 h. This mixture was poured
into a beaker containing 120 ml of methanol. The
solid was ültered oþ and dried under vacuum, to
give 0.424 g (80.0%) of white polyamide (7A), m.p.
170¡C. IR (KBr): 3050(w), 2920(m), 2850(w),
1800(s,sh), 1750(s), 1600(w), 1500(m), 1460(m),
1410(s), 1320(s,br), 1170(m), 1060(m), 1020(m),
760(m,br), 690(m), cm~1 ; 1H NMR (DMSO-d ,
6
TMS): d 1.25–1.90 (m,br,8H), 2.75–3.15 (m,4H),
7.70 (s,5H).
Analysis. Calcd for C H O N : C, 60.94% ; H,
16 17 4 3
5.44% ; N, 13.33%. Found : C, 60.70% ; H, 5.70% ;
N, 12.40%.
Method B
The above polyamidation reaction was repeated in
3 ml of chloroform, 1 ml of DMAc and 0.5 ml of
pyridine. The chloroform was removed and the
viscous mixture was precipitated in water to give
0.481 g (90.0%) of polyamide (7B), mp 170¡C.
Polym Int 48 :41–46 (1999)
Synthesis of aliphatic polyamides with 4-phenylurazole linkages
Method C
The polymerization reaction was repeated the same
way as in method B, but the solvents were completely dried prior to use. The yield was 93.0%, mp
170¡C.
Polymerization of compound (1) with suberoyl
chloride (5) : interfacial polymerization
Method A
Into a 25 ml one-necked round-bottomed ýask were
placed 0.20 g (1.10 ] 10~3 mol) of compound (1),
2 ml of DMAc and 0.1 ml of pyridine. The stirrer
was started and a clear solution was formed. Suberoyl chloride (0.203 ml, 1.10 ] 10~3 mol) in 2.5 ml of
cyclohexane was added dropwise on the surface of
the DMAc solution. The mixture was stirred for 24 h
and was poured into a beaker containing methanol/
water (80 : 20). The solid was ültered oþ and dried
under vacuum, to give 0.340 g (97.7%) of white polyamide (7A1), mp 154–157¡C.
Method B
The above polyamidation reaction was repeated in
4 ml of DMAC, 3 ml of cyclohexane and 0.5 ml of
pyridine. The yield of polyamide (7A2) was 100%,
mp 66–70¡C.
RESULTS AND DISCUSSION
Model compound studies
Compound (1) was allowed to react with excess
acetyl chloride in DMAc solution and gave 1,2diacetyl-4-phenylurazole (3) in high yield (Scheme
1). Compound (3) was characterized by IR, 1H
NMR, DSC and elemental analysis. The IR spectrum of (3) showed two strong peaks at 1800 and
1750 cm~1 for the carbonyl groups. These are characteristic patterns for the urazole moiety. The 1H
NMR (Fig 1) spectrum of (3) shows a singlet at
2.65 ppm for the two methyl groups attached to the
Scheme 1
carbonyl groups. This peak shows that the Nacylation reaction has occurred. The other peaks are
consistent with the proposed structure of (3).
Polymerization reactions
1,2-Diacetyl-4-phenylurazole (3) as a model compound was synthesized in high yield and purity ;
therefore we were interested in performing this type
of reaction for the formation of the novel polyamides.
Thus, adipoyl chloride and suberoyl chloride were
selected as aliphatic diacid chlorides. The reaction of
monomer (1) with adipoyl chloride was performed
by two methods via solution polymerization. In
method A, the reaction was carried out in DMAc
solution with pyridine as a scavenger and the
resulting polymer was obtained in quantitative yield
(6A) (Scheme 2). This polymer is a gummy solid on
which no further characterization was performed. In
method B, the solution polymerization was carried
out in DMAc/chloroform solution and the resulting
polymer (6B) was obtained as a white solid in high
yield. Polymer (6B) was characterized by IR and 1H
NMR spectroscopy. The 1H NMR spectrum of
polymer (6B) (Fig 2) shows peaks as a broad multiplet at 1.75 ppm which is assigned to the two methylene protons, peaks at 2.90 ppm as a broad multiplet
which is assigned to the other two methylene protons
which are attached to the nitrogen atoms, and a peak
Figure 1. 1H NMR (90 MHz)
s pectrum of model compound
(3) in CDCl at room
3
temperature.
Polym Int 48 :41–46 (1999)
43
SE Mallakpour, B Sheikholeslami
Scheme 2
as a singlet at 7.55 ppm which is assigned to the
phenyl group. Polymer (6B) is soluble in organic solvents such as DMSO, DMF, THF and CH Cl ,
2 2
and is insoluble in solvents such as water, methanol,
acetone and non-polar solvents such as cyclohexane
and n-hexane.
The polymerization reaction of suberoyl chloride
(5) with monomer (1) was performed by both the
solution and interfacial techniques. Solution polymerization was carried out by three methods. In
method A, only DMAc was used as a reaction
solvent and the resulting polymer was obtained as a
white solid with a yield of 80% and inherent viscosity of 0.108 dl g~1 (7A). The structure of polymer
(7A) was characterized by IR and 1H NMR spectra.
The 1H NMR spectrum of polymer (7A) (Fig 3)
shows peaks as a broad multiplet between 1.25 and
1.90 ppm which is assigned to the four methylene
protons ; peaks between 2.25 and 3.15 ppm appear as
a broad multiplet assigned to the other two methylene protons which are attached to the nitrogen
atoms ; a singlet peak at 7.70 ppm is assigned to the
phenyl group.
In method B, mixtures of DMAc/chloroform were
used as solvents for the polymerization reaction and
both higher yield and higher viscosity were obtained.
Figure 2. 1H NMR (90 MHz)
s pectrum of compound (6B) in
DMSO-d at room temperature.
6
Figure 3. 1H NMR (90 MHz)
s pectrum of compound (7A) in
DMSO-d at room temperature.
6
44
Polym Int 48 :41–46 (1999)
Synthesis of aliphatic polyamides with 4-phenylurazole linkages
Table 1. Reaction conditions for the polymerization of monomer (1) with diacid chlorides in pres ence of pyridine and s ome phys ical
properties of polyamides (6A), (6B), (7A), (7B), (7C), (7IN1) and (7IN2)
Polymer
Acid chloride
Solvent
Run time
(h )
Non -s olvent
Yield
(%)
6Ac
6Bc
7Ac
7Bc
7Cc
7IN1f
7IN2f
ACd
AC
SCd
SC
SC
SC
SC
DMAc
DMAc/CHCl
3
DMAc
DMAc/CHCl
3
DMAc/CHCl
3
DMAc/CYg
DMAc/CY
60
60
60
60
60
24
24
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH/H O
2
H O
2
100
92
80
90
93
98
100
a
mp b
(¡C )
–
0.192
0.108
0.359
0.396
0.092
0.045
–e
150
170
170
170
157
70
g
inh
a Inherent vis cos ity (dl gÉ1), meas ured at a concentration of 0.5 g dlÉ1 in DMF at 25¡C.
b Meas ured by melting point apparatus .
c Solution polymerization.
d AC, adipoyl chloride ; SC, s uberoyl chloride.
e Gummy s olid.
f Interfacial polymerization.
g CY, cyclohexane.
In method C, the polymerization reaction was performed under completely dry solvent condition and a
small increase in both yield and viscosity resulted.
The polymerization reaction was repeated by the
interfacial technique in the DMAc/cyclohexane
system. Although higher yields were obtained, low
inherent viscosities resulted (7IN1) and (7IN2).
Polymers (7A), (7B) and (7C) are soluble in
organic solvents such as DMSO, DMF, sulphuric
acid, methylene chloride and THF, and insoluble in
solvents such as water, toluene and n-hexane. The
reaction conditions and some physical properties for
these novel polyamides are summarized in Table 1
and 2.
The DSC curve of compound (3) is shown in Fig
4. This model compound exhibits an endotherm
peak with a maximum of 167¡C. The DSC curve of
polymer (7C) is shown in Fig 5. This polymer shows
an endothermic peak with a maximum at around
159¡C.
CONCLUSIONS
The present work has shown that 4-phenylurazole
(1) is an interesting monomer for polycondensation
reactions. Compound (1) has two acidic NwH
groups and can be readily acylated. This acylation
reaction with acetyl chloride gives an N-acylation
adduct in quantitative yield and high purity. Thus,
compound (1) can act as a bifunctional monomer
and its polymerization with aliphatic diacid chlorides gives novel polyamides with urazole linkages.
The best conditions under which to obtain a polymer
with high yield and viscosity are solution polymerizations in a DMAc/chloroform system. The
resulting polymers are soluble in most organic solvents and can be used as thermoplastic materials. The
4-position of the urazole group can readily be substituted with a wide variety of functional groups, so that
one can readily achieve properties such as supermolecular aggregation by hydrogen bonding, optical
activity and liquid crystal behaviour. 4-Phenylurazole
Figure 4. DSC curve of model
compound (3).
Polym Int 48 :41–46 (1999)
45
SE Mallakpour, B Sheikholeslami
Figure 5. DSC curve of
polymer (7C).
also reacts with isocyanates at room temperature to
give urea derivatives in quantitative yields. Polymerization of this monomer with diisocyanates is
under investigation and will be reported later.
ACKNOWLEDGEMENTS
Partial ünancial support of this work by the Research
Aþairs Division Grant No 1CHD 761 Isfahan University of Technology (IUT), Isfahan, Iran, is gratefully acknowledged. Further ünancial support from
Gradual School (IUT) is also acknowledged. We also
thank Mr M Ardani for recording DSC data. We
thank Mrs Zadhoosh for the reading of this manuscript.
Table 2. Solubilities of polymers (6B), (7A), (7B) and (7C) in
various s olvents a
Solvent
(6B )
(7A ), (7B ) or (7C )
DMSO
DMF
H SO
2 4
THF
Ethyl acetate
CH COOH
3
CH Cl
2 2
CHCl
3
Acetone
Toluene
n -Hexane
Ether
Water
]
]
]
]
]
]
]
]
]
[
[
[
[
]
]
]
]
[
[
]
]
[
[
[
[
[
a Concentration : 5 mg mlÉ1 ; ], s oluble within 1 h at room
temperature ; [, ins oluble even heated up to 100¡C.
46
REFERENCES
1 Mallakpour SE and Zolügol MA, Indian J Chem 34B :183
(1995).
2 Mallakpour SE and Asghari J , Iranian Polym J 5 :87 (1996)
3 Mallakpour SE, Asghari J and Schollmeyer D, Polym Int
41 :43 (1996).
4 Mallakpour SE, Mohammdi F and Kolshorn H, Polym Int
42 :328 (1997).
5 Mallakpour SE, J Chem Educ 69 :238 (1992).
6 Ohashi S, Leong KW, Matyjaszewski K and Butler GB, J Org
Chem 45 :3467 (1980).
7 Simlot R, Izydore RA, Wong OT and Hall IH, J Pharm Sci
82 :408 (1993).
8 Ager DJ , Allen DR and Schaad DR, Synthesis 1283 (1996).
9 Mallakpour SE, Karami-Dezcho B and Sheikholeslami B,
Polym Int 45 :98 (1998).
10 Mallakpour SE and Sheikholeslami B, Iranian Polym J 7 :121
(1998).
11 Bausch MJ , David B, Selmarten D and Wang LH, CmposTechnol, 7th Annual Conference on Materials Technology,
p 41 (1991). CA vol 119, p 9244 (1993) No 9242p.
12 Wilson RM and Hengge A, J Org Chem 52 :2699 (1987).
13 Williams AG and Butler GB, J Polym Sci Polym Chem Ed
17 :1117 (1979).
14 Leong KW and Butler GB, J Macromol Sci Chem A14(3):287
(1980).
15 Chen TCS and Butler GB, J Macromol Sci Chem A16(3):757
(1981).
16 J acobi MM and Stadler R, Makromol Chem Rapid Commun
9 :709 (1988).
17 Kuhrau M and Stadler R, Makromol Chem 191 :1787 (1990).
18 Hilger C and Stadler R, Makromol Chem 191 :1347 (1990).
19 Hilger C and Stadler R, Makromol Chem 192 :805 (1991).
20 Hilger C and Stadler R, Polymer 32 :3244 (1991).
21 Dardin A and Stadler R, Makromol Chem 194 :3467 (1993).
22 Mallakpour SE, Raüemanzelat F and Sheikholeslami B,
Iranian Polym J 6 :235 (1997).
23 Mallakpour SE, Hajipour AR, Khoee S and Sheikholeslami B,
Polym Int 47 :193 (1998).
24 Cookson RC, Gilani SSH and Stevence LD, Tetrahedron Lett
14 :615 (1962).
25 Cookson RC, Gilani SSH and Stevence LD, J Chem Soc C
1905 (1967).
26 Gilani SSH and Triggle J D, J Org Chem 31 :2397 (1966).
Polym Int 48 :41–46 (1999)
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