Synthesis of furan dimer-based polyamides with a high melting point

Article abstract of DOI:10.1002/pola.29031

Polyamide composed of furan dimer, which is prepared from biomass-derived organic molecule 2-furfural, is synthesized. The reaction of 2,2′-furan dimer 5,5′-dicarbonyl chloride with several 1,ω-diamines was carried out with a solution or interfacial polycondensation leading to the corresponding polyamide. Measurement of the melting point was performed resulting to exhibit a higher temperature compared with the related polyamide bearing a single furan ring composed of furan-2,5-dicarboxylic acid (FDCA). Thermal analyses (TG–DTA) also indicated higher temperatures of decomposition than those of FDCA-derived polyamide.

Full text of DOI:10.1002/pola.29031

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Synthesis of Furan Dimer-Based Polyamides with a High Melting Point
Naoki Miyagawa, Toyoko Suzuki, Kentaro Okano, Takuya Matsumoto,
Takashi Nishino, Atsunori Mori
Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
Correspondence to: A. Mori (E-mail: amori@kobe-u.ac.jp)
Received 18 March 2018; accepted 10 April 2018; published online 00 Month 2018
DOI: 10.1002/pola.29031
ABSTRACT: Polyamide composed of furan dimer, which is pre-
composed of furan-2,5-dicarboxylic acid (FDCA). Thermal anal-
yses (TG–DTA) also indicated higher temperatures of decompo-
pared from biomass-derived organic molecule 2-furfural, is
0
0
C
synthesized. The reaction of 2,2 -furan dimer 5,5 -dicarbonyl
chloride with several 1,x-diamines was carried out with a solu-
tion or interfacial polycondensation leading to the correspond-
ing polyamide. Measurement of the melting point was
performed resulting to exhibit a higher temperature compared
sition than those of FDCA-derived polyamide. V 2018 Wiley
Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 00,
000–000
KEYWORDS: biomass; FDCA; furan dimer; furfural; polyconden-
sation; polyamides; thermal analyses; interfaces
with the related polyamide bearing
a single furan ring
INTRODUCTION Utilization of biomass-derived organic mole-
cule toward preparation of organic or polymer materials
recently attracts much attention to replace the established
petrochemical process with a system employing nonedible
EXPERIMENTAL
General
Melting points were measured on a Yanaco MP-J3 Model
1
melting point apparatus. Measurements of H (400 MHz)
1
,2
feedstock biomass cellulose cascade. Since furfural deriva-
tives, which involves five-membered heteroaromatic struc-
ture, can be readily obtained by degradation of cellulose
1
3
1
and C{ H} (100 MHz) NMR spectra were performed with
JEOL ECZ 400 as a CDCl , DMSO-d , or TFA-d (CF CO D)
3
6
3
2
solution. HRMS were measured by JEOL JMS-T100LP Accu-
TOF LC-Plus (ESI) with a JEOL MS-5414DART attachment. IR
spectra were recorded on Bruker Alpha with an ATR attach-
ment (Ge). Thermal analyses were carried out with RIGAKU
Thermo plus EVO DSC8230 and EVO2 TG-DTA 8121. Synthe-
3
–6
through the formation of C5 and C6 monosaccharides.
We
have recently shown that furan dimer dicarboxylate, which is
converted by the transformation of furfural through several
steps, reacts with 1,x-diols by polycondensation and leads to
7
,8
biopolyesters.
Those melting points were shown to be
0
0
sis of (2,2 -bifuryl)-5,5 -dicarboxylic acid diethyl ester (1)
superior to those of the related polyesters composed of a
7
was performed according to our previous report and 1,x-
9
single furan ring 2,5-furan dicarboxylate unit. Since such
diamines (x 5 4, 5, 6, 10) were purchased and used without
further purification. NMP (N-methylpyrrolidone; anhydrous
grade) and distilled water were purchased from Wako Pure
Chemicals Industries, Ltd. THF (anhydrous grade) was pur-
chased from Kanto Chemicals, Ltd. and passed through a
Glass Contour MINI Ultimate solvent system prior to use.
polyesters involve potential use as a surrogate of petro-
derived terephthalates representative as PET (polyethylene
terephthalate), it is remarkable that polyester derived from
furan dimer shows a comparable melting point with PET
1
0
that is recognized as widely available plastics. On the other
hand, polyamides bearing a rigid aromatic framework serve
as engineering plastics due to the multiple interchain hydro-
0
0
14
(2,2 -Bifuryl)-5,5 -dicarboxylic acid: To a 500 mL of two-
necked flask equipped with a magnetic stirring bar and
reflux condenser were added THF (90 mL) and water
1
1–13
gen bonds.
Our further concern employing furan dimer
to biomass-derived polymer materials has turned to prepare
polyamides bearing furan dimer, which would also show
highly rigid structure. Herein, we report that a bifunctional
acid chloride composed of furan dimer reacts with 1,x-
diamines leading to polyamides to show thermal stability
based on the rigid structure.
0
(60 mL). To the mixture were added 5,5 -(diethoxycarbonyl)-
0
2,2 -bifuryl (1) (5.63 g, 20 mmol) and 22 g of KOH and
heated at 90 8C for 4 h. After cooling to room temperature
the mixture was poured into 6 M hydrochloric acid to form
precipitates and filtered off. The residue was washed with
Additional Supporting Information may be found in the online version of this article.
2018 Wiley Periodicals, Inc.
V
C
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water and ethanol to afford 4.30 g of dicarboxylic acid as a
solid (97%).
3324, 3270, 3252, 2927, 2853, 1649, 1568, 1534, 1473,
2
1
1455, 1305, 1179, 1020, 798 cm
.
1
0
0
0
H NMR (DMSO-d ) d 7.08 (d, J 5 3.7 Hz, 2H), 7.36 (d, J 5 3.7
Poly{(1,10-diaminodecan-N,N -diyl)-[(2,2 -bifuryl)-5,5 -dicarbonyl]}
(4b): H NMR (TFA-d/CDCl
6
1
3
1
1
Hz, 2H). C{ H} NMR (DMSO-d ) d 110.1, 119.7, 145.0,
) d 1.36–1.61 (m, 12H), 1.71–1.94
3
6
1
47.2, 159.1. IR (ATR) 3131, 2688, 2570, 1672, 1572, 1456,
(m, 4H), 3.28 (t, J 5 7.2 Hz, 0.18H), 3.56–3.78 (m, 4H), 6.96–7.08
(m, 2H), 7.48–7.60 (m, 2H). C{ H} NMR (DMSO-d ) d 26.5, 28.8,
6
2
1
13
1
1311, 1166, 1029, 953, 918, 883, 812, 761 cm . The
obtained product was used for the following reaction without
further purification.
29.0, 29.3, 38.6, 108.9, 115.0, 145.8, 147.7, 157.3. IR (ATR) 3315,
3284, 2926, 2854, 1739, 1634, 1587, 1529, 1474, 1455, 1366,
2
1
1300, 1229, 1216, 1015, 806 cm
.
0
0
(
2,2 -Bifuryl)-5,5 -dicarbonyl dichloride (2): To a 200 mL of
two-necked flask equipped with a magnetic stirring bar was
General procedure of polyamide synthesis by interfacial poly-
condensation (Method B): To a 20 mL screw-capped test tube
equipped with a magnetic stirring bar was dissolved acid
chloride 2 (78 mg, 0.3 mmol) in 1.0 mL of dichloromethane.
To the resulting solution was slowly added aqueous 1 M
solution of KOH (0.3 mL) to result in phase separation. Then,
1,6-diaminohexane (35 mg, 0.3 mmol) dissolved in 1 M KOH
(0.7 mL) was added. The resulting mixture was vigorously
stirred to initiate the polymerization for 1 h. The formed
precipitates were filtered off and the residue was washed
0
0
added (2,2 -bifuryl)-5,5 -dicarboxylic acid (2.02 g, 9.1 mmol),
which was dissolved in 10 mL of dichloromethane and the
resulting solution was cooled to 0 8C in an ice bath. Oxalyl
chloride (3.4 mL, 40 mmol) and DMF (0.1 mL) were then
added to the mixture and stirring was continued at 0 8C to
room temperature for 15 h. The mixture was concentrated
under reduced pressure to leave a crude solid, which was
purified by column chromatography on silica gel using CHCl
as an eluent to afford 2.06 g of (2,2 -bifuryl)-5,5 -dicarbonyl
3
0
0
with H O, methanol, and dichloromethane, successively to
dichloride (2). (87%) Mp 138–140 8C.
2
0
0
leave 55 mg of poly{(1,6-diaminohexan-N,N -diyl)-[(2,2 -
1
0
H NMR (CDCl ) d 7.08 (d, J 5 3.7 Hz, 2H), 7.59 (d, J 5 3.7 Hz,
H). Attempted measurement of C{ H} NMR in CDCl was
3
bifuryl)-5,5 -dicarbonyl]} (4a) (61% yield).
3
1
3
1
2
0
0
Synthesis of poly{(1,4-diaminobutan-N,N -diyl)-[(2,2 -bifuryl)-
found unsuccessful because of difficulties in the solubility,
while attempted measurement in DMSO-d resulted in observ-
0
0
5
,5 -dicarbonyl]} (4c) and poly{(1,5-diaminopentan-N,N -diyl)-
6
0
0
[
(2,2 -bifuryl)-5,5 -dicarbonyl]} (4d) were carried out in the
ing the hydrolyzed product as well as in the measurement of
1
3
1
above manner for 1 h with 1,4-diaminobutane and for 4 h
with 1,6-diaminohexane, respectively.
HRMS. C{ H} NMR (DMSO-d ) d 110.2, 119.8, 145.1, 147.2,
6
1
59.1. IR (ATR) 3138, 3132, 1732, 1548, 1429, 1240, 1035,
2
967, 884, 827, 807, 693, 550 cm 1. HRMS (DART1) Calcd for
0
0
0
Poly{(1,4-diaminobutan-N,N -diyl)-[(2,2 -bifuryl)-5,5 -dicarbonyl]}
1
C H O [M 1 H] : 258.9564; found: m/z 258.9568.
1
6
19
8
1
(
4c): 71% yield. H NMR (TFA-d/CDCl : 9:1 v/v) d 1.81–2.12
3
(
m, 4H), 3.35–3.45 (m, 0.05 H), 3.60–3.87 (m, 4H), 7.00 (d,
General procedure of polyamide synthesis (Method A): To a
0 mL Schlenk tube equipped with a magnetic stirring bar
1
3
1
J 5 3.6 Hz, 2H), 7.50 (d, J 5 3.6 Hz, 2H) C{ H} NMR (DMSO-
d6) d 25.9, 38.0, 108.6, 114.4, 145.5, 147.7, 156.9. IR (ATR)
3
2
0
0
were added (2,2 -bifuryl)-5,5 -dicarbonyl dichloride (2,
30 mg, 0.5 mmol), NMP (1.0 mL), triethylamine (0.21 mL, 1.5
300, 3271, 2933, 1643, 1586, 1531, 1475, 1455, 1298, 1218,
1
2
1
1
170, 1017, 810 cm
.
mmol), and 1,10-diaminodecane (86.2 mg, 0.5 mmol) under a
nitrogen atmosphere. The resulting mixture was heated at 100
0
0
0
Poly{(1,5-diaminopentan-N,N -diyl)-[(2,2 -bifuryl)-5,5 -dicarbonyl]}
8C for 144 h. After cooling to room temperature, the mixture
1
(4d): 48% yield. H NMR (TFA-d/CDCl : 9:1 v/v) d 1.46–1.75
3
was poured into water to form precipitates, which were
washed with water and methanol. The residue was dissolved
in 1,1,1-trifluoroethanol/chloroform (2 mL/2 mL) and the
solution was added into 20 mL of methanol to form precipi-
tates, which were filtered off. The residue was washed with
chloroform repeatedly and dried under reduced pressure with
heating at 80 8C to afford 66 mg of 4b (37%).
(
m, 2H), 1.75–2.15 (m, 4H), 3.28–3.38 (m, 0.11H), 3.53–3.92
13
1
(m, 4H), 6.82–7.19 (m, 2H), 7.41–7.65 (m, 2H). C{ H} NMR
(DMSO-d ) d 23.6, 28.5, 38.3, 108.4, 114.2, 145.4, 147.6, 157.0.
6
IR (ATR) 3329, 3285, 2947, 2936, 1642, 1584, 1527, 1475,
1
21
453, 1298, 1018, 812, 800, 753 cm
.
Synthesis of model compound 5a for the estimation of the
degree of polymerization was carried out in a similar manner
to Method A with acid chloride 2 (0.3 mmol), triethylamine
0
0
Poly{[(2,2 -bifuryl)-5,5 -dicarbonyl]-(1,6-diaminohexyl)} (4a):
The reaction was carried out in a similar manner to the above
(
0.9 mmol), and 1,6-diaminohexane (3a) (6.0 mmol). After stir-
0
0
procedure employing (2,2 -bifuryl)-5,5 -dicarbonyl dichloride
2, 130 mg, 0.5 mmol), NMP (1.0 mL), triethylamine (0.21 mL,
.5 mmol), and 1,6-diaminohexane (58.1 mg, 0.5 mmol) to
ring the mixture at 100 8C for 1 h, an aliquot of the reaction
mixture was taken and poured into water to form a precipitate,
which was subjected to the measurement of H NMR spectrum
in TFA-d to observe signals at d 5 3.31 (0.38H) and 3.69 (4H).
(
1
1
yield 48 mg of 4a (48%).
1
H NMR (TFA-d/CDCl : 9:1 v/v) d 1.48–1.70 (m, 4H), 1.71–
3
RESULTS AND DISCUSSION
2
7
.04 (m, 4H), 3.26–3.36 (m, 0.12H), 3.48–3.88 (m, 4H), 6.94–
1
3
1
.07 (m, 2H), 7.42–7.59 (m, 2H). C{ H} NMR (DMSO-d
6
)
Preparation of acid chloride of the furan dimer 2 as a mono-
d 25.8, 28.7, 38.3, 108.4, 114.2, 145.4, 147.6, 157.0. IR (ATR)
mer species was carried out by the hydrolysis of the
2
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SCHEME 3 The model compound 5a for the estimation of the
1
degree of polymerization by H NMR.
SCHEME 1 Preparation of carboxylic acid chloride of furan
shorter chain length (x 5 3–5) was attempted, little polymer
was obtained under similar conditions. Synthesis of such pol-
ymers was found to be achieved using interfacial polycon-
dimer.
1
5
densation under biphasic conditions.
performed with a dichloromethane solution of acid chloride
and diamine 3a (x 5 6) in aqueous 1 M KOH solution at
The reaction was
2
room temperature. Vigorous stirring of the mixture initiated
the polymerization at the interface and immediate precipita-
tion resulted to form polymer 4a in 61% yield. The reaction
of 1,4-diaminobutane (3c) and 1,5-diaminopentane (3d) also
afforded the corresponding polymers 4 in 71% and 48%
yields, respectively, while the attempted polymerization of
1,3-diaminopropane was unsuccessful.
The use of 1,x-diamine 3 composed of a long alkylene chain
seems to favor solution polymerization, while polymer 4
employed by 3 of a shorter chain length was smoothly
obtained by interfacial polycondensation. However, polyamide
composed of 1,3-propanediamine was not obtained even by
interfacial polycondensation to result in forming a solid, which
was easily dissolved in methanol. We consider that polyamide
bearing a short alkylene chain with less rotation freedom only
formed oligomers and the rigid structure of bifuryl moiety
caused propagation of the polymer, accordingly.
SCHEME 2 Polymerization of furan dimer 2 with 1,x-diamine 3
by solution or interfacial polycondensation.
1
3
corresponding diethyl ester 1
and following treatment
with oxalyl chloride. The obtained 2 was subjected to the
polymerization with 1,x-diamine 3 as shown in Schemes 1
and 2. We initially examined solution polymerization in NMP
1
4
in the presence of triethylamine (3.0 equiv). When the
reaction was carried out employing 1,6-diaminohexane (3a),
the corresponding polymer 4a was obtained in 48% isolated
yield after stirring at 100 8C for 144 h. The reaction with
Although attempted SEC analysis was unsuccessful due to the
extremely inferior solubility of polymers 4 in chloroform and
THF, measurement of NMR spectra showed formation of poly-
amide and allowed to estimate the degree of polymerization
1,10-diaminodecane (3b) was also performed in a similar
manner to afford 37% of polymer 4b (isolated yield).
Although the similar polymerization of 1,x-diamines of a
1
(DP) as 23–79. Comparing the H NMR spectrum of 4a with
a
TABLE 1 Thermal Analyses of Polyamide 4
Yield
(%)
M
n
b
5
c
10
d
50
e
f
Entry
4 (x)
(NMR)
Td (8C)
Td (8C)
Td (8C)
m
T (8C)
1
2
3
4
5
4a (6)
4b (10)
4a (6)
4c (4)
48
37
61
71
48
9,700
386
393
408
377
297
413
414
418
407
406
449
211
163
215
7,900
453
23,900
22,800
10,000
454
g
444
198 (283)
4d (5)
437
213
h
6
a (6)
287 6 5
275 6 6
355 6 5
350 6 4
h
6
c (4)
a
e
Measurements of thermal analyses were carried out by TG/DTA and
flow.
The temperature at 50% mass loss by TG/DTA.
The melting point by DSC.
f
DSC at a heating rate of 10 8C/min under N
b
2
1
g
h
The molecular weight measured by H NMR analysis.
The temperature at 5% mass loss by TG/DTA.
The temperature at 10% mass loss by TG/DTA.
The peak top of the main endotherm was defined as melting point.
Results of polyamide derived from 1,x-diamine (x 5 4 or 6) and 2,5-
c
d
furan dicarbonyl dichloride. See ref 16.
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that of model compound 5a, which is the product by the
reaction of 2 with excess amounts of diamine 3a, little signal
derived from the end group observed at 3.31 ppm was
detected in 4a (Schemes 3).
ACKNOWLEDGMENTS
This work was supported by Special Coordination Funds for
Promoting Science and Technology, Creation of Innovation Cen-
ters for Advanced Interdisciplinary Research Area (Innovative
Bioproduction Kobe), MEXT, Japan. N. M. thanks the Sasakawa
Scientific Research Grant from The Japan Science Society.
The obtained polymer 4 either by solution or interfacial
polycondensation was then subjected to analyses of DSC and
DG-DTA. These results are summarized in Table 1. Thermal
properties of polyamide 4a prepared by solution and interfa-
cial polycondensations were found to be similar suggesting
that the property is irrespective of the method of polymeri-
zation. Compared with those of polyamide 6a composed of a
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3
4
5
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m
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m
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1
4
9 Although the related polyamide composed of 1,1 -biphenyl-
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4
showed higher melting points compared with the related
0
19
20
furan dimer polyester. It was also found that thermal analy-
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the higher melting points and thermal decomposition tempera-
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chains (x > 10) are only reported.
to those of furan dimer polyesters as well as those com-
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