Synthesis and Characterization of bis(Tetrahydrofurfuryl) Ether

Article abstract of DOI:10.1002/open.201600013

Despite the availability of a large number of alkyl tetrahydrofurfuryl ethers that have a wide range of applications, pure bis(tetrahydrofurfuryl) ether (BTHFE) has not been previously synthesized. Here, we report the synthesis of BTHFE (consisting of the RR, SS, and meso stereoisomers) at greater than 99 % purity from tetrahydrofurfuryl alcohol, using (tetrahydrofuran-2-yl)methyl methanesulfonate as an intermediate. Additionally, we demonstrate that BTHFE can be used as a non-volatile solvent in poly(3,4-propylenedioxythiophene)-based supercapacitors. Supercapacitor devices employing solutions of the ionic liquid 1-ethyl-3-methyl-imidizolium bis(trifluoromethylsulfonyl)imide in BTHFE display similar performances to those prepared by using the neat ionic liquid as an electrolyte, although solution-based devices exhibit a somewhat higher resistance.

Full text of DOI:10.1002/open.201600013

DOI: 10.1002/open.201600013
Synthesis and Characterization of bis(Tetrahydrofurfuryl)
Ether
John D. Stenger-Smith, Lawrence Baldwin, Andrew Chafin, and Paul A. Goodman*[a]
Despite the availability of a large number of alkyl tetrahydro-
furfuryl ethers that have a wide range of applications, pure
bis(tetrahydrofurfuryl) ether (BTHFE) has not been previously
synthesized. Here, we report the synthesis of BTHFE (consisting
of the RR, SS, and meso stereoisomers) at greater than 99%
purity from tetrahydrofurfuryl alcohol, using (tetrahydrofuran-
2-yl)methyl methanesulfonate as an intermediate. Additionally,
we demonstrate that BTHFE can be used as a non-volatile sol-
vent in poly(3,4-propylenedioxythiophene)-based supercapaci-
tors. Supercapacitor devices employing solutions of the ionic
liquid 1-ethyl-3-methyl-imidizolium bis(trifluoromethylsulfonyl)-
imide in BTHFE display similar performances to those prepared
by using the neat ionic liquid as an electrolyte, although solu-
tion-based devices exhibit a somewhat higher resistance.
several reports of methods for their synthesis.[1,7] One tetrahy-
drofurfuryl ether derivative that has remained elusive is bis(te-
trahydrofurfuryl) ether (BTHFE). We found one previous report
of its synthesis, but this report lacked an in-depth characteriza-
tion of the compound, which left some doubt as to the true
identity of the reported product.[8]
When Kirner attempted to make methyl tetrahydrofurfuryl
ether using tetrahydrofurfuryl chloride and methanol as start-
ing materials, he found that the chloride reacted very slowly,
the reaction only occurred to a slight extent, and it had the
added disadvantage of producing an unsaturated tetrahydro-
furan derivative, 2-methylene tetrahydrofuran, as a byproduct.[1]
Previously, it has been reported that BTHFE had been pro-
duced by reacting tetrahydrofurfuryl bromide with sodium tet-
rahydrofurfurylate. In the previously published report of the
synthesis, the chief spectroscopic evidence that the authors
used to identify the compound was an IR spectrum.[8] The IR
spectrum for the BTHFE that we produced is shown in
Figure 1. The peaks near 2800 cmÀ1 (ca. 95% transmittance)
A relatively large number of scientific publications and patents
have analyzed, or proposed, the use of alkyl tetrahydrofurfuryl
ethers for a diverse array of applications. In 1930, Kirner syn-
thesized a small library of alkyl tetrahydrofurfuryl ethers, and
analyzed their toxicity in mice and guinea pigs.[1] His study
demonstrated that this class of ethers exhibit significant anes-
thetic effects when administered intraperitoneally. Kirner also
noted that, in larger doses, the compounds were toxic and,
even at low doses, they appeared to initiate intestinal necrosis,
which often proved fatal for the test animals. The synthetic
methods employed by Kirner were very similar to those used
by Wissell and Tollens when they first synthesized furfuryl
ether derivatives in 1892.[2] A significant body of published
work shows the utility of these compounds as structural modi-
fiers in rubbers. Modification of rubber with various alkyl tetra-
hydrofurfuryl ethers increases the static friction coefficient, and
the rubber can be used in automobile tires.[3] Additionally,
these compounds have been proposed as components of heat
pumps,[4] paint strippers,[5] and as fuel additives.[6] There is
clearly a potential market for these compounds, and there are
Figure 1. IR spectrum of BTHFE with the structure (ambiguous stereochemis-
try) inset.
[a] Dr. J. D. Stenger-Smith, Dr. L. Baldwin, A. Chafin, Dr. P. A. Goodman
Chemistry Division, Code 4F0000D, Research Department
Naval Air Warfare Center Weapons Division
1 Administration Circle
correspond to CÀH stretching. The peaks at 1460 and
1360 cmÀ1 (ca. 97% transmittance) correspond to CÀH bend-
ing, and the large peak near 1070 cmÀ1 (ca. 75% transmit-
tance) corresponds to ether CÀO stretching. This spectrum is
largely in agreement with the one presented by Prutkov et al.,
except for the area around 1700 cmÀ1. In the spectrum pre-
sented by Prutkov et al., there is a medium intensity peak at
approximately 1700 cmÀ1 that is absent in our spectrum.[8]
Alkene stretching occurs at this frequency, and we suspect,
based on the evidence presented by Kirner related to the diffi-
China Lake, CA 93555 (USA)
E-mail: paul.goodman@navy.mil
Supporting Information and the ORCID identification number(s) for the
author(s) of this article can be found under http://dx.doi.org/10.1002/
open.201600013.
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This is an open access article under the terms of the Creative Commons
Attribution-NonCommercial License, which permits use, distribution and
reproduction in any medium, provided the original work is properly
cited, and is not used for commercial purposes.
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culty of producing alkyl tetrahydrofurfuryl ethers using tetrahy-
drofurfuryl halides as reagents, that the previously reported
synthesis of BTHFE actually produced a mixture of the ether
and 2-methylene tetrahydrofuran.
Additionally, Prutkov et al. determined that the molecular
weight of their product was 172.5 gmolÀ1, as determined by
freezing-point depression in benzene. The true molecular
weight of BTHFE is 186 gmolÀ1. It is possible that the
172.5 gmolÀ1 that they observed is within the expected error
of the freezing-point depression measurement; however, given
the peak at 1700 cmÀ1 in the IR spectrum that they presented,
it seems equally, if not more, likely that their freezing-point de-
pression analysis solutions contained a mixture of BTHFE and
2-methylene tetrahydrofuran, which has a molar mass of only
84 gmolÀ1. A mixture that contained approximately 87%
BTHFE with 13% 2-methylene tetrahydrofuran would result in
an observed molar mass of 172.5 gmolÀ1 in a freezing-point
depression experiment. Based on these observations, we be-
lieve that, although Prutkov et al. did synthesize BTHFE, we
have successfully improved upon their synthesis by using (tet-
rahydrofuran-2-yl)methyl methanesulfonateas a starting materi-
al. We were able to limit the side reaction that produces 2-
methylene tetrahydrofuran, because the methanesulfonate ion
is a better leaving group for an SN2 reaction than bromide,
which resulted in substitution, rather than elimination, being
the strongly preferred reaction pathway.
1
Figure 2. The H (top axis), 13C (left axis), and HMQC (in plane) NMR spectra
for BTHFE with peak assignments noted in plane. The structure of the mole-
cule is in the inset with the hydrogens labeled.
termined by using HMQC experiments. In the 13C NMR spec-
trum, two resonances are observable for each carbon, except
for C1. Each individual shift of the carbon resonance pairs rep-
resents the RR/SS isomers, which have identical chemical shifts,
and the meso isomer, which has a slightly different resonance.
The singlet assigned as C1 is likely a result of overlap, as this
carbon is isolated from the stereocenter enough to dampen its
effect on the chemical shift. Temperature-dependent peak
The total ion chromatogram obtained through GC–MS analy-
sis showed product purity of >99%. The molecular ion was
not observed, because electron ionization resulted in signifi-
cant fragmentation in the GC–MS measurements. We per-
formed chemical ionization (CI) mass spectrometry with meth-
ane to identify the molecular ion and help verify the identity
of the product. The most abundant ion observed in these
measurements was m/z=187, which corresponds to the M+H
ion. The spectrum contained a peak with approximately 10%
abundance, relative to the M+H ion, at m/z=188, which cor-
responds to the expected 12C/13C isotopic effect for a molecule
with 10 carbon atoms, such as the molecular ion. The second
most abundant peak in the CI mass spectrum was m/z=85,
which is consistent with fragmentation at the central oxygen
atom that results in an ion with the molecular formula C5H9O+.
An additional peak at m/z=86 proved to have 5% abundance
relative to the peak at m/z=85, which is consistent with the
12C/13C isotopic effect expected for this fragmentation.
1
shifts were observed in the H spectra that were not observed
by Plavec et al., and the shifts were particularly large for the H5
and H5’ resonances. The cause of these apparently unique
shifts is beyond the scope of this paper, but further analysis is
underway.
One intriguing property of BTHFE is its relatively high boiling
point (628C at 0.3 mmHg). One of the drawbacks to typical
electrochemical capacitors is that they contain relatively low-
boiling, flammable solvents (e.g. acetonitrile), which limit their
useful temperature range and present a safety hazard. The use
of ionic liquids (ILs) as electrolytes can eliminate the tempera-
ture and safety concerns, but they often come with their own
limitations, like cost and the fact that they generally have
a lower conductivity than traditional electrolyte solutions.[10]
Previously, this laboratory has performed extensive analysis of
conducting polymer supercapacitors that employed neat
EMIBTI as an electrolyte.[11] We chose to do a preliminary analy-
sis of BTHFE as a solvent for EMIBTI in poly(3-4, propylenedi-
oxythiophene) capacitor devices, with the hope that solvation
of the IL would increase the conductivity of the electrolyte by
breaking up ion-pairing interactions, and, because BTHFE has
a high boiling point, it does not introduce the same tempera-
ture limitations as other solvents. For this preliminary analysis,
we compared devices that used neat EMIBTI as an electrolyte
against devices containing 1m EMIBTI in BTHFE as an electro-
lyte. Voltammetrically, the devices prepared by using either
electrolyte system showed a typical box-like response (Figures
S1a and S1b in the Supporting Information). In fact, aside
Interestingly, the BTHFE produced for this work can be
thought of as pure, based on the IR and GC–MS analysis, but,
because it contains two stereocenters, it can also be consid-
ered a mixture of three distinct compounds (RR, SS, and meso),
1
1
13
as evidenced by the H, 13C, and HÀ C heteronuclear multi-
quantum correlation (HMQC) NMR spectra (Figure 2). The 1H
spectral assignments are shown in Figure 2, and they were de-
duced based on a paper by Plavec et al., wherein the chemical
shifts and three-bond proton–proton coupling constants for
(S)-tetrahydrofurfuryl alcohol were reported.[9] As the sample
contains a combination of stereoisomers that have overlapping
1
resonances, we observe broad multiplets in the H spectrum.
The 13C NMR assignments of the BTHFE ether mixture were de-
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from a slight difference in capacitance, which is evident from
the difference in the magnitude of the plateau current in the
voltammograms (Figure S1c) and is attributed to slightly differ-
ent amounts of polymer being present on the electrodes in
each device, the devices appear to perform identically. Based
solely on the cyclic voltammetry, one might incorrectly con-
clude that the addition of the solvent made no difference to
device performance.
ously been reported for molecules of this type. We also per-
formed preliminary analysis of BTHFE as a solvent in electro-
chemical supercapacitors. In this capacity, the BTHFE proved to
be electrochemically stable, even though 1m solutions of the
IL 1-ethyl-3-methyl-imidizolium bis(trifluoromethylsulfonyl)i-
mide had resistances that were approximately 20 W higher
than the neat IL. Further analysis of both the NMR and electro-
chemical properties of BTHFE are ongoing.
We performed electrochemical impedance spectroscopy
(EIS) measurements on the devices to shed light on any subtle
differences in capacitive performance, as well as to gain insight
into the resistance of the electrolyte that contributed to the
systems. The high-frequency plateau in the Bode magnitude
plot, which can be used to determine the solution resistance
of the device, shows that the 1m EMIBTI solution has a resist-
ance that is approximately 20 W higher than that of neat
EMIBTI (see Figure S1d). This result was consistent for each
device analyzed. To verify that this resistance was caused by
the electrolyte solution, and not caused by the conducting
polymer that was on the electrodes, we performed EIS meas-
urements on devices that contained only the separator paper
soaked in electrolyte and electrodes that did not have any
polymer on them. These measurements yielded device resis-
tances of 18Æ6 and 45Æ10 W at the 90% confidence level for
the neat EMIBTI and 1m EMIBTI solutions, respectively. The dif-
ference between the resistances measured for devices that
contained polymer and those that did not contain polymer is
not statistically significant, but the difference between neat
EMIBTI and the 1m EMIBTI solution is statistically significant.
These results are counter to our hypothesis that the addition
of solvent would lower the resistance by breaking up the ion-
pairing interactions that are present in neat EMIBTI. Further ex-
ploration showed that the conductivities of EMIBTI/BTHFE solu-
tions are directly proportional to the concentration of EMBTI,
up to approximately 90% EMIBTI, where it plateaus, at about
9 mScmÀ1 (see Figure S2 in the Supporting Information).
The Bode phase-angle plot (see Figure S1e) shows that, at
frequencies below approximately 1 Hz, the phase angle for
both neat EMIBTI and the BTHFE solution approaches À90%,
and is indicative of nearly ideal capacitive behavior. These re-
sults suggest that BTHFE solutions warrant further analysis in
electrochemical capacitors, because it appears that the solvent
is relatively stable electrochemically.
Experimental Section
Tetrahydrofurfurylalcohol (THFA, Sigma Aldrich,ꢀ98%), tetrahydro-
furan (THF, Sigma Aldrich, Reagent Grade,ꢀ99%, BHT inhibited),
sodium metal (Sigma Aldrich, Reagent Grade, dry stick), methane-
sulfonyl chloride (Sigma Aldrich, 99.7%), pyridine (Sigma Aldrich,
Anhydrous, 99.8%), and propylene carbonate (Sigma Aldrich, Anhy-
drous, 99.7%) were purchased and used as received. 1-Ethyl-3-
methyl-imidizolium bis(trifluoromethylsulfonyl)imide (EMIBTI), for
use in the electrochemical measurements, was synthesized as pre-
viously reported.[11] Elemental analyses were performed independ-
ently by Atlantic Microlabs, Inc., Norcross, GA; Intertek Pharma-
ceutical Services, Whitehouse, NJ; and MHW Labs, Phoenix, AZ. The
elemental analysis results reported with the synthetic procedures
are averages of the results from all three laboratories. Electrochem-
ical depositions and cyclic voltammetry were performed by using
a Pine Instruments Model AFCBP1 potentiostat. EIS measurements
were performed by using a Princeton Applied Research PARSTAT
2273 potentiostat. Conductivity measurements of EMIBTI/BTHFE
solutions were performed by using a Jenway 4590 conductivity
meter at 25Æ0.38C.
Synthesis of (Tetrahydrofuran-2-yl)methyl Methanesulfonate
A three-neck round-bottom flask was filled with 200 mL pyridine
and 88 mL (91.8 g, 0.90 moles) THFA. The mixture was placed in an
ice/water bath and purged with nitrogen for 1 h. Methanesulfonyl
chloride (73 mL, 108.4 g, 0.94 moles) was added drop-wise to the
continuously chilled mixture from an addition funnel over a period
of 12 h. The mixture was then allowed to warm to room tempera-
ture over the next 48 h, at which time it was combined with
500 mL of 1.2m HCl and extracted three times with 125 mL por-
tions of dichloromethane. The organic phases were combined and
then extracted once with 125 mL of 1.2m HCl, followed by 125 mL
of saturated NaCl. Finally, the dichloromethane solution was dried
with MgSO4, and the solvent was removed under reduced pres-
sure. The crude product was a light yellow liquid, and the yield of
crude material was 144 g (89%). Portions of the crude material
were vacuum distilled at 0.34 mmHg to obtain pure product
(125 g, 77% yield), which was a clear, colorless liquid. The head-
space temperature during distillation of the pure material was
We have synthesized bis(tetrahydrofurfuryl) ether (BTHFE) in
a high purity by using (tetrahydrofuran-2-yl)methyl methane-
sulfonate as a starting material. The methanesulfonate ion is
a more efficient leaving group for an SN2 reaction than bro-
mide, which had previously been employed to synthesize
BTHFE, and its use prevented the previously observed side
product, 2-methylene tetrahydrofuran, from forming. Generally,
we have demonstrated that the use of (tetrahydrofuran-2-yl)-
methyl methanesulfonate, rather than tetrahydrofurfuryl hal-
ides, provides a versatile starting material that permits the syn-
thesis of tetrahydrofurfuryl ethers with bulky substituents. The
NMR analysis of BTHFE demonstrated that the product was
a mixture of stereoisomers, as expected; although, we ob-
served temperature-dependent peak shifts that have not previ-
1028C. This material was characterized by using H and 13C NMR, 2-
1
D NMR, GC–MS, FTIR, and elemental analysis. CAUTION: (Tetrahy-
drofuran-2-yl)methyl methanesulfonateis stable in air at room tem-
perature, but will react violently if heated while exposed to air.
1H NMR (CDCl3 500 MHz) d=1.60 (m, 1H), 1.8 (m, 2H), 1.9 (m, 1H),
3.03 (s, 3H), 3.76 (m, 2H), 4.0 (m, 2H), ß4.14 ppm (m, 1H). 13C NMR
d=76.29, 71.65, 68.60, 37.55, 27.60, 25.75 ppm; elemental analysis:
calcd: 39.93% C, 6.71% H, 17.79% S; found: 40.1% C, 6.7% H,
18:01% S; GC–MS indicated 98.6% purity.
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Synthesis of bis(Tetrahydrofurfuryl) Ether
this effort. We would also like to thank Roxanne Quintana for
performing all of the mass spectrometry measurements for this
work.
A two-neck round-bottom flask was filled with 60 mL THF and
20.6 g (0.17 moles) of the sodium salt of THFA, which was prepared
by adding sodium metal to excess THFA and collecting the result-
ing solid. The mixture was placed under a nitrogen flow, heated to
approximately 708C by using an oil bath, and 29 g (0.16 moles) of
distilled (tetrahydrofuran-2-yl)methyl methanesulfonatewas added
drop-wise over several hours. Then, the temperature of the oil was
increased to approximately 1708C, and the THF was allowed to
evaporate while the progress of the reaction was monitored by re-
moving small aliquots from the mixture and recording the NMR
spectrum. The mixture was allowed to cool to room temperature
when the NMR spectrum indicated that the reaction was approxi-
mately 90% complete (after roughly 48 h). Diethyl ether (100 mL)
was added to the room-temperature mixture, which was then fil-
tered, and the ether was removed by rotary evaporation. The yield
of crude material, which was a brown-colored liquid, was 19 g
(63%). The crude material was purified by vacuum distillation and
produced a clear, colorless liquid. The temperature of the distillate
was 628C at 0.3 mmHg. The reaction yielded 14 g (47%) of product
Keywords: electrochemistry
· ion pairs · ionic liquids ·
supercapacitors · synthetic methods
[1] W. R. Kirner, J. Am. Chem. Soc. 1930, 52, 3251–3256.
[2] L. von Wissell, B. Tollens, Justus Liebigs Ann. Chem. 1893, 272, 291–306.
[3] a) A. F. Halasa, W. L. Hsu, Polymer Preprints ACS Division of Polymer
Chemistry. 1996, 37, 676–677; b) C. Wang, C. Li, G. Yu, A. Liang, J.
Zhang, L. Xu, P. Lv, H. Liu, China Petroleum & Chemical Corporation, P.
R. China, Sinopec Beijing Research Institute of Chemical Industry,
US20120108773A1, 2012; c) M. Liao, X. Zhang, C. Fan, L. Wang, M. Jin, J.
Appl. Polym. Sci. 2011, 120, 2800–2808; d) W. L. Hsu, A. F. Halasa, T. T.
Wetli, Rubber Chem. Technol. 1998, 71, 62–69; e) D. J. Zanzig, P. H. Sand-
strom, J. K. Hubbell, W. L. Hsu, A. F. Halasa, J. J. A. Verthe, Goodyear Tire
and Rubber Co., US5470929A, 1995; f) W. L. Hsu, A. F. Halasa, B. A. Ma-
trana, Goodyear Tire and Rubber Co., US5448003A, 1995; g) W. L. Hsu,
A. F. Halasa„ B. A. Matrana, Goodyear Tire and Rubber Co., US5336739A,
1994; h) W. L. Hsu, A. F. Halasa, B. A. Matrana, US5359016A, 1994;
i) W. L. Hsu, A. F. Halasa, B. A. Matrana,Goodyear Tire and Rubber Co.,
US5231153A, 1993; j) V. I. Aksenov, N. A. Golovina, V. S. Ryakhovskii, E. V.
Stepanova, A. D. Sokolova, V. P. Ziborova, V. A. Belikov, Otkrytoe Aktsio-
nernoe Obshchestvo “Efremovskii Zavod Sinteticheskogo Kauchuka”,
RU2206581C2, 2003; k) V. I. Aksenov, N. A. Golovina, V. S. Ryakhovskii,
E. V. Stepanova, A. D. Sokolova, V. P. Ziborova, V. A. Belikov, Otkrytoe
Aktsionernoe Obshchestvo “Efremovskii Zavod Sinteticheskogo Kauchu-
ka”, RU2200740C1, 2003.
1
that was found to be approximately 99% pure by GC–MS. H NMR
(CDCl3, 500 MHz) d=4.02–3.93 (broad m, 2H), 3.81–3.74 (m, 2H),
3.70–3.62 (m, 2H), 3.48–3.35 (m, 4H), 1.91–1.82 (broad m, 2H),
1.82–1.71 (broad m, 4H), 1.59–1.47 ppm (broad m); 13C NMR
(CDCl3, 500 MHz) d=77.95, 77.85, 74.18, 74.08, 68.25, 28.12, 28.10,
25.61, 25.58 ppm; elemental analysis: calcd: 64.5%C, 9.7% H,
25.8% O; found: 64.4%C, 9.7% H, 25.9% O.
[4] a) K. P. Murphy, B. A. Phillips, Int. J. Refrig. 1984, 7, 56–58; b) K. P.
Murphy, B. A. Phillips, Development of a Residential Gas Absorption Heat
Pump in Proceedings, 18th Intersociety Energy Conversion Engineering
Conference, Vol. 4, American Institute of Chemical Engineers, New York,
August 1983, pp. 1911–14; c) C. C. Li, Allied Chemical Corp.,
US4251382A, 1981; d) M. B. Berenbaum, F. E. Evans, R. E. Eibeck, M. A.
Robinson, Allied Chemical Corp., US4072027A, 1978.
[5] M. M. I. I. Marion, Rust-Oleum Corporation, US6030466, 2000.
[6] a) J.-P. Lange, E. van der Heide, J. van Buijtenen, R. Price, ChemSusChem
2012, 5, 150–166; b) E. de Jong, D. den Ouden, G.-J. Gruter, Preprints of
Symposia–ACS Division of Fuel Chemistry. 2010, 55, 207–208.
[7] a) Q. Cao, J. Guan, G. Peng, T. Hou, J. Zhou, X. Mu, Catal. Commun.
2015, 58, 76–79; b) H. R. Nychka, Allied Chemical Corp., GB2000771A,
1979.
Poly(3,4-propylenedioxythiophene) Electrochemical
Supercapacitor Analysis
Poly(3,4-propylenedioxythiophene) (poly(ProDOT)) was potentiody-
namically deposited onto 0.5 cm diameter gold disk electrodes
from 30 mm solutions of 3,4-propylenedioxythiophene in propyl-
ene carbonate that contained 100 mm EMIBTI as a supporting elec-
trolyte. The working electrode potential was swept between À1
and +1.7 V versus Ag+/Ag six times at 100 mVsÀ1 to produce the
electroactive films. Two-electrode capacitor devices were construct-
ed as previously reported.[11] The charge capacity for each elec-
trode was determined by integration of the voltammetric current
corresponding to the neutralization of the polymer film on the
electrode, and the difference in the capacity for electrodes that
were used in a single device was limited to <10%. The devices
were analyzed by using cyclic voltammetry and EIS.
[8] L. M. Prutkov, I. K. Sanin, I. V. Kamenskii, Khim. Geterotsikl. Soedin. 1966,
632–3.
[9] J. Plavec, W. Tong, J. Chattopadhyaya, J. Am. Chem. Soc. 1993, 115,
9734–9746.
´
[10] M. Galinski, A. Lewandowski, I. Ste˛pniak, Electrochim. Acta 2006, 51,
5567–5580.
[11] J. D. Stenger-Smith, C. K. Webber, N. Anderson, A. P. Chafin, K. Zong,
J. R. Reynolds, J. Electrochem. Soc. 2002, 149, A973–A977.
Acknowledgements
We gratefully acknowledge the NAWCWD Internal Investment
Program, Power Systems Initiative for the funding that supported
Received: February 10, 2016
Published online on && &&, 2016
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COMMUNICATIONS
Finally! Many asymmetric alkyl tetrahy-
drofurfuryl ethers are available, and
they have a wide range of potential ap-
plications. However, the preparation of
the symmetric molecule, bis(tetrahydro-
furfuryl) ether (BTHFE), has remained
elusive, until now. High-purity BTHFE
has been prepared and fully character-
ized for the first time. In addition, a pre-
liminary investigation of BTHFE as a sol-
vent in electrochemical supercapacitors
is reported.
J. D. Stenger-Smith, L. Baldwin, A. Chafin,
P. A. Goodman*
&& – &&
Synthesis and Characterization of
bis(Tetrahydrofurfuryl) Ether
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