New aryl-containing fluorinated sulfonic acids and their ammonium salts, useful as electrolytes for fuel cells or ionic liquids

Article abstract of DOI:10.1016/j.jfluchem.2008.06.009

Several aryl-containing ammonium sulfonates have been prepared either by cationic metathesis from the corresponding lithium sulfonates or from the corresponding sulfonic acids. The latter have been obtained by elution of an Amberlite resin with alcoholic

Full text of DOI:10.1016/j.jfluchem.2008.06.009

Journal of Fluorine Chemistry 129 (2008) 1029–1035
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
New aryl-containing fluorinated sulfonic acids and their ammonium
salts, useful as electrolytes for fuel cells or ionic liquids
R. Arvai a,b,c,d,e,f, F. Toulgoat a,b,c,d,e,f, M. Medebielle a,b,c,d,e,f, B. Langlois a,b,c,d,e,f,
´
*
,
F. Alloin g, C. Iojoiu g, J.Y. Sanchez g
a
´
´
ICBMS, Institut de Chimie et Biochimie Moleculaires et Supramoleculaires, Equipe SERCOF, 43 boulevard du 11 novembre 1918,
Villeurbanne F-69622, France
b CNRS, UMR5246, Villeurbanne F-69622, France
c Universite´ de Lyon, Lyon F-69622, France
d Uuniversite´ Lyon 1, Lyon F-69622, France
e INSA-Lyon, Villeurbanne F-69622, France
f CPE Lyon, Villeurbanne F-69616, France
g
´
Laboratoire d’Electrochimie et de Physico-chimie des Materiaux et des Interfaces, UMR 5631 CNRS-INPG-UJF,
`
BP.75, 38402 Saint-Martin-d’Heres, France
A R T I C L E I N F O
A B S T R A C T
Article history:
Several aryl-containing ammonium sulfonates have been prepared either by cationic metathesis from the
corresponding lithium sulfonates or from the corresponding sulfonic acids. The latter have been obtained
by elution of an Amberlite resin with alcoholic solutions of the lithium sulfonates. These ammonium
sulfonates exhibit interesting conductivities and thermal properties which allow them to be promising
candidates as electrolytes for electricity storage.
Received 29 March 2008
Accepted 4 June 2008
Available online 20 June 2008
Keywords:
ß 2008 Elsevier B.V. All rights reserved.
Fluoroalkanesulfonic acids
Fluoroalkanesulfonates
Electrolytes
Batteries
Fuel cells
Ionic liquids
1. Introduction
inhibition by fuel impurities. This problem was attempted to be
overcome mostly by synthesising novel polymer electrolyte
Several decades have already passed from the first appearance of
the Nafion1 perfluorinated ionomeric membrane, originally devel-
oped by E.I. Dupont de Nemours Co. [1]. Yet, it became probably the
most used and studied proton-conducting membrane for Proton
Exchange Membrane Fuel Cells (PEMFC). It has been demonstrated
that Nafion ionomers exhibit long-term stability, high ionic
conductivity, gas permeability and good mechanical properties
[2,3]. However, their high conductivity is tributary to their water
uptake (two to five molecules of H2O per H+) and dramatically
decreasesattemperatureshigherthan80 8C.Moreover,lowworking
temperature fuel cells (below 80 8C) can suffer from Pt-catalyst
membranes, by doping functional polymers with room temperature
ionic liquids [3,4] or acid proton carriers with low vapour pressure
(e.g. phosphoric acid [5], phosphotungstic acid [6] or zirconium
phosphate [2]) or by combination of both ionic liquid and acid
proton carriers [7,8]. An innovative approach was proposed by
Watanabe quite recently using protic ionic liquids [9–12]. The
physical and electrochemical properties of protic ionic liquids were
also deeply studied by Angell and co-workers [13]. While Watanabe
mostly studied salts from bis-(trifluoromethanesulfonyl) amide
and organic nitrogen bases, Angell and co-workers examined
ammonium salts from trifluoromethanesulfonic acid, trifluoroacetic
acid or formic acid. The highest conductivities were obtained with
trifluoromethanesulfonates and the influence of vapour pressure,
viscosity, conductivity and
DpKa (between the acid and the base)
* Corresponding author.
E-mail address: Bernard.Langlois@univ-lyon1.fr (B. Langlois).
was reported by Angell and co-workers.
0022-1139/$ – see front matter ß 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2008.06.009

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R. Arvai et al. / Journal of Fluorine Chemistry 129 (2008) 1029–1035
3a,d into the corresponding silanes 4a,d. The latter are further
converted to sulfinates 5a,d which are oxidized into sulfonyl
fluorides 1a,d by electrophilic fluorination with Selectfluor1
.
Oxidation of 1a,d by mCPBA delivers either 1b,e or 1c,f, depending
on the excess of mCPBA. Finally, saponification of 1a–f with lithium
hydroxide offers 2a–f in good to excellent overall yield (Scheme 2).
However, if lithium sulfonates 2a–f are potentially valuable
salts for lithium batteries, they are not adapted for fuel cells and
must be turned into proton conductors. Thus, we searched for
new routes to tertiary ammonium cations associated with the
same sulfonate anions as in 2a,c, potentially useful as proton-
conducting ionic liquids, and also to analogous quaternary
ammonium salts behaving as aprotic ionic liquids, which could
be used as ionic solvents valuable additives in batteries and fuel
cells.
For this purpose, cation metathesis between lithium sulfonates
2a,d and ammonium halides was first examined. In a typical
experiment, an aqueous solution of the ammonium chloride was
added to a solution of 2a,d in acetone. After stirring at room
temperature, evaporation to dryness, dissolution in water, extrac-
tion with dichloromethane and evaporation of the organic phase,
some organic sulfonates have been isolated. Such a process was
successful for different sulfonates, gathered in Table 1, which were
obtained in a pure state (no chloride anion was detected by cyclic
voltammetry).
However, this method failed with N-methylimidazolium 2-
(phenylsulfanyl)-1,1,2,2-tetrafluoroethanesulfonate which was
not hydrophobic enough to be extracted by dichloromethane.
So, we turned to the synthesis of the sulfonic acids corresponding
to 2a and 2c which, in principle would be very strong and could be
neutralized by a large variety of organic or inorganic bases. Only
few references were found in the literature for the preparation of
free aryl-containing perfluoroalkyl sulfonic acids by acidification of
the corresponding sulfonate [16,17] (Fig. 1).
Obviously, these acids, as those we plan to prepare, are not
volatile enough to be distilled from a suspension of the correspond-
ing alkaline sulfonate in pure sulfuric acid, as it is done for triflic
acid [18]. So, Prakash et al. prepared 4a,b in a dynamic process, by
Scheme 1. Phenyl-containing fluorinated sulfonyl fluorides and sulfonates.
In a recent work [14], we reported the synthesis of new phenyl-
containing fluorinated sulfonyl fluorides 1a–f and their saponifi-
cation into the corresponding lithium sulfonates 2a–f (Scheme 1),
which are under evaluation as promising salts in solid polymer
electrolytes for lithium batteries, having in mind the possibility
to prepare analogues bearing a reactive substituent on the phenyl
ring. Such moieties could allow the sulfonate incorporation (by
copolymerization or grafting) in a polymer, in order to decrease the
mobility of the anion and to increase the cationic conductivity of
Li+. This modification is under study and will be published soon.
In this context, despite the presence of the aromatic ring, the
resulting salts exhibit improved cationic conductivity as compared
to triflates. Indeed, the presence of the sulfanyl linker (n = 0) is
important to increase the flexibility of the anions whereas the
presence of the sulfonyl linker decreases the pKa of the conjugated
superacid and, consequently, the basicity, the nucleophilicity and
the oxidability of the sulfonate.
2. Discussion
As we previously described [14], perfluoroalkylsulfonyl fluor-
ides 1a,d, the key compounds in the synthesis of sulfonates,
are accessible in a good overall yield after condensation of ben-
zenethiolate with, respectively, 1,2-dibromo-1,1,2,2-tetrafluor-
oethane or dibromodifluoromethane, according to the protocol
of Suda and Hino [15], then transformation of resulted bromides
Scheme 2. Overall synthesis of lithium sulfonates 2a–f. (a) NaH, dry DMF, BrCF2CF2Br (m = 2) or CF2Br2 (m = 1); (b) Me3SiCl, Mg, THF, À78 8C to rt overnight; (c) SO2, CsF, dry
MeCN, rt, overnight; (d) Selectfluor1 (1 eq.), MeCN, À40 8C to rt; (e) LiOHÁH2O, Et2O; (f) mCPBA (2 eq., n = 1; 8 eq., n = 2), CH2Cl2 3 days.

R. Arvai et al. / Journal of Fluorine Chemistry 129 (2008) 1029–1035
1031
Table 1
Preparation of ammonium sulfonates 3ac–d and 3dc–d by cationic metathesis
(Isolated yield)a
(Isolated yield)a
3aa (74%)
Not prepared
3ab (89%)
3ac (62%)
Not prepared
3dc (79%)
3ad (81%)
3dd (69%)
a
Overall yields vs. RfSO2F.
provide an oxonium sulfonate. However, this is not a drawback
since these sulfonic acids were further neutralized to provide
different salts. This latter step was simply done by adding, at room
temperature, an inorganic hydroxide as well as a secondary or
tertiary amine to a solution of 6a,c in dichloromethane (Table 2).
Inordertohavea firstevaluation oftheinterest, aselectrolytes,of
most of these ammonium sulfonates, their conductivities (in the
pure state at 85–100 8C) and their thermal characteristics (glass
transition temperature, Tg, melting point, mp) have been measured.
Melting points have been determined either by differential scanning
calorimetry (DSC, indicating the beginning of melting) or in capillary
tubes (indicating the end of melting) and Tg have been measured by
DSC. Tg and mp are gathered in Table 3.
It has been also noticed that some ammonium sulfonates
crystallize at a much lower temperature than they melt, after
heating them above their melting point. For example, 3ac
crystallizes at À30 8C (melting point: 38 8C), 3dc at 41 8C (melting
point: 77 8C) and 3dd does not solidify at all. This phenomenon has
been often reported for ionic liquids.
Fig. 1. Exemples of perfluoroalkyl sulfonic acids with a pendant aromatic ring
[16,17].
elution of an acidic resin with an aqueous solution of the
corresponding sulfonates. Consequently, they obtained the sulfonic
acids as aqueous solutions, from which 4a,b could not be isolated by
evaporationsince theydecomposed underheating[16]. Ontheother
hand, as far as 5 is concerned, no experimental data are available.
Thus, we carried out a similar technique but we eluted the
Amberlite resin with a solution of 2a or 2c in pure ethanol. In such a
way, we anticipated that ethanol could be evaporated under
vacuum without heating and, consequently, without decomposi-
tion of the resulting sulfonic acids 6a,c. It must be noticed that, in
order to avoid any introduction of moisture, 2a,c were prepared
from 1a,c but not isolated. Indeed, it worked, though isolated 6a,c
were obtained as solvates with ethanol (about 1.5 EtOH/RfSO3H,
Scheme 3).
As it appears from Table 3, a number of ammonium sulfonates
exhibit a conductivity higher than 10À3 S cmÀ1, a very low glass
transition point and a moderate melting point. Such properties
allow them to be good candidates as proton-conducting electro-
lytes for PEMFCs operating above 100 8C. Deeper investigations,
such as the transference numbers, are under study to precise their
interest in such applications.
Such a solvation is not surprising since it can be thought that
ethanol is, at least, tightly associated by hydrogen bonds with such
strong acids or, acting as a base, could be even neutralized to
Scheme 3. Preparation of sulfonic acids 6a,c.

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R. Arvai et al. / Journal of Fluorine Chemistry 129 (2008) 1029–1035
Table 2
Preparation of ammonium sulfonates 3aa, 3ae–3ak, 3ca, 3ce–3cg, 3ci, 3cj
(Isolated yield)a
(Isolated yield)a
3aa (80%)
3ca (94%)
3ae (98%)
3af (95%)
3ce (96%)
3cf (97%)
3ag (99%)
3cg (94%)
3ah (90%)
3ai (89%)
Not prepared
3ci (88%)
3aj (96%)
3ak (65%)
3cj (95%)
Not prepared
a
Overall yields vs. RfSO2F.
Table 3
Conductivities and thermal properties of different ammonium sulfonates.
3. Conclusion
Sulfonate
Conductivity
s
(S cmÀ1
)
Differential scanning
In conclusion, several tertiary or quaternary ammonium aryl-
containing sulfonates, useful as aprotic ionic liquids or proton-
conducting ones, have been prepared by cationic metathesis
between the corresponding lithium sulfonates and ammonium
halides. In order to broaden the availability of such salts, the
corresponding sulfonic acids were synthesised by eluting Amber-
lite resin with an alcoholic solution of lithium sulfonates. In such a
way, these acids were easily isolated as solvates with ethanol, then
neutralized with a variety of secondary or tertiary amines in
dichloromethane, that allowed the resulting ammonium sulfo-
nates to be quickly isolated. Some of these ammonium sulfonates
exhibit good conductivities and rather low melting points, so that
they will be evaluated as proton-conducting electrolytes for fuel
cells. Their syntheses and properties have been recently patented
[19].
(at t 8C)
calorimetry (5 8C minÀ1
)
Tg (8C)
mp (8C)
3aa
3ca
3ac
3dc
3ad
3dd
3ae
3ce
3af
3cf
3ag
3cg
3ah
3ai
3ci
3aj
N.D.
N.D.
À43 8C
À36 8C
N.D.
43 8Ca
112 8C
38 8Cb
77 8Cb
Oil
4.9 Â 10À3 (90 8C)
5.9 Â 10À3 (90 8C)
3.8 Â 10À4 (85 8C)
6.5 Â 10À4 (90 8C)
4.0 Â 10À3 (100 8C)
1.3 Â 10À3 (100 8C)
2.6 Â 10À3 (100 8C)
N.D.
N.D.
À54 8Cb
N.D.
40 8Cb
Oil
À60 8C
À60 8C
À50 8C
N.D.
30 8C
Oil
Oil
3.3 Â 10À3 (90 8C)
7.8 Â 10À4 (100 8C)
2.1 Â 10À3 (100 8C)
4.0 Â 10À3 (100 8C)
1.5 Â 10À3 (100 8C)
4.0 Â 10À3 (100 8C)
2.2 Â 10À3 (100 8C)
1.1 Â 10À3 (100 8C)
À40 8C
À56 8C
N.D.
Oil
36 8C
Oil
À60 8C
À36 8C
N.D.
12 8C
48 8C
65 8C
85 8Cc
Oil
3cj
3ak
N.D.
4. Experimental
N.D.
N.D.: Not determined.
˚
Prior to use, solvents were distilled and stored over 3 A
a
mp: 76 8C in capillary tubes.
DSC at 10 8C minÀ1
b
molecular sieves under N2. Commercially available reagents were
used as received. Sulfonyl fluorides 1a,c and lithium sulfonates
.
c
Recrystallized compound. Before recrystallization, mp: 72 8C (capillary tube).

R. Arvai et al. / Journal of Fluorine Chemistry 129 (2008) 1029–1035
1033
3
2a,d were obtained according to ref. [14]. Amberlite (IR-120, H+-
2F, JF–F = 5.7 Hz). 1H NMR:
d
= 9.16 (s, 1H), 7.60–7.65 (m, 2H),
˚
form, Fluka, mesh 28–35 A) was activated (elution with 6 M HCl,
7.26–7.42 (m, 5H), 4.13 (t, 2H, 3J = 7 Hz), 3.91 (s, 3H), 1.75 (m, 2H),
1.25 (m, 2H), 0.89 (t, 3H, 3J = 7 Hz). 13C NMR:
130.3 (s), 129.0 (s), 124.5 (t, JF–C = 2.5 Hz), 124.2 (tt, JF–
C = 289.8 Hz, JF–C = 32.7 Hz), 123.6 (s), 122.1 (s), 115.1 (tt, JF–
C = 288.7 Hz, 2JF–C = 34 Hz), 49.7 (s), 36.3 (s), 31.9 (s), 19.2 (s), 13.3
then with deionized water, absolute ethanol and finally diethyl
ether) and dried in vacuo prior use. All reactions were carried out
under nitrogen atmosphere. TLC analyses were carried out on silica
gel (Merck Kieselgel 60F254) deposited on aluminum plates,
detection being done by UV (254 nm). Flash-chromatographies
were performed on silica gel Merck Geduran SI 60 (230–400 mesh).
d
137.1 (s), 136.5 (s),
3
1
2
1
(s).
Unless stated otherwise, NMR spectra were recorded in CDCl3. 1
NMR were recorded at 300 MHz and 13C NMR spectra at 75 MHz.
19F NMR spectra were recorded at 282 MHz. Chemical shifts (
are given in ppm vs. TMS (1H, 13C) or CFCl3 19F), used as internal
references. Coupling constants are given in hertz. The substitu-
tion pattern of the different carbons were determined by a ‘‘DEPT
135’’ sequence. Mass spectrometry was carried out on a Thermo
Finnigan Mat 95xL apparatus (mode of ionization: electros-
pray, chemical ionization or electron impact). Melting points
were determined either in capillary tubes on a Bu¨chi apparatus
(uncorrected) or by differential scanning calorimetry (DSC).
H
4.1.4. 1-n-Hexyl-3-methylimidazolium 2-(phenylsulfanyl)-1,1,2,2-
tetrafluoroethanesulfonate 3ad
3ad was prepared in the same way as 3aa, starting from 2a
(202 mg, 0.68 mmol), dissolved in acetone (8 mL), and 1-n-hexyl-
3-methylimidazolium chloride (132 mg, 0.65 mmol), dissolved in
water (5 mL). Yield: 81% (252 mg) from PhSCF2CF2SO2F. Oil. 19F
d
)
(
NMR:
NMR:
d
d
À85.2 (t, 2F, 3JF–F = 5.7 Hz), À113.0 (t, 2F, 3JF–F = 5.7 Hz). 1H
9.12 (s, 1H), 7.62–7.63 (m, 2H), 7.29–7.42 (m, 5H), 4.11 (t,
2H, 3J = 7.3 Hz), 3.89 (s, 3H), 1.79 (m, 2H), 1.24 (m, 6H), 0.80 (t, 3H,
3J = 7 Hz). 13C NMR:
d
137.1 (s), 136.8 (s), 130.3 (s), 129.0 (s), 124.5
3
1
2
(t, JF–C = 2.5 Hz), 124.2 (tt, JF–C = 289.8 Hz, JF–C = 32.7 Hz), 123.7
(s), 122.0 (s), 115.1 (tt, 1JF–C = 288.7 Hz, 2JF–C = 34 Hz), 50.0 (s), 36.2
(s), 30.9 (s), 30.0 (s), 25.7 (s), 22.3 (s), 13.9 (s).
4.1. Cationic metathesis between lithium sulfonates 2a,d and
ammonium halides
4.1.5. 1-n-Butyl-3-methylimidazolium 2-
4.1.1. Benzyldimethylammonium 2-(phenylsulfanyl)-1,1,2,2-
tetrafluoroethanesulfonate 3aa
(phenylsulfanyl)difluoromethanesulfonate 3dc
3dc was prepared in the same way as 3aa, starting from 2d
(200 mg, 0.81 mmol), dissolved in acetone (8 mL), and 1-n-butyl-
3-methylimidazolium chloride (140 mg, 0.80 mmol), dissolved in
water (5 mL). Yield: 79% (252 mg) from PhSCF2SO2F. White solid.
Benzyldimethylammonium chloride (125 mg, 0.74 mmol), dis-
solved in water (2 mL), was added, under inert atmosphere, to a
solution of 2a (290 mg, 0.96 mmol) in acetone (5 mL). The mixture
was stirred at room temperature for 6 h then evaporated to
dryness. Water was added to the residue and the aqueous phase
was extracted with CH2Cl2 (6 Â 10 mL). The gathered organic
phases were washed with water (3 Â 15 mL) then dried over
MgSO4 and evaporated. 3aa was obtained as a white solid (0.32 g,
0.86 mmol, 74% from 1 mmol of PhSCF2CF2SO2F [14]). mp: 43–
mp: 77 8C. 19F NMR:
d
À79.0 (s). 1H NMR:
d 9.22 (s, 1H), 7.60–7.64
(m, 2H), 7.32–7.40 (m, 5H), 4.16 (t, 2H, 2J = 7 Hz), 3.93 (s, 3H), 1.80
(m, 2H), 1.25 (m, 2H), 0.88 (t, 3H, 2J = 7 Hz). 13C NMR:
136.5 (s), 129.8 (s), 129.0 (s), 126.0 (t, JF–C = 289.8 Hz), 124.5 (t,
3JF–C = 2.5 Hz), 123.7 (s), 122.1 (s), 49.7 (s), 36.4 (s), 32.0 (s), 19.4
(s), 13.3 (s).
d 137.0 (s),
1
76 8C. 19F NMR:
d
À85.14 (t, 2 F, 3JF–F = 5.7 Hz), À112.24 (t, 2F, 3JF–
F = 5.7 Hz). 1H NMR:
d
7.64 (m, 2H), 7.36–7.46 (m, 8H), 6.85 (broad
4.1.6. 1-n-Hexyl-3-methylimidazolium 2-
s, 1H), 4.15 (s, 2H), 2.78 (s, 6H). 13C NMR:
d
137.2 (s), 130.8 (s),
(phenylsulfanyl)difluoromethanesulfonate 3dd.
3
130.6 (s), 130.2 (s), 129.4 (s), 129.2 (s), 128.9 (s), 124.2 (t, JF–
C = 2.5 Hz), 124.2 (tt, 1JF–C = 289.8 Hz, 2JF–C = 32.7 Hz), 115.1 (tt, 1JF–
3dd was prepared in the same way as 3aa, starting from 2d
(192 mg, 0.78 mmol), dissolved in acetone (8 mL), and 1-n-hexyl-
3-methylimidazolium chloride (152 mg, 0.75 mmol), dissolved in
water (5 mL). Yield: 69% (220 mg) from PhSCF2SO2F. Beige solid.
2
C = 288.7 Hz, JF–C = 34 Hz), 61.5 (s), 42.7 (s).
4.1.2. Tetra-n-octylammonium 2-(phenylsulfanyl)-1,1,2,2-
tetrafluoroethanesulfonate 3ab
mp: 40 8C. 19F NMR:
d
À79.1 (s). 1H NMR:
d 9.12 (s, 1H), 7.62–7.63
(m, 2H), 7.29–7.41 (m, 5H), 4.11 (t, 2H, 2J = 7 Hz), 3.89 (s, 3H), 1.78
2a (455 mg, 1.54 mmol) and tetra-n-octylammonium bromide
(842 mg, 1.54 mmol) were dissolved in acetone (10 mL) and stirred
at room temperature for 5 min. Then, the solvent was evaporated
and the residue was dispersed in CH2Cl2. After stirring, the
insoluble lithium bromide was filtered on Celite and washed with
dichloromethane. After evaporation, 3ab was obtained as an oil
(1.04 g, 1.37 mmol, 89% from PhSCF2CF2SO2F). 19F NMR (acetone):
(m, 2H), 1.24 (m, 6H), 0.80 (t, 3H, 2J = 7 Hz),. 13C NMR:
136.8 (s), 130.3 (s), 129.0 (s), 126.1 (t, JF–C = 289.8 Hz), 124.5 (t,
3JF–C = 2.5 Hz), 123.7 (s), 122.0 (s), 50.0 (s), 36.2 (s), 30.9 (s), 30.0 (s),
25.7 (s), 22.3 (s), 13.9 (s).
d
137.1 (s),
1
4.2. Synthesis of sulfonic acids 6a and 6c
3
3
d
À85.1 (t, 2F, JF–F = 8 Hz), À113.9 (t, 2F, JF–F = 8 Hz). 1H NMR
4.2.1. 2-(phenylsulfanyl)-1,1,2,2-tetrafluoroethanesulfonic acid 6a
Solid LiOHÁH2O (0.09 g, 2.18 mmol) was added, at room
temperature, to a stirred solution of PhSCF2CF2SO2F (0.27 g,
1 mmol), in Et2O (15 mL). Stirring was held for 24 h. The reaction
was followed by TLC (SiO2/pentane) and 19F NMR. After removal of
the solvent under vacuum, the solid residue was dissolved in
absolute ethanol (3 mL) and the solution was dropped slowly, over
10 min, through a column (15 cm) of Amberlite IR 120 (H+ form),
previously washed with absolute ethanol. Volatiles compounds
were removed for 24 h in vacuo. The residue was pure enough to be
(acetone):
d 7.61–7.64 (m, 2H), 7.40–7.54 (m, 3H), 3.38–3.43 (m,
8H), 1.66–1.83 (m, 8H), 1.27–1.83 (m, 40H), 0.84–0.88 (m, 12H).
13C NMR (acetone):
(tt, JF–C = 290 Hz, JF–C = 32 Hz), 115.6 (tt, JF–C = 290 Hz, JF–
C = 32 Hz), 59.1 (s), 32.3 (s), 29.7 (s), 29.5 (s), 26.8 (s), 23.2 (s),
22.4 (s), 14.4 (s).
d
137.4 (s), 130.9 (s), 129.8 (s), 126.2 (s), 124.9
1
2
1
2
4.1.3. 1-n-Butyl-3-methylimidazolium 2-(phenylsulfanyl)-1,1,2,2-
tetrafluoroethanesulfonate 3ac
3ac was prepared in the same way as 3aa, starting from 2a
(200 mg, 0.68 mmol), dissolved in acetone (8 mL), and 1-n-butyl-
3-methylimidazolium chloride (105 mg, 0.6 mmol), dissolved in
water (5 mL). Yield: 62% (180 mg) from PhSCF2CF2SO2F. Beige
used in the next step without further purification. Brown-red oil
3
(0.32 g, 0.86 mmol, 86%). 1H NMR:
d
10.38 (s, 4H), 7.64 (d, JH–
3
H = 7.0 Hz, 2H), 7.48–7.33 (m, 3H), 3.89 (q, JH–H = 7.1 Hz, 3.3H),
1.27 (t, 3JH–H = 7.1 Hz, 5H). 19F NMR:
d
À85.64 (t, 3JF–F = 5.1 Hz, 2F),
3
solid. mp: 38 8C. 19F NMR:
d
À85.0 (t, 2F, 3JF–F = 5.7 Hz), À113.0 (t,
À112.21 (t, JF–F = 5.1 Hz, 2F). 13C NMR:
d 137.28 (s), 130.70 (s),

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R. Arvai et al. / Journal of Fluorine Chemistry 129 (2008) 1029–1035
129.28 (s), 123.82 (t, 3JF–C = 2.5 Hz), 123.41 (tt, 1JF–C = 290.3 Hz, 2JF–
C = 32.7 Hz), 114.53 (tt, JF–C = 289.3 Hz, JF–C = 35.2 Hz), 60.12 (s),
F = 6.7 Hz). 13C NMR (acetone-d6):
(s), 125.73 (t, JF–C = 2.5 Hz), 124.91 (tt, JF–C = 289.3 Hz, JF–
C = 32.2 Hz), 115.65 (tt, 1JF–C = 288.5 Hz, 2JF–C = 31.7 Hz), 68.39 (s),
58.83 (s), 48.26 (s).
d
137.79 (s), 131.27 (s), 130.10
1
2
3
1
2
16.02 (s).
4.2.2. 2-Benzenesulfonyl-1,1,2,2-tetrafluoroethanesulfonic acid 6c
Brown-red oil (90% yield). 1H NMR:
d
10.40 (s, 2.5H), 8.00 (d,
4.3.6. Bis-(2-methoxyethyl)ammonium 2-(benzenesulfonyl)-1,1,2,2-
3JH–H = 7.0 Hz, 2H), 7.84–7.75 (m, 1H), 7.69–7.60 (m, 2H), 3.96 (q,
tetrafluoroethanesulfonate 3cf
3
3JH–H = 7.1 Hz, 3H), 1.30 (t, JH–H = 7.1 Hz, 4,5H). 19F NMR:
d
C
Yellowish oil (0.48 g, 1.06 mmol, 97%). 1H NMR (acetone-d6):
8.05 (d, JH–H = 7.9 Hz, 2H), 7.99–7.89 (m, 1H), 7.84–7.74 (m, 2H),
3.73 (t, 3JH–H = 5.0 Hz, 4H), 3.44 (t, 3JH–H = 5.0 Hz, 4H), 3.32 (s, 6H).
d
À110.51 (t, 3JF–F = 18.9 Hz, 2F), À112.67 (t, 3JF–F = 18.9 Hz, 2F). 13
3
NMR:
d
136.38 (s), 132.59 (s), 130.83 (s), 129.68 (m), 115.13 (tt, 1JF–
2
1
2
C = 299.7 Hz, JF–C = 35.9 Hz), 114.27 (tt, JF–C = 290.2 Hz, JF–
19F NMR (acetone-d6):
d
À106.82 (s), À109.62 (s). 13C NMR:
d
1
C = 33.5 Hz), 59.61 (s), 16.17 (s). UV (0.2 mM in CH2Cl2):
max = 268.4–229.8.
137.02 (s), 134.66 (s), 131.55 (s), 130.64 (s), 116.75 (tt, JF–
2
1
2
l
C = 287.3 Hz, JF–C = 33.5 Hz), 115.72 (tt, JF–C = 287.3 Hz, JF–
C = 33.5 Hz), 67.55 (s), 58.86 (s), 48.24 (s).
4.3. Neutralization of sulfonic acids 6a and 6c with amines
4.3.7. N-Ethylmorpholinium 2-(phenylsulfanyl)-1,1,2,2-
4.3.1. Benzyldimethylammonium 2-(phenylsulfanyl)-1,1,2,2-
tetrafluoroethanesulfonate 3aa
tetrafluoroethanesulfonate 3ag
Yellow oil (0.40 g, 0.99 mmol, 99%). 1H NMR (acetone-d6):
d
3
Benzyldimethylamine (637 mg, 4.71 mmol) was dropped at
0 8C, under argon, into a solution of 6a (1.5 g, 4.71 mmol) in
freshly distilled CH2Cl2 (30 mL). The solution was stirred at
room temperature for 1 h, then evaporated to dryness. The
residue was dried under vacuum (P < 0.02 mbar) to offer 3aa
(1.63 g, 80%), the characteristics of which are given in Section
4.1.1.
7.69–7.67 (m, 2H), 7.58–7.45 (m, 3H), 6.28 (s, 1H), 3.97 (t, JH–
H = 4.7 Hz, 4H), 3.35–3.25 (m, 6H), 1.37 (t, JH–H = 4.7 Hz, 3H). 19F
3
3
3
NMR (acetone-d6):
d
À85.45 (t, JF–F = 6.9 Hz), À113.67 (t, JF–
F = 6.9 Hz). 13C NMR (acetone-d6):
d 137.81 (s), 131.39 (s), 130.17
3
1
2
(s), 125.46 (t, JF–C = 1.9 Hz), 124.96 (tt, JF–C = 289.0 Hz, JF–
1
2
C = 31.8 Hz), 115.74 (tt, JF–C = 288.6 Hz, JF–C = 31.1 Hz), 64.43
(s), 53.40 (s), 52.39 (s), 9.13 (s).
4.3.2. Benzyldimethylammonium 2-(benzenesulfonyl)-1,1,2,2-
tetrafluoroethanesulfonate 3ca
4.3.8. N-Ethylmorpholinium 2-(benzenesulfonyl)-1,1,2,2-
tetrafluoroethanesulfonate 3cg
3ca was obtained in the same way as 3aa, starting from
benzyldimethylamine (537 mg, 3.97 mmol) and 6c (1.5 g,
3.97 mmol) in CH2Cl2 (30 mL). Beige solid (1.70 g, 94%). mp:
Yellow solid (0.42 g, 0.96 mmol, 94%). mp: 36 8C. 1H NMR
(acetone-d6):
d 8.06–8.04 (m, 2H), 7.96–7.91 (m, 1H), 7.84–7.79
3
(m, 2H), 4.19 (s, 1H), 6.26 (s, 1H), 3.96 (t, JH–H = 4.6 Hz, 4H),
3.32–3.21 (m, 6H), 1.34 (t, 3JH–H = 4.6 Hz, 3H). 19F NMR (acetone-
112 8C. 1H NMR:
d 9.00 (broad s, 1H), 8.00–7.99 (m, 2H), 7.80–7.56
3
3
(m, 3H), 7.40 (m, 5H), 4.19 (d, JH–H = 13.7 Hz, 2H), 2.79 (d, JH–
d6):
d
À113.53–113.37 (m), À110.72 to 110.57 (m). 13C NMR
H = 7.8 Hz, 6H). 19F NMR:
d
À110.2 (t, 3JF–F = 6.9 Hz, 2F), À112.4 (t,
(acetone-d6): d 137.12 (s), 134.28 (s), 131.50 (s), 130.64 (s),
116.73 (tt, JF–C = 290.6 Hz, JF–C = 34.8 Hz), 115.72 (tt, JF–
3JF–F = 6.9 Hz, 2F). 13C NMR:
d
136.01 (s), 130.65 (s), 130.52 (s),
1
2
1
1
2
2
130.08 (s), 129.41 (s), 129.18 (s), 116.73 (tt, JF–C = 289.3 Hz, JF–
C = 287.7 Hz, JF–C = 34.2 Hz), 64.89 (s), 53.33 (s), 52.66 (s),
1
C = 32.4 Hz), 115.71 (tt, JF–C = 289.3 Hz, 2JF–C = 32.4 Hz), 61.39 (s),
9.57 (s).
42.47 (s).
4.3.9. N-Methylpyrrolidinium 2-(phenylsulfanyl)-1,1,2,2-
4.3.3. Triethylammonium 2-(phenylsulfanyl)-1,1,2,2-
tetrafluoroethanesulfonate 3ah
tetrafluoroethanesulfonate 3ae
Yellow oil (90%). 19F NMR:
d
À85.4 (t, 3JF–F = 6.9 Hz), À112.6 (t,
Yellow oil (0.43 g, 1.10 mmol, 98%). 1H NMR (acetone-d6):
d
3JF–F = 6.9 Hz). 1H NMR:
d 9.6 (s), 7.68–7.63 (m, 2H), 7.44–7.32 (m,
3H), 3.84–3.76 (m, 2H), 3.00–2.80 (m, 2H), 2.90 (s, 3H), 2.20–2.00
(m, 4H).
7.68 (m, 2H), 7.44–7.56 (m, 3H), 3.32 (q, 3JH–H = 7.3 Hz, 6H), 1.36 (t,
3JH–H = 7.3 Hz, 9H). 19F NMR (acetone-d6):
d
À85.44 (t, JF–
3
3
F = 6.9 Hz, 2F), À113.72 (t, JF–F = 6.9 Hz, 2F). 13C NMR (acetone-
3
d6):
d
137.84 (s), 131.33 (s), 130.15 (s), 125.72 (t, JF–C = 2.5 Hz),
4.3.10. N-Butylpyrrolidinium 2-(phenylsulfanyl)-1,1,2,2-
tetrafluoroethanesulfonate 3ai
1
2
1
124.91 (tt, JF–C = 289.7 Hz, JF–C = 32.2 Hz), 115.69 (tt, JF–
2
C = 288.9 Hz, JF–C = 31.2 Hz), 47.54 (s), 9.04 (s).
Orange-red oil at room temperature (89%). mp: 12 8C. 1H NMR:
d
7.64–7.29 (2m, 5H), 7.11 (m, 1H), 3.30–3.15 (m, 4H), 3.00 (m, 2H),
4.3.4. Triethylammonium 2-(benzenesulfonyl)-1,1,2,2-
tetrafluoroethanesulfonate 3ce
2.00 (quint, 4H), 1.65 (m, 2H), 1.30 (sext, 2H), 0.85 (t, 3JH–H = 3.6 Hz,
3H). 19F NMR:
13C NMR:
137.10 (s), 132.40 (s), 130.40 (s), 129.06 (s), 124.24 (t,
3JF–C = 1.9 Hz), 123.96 (tt, JF–C = 289.0 Hz, JF–C = 31.8 Hz), 115.00
d
À85.4 (t, JF–F = 5.7 Hz), À112.7 (t, JF–F = 5.7 Hz).
3
3
White solid (0.39 g, 0.92 mmol, 96%). mp: 30 8C. 1H NMR
d
1
2
(acetone-d6): d 8.06 (m, 2H), 7.96 (m, 1H), 7.81 (m, 2H), 4.16 (s, 1H),
3
3
1
2
3.18 (q, JH–H = 7.4 Hz, 6H), 1.28 (t, JH–H = 7.4 Hz, 9H). 19F NMR
(tt, JF–C = 288.6 Hz, JF–C = 31.1 Hz), 55.42 (s), 54.18 (s), 22.84 (s),
(acetone-d6):
(acetone-d6):
d
À110.67 (m, 2F), À113.44 (m, 2F). 13C NMR
19.74 (s), 13.42 (s).
d
137.05 (s), 134.62 (s), 131.55 (s), 130.65 (s), 116.72
1
2
1
(tt, JF–C = 295.2 Hz, JF–C = 37.4 Hz), 115.71 (tt, JF–C = 286.6 Hz,
2JF–C = 37.4 Hz), 47.48 (s), 9.03 (s).
4.3.11. N-Butylpyrrolidinium 2-(benzenesulfonyl)-1,1,2,2-
tetrafluoroethanesulfonate 3ci
Beige solid (88%). mp: 48 8C. 1H NMR:
d
8.0 (d, 2H), 7.8–7.5 (m,
4.3.5. Bis-(2-methoxyethyl)ammonium 2-(phenylsulfanyl)-1,1,2,2-
3H), 6.0 (broad s, 1H), 3.4–3.2 (m, 4H), 3.0 (m, 2H), 2.2–2.0 (m, 4H),
tetrafluoroethanesulfonate 3af
1.7 (m, 2H), 1.4 (sext, 2H), 0.9 (t, 3H). 19F NMR:
d
À112.6 (m),
Yellow oil (0.40 g, 0.95 mmol, 95%). 1H NMR (acetone-d6):
d
À110.3 (m). 13C NMR:
d 135.9 (s), 133.2 (s), 130.9 (s), 129.4 (s),
3
7.69–7.66 (m, 2H), 7.56–7.45 (m, 3H), 6.25 (s, 1H), 3.69 (t, JH–
116.8 (tt, 1JF–C = 287.3 Hz, 2JF–C = 33.5 Hz), 115.7 (tt, 1JF–
3
2
H = 5.1 Hz, 4H), 3.34 (s, 6H), 3.28 (t, JH–H = 5.1 Hz, 4H). 19F
C = 287.3 Hz, JF–C = 33.5 Hz), 55.7 (s), 54.3 (s), 27.7 (s), 22.9 (s),
3
3
NMR (acetone-d6):
d
À85.39 (t, JF–F = 6.7 Hz), À113.78 (t, JF–
19.7 (s), 13.4 (s).

R. Arvai et al. / Journal of Fluorine Chemistry 129 (2008) 1029–1035
1035
4.3.12. 3-Methyl-3H-imidazol-1-ium 2-(phenylsulfanyl)-1,1,2,2-
samples were cooled down to À100 8C then heated at 5 8C/min up
to 100 8C. The oscillation period was 60 s and its amplitude was
Æ1 8C. Tg and mp were taken at the inflection point of, respectively,
the specific heat increment at the glass–rubber transition and at the
onset of the melting peak.
tetrafluoroethanesulfonate 3aj
Yellow solid (96%). mp: 65 8C. 1H NMR:
d 11.15 (s, 1H), 8.68 (s,
1H), 7.66–7.01 (m, 7H), 3.87 (s, 3H). 19F NMR:
d
À85.24 (t, JF–
3
3
F = 5.7 Hz), À112.67 (t, JF–F = 5.6 Hz). 13C NMR (acetone-d6):
d
3
137.81 (s), 131.27 (s), 130.11 (s), 127.97 (s), 125.83 (t, JF–
1
2
C = 2.8 Hz), 125.00 (tt, JF–C = 288.2 Hz, JF–C = 30.9 Hz), 123.91 (s),
Acknowledgement
1
2
121.53 (s), 115.78 (tt, JF–C = 288.2 Hz, JF–C = 30.9 Hz), 36.31 (s).
The authors gratefully acknowledge the Eras-Labo Co., espe-
cially Lionel Ogier, for synthetizing some of the described salts and
preparing the larger quantities required for the conductivity
measurements.
4.3.13. 3-Methyl-3H-imidazol-1-ium 2-(benzenesulfonyl)-1,1,2,2-
tetrafluoroethanesulfonate 3cj
Yellowish solid (95%). mp: 72 8C (85 8C after recrystallization in
3
CH2Cl2/pentane). 1H NMR:
d
8.62 (s, 1H), 8.02 (d, JH–H = 7.5 Hz,
2H), 7.81–7.74 (m, 1H), 7.67–7.59 (m, 2H), 4.41 (s, 3H), 3.90 (s, 3H).
19F NMR:
d
À110.14 (t, 3JF–F = 19.5 Hz), À112.67 (t, 3JF–F = 19.5 Hz).
References
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(s), 126.60 (s), 124.28 (s), 120.81 (s), 116.73 (tt, JF–C = 289.3 Hz,
2JF–C = 32.4 Hz), 115.73 (tt, JF–C = 289.3 Hz, JF–C = 32.4 Hz), 36.35
d 137.07 (s), 134.48 (s), 131.51 (s), 130.65
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d
13.7 (broad s, 1H), 8.94 (s, 1H),
7.62–7.60 (m, 2H), 4.18 (m, 2H), 1.80 (m, 2H), 1.30 (qi, 2H), 0.80 (t,
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3
3H). 19F NMR:
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À85.3 (t, JF–F = 5.7 Hz), À112.8 (t, JF–F = 5.6 Hz).
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1
2
120.7 (s), 115.6 (tt, JF–C = 288.2 Hz, JF–C = 30.9 Hz), 49.0 (s), 31.9
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