Synthesis and surface properties of new semi-fluorinated sulfobetaines potentially usable for 2D-electrophoresis

Article abstract of DOI:10.1016/j.jfluchem.2006.12.008

New semi-fluorinated amidosulfobetaines, homologs of hydrocarbon amidosulfobetaines (ASB) commonly used in two-dimensional gel electrophoresis (2DE), were prepared in three steps from 2-F-alkylethyl iodide or F-alkyl iodide. Their synthesis was described and their air-water interface properties were investigated and compared with their perhydrogenated counterpart properties. The influence of the relative lengths of the perfluorinated and hydocarbonated moieties was discussed. 2DE of a rat testicular membrane fraction was performed comparatively using one of these fluorinated sulfobetaines and its hydrocarbon homolog; these preliminary results showed the great potential of the semi-fluorinated sulfobetaines in proteomic analysis.

Full text of DOI:10.1016/j.jfluchem.2006.12.008

Journal of Fluorine Chemistry 128 (2007) 211–218
www.elsevier.com/locate/fluor
Synthesis and surface properties of new semi-fluorinated sulfobetaines
potentially usable for 2D-electrophoresis
b
Pascal Thebault a, Elisabeth Taffin de Givenchy a, , Mireille Starita-Geribaldi ,
*
Frederic Guittard a, Serge Geribaldi a
a
´ ´ ´
Laboratoire de Chimie des Materiaux Organiques et Metalliques, Institut de Chimie, Universite de Nice Sophia-Antipolis,
Parc Valrose, 06108 Nice Cedex 2, France
´
Connexines et Proliferation Germinale, Physiopathologie Cellulaire et Moleculaire (INSERM U670), UFR de Medecine,
b
´
Universite de Nice Sophia-Antipolis, 28 Avenue de Valombrose, 06107 Nice Cedex 1, France
Received 21 September 2006; received in revised form 6 December 2006; accepted 12 December 2006
Available online 16 December 2006
Abstract
New semi-fluorinated amidosulfobetaines, homologs of hydrocarbon amidosulfobetaines (ASB) commonly used in two-dimensional gel
electrophoresis (2DE), were prepared in three steps from 2-F-alkylethyl iodide or F-alkyl iodide. Their synthesis was described and their air–water
interface properties were investigated and compared with their perhydrogenated counterpart properties. The influence of the relative lengths of the
perfluorinated and hydocarbonated moieties was discussed. 2DE of a rat testicular membrane fraction was performed comparatively using one of
these fluorinated sulfobetaines and its hydrocarbon homolog; these preliminary results showed the great potential of the semi-fluorinated
sulfobetaines in proteomic analysis.
# 2006 Elsevier B.V. All rights reserved.
Keywords: Sulfobetaine; Semi-fluorinated; Surfactant; Critical micelle concentration; Surface tension; 2D electrophoresis
1. Introduction
demonstrated that the use of a charged detergent, i.e.
ammonium perfluorooctanoate, enabled high concentrations
in surfactant (40–80 g Lꢀ1) to be obtained, in which the
membranes (2–5 g proteins Lꢀ1) are at least partially solubi-
lized. Perfluorophosphocholines were used for the purification
of flavocytochrome B558 [12], but the encouraging results
obtained were not confirmed by the solubilization of other
membrane proteins. Pucci et al. showed that fluorinated
amphipols were able to preserve proteins in their native state,
which allowed the study of their activities [13,14]. All these
results suggest that semi-fluorinated surfactants have a role to
play in proteomic analysis. Furthermore, the impact of the
perfluorinated segment in membrane extraction and solubiliza-
tion followed by two-dimensional gel electrophoresis (2DE)
has never been demonstrated.
When a surfactant, a liquid crystal, a monomer, a polymer
and so on, present an activity or a specific property, most of the
time, this activity or property is largely modified when a
hydrogenated fragment of its structure is replaced by a
homologous perfluorinated moiety [1]. This quality of the
perfluoroalkyl chains has been used for a long time to enhance
the surface properties of surfactants in various domains like
paints [2], cleaning [3,4], electronics [5], emulsion [6],
microemulsions [7], fire retardant (AFFF) [8,9] or blood
substitute [10]. A field in which these exceptional properties
have just started to be explored is that of detergents for the
extraction and solubilization of membrane proteins. First
attempts were made by Shepherd and Holzenburg [11] on
various membrane proteins and seemed promising. They
Recently, amidosulfobetaine detergents (see ASB-n in Fig. 1)
have been shown to be effective in 2DE [15] with respect to a
great number of membrane proteins; efficiency is modulated by
thelengthofthehydrocarbontail, whichcanberelateddirectlyto
the hydrophobic properties. For instance, amidosulfobetaine-14
(ASB-14) was very efficient in solubilizing the membrane
* Corresponding author. Tel.: +33 4 92 07 6175; fax: +33 4 92 07 6156.
E-mail address: Elisabeth.Taffin-de-Givenchy@unice.fr
(E. Taffin de Givenchy).
0022-1139/$ – see front matter # 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2006.12.008

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P. Thebault et al. / Journal of Fluorine Chemistry 128 (2007) 211–218
Fig. 1. Synthesized amidosulfobetaines FASB-p,m and their perhydrogenated analogs ASB-n.
H+ATPase [16] and the highly hydrophobic transmembrane
protein B and 3 characterized by 12 transmembrane domains
[17,18].
perfluoroalkyl iodides followed by its radical addition to long
chain v-olefins a-functionalized.
The Brace condensation on undecenyl acid, followed by
reduction of the iodized synthon allowed us to obtain the
desired semi-fluorinated acids. Several methods have been
described in the literature for the reduction itself, we decided to
use the one involving metal zinc in acid medium [19].
For these reasons, while preserving the properties and
advantages brought by the polar head of amidosulfobetaine
detergents, we decided to modulate their hydrophobic and
lipophilic properties by introducing perfluorinated fragments in
the hydrophobic tail. In consequence, we decided to synthesize
semi-fluorinated detergents which have within the same
structure: a sulfobetaine polar head, an amide connector and
a perfluorinated terminal fragment of variable length (C2F5,
C4F9, C6F13, C8F17), itself connected to the structure by a short
hydrocarbon spacer (C2H4) or a longer one (C10H20). All the
structures synthesized are shown in Fig. 1. They were named
FASB-p,m, where p is the number of carbons of the
perfluorinated moieties and m the number of carbons in the
hydrocarbon spacer.
2.1.2. Step 2
All the acids synthesized were then converted into amides 2
via a condensation reaction with 3-N,N-dimethylaminopropy-
lamine. This conversion has been accomplished through three
different ways. Attempts were made first with the commercial
acid C8F17C2H4COOH. The first two methods involved the use
of different coupling agents which are classically used in
peptide syntheses, a third one utilises of a non conventional
synthesis using microwave irradiation. In general, the forma-
tion of amides from amines and carboxylic acids implies the
activation of the carboxy group by either the prior conversion to
a more reactive acylating agent such as acyl chloride or in situ
activation by coupling reagents [20]. The formation of the
compound FASB-8,2 via the perfluorooctylpropanoic acid
chloride was claimed in a patent describing the synthesis and
the use of various fluorinated sulfobetaines as fire extinguishing
agents [21]. However, we did not succeed to reproduce
this experiment because the product obtained while
following the protocol led to the formation of the salt
C8F17C2H4C(O)NH(CH2)3N+H(CH3)2ꢁClꢀ which was difficult
to deprotonate [21]. We tested two coupling agents known to
give good results in the literature [20]. One of the
reactions involved dicyclohexylcarbodiimide (DCC) assisted
by hydroxysuccinimide (HOSu) and the other 3-(dimethyla-
mino)propyl]-3-ethylcarbodiimide (EDC) and is catalysed with
4-dimethylaminopyridine (DMAP). In the DCC/HOSu couple
experiment, the DCC reacts with the perfluorooctylpropanoic
acid to form a reactive complex. Then, HOSu reacts with the
latter to form an even more reactive entity. Once the acid is
activated, the amine can condense and form the desired amide
with dicyclohexylurea (DCU), which precipitates in the
medium and allows elimination of water; HOSu is regenerated.
In this case, the amide C8F17C2H4C(O)NH(CH2)3N(CH3)2
was obtained with 63% yield. With EDC/DMAP, the principle is
the same. EDC (CH3)2N(CH2)3N C NCH2CH3ꢁHCl, is also a
carbodiimide which can activate the acid and trap the water
formedinthesameway asDCC. DMAP catalysesthereactionby
forming an even more reactive species. In this case, the treatment
is simplified compared to the preceding couple, since EDC and
the urea formed are water soluble and can be eliminated by a
simple washing. This method allowed us to obtain the amide
C8F17C2H4C(O)NH(CH2)3N(CH3)2 with 86% yield.
In order to support our hypothesis for the possible use of
semi-fluorinated sulfobetaines for 2DE analysis, a preliminary
experiment was performed on a membrane fraction of rat
testicular tissue by using extraction/solubilization followed by
a first dimension separation with these fluorinated surfactants.
As we were interested by the influence of the fluorinated chains,
we choose to start with the compound having the higher
contents in fluorine. That is the reason why FASB-8,2 was taken
as a model for this preliminary investigation.
2. Results and discussion
2.1. Synthesis
The semi-fluorinated surfactants FASB-p,m were obtained
from 2F-alkyl-ethyl iodides (RFC2H4I) for compounds with
m = 2, and from perfluoroalkyl iodides (RFI) for compounds
with a longer hydrocarbon spacer (m = 10) according to the
general reaction pathway summarized in Fig. 2.
2.1.1. Step 1
The iodides were initially transformed into acids 1. The
procedures involved in these syntheses depend on the length
of the hydrocarbon linker. The synthesis of the short
hydrocarbon segment acids involves the prior formation of
the magnesium form; the latter will react with carbon dioxide
to form the carboxylate intermediate. Acidic hydrolysis
allowed us to obtain the corresponding 3-perfluoroalkyl-
propanoic acids.
In order to synthesize the surfactants with long hydrocarbon
fragments (ten atoms of carbon in our case), the corresponding
acids were prepared using the method published by Brace [19].
It involved the homolytic rupture of the C–I bond in

P. Thebault et al. / Journal of Fluorine Chemistry 128 (2007) 211–218
213
Fig. 2. Reaction pathway for the synthesis of semi-fluorinated amidosulfobetaines FASB-p,m.
Lastly, we were also interested in a ‘‘non-usual’’ technique of
activation involving microwave irradiation [22]. It is now well
documented that solvent-free methods coupled to microwave
(MW) irradiation results in very efficient and clean procedures
with noticeable improvements over classical methods [23]. In
order to test this protocol, we used a domestic microwave.
Different combinations of time and irradiation power were
achieved in order to observe the complete conversion of the acid
into amide. The best results were obtained after three consecutive
irradiations of 1 min with full power (800 W). In these
conditions, we observed the complete conversion of the starting
acid without formation of side products or any noticeable
decomposition. However, the isolated yield (43%) remains
relatively weak, in part due to the evaporation of the products,
and this reaction would deserve to be optimized in closed vessels
with a laboratory microwave oven.
Taking into consideration the results obtained with these
different procedures, we decided to continue the synthesis of
our surfactants by using the method involving the couple EDC/
DMAP.
Table 1
Various processes used for the synthesis of the amide C8F17C2H4
C(O)NH(CH2)3N(CH3)2
Method
Reaction
Treatments
Isolated
time (min)
yield (%)
DCC/HOSua
EDC/DMAPb
1440
1440
3 ꢂ 1
Column chromatography
Ku¨gelrohr
63
86
43
Water extraction
Ku¨gelrohr
Microwave 800 W
Ku¨gelrohr
Table 1 summarizes the yields obtained for the synthesis of
the amide C8F17C2H4C(O)NH(CH2)3N(CH3)2 according to the
various processes used.
a
DCC: dicyclohexylcarbodiimide; HOSu: hydroxysuccinimide.
b
EDC: 3-(dimethylamino)propyl]-3-ethylcarbodiimide; DMAP: 4-dimethy-
laminopyridine.

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P. Thebault et al. / Journal of Fluorine Chemistry 128 (2007) 211–218
Table 2
Yields obtained for the different steps of FASB-p,m synthesis
Surfactants FASB-p,m
Step 1: isolated yield (%)
Step 2: (EDC/DMAP)a isolated yield (%)
Step 3: isolated yield (%)
Global yield (%)
FASB-4,2
FASB-6,2
FASB-8,2
FASB-2,10
FASB-4,10
50
82
83
86
71
78
66
59
62
49
54
27
20
53
17
24
40
Commercially available
48
56
a
EDC: 3-(dimethylamino)propyl]-3-ethylcarbodiimide; DMAP: 4-dimethylaminopyridine.
2.1.3. Step 3
For comparison, we also report here the values measured for
ASB-14 which is the hydrocarbon homologous of our semi-
fluorinated structures. This surfactant is commercially available
and the values of the gS and the CMC we obtained in water or in
an aqueous solution containing 10% of ethanol were identical.
From these data, it is apparent that all of the molecules can
self-organize at very low concentrations (CMC values range
from 0.018 to 6.03 mmol Lꢀ1) and have a high surfactant
activity, reducing the surface tension of water from
69 mN mꢀ1 (reference sample) to 18.5–34.3 mN mꢀ1 at the
CMC at 25 8C. As predicted by the literature, the introduction
of a semi-fluorinated chain into the surfactant structure
involves a dramatic reduction of the CMC (0.018 mmol Lꢀ1
for the best value obtained with FASB-4,10 against
6.03 mmol Lꢀ1 for the totally hydrogenated counterpart),
along with a reduction of the surface tension gS (from 18.5 to
25.2 for the semi-fluorinated compounds against 34.3 for the
perhydrogenated ASB-14).
The third step, which consisted in opening the propane
sultone with the different amides synthesized, allowed us to
obtain the semi-fluorinated amidosulfobetaines. The reaction
proceeded in a Et2O/CH3CN 2:1 mixture in which the starting
materials are soluble whereas the surfactants formed pre-
cipitate. Consequently, the amidosulfobetaines synthesized
could be isolated by filtration except for FASB-2,10 which was
soluble in the media and required purification by column
chromatography over silicagel.
The results obtained are summarized in Table 2.
2.2. Physicochemical study
The critical micelle concentration (CMC) can be determined
by various methods (conductimetry, colorimetry, tensiometry,
solubilization, etc.). We chose to use the tensiometric method,
which is based on the measure of the surface tension (gS) versus
the surfactant concentration (C) of an aqueous solution. Graphs
representing the variation of surface tension (gS) against log
concentration indicate clearly that gS decreases until a
particular concentration, the CMC, is reached and it remains
constant for concentrations higher than the CMC (Fig. 3). This
change in the slope of the curve is characteristic of micellar
aggregation and indicates the surfactant properties of the semi-
fluorinated amidosulfobetaines synthesized.
As expected within the semi-fluorinated series, we observed
that for a predetermined hydrocarbon spacer, the surface
tension gS decreases when the length of the perfluorinated chain
increases. The same trend was observed for the CMC values
which vary from 1.58 mmol Lꢀ1 for FASB-4,2 to
0.16 mmol Lꢀ1 for FASB-8,2. The CMC measured for the
surfactants with a long hydrocarbon spacer (C10H20) are
remarkably much lower than the one measured for the
surfactant with a shorter spacer. This is not surprising and
can be explained by the fact that micelle formation is favoured
when stabilizing hydrophobic interactions are accentuated [25].
Since, the surfactants synthesized were not totally water-
soluble, an aqueous solution containing 10% of ethanol was
used. In these conditions, the CMC varies very slightly [24].
The values of the gS and CMC were obtained at 25 8C and are
reported in Table 3.
2.3. 2D gel electrophoresis attempt
In order to test the potential of these semi-fluorinated
surfactants for 2DE analysis, some preliminary experiments
were performed on a rat testicular membrane by using FASB-
8,2 that presents an intermediate CMC value among the series
Table 3
Surface properties of amphiphilic compounds
Surfactants
gs (mN mꢀ1 a
)
CMC (mmol Lꢀ1
)
ASB-14
34.3
25.2
22.6
18.5
22.1
20.5
6.03
1.58
0.31
0.16
0.19
0.018
FASB-4,2
FASB-6,2
FASB-8,2
FASB-2,10
FASB-4,10
a
Fig. 3. Surface tension against log (concentration of FASB-p,2).
Value at the critical micelle concentration (CMC).

P. Thebault et al. / Journal of Fluorine Chemistry 128 (2007) 211–218
215
Fig. 4. Differential 2DE analysis after silver staining of a rat testicular membrane fraction extracted and solubilized with: (a) the classical detergent ASB-14; (b) a
semi-fluorinated surfactant FASB-8,2. Presence of a spot in a gel compared to the other gel is indicated by an arrow (!); better spot resolution area (R) in (a);
uncleared separation (*) in a narrow acidic zone in (b).
synthesized and it is the synthesized surfactant having the most
fluorinated tail.
showed that the synthesized semi-fluorinated surfactants were
able to extract different membrane proteins than those extracted
by their hydrocarbon homologous. The specificity observed
with these new semi-fluorinated amidosulfobetaines let us to
foresee their use in serial extraction of membrane proteins for
2DE. Further investigation is necessary to optimize the patterns
in order to enhance this specificity. Work on red blood cell
membrane will be reported elsewhere [28].
In the 2DE technology, proteins are separated according to
their isoelectric point by isoelectric focusing (IEF) in the first
dimension and according to their molecular weight by sodium
dodecylsulfate (SDS) electrophoresis in the second dimension
[26,27]. Thus, 2DE patterns of a rat testicular membrane
fraction were compared after that extraction/solubilization and
IEF were performed in a 3–10 linear IPG pH gradient,
respectively with ASB-14 (Fig. 4a) and FASB-8,2 (Fig. 4b).
Second dimensional gels were obtained with 3% SDS at the
equilibration step. The amount of protein loaded is highly
dependent on the separation distance in IEF, and in this
experiment the pH gradient is only a 7 cm IPG strip. The
comparison of the 2DE patterns obtained with ASB-14 and
FASB-8,2 (Fig. 4) displayed differences in the number of spots
thus showing the specificity of these surfactants; five spots or
train of spots appeared only when ASB-14 was used and three
spots appeared when FASB-8,2 was used. Some spots were less
resolved and some smears were present in the acidic end of the
2DE pattern resulting from FASB-8,2 extraction and separa-
tion. From these promising preliminary results it appears that
further investigation will be necessary to optimize the
fluorinated surfactant concentration as well as the SDS
concentration in the second dimension. Use of different
separation conditions will let us to enhance the sensitivity and
the resolution of the 2DE map.
4. Experimental
4.1. General experimental procedures
1H NMR and 19F NMR spectra were obtained using a Bruker
AC-200 spectrometer, in CDCl3 for 2-perfluoroalkylethanoic
1
acid, 1H NMR, 2D H NMR, 19F NMR and 13C NMR spectra
were obtained in MeOD for all the other compounds. Chemical
shifts d are given in ppm, using TMS as internal standard for 1H
1
NMR, 2D H NMR and 13C NMR, and CFCl3 for 19F NMR.
Mass spectra were obtained from a Finnigan MAT. (Thermo
Corp.) LCQ with an ESI API 2 source and a ITD (ion trap)
analyzer. High resolution mass spectra for the final amido-
sulfobetaines were performed on a Waters QStar Elite (Applied
Biosystems SCIEX) spectrometer with an ESI API source and a
TOF (time of flight) analyzer.
Fusion points were obtained from a Bu¨chi 510 apparatus.
Critical micelle concentration (CMC) and superficial tensions
were obtained using a tensiometer K100 from Kruss.
3. Conclusion
1-Iodo-2-perfluoroalkylethanes,
1-iodoperfluoroalkanes,
azobis-(dimethylvaleronitrile) (AIVN) were supplied by DuPont
de Nemours. Undecenyl acid, N-(3-dimethylaminopropyl)-N0-
ethylcarbodiimide hydrochloride (EDC), 4-dimethylaminopyr-
idine (DMAP), propanesultone, zinc granular 20 mesh and
3-[N,N-dimethyl(3-myristoylaminopropyl)ammonio]propane-
sulfonate (ASB-14) were purchased from Sigma–Aldrich, and
silica gel 60 from Fluka.
The diversity of the biological samples analyzed in 2DE
leads to the development of protocols with numerous steps of
extraction and solubilization requiring the use of one or a
combination of surfactants. In this perspective, simple and
efficient synthesis of a new series of semi-fluorinated
amidosulfobetaine amphiphiles homolog to hydrocarbon
amidosulfobetaines ASB-n largely used in proteomic analysis
is described. These fluorinated compounds self-organize in
water at low concentrations and present interesting surfactant
properties. The preliminary results obtained in rat testicular
membrane extraction and solubilization followed by 2DE
4.2. Synthesis of 3-perfluoroalkylpropanoic acid (1a–c)
Magnesium (2.4 g, 0.1 mol) was added to 25 mL of
anhydrous diethyl ether under nitrogen atmosphere, followed

216
P. Thebault et al. / Journal of Fluorine Chemistry 128 (2007) 211–218
by a drop wise addition of 1-iodo-2-perfluoroalkylethane
(0.1 mol) dissolved in anhydrous diethyl ether for 2 h. The
reaction was stirred for 2 h at room temperature, and then the
mixture was cooled in an ice water bath. Ten grams of dry ice
were added and the mixture was stirred at room temperature for
15 min. The reaction was cooled and a 10% aqueous solution of
sulfuric acid was added. The aqueous and organic layers were
separated. The organic layer was dried and evaporated under
vacuum. The acids F(CF2)n(CH2)2COOH were obtained as
white powders.
mixture was stirred for 12 h at 65 8C, 10-iodo-11-perfluor-
obutylundecanoic acid was not isolated, but directly reduced.
The procedure followed for the reduction was the same as
the one previously described for the reduction of 10-iodo-11-
perfluoroethylundecanoic acid.
The 11-perfluorobutylundecanoic acid was obtained in 56%
yield as a white powder.
1e—RF = C4F9; m = 10; m.p. = 48–49 8C; 1H NMR
(MeOD) d: 1.25 (12H, m,(CH2)6CH2C2H4CO2H); 1.5 (4H,
m, RFCH2CH2(CH2)6CH2); 1.95 (2H, m, RFCH2(CH2)8CH2
CO2H); 2.25 (2H, m, CH2COOH). 19F NMR (MeOD) d: ꢀ84.5
(3F, CF3); ꢀ118 (2F, CF2CH2); ꢀ128.5 (2F, CF2CF2CH2);
ꢀ129.5 (2F, CF3CF2).
1a—RF = C4F9; m = 2; m.p. = 43–44 8C; 1H NMR (CDCl3)
d: 2.3–2.8 (4H, m, CF2CH2CH2COOH). 19F NMR (CDCl3) d:
ꢀ82.5(3F, CF3); ꢀ116 (2F, CF2CH2); ꢀ125 (2F, CF3CF2CF2);
ꢀ127.5 (2F, CF3CF2).
1b—RF = C6F13; m = 2; m.p. = 63–64 8C; 1H NMR
(CDCl3) d: 2.3–2.8 (4H, m, CF2CH2CH2COOH). 19F NMR
(CDCl3) d: ꢀ82.5 (3F, CF3); ꢀ116 (2F, CF2CH2); ꢀ123 (2F,
CF2CF2CH2); ꢀ124 (2F, CF2CF2CF2CH2); ꢀ125 (2F,
CF3CF2CF2); ꢀ127.5 (2F, CF3CF2).
4.5. Synthesis of amides (2a–e)
4.5.1. By coupling agents (DCC/HOSu)
3-Perfluorooctylpropionic acid (807 mg, 1.64 mmol), dicly-
clohexylcarbodiimide (339 mg, 1.64 mmol) and N-hydrosuc-
cinimide (189 mg, 1.64 mmol) were added to 10 mL of
dichloromethane. The mixture was stirred for 1 h at room
temperature and 3-N,N-dimethylaminopropylamine (184 mg,
1.8 mmol) was added. After stirring for 24 h at room
temperature, the solvent was evaporated under reduced
pressure. The residue was purified by column chromatography
over silica gel using methanol as the eluant. The product was
obtained in 63% yields as colourless liquid.
1
1c—RF = C8F17; m = 2; m.p. = 91–92 8C; commercial; H
NMR (CDCl3) d: 2.3–2.8 (4H, m, CF2CH2CH2COOH). 19F
NMR (CDCl3) d: ꢀ81.2 (3F, CF3); ꢀ113.9 (2F, CF2CH2);
ꢀ122.2 (6F, (CF2)3CF2CH2); ꢀ123.3 (2F, CF2(CF2)3CF2CH2);
ꢀ123.9 (2F, CF3CF2CF2); ꢀ126.6 (2F, CF3CF2).
4.3. Synthesis of 11-perfluoroethylundecanoic acid (1d)
1-Iodoperfluoroethane (18.4 g, 75 mmol), 2,20-azobis(2,4-
dimethyl)valeronitrile (AIVN) (248 mg, 1 mmol) and 10-
undecenoic acid (9.2 g, 50 mmol) were added in a flask to
be sealed, cooled in a water iced bath. The flask was then cooled
in liquid nitrogen and sealed. The reaction was stirred for 24 h
at room temperature. The sealed flask was then opened and the
10-iodo-11-perfluoroethylundecanoic acid was not isolated, but
directly reduced.
4.5.2. By coupling agents (EDC/DMAP)
Acid (1.64 mmol), N-(3-dimethylaminopropyl)-N0-ethyl-
carbodiimide hydrochloride (314 mg, 1.64 mmol) and 4-
dimethylaminopyridine (20 mg, 0.164 mmol) were added to
10 mL of dichloromethane. The mixture was stirred for 1 h at
room temperature and 3-N,N-dimethylaminopropylamine
(184 mg, 1.8 mmol) was added. After stirring for 24 h at
room temperature, the reaction was washed three times with
water. The organic layer was dried and evaporated under
reduced pressure.
The reaction was cooled at room temperature, 0.22 mol of an
aqueous solution of hydrochloric acid 37% was added and the
mixture was heated at 70 8C. Metallic zinc (1.4 g, 22 mmol) in
powder was added and the reaction was stirred at 70 8C for
12 h.
The amides were obtained in 71–86% yields as colourless
liquids, excepted for FASB-4,10 which was obtained as white
powder.
The reaction mixture was cooled at room temperature and
filtered, rinsed with cold water. The product was purified by
crystallization in hexane. The 11-perfluoroethylundecanoic
acid was obtained in 48% yield as white powder.
1d—RF = C2F5; m = 10; m.p. = 37–38 8C; 1H NMR
(MeOD) d: 1.25 (12H, m,(CH2)6CH2C2H4CO2H); 1.5 (4H,
m, RFCH2CH2(CH2)6CH2); 1.95 (2H, m, RFCH2(CH2)8CH2
CO2H); 2.25 (2H, m, CH2COOH). 19F NMR (MeOD) d: ꢀ88.5
(3F, CF3); ꢀ121 (2F, CF2CH2).
4.5.3. By microwave irradiation
In order to test this protocol, a domestic microwave was used.
3-Perfluorooctylpropionic acid (807 mg, 1.64 mmol), and 3-
N,N-dimethylaminopropylamine (500 mg, 4.9 mmol) were
introduced in a 50 mL flask. Different combinations of time
and irradiation power were achieved in order to observe the
complete conversion of the acid into amide. The best results
were obtained after three consecutive irradiations of 1 min with
full power (800 W). In these conditions, we observed the
complete conversion of the starting acid without formation of
side products or any noticeable decomposition. The pure
product was obtained after evaporation of the excess of amine
using a Kugelrohr apparatus. Isolated yield: 43%.
4.4. Synthesis of 11-perfluorobutylundecanoic acid (1e)
1-Iodoperfluorobutane (25.9 g, 75 mmol) and 2,20-azo-
bis(2,4-dimethyl)valeronitrile (AIVN) (248 mg, 1 mmol) were
placed under a nitrogen atmosphere. The reaction was heated at
65 8C and 10-undecenoic acid (9.2 g, 50 mmol) was added. The
2a—RF = C4F9; m = 2; bp (8C)/mmHg = 121/7.6 ꢂ 10ꢀ3
;
1H NMR (MeOD) d: 1.65 (2H, m, NHCH2CH2); 2.2 (6H, s,

P. Thebault et al. / Journal of Fluorine Chemistry 128 (2007) 211–218
217
N(CH3)2); 2.35 (2H, m, CH2 N(CH3)2); 2.4–2.6 (4H, m,
CF2CH2CH2); 3.15 (2H, t, J = 7 Hz, NHCH2). 19F NMR
(MeOD) d: ꢀ82.5 (3F, CF3); ꢀ116 (2F, CF2CH2); ꢀ125 (2F,
CF3CF2CF2); ꢀ127.5 (2F, CF3CF2).
1H NMR (MeOD) d: 1.65 (2H, m, NHCH2CH2); 2.2 (6H, s,
N(CH3)2); 2.35 (2H, m, CH2N(CH3)2); 2.4–2.6 (4H, m,
CF2CH2CH2); 3.15 (2H, t, J = 7 Hz, NHCH2). 19F NMR
(MeOD) d: ꢀ82.5(3F, CF3); ꢀ116 (2F, CF2CH2); ꢀ125 (2F,
CF3CF2CF2); ꢀ127.5 (2F, CF3CF2).
CF2CH2CH2); 2.85 (2H, m, CH2SO3ꢀ); 3.05 (6H, s,
N+(CH3)2); 3.3–3.6 (6H, m, NHCH2CH2N+(CH3)2CH2). 19F
NMR (MeOD) d: ꢀ82.5 (3F, CF3); ꢀ116 (2F, CF2CH2); ꢀ123
(2F, CF2CF2CH2); ꢀ124 (2F, CF2CF2CF2CH2); ꢀ125 (2F,
CF3CF2CF2); ꢀ127.5 (2F, CF3CF2); 13C NMR (MeOD) d:
18.5(1C, s, CH2CH2SO3ꢀ); 22(1C, s, NHCH2CH2); (1C, s,
CH2SO3ꢀ); 26.5 (2C, m, CF2CH2CH2); 36 (1C, s, NHCH2);
47(1C, s, CH2SO3ꢀ); 50.5 (2C, s, N+(CH3)2); 62 (2C, m,
CH2N+(CH3)2CH2). This structure was also confirmed by the
2b—RF = C6F13; m = 2; bp (8C)/mmHg = 128/7.6 ꢂ 10ꢀ3
;
1
2D H NMR COSY spectrum. Mass spectrum (ESI+)—m/z:
2c—RF = C8F17; m = 2; bp (8C)/mmHg = 140/7.6 ꢂ 10ꢀ3
;
599.3 [M + H]+; 621 [M + Na]+; 1219.5 [2M + Na]+. HRMS:
(m/z) calcd for C17H23N2O4SF13 [M + H]+, 599.1242; found
599.1244.
1H NMR (MeOD) d: 1.65 (2H, m, NHCH2CH2); 2.2 (6H, s,
N(CH3)2); 2.35 (2H, m, CH2 N(CH3)2); 2.4–2.6 (4H, m,
CF2CH2CH2); 3.15 (2H, t, J = 7 Hz, NHCH2). 19F NMR
(MeOD) d: ꢀ82.5 (3F, CF3); ꢀ116 (2F, CF2CH2); ꢀ123 (2F,
(CF2)3CF2CH2); ꢀ124 (2F, CF2CF2CF2CH2); ꢀ125 (2F,
CF3CF2CF2); ꢀ127.5 (2F, CF3CF2).
3c—RF = C8F17; m = 2, refractive index = 1.4196; 1H NMR
(MeOD) d: 1.95 (2H, m, NHCH2CH2); 2.2 (2H, m,
CH2CH2SO3ꢀ); 2.5 (4H, m, CF2CH2CH2); 2.85 (2H, m,
CH2SO3ꢀ); 3.05 (6H, s, N+(CH3)2); 3.3–3.6 (6H, m, NHCH2,
CH2N+(CH3)2CH2). 19F NMR (MeOD) d: ꢀ82.5 (3F, CF3);
ꢀ116 (2F, CF2CH2); ꢀ123 (2F, (CF2)3CF2CH2); ꢀ124 (2F,
CF2CF2CF2CH2); ꢀ125 (2F, CF3CF2CF2); ꢀ127.5 (2F,
CF3CF2). 13C NMR (MeOD) d: 18.5(1C, s, CH2CH2SO3ꢀ);
22(1C, s, NHCH2CH2); 26.5 (2C, m, CF2CH2CH2); 36 (1C, s,
NHCH2); 47(1C, s, CH2SO3ꢀ); 50.5 (2C, s, N+(CH3)2); 62 (2C,
m, CH2N+(CH3)2CH2). This structure was also confirmed by
the 2D 1H NMR COSY spectrum. Mass spectrum (ESI+)—m/z:
699.3 [M + H]+. HRMS: (m/z) calcd for C19H23N2O4SF17
[M + H]+, 699.1179; found 699.1181.
2d—RF = C2F5; m = 10; bp (8C)/mmHg = 112/7.6 ꢂ 10ꢀ3
;
1H NMR (MeOD) d: 1.3 (12H, m, (CH2)6CH2C2H4CO); 1.5
(6H, m, RFCH2CH2(CH2)6CH2, NHCH2CH2); 2.2 (12H, m,
CF2CH2,CH2CO,CH2N(CH3)2); 3.2 (2H, m, NHCH2). 19F
NMR (MeOD) d: ꢀ88.5 (3F, CF3); ꢀ121 (2F, CF2CH2)
2e—RF = C4F9; m = 10; m.p. = 40–41 8C; 1H NMR
(MeOD) d: 1.3 (12H, m, (CH2)6CH2C2H4CO); 1.5 (6H, m,
RFCH2CH2(CH2)6CH2, NHCH2CH2); 2.2 (12H, m, CF2CH2,
CH2CO,CH2N(CH3)2); 3.2 (2H, m, NHCH2). 19F NMR
(MeOD) d: ꢀ84.5 (3F, CF3); ꢀ118 (2F, CF2CH2); ꢀ128.5
(2F, CF2CF2CH2); ꢀ129.5 (2F, CF3CF2).
3d—RF = C2F5; m = 10; bp (8C)/mmHg = 160/7.6 ꢂ 10ꢀ3
;
refractive index = 1.4280; 1H NMR (MeOD) d: 1.3 (12H,
m,(CH2)6CH2C2H4CO); 1.6 (4H, m, RFCH2CH2(CH2)6CH2);
1.95 (2H, m, NHCH2CH2); 2.2 (6H, m, CF2CH2,CH2
CO,CH2CH2SO3ꢀ); 2.85 (2H, m, CH2SO3ꢀ); 3.05 (6H, s,
N+(CH3)2); 3.3–3.5 (6H, m, NHCH2,CH2N+(CH3)2CH2). 19F
NMR (MeOD) d: ꢀ88.5 (3F, CF3); ꢀ121 (2F, CF2CH2); 13C
NMR (MeOD) d: 18.5 (1C, s, CH2CH2SO3ꢀ); 20 (1C, s,
CF2CH2CH2); 22(1C, s, NHCH2CH2); 25 (1C, s, CH2CH2CO);
28 (6C, s, CH2(CH2)6CH2); 29,5 (1C, m, CF2CH2); 36 (2C, s,
CH2CONHCH2); 47 (1C, s, CH2SO3ꢀ); 50.5 (2C, s, N+(CH3)2);
62 (2C, m, CH2N+(CH3)2CH2). This structure was also
confirmed by the 2D 1H NMR COSY spectrum. Mass spectrum
(ESI+)—m/z: 511.4 [M + H]+; 533.4 [M + Na]+; 1043.7
[2M + Na]+; HRMS: (m/z) calcd for C21H39N2O4SF5
[M + H]+, 511,2623; found 511,2624.
4.6. Synthesis of surfactants (3a–e)
A mixture of 2 ꢂ 10ꢀ3 mole of the amide previously
prepared and 5 ꢂ 10ꢀ3 mole of propanesultone was added to
20 mL of a mixture of diethyl ether/acetonitrile (2/1). The
reaction was stirred and heated at 50 8C for 24 h.
White precipitates were filtered and washed with acetone
several times. FASB-2.10 was also purified by column
chromatography over silica gel using methanol as the eluant.
The surfactants were obtained in 49–66% yield as oils,
excepted for FASB-4,2 which was obtained as white powder
and FASB-2,10 as colourless liquid.
3a—RF = C4F9; m = 2; m.p. = 108–109 8C; 1H NMR
(MeOD) d: 1.9 (2H, m, NHCH2CH2); 2.2 (2H, m,
CH2CH2SO3ꢀ); 2.5 (4H, m, CF2CH2CH2); 2.85 (2H, m,
CH2SO3ꢀ); 3.05 (6H, s, N+(CH3)2); 3.3–3.6 (6H, m,
NHCH2,CH2N+(CH3)2CH2); 19F NMR (MeOD) d: ꢀ82.5
(3F, CF3); ꢀ116 (2F, CF2CH2); ꢀ125 (2F, CF3CF2CF2);
ꢀ127.5 (2F, CF3CF2). 13C NMR (MeOD) d: 18.5(1C, s,
CH2CH2SO3ꢀ); 22(1C, s, NHCH2CH2); 26.5 (2C, m,
CF2CH2CH2); 36 (1C, s, NHCH2); 47(1C, s, CH2SO3ꢀ);
50.5 (2C, s, N+(CH3)2); 62 (2C, m, CH2N+(CH3)2CH2). This
structure was also confirmed by the 2D 1H NMR COSY
spectrum. Mass spectrum (ESI+)—m/z: 499.3 [M + H]+; 521.3
[M + Na]+. HRMS: (m/z) calcd for C15H23N2O4SF9 [M + H]+,
499.1307; found 499.1308.
3e—RF = C4F9; m = 10; refractive index = 1.4430; 1H NMR
(MeOD) d: 1.3 (12H, m,(CH2)6CH2C2H4CO); 1.6 (4H, m,
RFCH2CH2(CH2)6CH2); 1.95 (2H, m, NHCH2CH2); 2.2 (6H,
m, CF2CH2,CH2CO,CH2CH2SO3ꢀ); 2.85 (2H, m, CH2SO3ꢀ);
3.05 (6H, s, N+(CH3)2); 3.3-3.5 (6H, m, NHCH2,
CH2N+(CH3)2CH2; 19F NMR (MeOD) d: ꢀ84.5 (3F,
CF3,3F); ꢀ118 (2F, CF2CH2); ꢀ128.5 (2F, CF2CF2CH2);
ꢀ129.5 (2F, CF3CF2); 13C NMR (MeOD) d: 18.5 (1C, s,
CH2CH2SO3ꢀ); 20 (1C, s, CF2CH2CH2); 22(1C, s, NHCH2
CH2); 25 (1C, s, CH2CH2CO); 28 (6C, s, CH2(CH2)6CH2); 29,5
(1C, m, CF2CH2); 36 (2C, s, CH2CONHCH2); 47 (1C, s,
CH2SO3ꢀ); 50.5 (2C, s, N+(CH3)2); 62 (2C, m, CH2N+(CH3)2
1
1
3b—RF = C6F13; m = 2; H NMR (MeOD) d: 1.95 (2H, m,
CH2). This structure was also confirmed by the 2D H NMR
COSY spectrum. Mass spectrum (ESI+)—m/z: 611.4 [M + H]+;
NHCH2CH2); 2.2 (2H, m, CH2CH2SO3ꢀ); 2.5 (4H, m,

218
P. Thebault et al. / Journal of Fluorine Chemistry 128 (2007) 211–218
633.4 [M + Na]+; 1243.7 [2M + Na]+; HRMS: (m/z) calcd for
C23H39N2O4SF9 [M + H]+, 611.2559; found 611.2555.
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Rat testis (600 mg) was homogeneized in a Thomas potter
with 6 mL of 50 mmol Lꢀ1 Tris–HCl buffer pH 7.5 containing
a protease inhibitor cocktail CompleteTM (1 mmol Lꢀ1
EDTA) from Roche Applied Science (Roche, Mannheim,
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