L. Conte et al. / Journal of Fluorine Chemistry 125 (2004) 243–252
251
ammonium salt (46.3 g, 0.149 mol, yield 94%). This inter-
mediate was dissolved in acetone (200 ml), stirred with
have been synthesized mainly starting from the related
intermediate alkanesulfonylfluoride that were appropriately
prepared and fluorinated by ECF. Different procedures have
been experienced along the steps of fluorination, imidation,
salts formation and purification.
In relation with the application of the final lithium salts
as electrolytes in secondary batteries a lot of attention was
finalized to the purification of intermediates and final pro-
ducts with respect to contaminant water and foreign ions.
The products have been characterized in their general
physical and chemical properties, their identification was
achieved with complementary support of IR spectroscopy,
NMR and element analysis.
Electrical conductivity measurements of perfluoroalkane-
sulfonylimide lithium salts showed the conductivity
increased from the lightest asymmetric imide salt to the
lightest symmetric one, moreover the cyclic 1,3-hexafluor-
opropane-disulfonylimide salt exhibited the highest value of
the series.
LiOHꢂH O (10 g, 0.24 mol) for 48 h, added with activated
2
carbon stirred and filtered. The solution was added with
Ca(OH) (10 g) stirred for 3 h, filtered, distilled from solvent
to obtain a brown oil residue.
2
The residue was dissolved in water (200 ml) and the
solution washed three times with CH Cl (50 ml), dried
under vacuum obtaining a white salt, that was dissolved
2
2
in acetone (100 ml) stirred with Ca(OH) (5 g), filtered and
2
the solvent evaporated, dried at 100 8C/2 KPa to obtain a
white solid (27.9 g, 0.093 mol, yield 59%, containing
ꢀ
1
1
7 ppm of F ion). IR spectroscopy:1460 (s), 1360 (s),
290 (m), 1180 (m), 1180 (s), 1120 (m), 1030 (s), 1010
ꢀ
1
w), 900 (m), 830 (m), 770 (s) cm . Elemental anal. calcd.
(
for C F NS O Li: C, 12.04; Li, 2.34. Found: C, 11.95;
3
6
2 4
1
9
Li, 2.3. F NMR: (d, ppm) ꢀ127.56 (–CF –CF –),
2
2
ꢀ
121.2 (–CF –SO –).
2
2
The preparation was repeated by bubbling anhydrous
ammonia (47 g, 2,76 mol) in 5 h into a solution of hexa-
fluoropropane-disulfonylfluoride (50 g, 0.16 mol) in triethy-
lamine (200 ml). The suspension was filtered and the
solid was dissolved in water then extracted with diethylether,
the organic phase was separated, dried on sodium sulphate,
evaporated from solvent to obtain a brown residue
Further efforts are still in progress in order both to
optimize the purity degree of electrolytes and identify other
structures possibly able to show an improved balance of
electrochemical performances.
(
55.5 g).
The residue was treated with a solution of 15 g of
Acknowledgements
LiOHꢂH O dissolved in water (100 ml), after stirring for
The authors are grateful to Daikin Industries Ltd., Chemi-
cal Division, for the financial support to this work, to ENEA
(Idrocomb) for partaking interest in the subject, to Prof. R.
Bertani, Istituto di Scienze e Tecnologie Molecolari CNR
Universit a` di Padova, for the NMR spectroscopy.
2
4
8 h the solution was washed with CH Cl (50 ml), evapo-
2 2
rated from water at 70 8C/2 KPa, obtaining a brown solid
48.5 g). The residue was dissolved in water (100 ml) stirred
with Ca(OH) (6.3 g), the suspension filtered and water
(
2
evaporated; the residue redissolved in acetone, the solution
filtered, stirred with lithium hydroxide (1 g) and 0.2 g of
oxalic acid, the suspension filtered and the solvent was
evaporated to obtain a white solid residue recognized as
References
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[
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ꢀ
5
7.5%), containing less than 10 ppm of F ions.
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.7. Ionic conductivity measurements
[
[
The lithium perfluoro sulfonylimides and CF SO Li
3
3
[
[
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(
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[
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[
(
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(
(
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received. All operations were performed in a dryroom
[
[
[
[
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(
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(
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4
. Conclusion
A limited number of perfluoroalkanesulfonylimide
lithium salts, with symmetric, asymmetric, cyclic structures,
3720;
S. Singh, D.D. Desmarteau, Inorg. Chem. 29 (1990) 2982.