Perfluoroethanesulfonyl fluoride: Preparation from sultone

Article abstract of DOI:10.1134/S1070427207090224

A procedure was developed for preparing perfluoroethanesulfonyl fluoride by synthesis of hexafluoropropane-2-β-sultone from sulfuric anhydride and perfluoropropene, followed by hydrolysis of the sultone to α- tetrafluoroethanesulfonyl fluoride and fluorination of the latter with elemental fluorine.

Full text of DOI:10.1134/S1070427207090224

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 9, pp. 1562 1565. Pleiades Publishing, Ltd., 2007.
Original Russian Text S.M. Nurgalieva, T.A. Bispen, A.N. Il’in, D.D. Moldavskii, E.A. Rozhkova, 2007, published in Zhurnal Prikladnoi Khimii, 2007,
Vol. 80, No. 9, pp. 1529 1532.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Perfluoroethanesulfonyl Fluoride: Preparation from Sultone
S. M. Nurgalieva, T. A. Bispen, A. N. Il’in, D. D. Moldavskii, and E. A. Rozhkova
Prikladnaya Khimiya Russian Scientific Center, St. Petersburg, Russia
Galogen Open Joint-Stock Company, Perm, Russia
Received November 21, 2006; in final form, March 2007
Abstract A procedure was developed for preparing perfluoroethanesulfonyl fluoride by synthesis of hexaflu-
oropropane-2- -sultone from sulfuric anhydride and perfluoropropene, followed by hydrolysis of the sultone
to -tetrafluoroethanesulfonyl fluoride and fluorination of the latter with elemental fluorine.
DOI: 10.1134/S1070427207090224
Perfluoroalkanesulfonyl halides (PFASHs), includ-
ing sulfonyl fluorides, are starting compounds for
preparing perfluoroalkanesulfonic acids and their salts.
They are also used as sources of perfluoroalkanesulfo-
nyl groups in the synthesis of surfactants, dyes, anti-
oxidants, UV stabilizers, and materials for chemical
power cells [1 6]. Among PFASHs, of particular
interest are lower homologs with 1 3 carbon atoms.
However, application of PFASHs is limited by their
high cost, caused by the lack of an efficient synthesis
process. There are a number of procedures for prepar-
ing PFASHs, each having certain features and short-
comings. The best studied process is electrochemical
fluorination (ECF), i.e., electrolysis of solutions of
alkanesulfonyl halides in hydrogen fluoride [7, 8]:
diate conversion of ethanesulfonyl chloride into eth-
anesulfonyl fluoride by the reaction with HF in the
presence of a chromium magnesium catalyst [9] al-
lowed the PFESF yield to be increased to 70%, but its
isolation appeared to be difficult. In electrolysis of
higher alkanesulfonyl chlorides, the PFASH yields are
as low as 25 30%. Another route to PFASHs is the
reaction of perfluoroalkyl iodides or bromides with
sodium dithionite, followed by chlorination of the
resulting sodium perfluoroalkanesulfinate [10 12]:
RfHal + Na2S2O4
RfSO2Na + Cl2
RfSO2Na,
RfSO2Cl + NaCl,
where R is perfluoroalkyl, and Hal is Br or I.
f
The reaction was performed in a water acetonitrile
mixture. The yield of perfluoroalkylsulfonyl chlorides
reached 80%. We reproduced this procedure with per-
fluoroethyl iodide and obtained perfluoroethanesul-
fonyl chloride in 76% yield. Despite reasonable yield
of PFASH, this procedure has significant drawbacks:
HF, e
RSO2Hal
RfSO2F,
where Hal is F or Cl, R is alkyl, and R is perfluoro-
f
alkyl.
In Russia, the method is implemented at the An-
garsk Electrochemical Plant for the production of tri-
fluoromethanesulfonyl fluoride from methanesulfonyl
chloride; the yield is 80 85%. Methanesulfonyl chlo-
ride, like other lower alkanesulfonyl chlorides, is not
produced in Russia. Commercial electrochemical syn-
thesis of perfluoroethanesulfonyl fluoride (PFESF)
from ethanesulfonyl fluoride appeared to be unfeasible
because of the low yield, which did not exceed 45%.
The electrolysis is accompanied by formation of a
large amount of impurities with boiling points close to
that of PFESF; furthermore, a part of PFESF is mixed
with hydrogen fluoride, and its significant fraction (up
to 30%) remains dissolved in the electrolyte. Interme-
(1) use of expensive perfluoroalkyl iodides and
bromides, which are in short supply, as starting com-
pounds;
(2) use of sodium dithionite, which is not pro-
duced in Russia, and instability of this salt in storage,
which gives rise to additional problems;
(3) strong corrosion of apparatus and pipelines,
caused by chlorination of sodium perfluoroalkanesul-
finates in aqueous solutions;
(4) overall complexity of the process: It involves
steps of extraction, filtration, and regeneration of
solvents. Implementation of the process requires a
1562

PERFLUOROETHANESULFONYL FLUORIDE: PREPARATION FROM SULTONE
1563
large set of equipment, and many operations are per-
formed manually;
Experiments on optimization of the sultone syn-
thesis showed that sulfuric anhydride should contain
as low amounts of the monohydrate as possible: At
0.2% content of the monohydrate, the yield of the
sultone is 98%. An increase in the monohydrate con-
tent leads to an increase in the content of impurities:
(4) large amount of wastes: 1.5 t of solid and 2.5 t
of liquid wastes are formed per ton of the finished
product. The wastes mainly consist of toxic fluori-
nated compounds, and their regeneration and detoxica-
tion require additional chemicals, equipment, time,
and energy.
monohydroperfluorocarboxylic acids R CFH COOH,
f
perfluoroalkenyl fluorosulfonates R CF=CF OSO F,
f
2
sulfuryl fluoride, and carbonyl fluoride. At 2% content
of the monohydrate in sulfuric anhydride, the content
of impurities reaches 15%.
Another procedure suggested for preparing PFASHs
is based on the reaction of perfluoroolefins with sul-
furyl fluoride or sulfuryl fluorochloride in the pres-
ence of cesium fluoride [13, 14]:
The optimal temperature of sultone synthesis is
105 C. Above this temperature, the sultone starts to
decompose, and its yield decreases. At temperatures
below 100 C, the reaction becomes slower. At 50 C,
the yield is 53%.
CsF
RfCF=CF2 + SO2Hal2
HalCF(Rf) CF2SO2Hal,
where Hal is Cl or F.
The monomer should be taken in 5 7% excess rela-
tive to the stoichiometry, to ensure complete binding
of sulfuric anhydride. Free sulfuric anhydride pro-
motes the subsequent acid hydrolysis of the sultone,
with polyfluoroalkanoic and sulfonic acids becoming
the major products.
We checked this procedure and found that CsF,
olefins, and solvents should be thoroughly dried.
The water content should not exceed 0.001 wt %.
However, even with such precautions the reaction
mainly yielded a mixture of olefin oligomers and
polymeric sulfonyl halides Hal(R CF CF ) SO Hal,
f
2 n
2
Hydrolysis of hexafluoropropane-2- -sultone in-
volves two successive reactions: formation of (fluoro-
sulfonyl)perfluoropropionic acid and its spontaneous
decarboxylation with the formation of -hydrotetra-
fluoroethanesulfonyl fluoride (TFESF):
(R CF CF ) , n = 1 50. The yield of monomeric
f
2 n
PFASHs did not exceed 20%. It should be noted that
polymeric sulfonyl halides are used as surfactants,
lubricants, and components of impregnating formula-
tions, ion-exchange membranes, and film materials.
CF (SO F) COOH HF
+
CF H O
CF3
CF3 CF
O2 S
,
+
The drawbacks of the above-considered procedures
for preparing PFASHs make it necessary to search for
a simple procedure for their synthesis involving chem-
icals commercially produced in Russia and to develop
an efficient technology based on this procedure.
Among possible routes to PFASHs, we chose conver-
sion of sultones. In accordance with [15 17], polyflu-
orinated alkanesulfonyl fluorides are formed by hy-
drolysis of perfluorinated sultones which, in turn, are
prepared by the reaction of sulfuric anhydride with
perfluoroolefins. According to data reported by Knu-
nyants [15, 16] and results of our experiments, the
yield of hexafluoropropane-2- -sultone is as high as
96 98%. The impurities (0.5 2%) are the linear iso-
mer CF CF(SO F) COF, six- and eight-membered
2
2
2
O
CF3 CF(SO2F) COOH
CF3CFH SO2F + CO2.
The formation of hydrogen fluoride in the course of
hydrolysis leads to the formation of tetrafluoropropi-
onic acid:
HF
CF3 CF(SO2F) COOH + H2O
CF3CFH COOH
+ H2SO4 + HF.
The optimal hydrolysis temperature is 0 2 C. At
this temperature, the yield of TFESF is 90%. TFESF
contained up to 1% water. The content of other im-
purities did not exceed 0.03 wt %. After drying, the
product was used for fluorination without additional
purification.
3
2
sultones, and perfluoroallyl sulfate CF =CF CF O
2
2
SO F. Sultones are hydrolyzed to -hydroperfluoro-
2
alkanesulfonyl fluorides (HPFSFs), which, as we ex-
pected, can be fluorinated to perfluoroalkanesulfonyl
florides:
Fluorination of polyfluorinated paraffins, ethers,
tertiary amines, and their heterocyclic analogs by
various procedures, including that with elemental
fluorine, is a fairly well studied process, and high
yields of the target products can be attained [18].
Fluorination of compounds containing an S C bond is
R CF CF2
R CF=CF + SO3
f
f
2
O2S
O
H O
2
F
2
RfCFHSO2F
RfCF2SO2F.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 9 2007

1564
NURGALIEVA et al.
much less studied. The energy of S C bonds (about
Apparently, the amount of HF correlates with the
1
270 kJ mol ) is appreciably lower than that of C C
amount of supplied F . According to the theory of
2
1
1
1
(480 kJ mol ), C O (360 kJ mol ), and even C N
one-electron transfer, the optimal HF : F ratio should
2
(305 kJ mol ) bonds, which gives rise to certain
be 1 : 1, i.e., the molar ratio of the components should
correspond to the stoichiometric ratio. Indeed, as the
HF concentration is decreased to 0.71 mol per mole
problems in fluorination, because the cleavage of the
C S bond and formation of C F and S F bonds (ener-
1
gy 480 and 290 kJ mol , respectively) is thermody-
of F , the selectivity decreases by 15 20%, and when
2
namically favorable. Kornilov et al. [19] studied fluo-
rination of mercaptans with cobalt trifluoride. The
it is increased to 1.5 mol per mole of F , the conver-
2
sion of the starting reactants decreases, apparently due
to the inhibiting effect of HF and a decrease in the
fluorination rate.
major products were SF and polyfluorinated paraf-
6
fins. In our experiments on fluorination of TFESF
with cobalt trifluoride, the yield of PFESF was 19%;
the other products were SF , SO F , CF , and C F .
Another major factor affecting the reaction is tem-
perature. We found that 120 130 C is the optimal
temperature of PFESF synthesis. Based on the results
obtained, a pilot plant for PFESF synthesis was con-
structed at the Galogen Open Joint-Stock Company.
The installation consists of units for distillation of
sulfuric anhydride, synthesis of sultone, hydrolysis of
sultone, fluorination of TFESF, neutralization of crude
PFESF with alkalis, its drying with zeolites, and frac-
tional distillation of PFESF to obtain the 99.9% pure
products. The results of studies on fluorination of
polyfluorinated alkanesulfonyl fluorides were pro-
tected with RF patents [22, 23].
6
2 2
4
2 6
Fluorination of TFESF with elemental fluorine
appeared to be more successful. Under static condi-
1
tions, with slow supply of fluorine (0.5 0.7 ml s ) at
0 20 C into a reactor containing TFESF and packed
with copper chips, the yield of PFESF was 92%.
In dynamic experiments with a tubular reactor (nickel
tube packed with copper chips), we sometimes ob-
served plops when the rates of feeding the reactants
changed or even without any apparent causes. In this
case, SO F , SF , C F , CF , and carbon black be-
2 2
6
2 6
4
came the major products. This result is attributable to
inefficient removal of excess energy released in the
course of fluorination. To remove this energy, it is
recommended to use solvating solvents in combina-
tion with a heat-removing packing [20]. Among the
examined compounds, the best results were obtained
with HF and somewhat worse results, with TFESF
and N . At the molar ratio F : TFESF : HF = 1 : 1 : 1,
EXPERIMENTAL
The reaction products were analyzed by gas chro-
matography [LKhM-80 chromatograph, thermal con-
ductivity detector, 2-m column packed with Silo-
khrom + 20% 1,1,1-tris( -cyanoethyl)acetophenone]
and gas chromatography mass spectrometry (Aligent-
5973N, DB-5ms capillary column 60 m long).
2
2
97% conversion and 95% selectivity were attained.
If we consider the reactants as a donor acceptor sys-
tem [21] in which an electron is transferred from the
donor (TFESF) to the acceptor (F )
Hexafluoropropane-2- -sultone was prepared as
described in [15]. Optimal conditions: hexafluoro-
2
CF3 CFHSO2 F
F
+
CF3 CSO2F
2
propene : SO ratio (1.05 1.08) : 1, 105 107 C, 12
3
14 h. -Tetrafluoroethanesulfonyl fluoride was pre-
pared by the procedure described in [15] with some
modifications. Namely, the sultone was fed into water,
which allowed us to increase the TFESF yield to 92%.
+
...
,
H
F
F
CF3CFSO2F + F + HF
with the formation of a radical pair, a diluent is re-
quired for stabilization of this pair and absorption of
excess energy. This leads to temporary stabilization of
the transition state, so that the radicals have time to
recombine before escape into the reaction volume:
Fluorination of tetrafluoroethanesulfonyl fluo-
ride with cobalt trifluoride. Into a nickel tube
800 mm long and 38 mm in diameter, packed with
controllable heating, TFESF was fed from a batcher
1
at a rate of 1 3 ml min . The best results were ob-
tained at 260 290 C. According to the gas-chromato-
graphic analysis, the reaction mixture (after neutraliza-
HF
CF
F
3CFSO2 F
CF3CFHSO2F + 2... ,
+
tion with aqueous NaOH) contained 23% SO F , 15%
2 2
... ,
H
...
HF
F
F
SF , 35% C F , 8% CF , and 19% C F SO F.
6
2 6
4
2 5
2
...
CF CFSO F
F
+ HF,
HF
+
3
2
Fluorination with elemental fluorine under stat-
ic conditions. A 2.0-l 12Cr18Ni10Ti stainless steel
CF3CFSO2F + F...HF
HF + CF3CF2SO2F.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 9 2007

PERFLUOROETHANESULFONYL FLUORIDE: PREPARATION FROM SULTONE
1565
vessel packed with copper chips and cooled to 0 C
was charged with 18.5 g of TFESF, and fluorine was
fed at a rate of 0.5 0.7 ml s for 1 h (the procedure
ftororganicheskim soedineniyam (IV All-Union Conf.
on Fluorinated Organic Compounds), Tashkent, Sep-
tember 9 12, 1982, Moscow, 1982, p. 172.
1
was performed in a steel box). After 24 h, the reaction
mixture was condensed in a 12Cr18Ni10Ti stainless
steel trap cooled with liquid nitrogen. After warming,
it was neutralized with aqueous NaOH, dried over
CaA zeolite, and collected in a trap cooled to 30 C.
The product (yield 20 g) contained 95% PFESF and
5% impurities (CF SO F, SO F , C F , CF , SF ).
3. Yagupol’skii, Yu.L., Haas, A., and Savina, T.I.,
Zh. Org. Khim., 1999, vol. 35, no. 12, pp. 1802 1804.
4. Kondratenko, N.V., Kolomeitsev, A.A., and Yagu-
pol’skii, L.M., Abstracts of Papers, IV Vsesoyuznaya
konferentsiya po ftororganicheskim soedineniyam (IV
All-Union Conf. on Fluorinated Organic Compounds),
Tashkent, September 9 12, 1982, Moscow, 1982, p. 7.
5. FRG Patent Appl. 10126929 A1.
6. Ukrainian Patent 27067.
7. Gramstad, T. and Haszeldine, R.N., J. Chem. Soc.,
1956, no. 1, pp. 173 180.
8. Gramstad, T. and Haszeldine, R.N., J. Chem. Soc.,
3
2
2 2
2 6
4
6
Fluorination under dynamic conditions. A solu-
tion containing 92 g of TFESF and 10 g of HF was
1
fed at a rate of 0.8 1.0 g min from a batcher to a
vaporizer (nickel tube 38 mm in diameter and 500 mm
long, heated to 80 100 C). Fluorine was also fed to
1
1957, no. 11, pp. 2640 2643.
this tube at a rate of 120 130 ml min . Then the
mixture of the components came into a reactor (nickel
tube 38 mm in diameter and 900 mm long, packed
with copper chips and heated to 130 140 C). The
reaction products were collected in a 12Cr18Ni10Ti
stainless steel trap cooled to 120 C. After the reac-
tion completion, the condensate was worked up as
described above. The product (yield 90 g) contained
96.5% PFESF and 3.5% impurities (CF SO F, SO F ,
9. Matalin, V.A., Shkul’tetskaya, L.V., and Moldav-
skii, D.D., Abstracts of Papers, 3-ya mezhdunarod-
naya konferentsiya Khimiya, tekhnologiya i primene-
nie ftorsoderzhashchikh soedinenii v promyshlennosti
(3rd Int. Conf. Chemistry, Technology, and Industrial
Applications of Fluorinated Compounds ), St. Peters-
burg, June 3 6, 2001, pp. 21 22.
10. Furin, G.G., Usp. Khim., 2000, vol. 69, no. 6, pp. 538
3
2
2 2
570.
C F , CF , SF ).
2 6
4
6
11. Wei-Yuan Huang and Yian-Long Chen, J. Fluorine
Chem., 1987, vol. 35, no. 1, pp. 19 21.
CONCLUSIONS
12. Jin-Tao Liu, Guo-Dong Sui, and Wei-Yuan Huang,
J. Fluorine Chem., 1999, vol. 93, no. 1, pp. 49 51.
(1) A procedure was developed for preparing per-
fluoroethanesulfonyl fluoride by fluorination of tetra-
fluoroethanesulfonyl fluoride.
13. US Patent 2877267.
14. US Patent 3542864.
15. Knunyants, I.L. and Yakobson, G.G., Sintezy ftororga-
nicheskikh soedinenii (Syntheses of Fluorinated Or-
ganic Compounds), Moscow: Khimiya, 1973.
(2) The steps of perfluoroethanesulfonyl fluoride
synthesis were optimized, and its pilot production was
set up at the Galogen Open Joint-Stock Company.
16. Knuniants, I.L. and Sokolski, G.A., Angew. Chem.,
Int. Ed. Engl., 1972, vol. 11, no. 7, pp. 583 595.
ACKNOWLEDGMENTS
17. Dmitriev, M.A., Sokol’skii, G.A., and Knunyants, I.L.,
Izv. Akad. Nauk SSSR, Ser. Khim., 1960, no. 6,
pp. 1035 1038.
The authors are sincerely grateful to N.V. Baranov
and G.G. Furin for the assistance in the work.
18. Bispen, T.A., Moldavskii, D.D., and Furin, G.G.,
Zh. Prikl. Khim., 1998, vol. 71, no. 6, pp. 977 981.
REFERENCES
19. Kornilov, V.V., Kostyaev, R.A., and Maksimov, B.N.,
Zh. Prikl. Khim., 1995, vol. 68, no. 9, pp. 1409 1418.
1. Nikonorov, Yu.I. and Karelin, A.I., Abstracts of
Papers, IV Vsesoyuznaya konferentsiya po ftororgani-
cheskim soedineniyam (IV All-Union Conf. on Fluori-
nated Organic Compounds), Tashkent, September 9
12, 1982, Moscow, 1982, p. 12.
20. Zakharov, V.Yu., Denisov, A.K., and Novikova, M.D.,
Zh. Org. Khim., 1998, vol. 30, no. 12, pp. 1844 1846.
21. Mukhametshin, F.Kh., Zh. Prikl. Khim., 1997, vol. 70,
no. 1, pp. 127 134.
22. RF Patent 2237659.
23. RF Patent 2280030.
2. Eleev, A.F., Fetisov, V.I., and Sokol’skii, G.A., Abs-
tracts of Papers, IV Vsesoyuznaya konferentsiya po
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 9 2007