Reaction of fluorosulfonyloxypentafluoroacetone in the presence of alkali metal fluorides

Article abstract of DOI:10.1007/s11172-009-0174-4

2-Fluorosulfonyloxytetrafluoropropionyl fluoride (3) is the product of isomerization of fluorosulfonyloxypentafluoroacetone (1). In the presence of CsF at low temperatures compound 3 forms 2-fluorosulfonyloxyperfluoropropoxy anion, and at -25 °C CsF catalyzes the decomposition of compounds 1 and 3 with the formation of trifluoropyruvoyl fluoride isolated as cyclodimer. ; 2009 Springer Science+Business Media, Inc.

Full text of DOI:10.1007/s11172-009-0174-4

Russian Chemical Bulletin, International Edition, Vol. 58, No. 6, pp. 1318—1320, June, 2009
1318
Reaction of fluorosulfonyloxypentafluoroacetone
in the presence of alkali metal fluorides
S. R. Sterlin and E. A. Avetisyan
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 6549. Eꢀmail: lsg@ineos.ac.ru
2ꢀFluorosulfonyloxytetrafluoropropionyl fluoride (3) is the product of isomerization of
fluorosulfonyloxypentafluoroacetone (1). In the presence of CsF at low temperatures comꢀ
pound 3 forms 2ꢀfluorosulfonyloxyperfluoropropoxy anion, and at ∼25 °С CsF catalyzes the
decomposition of compounds 1 and 3 with the formation of trifluoropyruvoyl fluoride isolated
as cyclodimer.
Key words: fluorosulfonyloxypentafluoroacetone, 2ꢀfluorosulfonyloxytetrafluoropropionyl
fluoride, trifluoropyruvoyl fluoride, hexafluoropropylene oxide, fluorosulfonic acid.
It has been shown previously1 that hexafluoropropylene
oxide (HFPO) reacts with sulfuric anhydride to form a
mixture of fluorosulfonyloxypentafluoroacetone (1) and
perfluoropropylene sulfate (2) with predomination of comꢀ
pound 1. It was found that ketone 1 decomposed under
the action of CsF in MeCN to give trifluoropyruvoyl fluoꢀ
ride,* representing a synthone with a high synthetic
potential.2,3 The compound was characterized as an
adduct of trifluoropyruvic acid anilide with aniline and
isolated in low yield.
to an equilibrium mixture of isomers 3 and 2. The hyꢀ
drolysis of the obtained mixture affords (Scheme 1)
2ꢀfluorosulfonyloxytetrafluoropropionic acid (4) (under
these conditions, only acyl fluoride 3 is hydrolyzed).
Scheme 1
According to Ref. 4, ketone 1 decomposes in the presꢀ
ence of both CsF and less nucleophilic NaF to form oliꢀ
gomerization products of undetermined structure. At the
same time, under the action of NaI in an aprotic medium
compound 1 isomerizes to 2ꢀfluorosulfonyloxytetrafluoroꢀ
propionyl fluoride (3) in 68% yield.
One of the fundamental tasks of the chemistry of
fluoroaliphatic compounds is the development of new
methods for their functionalization. Since the FSO3CF
fragment is a latent form of the carbonyl group, we
studied a possibility of generation and use in synthesis
of 2ꢀfluorosulfonyloxyhexafluoropropoxy anion, whose
formation could be expected upon the reaction of acyl
fluoride 3 with an alkaline metal fluoride.
i. [KHF ]/PhNO ; ii. [H O]/pentane.
2
2
2
We found that using such a lowly active source of
fluoride ion as KHF2 in PhNO2 results in the quantitative
isomerization of ketone 1, which was obtained by a modiꢀ
fied procedure4 (see Experimental), to a mixture of acyl
fluoride 3 and sulfate 2 in the ratio 3 : 2 = 7 : 1. This ratio
remains unchanged in time and, most likely, corresponds
As it turned out, in the presence of CsF in diglyme
a mixture of compounds 3 and 2 interacts with HFPO at
–30—–35 °С (Scheme 2**) to form a mixture of fluoroꢀ
sulfonyloxyacyl fluoride (6), cyclic dimer of trifluoroꢀ
pyruvoyl fluoride (7), and cycloadduct of trifluoropyruvoyl
** Both acyl fluoride 3 and sulfate 2, which undergoes opening
by CsF in diglyme to form 3, are involved in the formation of
anion 5.
* Probably, a cyclodimer of trifluoropyruvoyl fluoride was
obtained, which, however, was not isolated and characterized.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1281—1283, June, 2009.
1066ꢀ5285/09/5806ꢀ1318 © 2009 Springer Science+Business Media, Inc.

Reactions of FSO3CF2C(O)CF3/[F–]
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
1319
was added to the reaction mixture, the autoclave was shaken for
8—10 min more, and the liquid part of the reaction mixture was
decanted from the precipitate. The fraction with b.p. 50—100 °С
was isolated by distillation, the distillate was washed with
12—15 mL of concentrated H2SO4, and the organic layer was
separated and distilled above concentrated H2SO4. Ketone 1
was obtained in a yield of 84.5 g (95%), b.p. 56—58 °С (b.p. and
the 19F NMR spectrum are identical to the literature data1,4).
The HSO3F and Cr2O3 remained after the treatment of the reacꢀ
tion mixture can multiply be used for the synthesis of ketone 1.
2ꢀFluorosulfonyloxytetrafluoropropionyl fluoride (3) and
perfluoropropylene sulfate (2). Ketone 1 (13.8 g, 56 mmol) was
added dropwise to a suspension of KHF2 (1 g) in anhydrous
PhNO2 (25 mL). After the end of the exothermic reaction, the
mixture was stirred for 15 min at 45 °С and heated to 50—60 °С
(100 Torr), and volatile products were distilled off and collected
in a cooled receiver (–78 °С). The distillation of the distillate
gave 13.3 g (95%) of a mixture of acyl fluoride 3 and perfluoroꢀ
propylene sulfate 2 (3 : 2 = 88 : 12) (according to the 19F NMR
data) (cf. Refs 1 and 4).
fluoride and HFPO (8) (6 : 7 : 8 = 7 : 2 : 1) (oxalactones
7 and 8 and the methods of their synthesis from trifluoroꢀ
pyruvoyl fluoride were described5). The yield of comꢀ
pound 6 was 33%. Although lactones 7 and 8 are formed
in rather small amounts, their formation indicates that
the decomposition of compounds 2 and 3 to trifluoroꢀ
pyruvoyl fluoride cannot completely be prevented even at
such low temperatures.
Scheme 2
2ꢀFluorosulfonyloxytetrafluoropropionic acid (4). Water
(17 mL, 95 mmol) was gradually added with stirring to a solution
of the obtained mixture of 3 and 2 (15 g, 60 mmol) in pentane
(20 mL). The reaction mixture was washed with dilute aqueous
solutions of CaCl2, the aqueous layer was extracted with ether,
the extract was evaporated, and the residue was distilled above
concentrated H2SO4. 2ꢀFluorosulfonyloxytetrafluoropropionic
acid semihydrate 4, b.p. 55—59 °С (10 Torr), was obtained in a
yield of 12.8 g (4% based on compound 3 taken in the reaction).
Found (%): С, 13.93; Н, 0.77; F, 37.45. C3H2F5O2,5S. Calcuꢀ
lated (%): С, 14.23; Н, 0.79; F, 37.55. 19F NMR: –127.0 (FSO3);
7.0 (CF3); 54.5 (CF).
CsF/Diglyme
Reaction of a mixture of compounds 3 and 2 with hexafluoroꢀ
propylene oxide in the presence of CsF. A mixture of compounds
3 : 2 (88 : 12) (18.5 g, 75 mmol) was added at –30 to –32 °С to a
suspension of CsF (1.13 g) in anhydrous tetraglyme (6 mL) and
diglyme (3 mL). The mixture was stirred for 30 min, and then
HFPO (13.3 g, 80 mmol) was gradually introduced within 2 h.
The mixture was stirred for 30 min, cooled to –40 °С, and
poured into iceꢀcold water. The organic layer was separated
(according to the 19F NMR data, the layer contains a mixture
of compounds 6 : 7 : 8 = 7 : 2 : 1), rapidly shaken with a
small amount of P2O5, and decanted into a distillation device.
2ꢀ(2ꢀFluorosulfonyloxyhexafluoropropoxy)tetrafluoropropionyl
fluoride (6) was isolated by rectification in a yield of 8 g (33%),
b.p. 48—50 °С (63 Torr). Found (%): С, 18.08; F, 56.11.
C6F12O5S. Calculated (%): С, 17.48; F, 55.34. 19F NMR, δ:
–126.5 (1 F(7)); –102.0 (1 F(6)); AB quartet with centers at
0.5 and 8.5 (1 F(3) + 1 F(4)), Jab = 254 Hz; 3.2 (3 F(1)); 6.5
(3 F(8)); 54.7 (1 F(5)); 65.2 (1 F(2)).
COF
CF3
When heating a mixture of compounds 2 and 3 or,
which is more convenient, their precursor ketone 1,
HFPO, CsF, and diglyme to ∼25 °С, the single reaction
product is oxalactone 8 formed in a yield higher than
80%. Similarly, oxalactone 7 is formed in high yield from
1 under the action of CsF.
Thus, although ketone 1 and its isomers 2 and 3 easily
decompose under the action of F–, we succeeded to perꢀ
form the sequence of transformations of 1, generating
anion 5 and to synthesize a compound containing the
2ꢀfluorosulfonyloxyfluoropropoxy group.
Experimental
19F NMR spectra were recorded on a Bruker 200SY instruꢀ
ment (188.3 MHz) in ССl4 solutions using CF3COOH as an
external standard.
6
Perfluoroꢀ5ꢀfluorocarbonylꢀ3,5ꢀdimethylꢀ1,3ꢀdioxolanꢀ2ꢀone
(7). Ketone 1 (25.7 g, 0.104 mol) was added at –35 °С to a
suspension of CsF (0.3 g) in diglyme (1.5 mL). The reaction
mixture was slowly warmed to –15—–10 °С, stirred for 30 min,
Fluorosulfonyloxypentafluoroacetone (1). A mixture of HSO3F
(100 mL), Сr2O3 (10 g), and HFPO (60 g, 0.36 mol) was
shaken in a 200ꢀmL steel autoclave for 8 h at ∼25 °С, then the
autoclave was cooled to ∼0 °С, freshly distilled SO3 (29 g, 0.36 mol)

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Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
Sterlin and Avetisyan
then stirred for 3 h at ∼20 °С, and distilled in vacuo, collecting
the fraction that boils out below 60 °С (40 Torr) to a cooled
receiver (–78 °С). The distillation of the distillate gave oxaꢀ
lactone 7 in a yield of 12.6 g (84%), b.p. 71—73 °С (b.p. and the
19F NMR spectrum are identical to those described in the
literature5).
Perfluoroꢀ3,6ꢀdimethylꢀ1,4ꢀdioxanꢀ2ꢀone (8). Anhydrous
diglyme (3 mL) and CsF (0.8 g) were placed in a steel autoclave
(100 mL) and cooled under Ar atmosphere to –30 °С, and
ketone 1 (37.9 g, 154 mmol) was added. Then HFPO (25.6 g,
154 mmol) was condensed into the evacuated autoclave cooled
to –196 °С, and the autoclave was shaken for 8 h at ∼25 °С and
cooled to 0 °С. Gaseous SO2F2 was bleed, and the reaction
mixture was transferred to a distillation device. The products
volatile below 45—50 °С (35—40 Torr) were distilled off to a
receiver (–78 °С). Dissolved SO2F2 was distilled off from the
distillate on a column equipped with the complete condensation
packing, and the distillation of the residue gave oxalactone 8
(39.2 g, 84%), b.p. 70—72 °С (b.p. and the 19F NMR spectrum
are identical to those described in the literature5).
References
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3. N. Sewald, K. Burger, V. P. Kukhar, V. A. Soloshonok, in
Fluorine Containing Amino Acids. Synthesis and Properties,
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This work was financially supported by the DuPont
company.
Received January 15, 2009;
in revised form March 23, 2009