Synthesis of FSO2CF2CF2OCF2I from difluoro(fluorosulfonyl)acetyl fluoride and its relevant salt FSO 2CF2CF2O-K+ in the presence of I2 or CF2

Article abstract of DOI:10.1016/j.jfluchem.2013.01.001

The synthesis of FSO₂CF₂CF₂OCF ₂I via two routes was studied: the direct reaction between ICF ₂I and FSO₂CF₂CF₂O^-K ⁺ and the reaction between FSO

Full text of DOI:10.1016/j.jfluchem.2013.01.001

Accepted Manuscript
Title: Synthesis of FSO2CF2CF2OCF2I from
difluoro(fluorosulfonyl)acetyl fluoride and its relevant salt
FSO2CF2CF2O−K+ in the presence of I2 or CF2I2
Authors: Jolanta Ignatowska, Oleg Shyshkov, Klaus Hintzer,
¨
Gerd-Volker Roschenthaler
PII:
S0022-1139(13)00005-5
DOI:
Reference:
doi:10.1016/j.jfluchem.2013.01.001
FLUOR 8002
To appear in:
FLUOR
Received date:
Revised date:
Accepted date:
26-10-2012
31-12-2012
2-1-2013
¨
Please cite this article as: J. Ignatowska, O. Shyshkov, K. Hintzer, G.-V. Roschenthaler,
Synthesis of FSO2CF2CF2OCF2I from difluoro(fluorosulfonyl)acetyl fluoride and its
relevant salt FSO2CF2CF2O−K+ in the presence of I2 or CF2I2, Journal of Fluorine
Chemistry (2010), doi:10.1016/j.jfluchem.2013.01.001
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*Graphical Abstract - Pictogram
Graphical Abstract
Page 1 of 12

*Highlights (for review)
Highlights
The reaction of diiododifluoromethane with fluorinated alkoxide.
The reaction of difluorocarbene with fluorinated alkoxide.
The synthesis of fluorinated telomers.
Page 2 of 12

*Manuscript
1
Synthesis of FSO2CF2CF2OCF2I from
difluoro(fluorosulfonyl)acetyl fluoride and its relevant salt
FSO2CF2CF2O−K+ in the presence of I2 or CF2I2.
Jolanta Ignatowska,a* Oleg Shyshkov,b Klaus Hintzer,b
Gerd-Volker Röschenthalera
aSchool of Engineering and Science, Jacobs University Bremen GmbH, Campus Ring 1, D-
28759 Bremen, Germany
bDyneon GmbH, D-84504 Burgkirchen Werk Gendorf, Germany
Abstract
The synthesis of FSO2CF2CF2OCF2I via two routes was studied: the direct reaction between ICF2I and
FSO2CF2CF2O-K+ and the reaction between FSO2CF2CF2O-K+ and difluorocarbene generated from
difluoro(fluorosulfonyl)acetyl fluoride in the presence of iodine.
Keywords: DFSAF, difluorodiiodomethane, perfluoroalkyl sulfonyl fluoride
1. Introduction
Difluoro(fluorosulfonyl)acetyl fluoride (FSO2CF2COF (1), DFSAF) under treatment
of KF gives fluorosulfonyltetrafluoro potassium ethanolate FSO2CF2CF2O−K+ (5) which
reacts further with tetrafluoroethylene and iodine to give 2-(2-iodo-1,1,2,2-tetrafluoroethoxy)-
1,1,2,2-tetrafluoroethanesulfonyl fluoride FSO2CF2CF2OCF2CF2I (2). This compound can be
converted into higher telomers possessing iodo and fluorosulfonyl as terminal groups by
radical addition of 2 to TFE or C3F6 [1].
DFSAF can serve also as a source of difluorocarbene. In the presence of catalytic
amounts of SiO2, (1) reacts with potassium iodide and iodine to give difluorodiiodomethane
(3) in 60-70% yield [2]. The modification of that procedure by us resulted in a mixture of
 Corresponding author. Tel.: +49(0)4212003138, Fax: +49(0)421 2003229.
E-mail address: j.ignatowska@jacobs-university.de (J.Ignatowska), g.roeschenthaler@jacobs-university.de
(G.V.Röschenthaler).
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2
ICF2I (3) and FSO2CF2CF2OCF2I (4) in a ratio 2.6:1. The formation of 4 in a reaction
conditions can be explained by reaction of FSO2CF2CF2O−K+ (5) with :CF2 generated from 1
followed by the reaction with iodine. 2-(Difluoro-iodo-methoxy)-1,1,2,2-tetrafluoro-ethane
sulfonyl fluoride (4) is an interesting monomer which formation in low yields was previously
revealed during the reaction of tetrafluoroethane-β-sultone with TFE and ICl in the presence
of KF [3].
Considering other possibilities of FSO2CF2CF2OCF2I (4) formation we decided also to
study the direct reaction of difluorodiiodomethane (3) with FSO2CF2CF2O−K+ (5). Similar
reactions of ICF2I with ethoxide, phenoxide and thiophenoxide ions were reported. However
only with phenoxide and thiophenoxide ions corresponding aryldifluoroiodoethers and
thioeters were obtained in low yields [4]. In the case of ethoxide ion as main products
carbonate (EtOCOOEt) and fluoride ion were obtained. Such reactions occur via anionic
chain mechanism (with evolution of difluorocarbene) or via single electron transfer [4].
Here we report the results of our studies on the reaction between FSO2CF2CF2O−K+
(5) and :CF2 generated from 1 in the presence of iodine and on the direct reaction of
difluorodiiodomethane (3) with FSO2CF2CF2O−K+ (5).
2. Results and discussion
It was reported by Xiao that formation of ICF2I requires the following conditions: ratio
KI:I2 equal 1:1, the presence of SiO2 used in amounts of 5-10 mol% and the concentration of
−
I3 in a range 1.3-1.5 mol/l. The authors claimed also that formation of ICF2I is inhibited in
the absence of KI or if less than 1 eq. of KI was used (Scheme 1).
Scheme 1
Reproducing of that procedure we discovered that decreasing temperature to 40-50⁰C and
adding DFSAF (1) relatively fast under reduced pressure led to a mixture of ICF2I (3) and
FSO2CF2CF2OCF2I (4) in a 2.6:1 ratio. We suppose that 4 was formed via the following
pathway: first in a reaction between fluoride ion and DFSAF, the FSO2CF2CF2O−K+ (5) is
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3
generated, which further reacts with :CF2 and then with iodine to give compound 4 (Scheme
2).
Scheme 2
Initial attempts to separate the mixture of 3 and 4 by distillation were not successful implying
similar physical properties and structures of both compounds. Compound
FSO2CF2CF2OCF2CF2I (2), with a boiling point 127°C [1] let us presume that 4 ought to have
a boiling point between 127 and 95°C, whereas CF2I2 boils at 101°C. ICF2I can be isolated
with minor losses by washing the mixture of both compounds with 5% solution of NaOH in
19
methanol at 0-10°C. The structure of compound 4 was confirmed not only by F NMR, but
also by GC-MS. No molecular ion was found, but peaks corresponding to FSO2CF2CF2OCF2,
13
ICF2O, ICF2, FSO2, FSO2CF2, OCF2 fragments were observed. In the C NMR spectrum of
the sample of both compounds (4 : 3 in a 5:1 ratio), beside a signal of ICF2I at 1.6 ppm (t, J =
377 Hz) [lit. 2.29 ppm, t, J = 378 Hz], we observed a triplet at 74.95 ppm (J = 343 Hz), which
we assigned to the OCF2I group and two signals: at 114.06 ppm (ttd, J = 293 Hz, J = 30 Hz, J
= 2Hz) due to FSO2CF2CF2O and at 112.47 ppm (tq, J = 303 Hz, J = 39 Hz) due to the
FSO2CF2CF2 group. Additionally, the sample of compounds (4 : 3 in a 5:1 ratio) was treated
with phenol in the presence of DBU and the product PhOSO2CF2CF2OCF2I (7) was isolated
after column chromatography in 46% yield (Scheme 3).
Scheme 3
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4
In a further investigation we decided to prove if compound 4 can be obtained
exclusively if the external source of fluoride ion, namely KF will be applied. The reactions
were conducted only in the presence of iodine without KI aiming to inhibit the formation of
ICF2I, however it should be taken into account that KI is generated in situ during reaction
-
between iodine and FSO2CF2CF2OCF2 K+ (6) and probably the formation of ICF2I can be
only limited but not excluded. The results are summarized in Table 1. The yields of 4 were
estimated by NMR spectroscopy. In all cases the mixture of ICF2I (3) and FSO2CF2CF2OCF2I
(4) was obtained. The yields of compound 4 were rather low and did not exceed 40%, what
can be explained by competition between two reactions: reaction of :CF2 with KI3 leading to
ICF2I (3) and the reaction of :CF2 with FSO2CF2CF2O-K+ (5) leading to 4.
Table 1
Synthesis of 4 from DFSAF in a presence of KF and I2
d
SiO2
Ratio of productsb
ICF2SO2F (8) ICF2OCF2CF2SO2F (4)
Yieldc
[%]
No DFSAFa
KF
I2
(mol%)
ICF2I (3)
1.95
1
1
1
1
1.0
1.0
0.66
1
4
12
9
1
1
1
1
4
7
12
35
42(28)f
25e
1
2
3
4
4
2
2
2
1.8
23
32
2.2
24
15
a
all reactions were carried out in ampoule in MeCN at 45-50⁰C during 21-23h; b after work up procedure (the mixture was
poured into water and the bottom phase was collected); c NMR yield of 4 based on amount of I2 used; dcounted on amount of
DFSAF; etwo days of stirring at 45⁰C; f NMR yield of 4 based on amount of KF used.
It is known that FSO2CF2CF2O-K+ (5) is not stable [5] and in 50-60⁰C in diglyme
-
undergoes fragmentation to give FSO2CF2 K+ (9) which decomposes further to
difluorocarbene (Scheme 4). Decomposition of 5 during prolonged heating was the reason
why an excess of 1 was required and lower temperature (45-50⁰C) was applied. Acetonitrile
was used as a reaction medium because the increased stability of 5 in that solvent was
reported [6].
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5
Scheme 4
Our attempts to obtain compound 4 via decomposition of 5 in a presence of iodine
were not successful.
The reaction between ICF2I (3) and FSO2CF2CF2O-K+ (5) was also investigated. An
initial experiment conducted with a reagent 3 : 5 ratio of 1:1 at 48⁰C gave a mixture of ICF2I
(3) and FSO2CF2CF2OCF2I (4) in a ratio 1.1:1. The NMR yield of 4 was estimated for 42%.
19
When the progress of the reaction of 5 : 3 in a 1.2:1 ratio was followed by F NMR, it was
found that reactions start immediately at room temperature, resulting in a mixture of products
3 : 4 (1:1.8) after 1 day at 45°C. Further progress of the reaction was not observed, what let
us to conclusion that 5 decomposes slowly and an excess of this reagent is required to reach
higher conversion.
It was proven that the application of an excess of 5 resulted not only in an advantageous
ratio of products 4 : 3 (6:1) but also increased amount of by-products from decomposition of
5, however most of them were easily washed off with water. The main signals can be assigned
to sulfone 10 (5% in a reaction mixture after work-up). It seems interesting that the
-
intermediary carbanion FSO2CF2CF2OCF2 (6) (see Scheme 4) formed during decomposition
of FSO2CF2CF2O-K+ (5) did not react with ICF2I. Similar reactions of carbanions with CF2Br2
were reported [7].
Application of excess of 5 resulted also in a product of double substitution
CF2(OCF2CF2SO2F)2 (11). Compound 11 was previously synthesized by electrochemical
Page 7 of 12

6
fluorination of the corresponding disulfonyl fluoride [8]. In the 19F NMR spectrum of the
reaction mixture (see entry 5, Table 2) a signal at -46.58 ppm was observed which was
assigned to the OCF2O group of compound 11 (2.4% in reaction mixture after work-up).
The results of the reaction between FSO2CF2CF2O-K+ (5) and ICF2I (3) are
summarized in Table 2. The yields of 4 were estimated by NMR spectroscopy. In all cases
complete conversion was not reached and ICF2I was always present in the reaction mixtures.
Table 2
Results of reaction between FSO2CF2CF2O-K+ (pre-generated) and ICF2I
Ratio of productsb
Yield (4)
[%]b,c
42
No DFSAFa
KF
ICF2I
Temp.[C]
Time [h]
ICF2OCF2CF2SO2F (4) ICF2I (3)
1
1
1
1
1
1
1
48
45
23.5
48
1.1
5.5
1.2
3.2
6
1
1
1
1
1
1
2
3
4
5
1.6
1.4
3.4
4.6
1.5
1.18
3.2
4.1
55
r.t
26
48
35-37
35-37, 45d
23
51
67b,c
48
b
aall reactions were carried out in MeCN in ampoule; after work up procedure (the mixture was poured into water and the
bottom phase was collected) ; c NMR yield based on amount of ICF2I used.; d1 day at 35-37⁰C, 1 day at 45⁰C;
It was found that, application of a longer reaction time or four-fold excess of
FSO2CF2CF2O-K+ (5) lead to an optimal yield and ratio of ICF2I (3) : ICF2OCF2CF2SO2F (4)
(entry 5, Table 2). However similar result can be obtained using 1.4 fold excess of 5 and
conducting the reaction at room temperature (entry 3, Table 2), what can be explained by
slower decomposition of 5 in that temperature. Once the reaction is completed the product can
be isolated by phase separation after addition of water. Having in mind that 4 cannot be
separated from 3 by distillation, the crude mixture of both compounds (entry 5, Table 2) was
treated with PhOH in a presence of DBU and gave after column chromatography
PhOSO2CF2CF2OCF2I (7) in 30% yield.
The yields of 4 (42-67%) obtained in the direct reaction between ICF2I (3) and
FSO2CF2CF2O-K+ (5) were higher than yields of 4 (12-35%) obtained in the reaction between
FSO2CF2CF2O-K+ (5) and :CF2 generated from 1. In the case of ICF2I (3) and FSO2CF2CF2O-
K+ (5), two pathways can occur via anionic chain mechanism (with evolution of
difluorocarbene) or via single electron transfer (Scheme 5).
Page 8 of 12

7
Scheme 5
It was never proven which mechanism is more favoured during the reaction between ICF2I (3)
and nucleophiles like phenoxide or thiopenoxide ions [4]. According to our knowledge the
reaction of such nucleophile like FSO2CF2CF2O-K+ (5) with compounds type CF2X2 (X = Cl,
Br, I) was not reported previously.
3. Experimental
1
Boiling points were measured during distillation; both are uncorrected. H NMR (400
MHz), 13C NMR (100 MHz) and 19F NMR (376 MHz) spectra were recorded with JEOL ECX
400 spectrometer, in CDCl3 or CD3CN solutions. Chemical shifts are quoted in ppm from
internal TMS for 1H and from internal CFCl3 for 19F nuclei. GC-MS analyzes were performed
with
a
Varian Saturn 2100T apparatus (30 m, capillary column, VF-5ms).
Difluoro(fluorosulfonyl)acetyl fluoride was donated us by DUPONT. ICF2I was prepared
according known procedures [2, 9].
3.1. General procedure for the reaction between ICF2I (3) and FSO2CF2CF2O-K+ (5)
In a glass ampoule 5.01 g (0.086 mol) of dry KF and 1.8 ml of dry MeCN were placed, than
17.7 g (0.098 mol) of FSO2CF2COF was condensed into it. The content of ampoule was
stirred 2 h at room temperature, than the ampoule was cooled down to -30⁰C, opened under
nitrogen, than 6.64 g (0.021 mol) of ICF2I and 60 ml of dry acetonitrile was added into it. The
reaction mixture was stirred 24 h in 35-37⁰C and 24 h in 45⁰C. After that time the ampoule
was opened and analyzed by NMR spectroscopy, than the content of ampoule was poured into
water. The bottom organic phase (7.58 g) was collected, dried over sodium sulfate and
analyzed by NMR with BTF as standard, proving the presence of ICF2I (3) and
ICF2OCF2CF2SO2F (4) in a ratio 1:6. The NMR yield of 4 was 67%. In the collected organic
phase beside signals of compound 3 and 4, three minor signals from compound 10 were
observed (5%) and signals of compound 11 (2.4 %).
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8
Difluorodiiodomethane (3):
13
19F NMR (CD3CN) δ: 17.76 (s, 2F), C NMR (CDCl3) δ: 1.6 (t, J = 377 Hz); GC-MS: m/z:
304 (M)+; 177 (ICF2)+;
2-(Difluoro-iodo-methoxy)-1,1,2,2-tetrafluoro-ethane sulfonyl fluoride (4):
19F NMR (CD3CN) δ: 44.7 (m, 1F, SO2F), -10.3 (m, 2F, OCF2I), -83.1 (m, 2F, OCF2CF2), -
113.1 (m, 2F, CF2CF2SO2F); 13C NMR (CDCl3) δ: 74.95 (J = 343 Hz, OCF2I); 114.06 (ttd, J
= 293 Hz, J = 30 Hz, J = 2Hz, FSO2CF2CF2); 112.47 (tq, J = 303 Hz, J = 39 Hz,
FSO2CF2CF2); GC-MS: m/z: 249 (M-I)+; 193 (ICF2O)+; 183 (FSO2CF2CF2)+; 177 (ICF2)+;
133 (FSO2CF2)+, 119 (C2F5)+; 100 (C2F4)+; 83 (FSO2)+; 67 (CF2O)+;
2,2,4,4,5,5-Hexafluoro-[1,3]-oxathiolane-3,3-dioxide (10):
19F NMR (CD3CN) δ: -75.41 (m, 2F), -82.92 (m, 2F), -119.22 (m, 2F);
2-[Difluoro-(1,1,2,2-tetrafluoro-2-fluorosulfonyl-ethoxy)-methoxy]-1,1,2,2-tetrafluoro-ethane
sulfonyl fluoride (11):
19F NMR (CD3CN) δ: 44.7 (m, 2F, SO2F); -46.58 (m, 2F, OCF2O); -83.1 (m, 4F, OCF2CF2); -
113.1 (m, 4F, CF2CF2SO2F);
3.2. Synthesis of 2-(Difluoro-iodo-methoxy)-1,1,2,2-tetrafluoro-ethane-sulfonic acid phenyl
ester PhOSO2CF2CF2OCF2I (7):
In a glass ampoule 4.86 g (0.083 mol) of dry KF and 1.8 ml of dry MeCN were placed, than
17.9 g (0.099 mol) of FSO2CF2COF was condensed into it. The content of ampoule was
stirred 2 h at room temperature, than the ampoule was cooled down to -30⁰C, opened under
nitrogen, than 6.66 g (0.021 mol) of ICF2I and 60 ml of dry acetonitrile was added into it. The
reaction mixture was stirred 48 h in 45⁰C. After that time the ampoule was opened and
analyzed by NMR spectroscopy, than the content of ampoule was poured into water. The
bottom organic phase (8.41 g) was collected, dried over sodium sulfate and analyzed by NMR
with BTF as standard, proving the presence of ICF2I (3) and ICF2OCF2CF2SO2F (4) in a ratio
1:5. In the collected organic phase beside signals of compound 3 and 4, three minor signals
from compound 10 were observed (9.5%) and signals of compound 11 (3.5 %).
In a flask under nitrogen 2.19 g (0.023 mol) of phenol, 6.07 g (0.039 mol) of DBU and 25 ml
of dry CH2Cl2 were placed. The flask was cooled down to -60⁰C and the mixture (8.41 g) of
Page 10 of 12

9
compounds 3 : 4 in a ratio 1:5 was added into it. The flask was slowly warm up to the room
temperature and the content of it was stirred 2 h at that temperature. After that time, reaction
mixture was poured into water. The organic phase was washed twice by water and dried over
sodium sulfate. The solvent was removed at rotary evaporator and the residue (4.93 g) was
purified by column chromatography to give compound 7 in 30% (3.02 g) yield.
2-(Difluoro-iodo-methoxy)-1,1,2,2-tetrafluoro-ethane-sulfonic acid phenyl ester (7):
19
Yellowish liquid. F NMR (CDCl3) δ: -8.32 (t, J = 11.56 Hz, 2F); -81.74 (t, J = 11.56 Hz,
2F); -112.7 (m, 2F); 13C NMR (CDCl3) δ: 75.26 (t, J = 341.9 Hz, OCF2I); 112.87 (tt, J =
300.55 Hz, J = 37.6 Hz, OCF2CF2); 114.65 (tt, J = 290.92 Hz, J = 29.9 Hz, OCF2CF2SO2);
1
121.51 (C-2, Ph); 128.38 (C-4, Ph); 130.31 (C-3, Ph); 149.95 (C-1, Ph); H NMR (CDCl3) δ:
7.28-7.32 (m, 2H), 7.38-7.49 (m, 3H);
3.3. General procedure for the reaction between FSO2CF2CF2O-K+ (5) and :CF2 generated
from FSO2CF2COF (1):
In a glass ampoule 4.05 g (0.069 mol) of dry KF and 11.7 g (0.046 mol) of I2, 0.15 g (0.0025
mol) of SiO2, 40 ml of dry MeCN were placed, than 25.5 g (0.141 mol) of FSO2CF2COF was
condensed into it. The content of ampoule was stirred 21-23 h in 45-50°C. After that time the
reaction mixture was poured into water. The bottom organic phase (13.87 g) was collected,
dried over sodium sulfate and analyzed by NMR with BTF as standard, proving the presence
of ICF2I (3) and ICF2OCF2CF2SO2F (4) and ICF2SO2F (8) in a ratio: 23: 32: 1. The NMR
yield of 4 was 28.3% (based on the amount of KF used).
Difluorodiiodomethane (3): 19F NMR (CDCl3) δ: 19.2 (s, 2F);
2-(Difluoro-iodo-methoxy)-1,1,2,2-tetrafluoro-ethane sulfonyl fluoride (4): 19F NMR (CDCl3)
δ: 46.00 (s, 1F); -8.85 (m, 2F); -82.04 (m, 2F); -111.91 (m, 2F);
Difluoro-iodo-methane-sulfonyl fluoride (8): 19F NMR (CDCl3) δ: 26.0 (m, 1F); -50.4 (m,
2F); GC-MS: m/z: 260 (M)+; 177 (ICF2)+; 67 (CF2O)+; 48 (SO) +;
4. Acknowledgment
J. I. and G.-V. R. are very grateful for the financial support of Dyneon GmbH, Burgkirchen
(Germany).
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References:
[1] G. A. Bargigia, G. Caporiccio, M. Pianca, J. Fluorine Chem. 19 (1982) 403-410;
[2] J.Ch. Xiao, J.X. Duan, A.R. Li, Y. Guo, Q.Y. Chen, Collect. Czech. Chem. Commun. 67
(2002) 1320-1324;
[3] Shanghai Institute of Organic Chemistry, Huaxue Xuebao (1978) 315-324;
[4] Y. Guo, Q.Y. Chen, J. Fluorine Chem. 102 (2000) 105-109;
[5] C. G. Krespan, J. Fluorine Chem. 16 (1980) 385-390;
[6] W. Storzer, D.D. DesMarteu, Inorg. Chem. 30 (1991) 4821-4826;
[7] I. Rico, D. Cantacuzene, C. Wakselman, J. Chem. Soc. Perkin 1 (1982) 1063;
[8] G.L. Gard, N.N. Hamel, J. Mohtasham, J. Fluorine Chem. 55 (1991) 313-321;
[9] Z. Y. Yang, J. Am. Chem. Soc. 118 (1996) 8140-8141;
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