The synthesis of phosphonate ester containing fluorinated vinyl ethers

Article abstract of DOI:10.1021/jo961086a

Three novel perfluorovinyl ethers containing phosphonate ester groups, diethyl 1,1,2,2,3,3,5,6,6-nonafluoro-4-oxa-5-hexenylphosphonate, (EtO)₂P(O)(CF₂)₃OCF=CF₂ (1), diethyl 1,1,2,2,4,5,5-heptafluoro-3-oxa-4-pentenylphosphonate, (EtO)₂P(O)(CF₂)₂OCF=CF₂ (2), and diethyl 1,1,2,2,4,5,5,7,8,8-decafluoro-4-trifluoromethyl-3,6-dioxa-7-octenylph osphonate, CF₂=CFOCF₂CF(CF₃)O(CF₂)₂P(O)(OEt)₂ (3), have been synthesized. Perfluorovinyl ethers 1 and 2 were synthesized from methyl 4-trifluoroethenoxy-2,2,3,3,4,4-hexafluorobutanoate and methyl 3-trifluoroethenoxy-2,2,3,3-tetrafluoropropanoate, respectively, while perfluorovinyl ether 3 was synthesized either from 5-trifluoroethenoxy-4-trifluoromethyl-3-oxa-1,1,2,2,4,5,5-heptafluorop entylsulfonyl fluoride or methyl 6-trifluoroethenoxy-5-trifluoromethyl-4-oxa-2,2,3,3,5,6,6-heptafluoroh exanoate. The carboxylate esters were converted to the corresponding fluoroalkyl iodides via a free-radical iododecarboxylation. The sulfonyl fluoride was converted to its corresponding fluoroalkyl iodide via iododesulfination. The intermediate iodides were found to be useful precursors for the incorporation of the phosphonic ester groups via a photoreaction with tetraethyl pyrophosphite to produce diethyl fluorophosphonites. The diethyl fluorophosphonites were oxidized to the desired phosphonates, 1, 2, and 3, utilizing hydrogen peroxide as the oxidant. Moderate to good overall yields of perfluorovinyl ethers 1-3 have been achieved.

Full text of DOI:10.1021/jo961086a

8024
J . Org. Chem. 1996, 61, 8024-8031
Th e Syn th esis of P h osp h on a te Ester Con ta in in g F lu or in a ted Vin yl
Eth er s
Scot D. Pedersen, Weiming Qiu, Zai-Ming Qiu, Stefan V. Kotov, and Donald J . Burton*
Department of Chemistry, University of Iowa, Iowa City, Iowa 52242
Received J une 10, 1996X
Three novel perfluorovinyl ethers containing phosphonate ester groups, diethyl 1,1,2,2,3,3,5,6,6-
nonafluoro-4-oxa-5-hexenylphosphonate, (EtO)2P(O)(CF2)3OCFdCF2 (1), diethyl 1,1,2,2,4,5,5-hep-
tafluoro-3-oxa-4-pentenylphosphonate, (EtO)2P(O)(CF2)2OCFdCF2 (2), and diethyl 1,1,2,2,4,5,5,7,8,8-
decafluoro-4-trifluoromethyl-3,6-dioxa-7-octenylphosphonate, CF2dCFOCF2CF(CF3)O(CF2)2P(O)(OEt)2
(3), have been synthesized. Perfluorovinyl ethers 1 and 2 were synthesized from methyl
4-trifluoroethenoxy-2,2,3,3,4,4-hexafluorobutanoate and methyl 3-trifluoroethenoxy-2,2,3,3-tet-
rafluoropropanoate, respectively, while perfluorovinyl ether 3 was synthesized either from
5-trifluoroethenoxy-4-trifluoromethyl-3-oxa-1,1,2,2,4,5,5-heptafluoropentylsulfonyl fluoride or methyl
6-trifluoroethenoxy-5-trifluoromethyl-4-oxa-2,2,3,3,5,6,6-heptafluorohexanoate. The carboxylate
esters were converted to the corresponding fluoroalkyl iodides via a free-radical iododecarboxylation.
The sulfonyl fluoride was converted to its corresponding fluoroalkyl iodide via iododesulfination.
The intermediate iodides were found to be useful precursors for the incorporation of the phosphonic
ester groups via a photoreaction with tetraethyl pyrophosphite to produce diethyl fluorophospho-
nites. The diethyl fluorophosphonites were oxidized to the desired phosphonates, 1, 2, and 3,
utilizing hydrogen peroxide as the oxidant. Moderate to good overall yields of perfluorovinyl ethers
1-3 have been achieved.
In tr od u ction
immediately dealkylate to generate alkylphosphonates
(Scheme 1). A modification of the Arbuzov reaction was
reported by Michaelis and Becker.7 The Michaelis-
Becker reaction involves attack of a dialkyl phosphite
anion on an alkyl halide to yield alkanephosphonates by
nucleophilic substitution (Scheme 2). The general scope
and applicability of the Arbuzov and Michaelis-Becker
syntheses, however, cannot be generally extended to
fluorinated alkyl halides. The strong electron-withdraw-
ing ability of the fluorine atom causes the site of nucleo-
philic attack to be the halogen rather than the carbon.
In the past 2 decades, there has been a major research
effort in the area of ion-containing copolymers (ionomers).
Specifically, those ionomers that are based on poly-
(tetrafluoroethylene) are of great interest as membranes
in chloralkali cells and fuel cells. The vast majority of
the research done to date has concentrated on poly-
(tetrafluoroethylene)-based membranes that contain ei-
ther sulfonate1 or carboxylate2 groups or a combination
of sulfonate and carboxylate3 groups as the ionic species.
The literature lacks studies on, and methodologies for,
the preparation of membranes that utilize either phos-
phonic acid groups or quarternary alcohol groups due to
the difficulties in monomer production.4 However, it has
been suggested that perfluorinated phosphonic acids may
be useful as substitutes for, or additives to, H3PO4
electrolytes in fuel cells.5 The above discussions led us
to explore the production of possible phosphonate ester
containing monomers for copolymerization with tet-
rafluoroethylene.
Fluoropoly(halomethanes) have been reported to un-
dergo Arbuzov-type reactions. Burton et al.8 reported
that some difluorodihalomethanes yield Arbuzov products
in the presence of trialkyl phosphites (Scheme 3). It has
been suggested,8 however, that the mechanism for the
formation of difluorohalomethylphosphonates occurs via
trapping of the corresponding difluorocarbene. Genera-
tion of difluorocarbene presumably occurs via halophilic
attack of the trialkyl phosphite on the difluorodihalom-
ethanes. Fluorodihalomethanephosphonates have also
been synthesized when fluorotrihalomethanes were re-
acted with trialkyl phosphites (Scheme 3). However, the
mechanism for the formation of fluorodihalomethane-
phosphonates does not proceed via the direct nucleophilic
attack on the carbon center of the fluorotrihalomethanes.8
Longer chain fluorinated alkyl halides, however, have not
been shown to undergo such Arbuzov-like reactions.
The synthesis of phosphonic acid containing monomers,
or organophosphorous compounds in general, must in-
volve at some stage the formation of a carbon-phospho-
rus linkage. The most widely recognized method for the
generation of the carbon-phosphorus bond is the Arbu-
zov6 reaction, where trialkyl phosphites react with alkyl
halides to form quasi-phosphonium intermediates which
It has also been reported9 that iodotrifluoromethane
and iodopentafluorobenzene react with triethyl phosphite
when irradiated with 350 nm light (Scheme 4) to yield
diethyl trifluoromethylphosphonate and diethyl pen-
tafluorophenylphosphonate in 51% and 32% yield. How-
ever, other perfluoroalkyl halides have not been reported
to undergo similar reactions.
X Abstract published in Advance ACS Abstracts, October 15, 1996.
(1) Vaughan, D. J . Du Pont Innovation, 1973, 4, 10.
(2) Seko, M. (to Asahi Chemical Ind. Co., Ltd) U.S. Patent 4 178
218, 1979; Chem. Abstr. 1976, 84, 23757d.
(3) Molnar, C. J .; Price, E. H.; Resnick, P. R. (to E. I. du Pont de
Nemours and Co.) U.S. Patent 4 176 215, 1979; Chem. Abstr. 1980,
92, 66849q.
(4) Perfluorinated Ionomer Membranes; Eisenberg, A., Yeager, H.
L., Eds.; ACS Symposium Series 180; American Chemical Society:
Washington, DC, 1982.
(5) Mahmood, T.; Shreeve, J . M. Inorg. Chem. 1986, 25, 3128.
(6) Harvey, R. G., LeSombre, E. R. In Topics in Phosphorous
Chemistry; Grayson, M. and Griffith, E. J ., Eds.; Interscience: New
York, 1964; Vol. 1, p 58.
(7) Michaelis, A.; Becker, T. Chem. Ber. 1897, 30, 1003.
(8) Flynn, R. M.; Burton, D. J . J . Fluorine Chem. 1977, 10, 329.
(9) Flynn, R. M.; Burton, D. J . Synthesis 1979, 615.
S0022-3263(96)01086-9 CCC: $12.00 © 1996 American Chemical Society

Synthesis of Fluorinated Vinyl Ethers
J . Org. Chem., Vol. 61, No. 23, 1996 8025
Sch em e 1. Th e Ar bu zov Rea ction
Sch em e 7. Syn th esis of a F lu or in a ted Vin yl Eth er
Con ta in in g a P h osp h on a te Ester Gr ou p
Sch em e 2. Th e Mich a eliu s-Beck er Rea ction
Sch em e 3. Rea ction of Tr ia lk yl P h osp h ites w ith
P er h a lom eth a n es
Sch em e 4. Rea ction of Tr ia lk yl P h osp h ites w ith
P er flu or oa lk yl Iod id es
Sch em e 8. P h otor ea ction of P er flu or oa lk yl
Iod id es w ith Tetr a eth yl P yr op h osp h ite
Sch em e 5. Rea ction of Sod iu m Dia lk yl P h osp h ite
w ith Ch lor od iflu or om eth a n e
ester 4 containing a trifluorovinyl ether group using
excess chlorine. Subsequent synthetic steps convert the
ester 4 to the dimethyl phosphonate. This synthetic
methodology suffers severely due to synchronous dealky-
lation of the phosphonate upon removal of the chlorine
protection from the trifluorovinyl ether function. At-
tempts to reproduce this work in our laboratory resulted
in low yields due to the difficult and cumbersome distil-
lation of the intermediate phosphoryl chlorides.
Recent work in our laboratories has provided an
improvement over the procedure of Kato and Yamabe.12,13
Nair and Burton14 reported in 1994 that perfluoroalkyl
iodides, including 1,3-, 1,4-, and 1,6-diiodides, reacted
with tetraethyl pyrophosphite under ultraviolet irradia-
tion to afford, in good to excellent yields, the correspond-
ing perfluoroalkylphosphonites and bisphosphonites, which
could be easily oxidized to the corresponding perfluoro-
alkylphosphonates and bisphosphonates (Scheme 8). The
much milder reaction temperatures should allow for more
complex perfluoroalkyl iodides to be employed in the
photochemical reaction versus the higher temperature
Kato-Yammabe method.
Herein, we report the complete synthesis of three novel
fluoroalkylphosphonates containing the trifluorovinyl
ether group.15 These phosphonates have been synthe-
sized for co- and ter-polymerization with tetrafluoroet-
hylene and perfluoropropyl vinyl ether to examine the
structural and electrochemical properties of the resulting
ionomers.16 These fluoroalkylphosphonates provide a
reasonable method for the incorporation of phosphonic
acid groups into poly(tetrafluoroethylene)-based mem-
branes.
Sch em e 6. F r ee-Ra d ica l Rea ction of
P er flu or oa lk yl Iod id es w ith Tetr a eth yl
P yr op h osp h ite
Soborovskii and Baiva10 have reported that difluorom-
ethylphosphonates can be prepared by the reaction of
chlorodifluoromethane with sodium dialkyl phosphite
(Scheme 5). This reaction proceeds presumably via the
generation and subsequent trapping of difluorocarbene.11
This synthetic method suffers the same shortcomings as
described above, specifically, it is not a general approach
to a wide variety of fluorinated phosphonates.
In 1981, Kato and Yamabe12 reported the synthesis of
perfluoroalkanephosphonates from the corresponding
perfluoroalkyl iodides via the phosphonites (Scheme 6).
Thermal decomposition of di-tert-butyl peroxide leads to
the abstraction of an iodine atom from the perfluoroalkyl
iodide to produce the reactive perfluoroalkyl radical. The
perfluoroalkyl radical, then, reacts with tetraethyl py-
rophosphite resulting in perfluoroalkylphosphonite.
Simple oxidation with tert-butyl hydroperoxide provides
the desired perfluoroalkylphosphonates. Kato and Yam-
abe applied this strategy to the preparation of a perfluo-
rovinyl ether containing a phosphonate ester group
(Scheme 7).13 During their synthesis, Kato et al. protect
the trifluorovinyl ether functionality of a carboxylate
(10) Soborovskii, L. Z.; Baiva, N. F. Zh. Obshch. Khim. 1959, 29,
1144.
(14) Nair, H. K.; Burton, D. J . Tetrahedron Lett. 1995, 36, 347.
(15) Presented in part at the 12th Winter Fluorine Conference.
Pedersen, S. D.; Qiu, Z-M.; Qiu W.; Kotov, S.; Burton, D. J . Abstracts
of Papers, 12th Winter Fluorine Conference, St. Petersburg, FL;
American Chemical Society: Washington, DC, 1995; Abstract P68.
(16) Kotov, S.; Pedersen, S. D.; Qiu, W.; Qiu, Z-M.; Burton, D. J . J .
Fluorine Chem., in press.
(11) Flynn, R. M. Ph.D. Thesis, University of Iowa, Iowa City, IA,
1979.
(12) Kato, M.; Yamabe, M. J . Chem. Soc., Chem. Commun. 1981,
1173.
(13) Kato, M.; Akiyama, K.; Akatsuka, Y.; Yamabe, M. Repr. Res.
Lab.; Asahi Glass Co., Ltd. 1982, 32, 117.

8026 J . Org. Chem., Vol. 61, No. 23, 1996
Pedersen et al.
Sch em e 9. Syn th esis of P h osp h on a te Ester 1
Sch em e 10. Syn th esis of P h osp h on a te Ester 2
lation of the phosphonate when deprotecting the trifluo-
rovinyl ether moiety. They corrected the problem by
reacting the mixture of phosphonate, monophosphonic
acid, and phosphonic acid with phosphorus pentachloride
to produce a mixture of phosphoryl chlorides. The
phosphoryl chloride was then converted to the methyl
phosphonate by stirring with methanol (Scheme 7).
Initial attempts to relieve the problem of the dealky-
lation of the protected phosphonate as Kato et al.
described proved to be highly unsuccessful in our hands.
The major complication in the sequence proved to be
isolation of the phosphoryl chlorides. Kato et al.13
distilled the phosphoryl chlorides directly from the reac-
tion mixture as they were formed. However, attempts
to repeat this process produced only very poor yields of
the desired chlorides. The reaction mixture always
produced a solid, tarlike substance that yielded only
small amounts of the phosphoryl chlorides.
This problem was overcome when it was discovered
that deprotection of the trifluorovinyl ether moiety prior
to oxidation results in no dealkylation of the phosphonite
7. In our improved synthetic pathway (Scheme 9), the
intermediate phosphonite 7 is deprotected with activated
zinc in N,N-dimethylformamide (DMF) at 80 °C for 4 h.
The dechlorinated phosphonite 8 is then oxidized. Kato
et al.13 utilized tert-butyl hydroperoxide at -5 °C. We
found that 30% hydrogen peroxide (aqueous) could be
successfully employed as an oxidant in DMF solvent at
0 °C. The fact that dealkylation is prevented when the
phosphonite 7 is deprotected first and oxidized second
allows the synthesis in good yields (69% based on starting
iodide 6) of the perfluorinated diethyl phosphonate 1
without isolation of the troublesome phosphoryl chlorides.
This reaction sequence (Scheme 9) also provides the
phosphonate ester from the fluorinated iodide 6 without
isolation of either the protected phosphonite or the
deprotected phosphonite. Effectively, the production of
the diethyl phosphonate 1 from the fluorinated iodide 6
is a one-pot synthesis, increasing both the simplicity and
yield of the diethyl 1,1,2,2,3,3,5,6,6-nonafluoro-4-oxa-5-
hexenylphosphonate, 1.
Resu lts a n d Discu ssion
I. (EtO)2P (O)(CF 2)3OCF dCF 2 (1). Our initial efforts
to produce trifluorovinyl ethers containing phosphonate
ester groups were based on the work reported by the
Asahi Glass Co.13 Kato et al. produced a trifluorovinyl
ether containing a dimethyl phosphonate ester from
methyl 4-trifluoroethenoxy-2,2,3,3,4,4-hexafluorobutanoate,
4. The Kato et al. reaction sequence is illustrated in
Scheme 7. We attempted to use a similar sequence of
reactions to produce phosphonate esters 1 and 2. How-
ever, we found several problem areas in our synthetic
efforts that had to be corrected to achieve acceptable
yields of phosphonate 1.
Protection of the trifluorovinyl group with excess
chlorine in 1,1,2-trichloro-1,2,2-trifluoroethane (F-113)
and saponification of the ester moiety of 4 (Scheme 9)
proved quite successful and occurred in nearly quantita-
tive yields (95%). Carboxylic acid 5 could be decarboxy-
lated with benzoyl peroxide in the presence of iodine in
F-113 at 120 °C in a sealed tube. The yields of the
fluorinated iodide 6 were moderate to good. It proved to
be quite difficult to completely dry the hygroscopic
fluorinated carboxylic acid 5. It should be noted that the
Hunsdicker reaction17 was rejected as a possible route
to convert the carboxylic acid 5 to the fluorinated iodide,
6, because the silver salts employed in the Hunsdicker
reaction must be completely dry.
The carbon-iodine bond in 6 was replaced with a
carbon-phosphorus linkage via a photoreaction with
tetraethyl pyrophosphite (TEPP). As described by Nair
and Burton,14 the fluorinated iodide 6 was placed in a
quartz Rotoflo tube with TEPP and a small amount of
F-113 and irradiated at 254 nm for 18 h. The resulting
phosphonite 7 was not isolated. Occasionally, if the
reaction was irradiated after the total consumption of the
fluorinated iodide 6, the overall yield of final phosphonate
1 was severely reduced. In order to maximize the yield
of 1, the consumption of fluorinated iodide 6 had to be
closely monitored by 19F NMR and the irradiation stopped
shortly after it was completely consumed.
Kato et al.13 oxidized the protected phosphonite 7
directly. Attempts to oxidize the phosphonite 7 followed
by dechlorination, however, always resulted in significant
amounts of mono- and bis-dealkylated products. Kato
et al.13 noted that they were troubled also by the dealky-
II. (EtO)2P (O)(CF 2)2OCF dCF 2 (2). Similarly, di-
ethyl 1,1,2,2,4,5,5-heptafluoro-3-oxa-4-pentenylphospho-
nate, 2, could be prepared from methyl 3-trifluoroethenoxy-
2,2,3,3-tetrafluoropropanoate, 9. Scheme 10 demonstrates
the reaction sequence. The protection and saponification
of 9 again occurred in an almost quantitative yield (74%)
to produce the protected carboxylic acid 10. The fluori-
nated iodide 11 was synthesized by decarboxylation of
(17) Hudlicky, M. Chemistry of Organic Fluorine Compounds; J ohn
Wiley and Sons Inc.: New York, 1976; p 225.

Synthesis of Fluorinated Vinyl Ethers
J . Org. Chem., Vol. 61, No. 23, 1996 8027
Sch em e 11. An Alter n a tive Syn th esis of
Sh or t-Ch a in Ca r boxylic Acid 10
Sch em e 12. Attem p ted Syn th esis of
Br a n ch ed -Ch a in Iod id e 13, Resu ltin g in a Low
Boilin g Azeotr op e of 13 a n d Iod oben zen e
10 using benzoyl peroxide and iodine in F-113 at 120 °C.
However, a significantly lower yield (69%) of the iodide,
11, was obtained than with the longer chain analogue.
The lower boiling point of the short-chain iodide may
contribute to some of the loss in the yield due to
difficulties in the separation of it from the reaction
byproducts. Subsequent photochemical reaction of iodide
11 with TEPP in a quartz Rotoflo tube for 20 h afforded
the crude protected phosphonite. The crude protected
phosphonite was dechlorinated using zinc dust in DMF
and then oxidized at 0 °C using hydrogen peroxide
yielding the desired diethyl 1,1,2,2,4,5,5-heptafluoro-3-
oxa-4-pentenylphosphonate, 2. The overall yield of phos-
phonate 2 was 54% based on fluorinated iodide 11.
Initially, we lacked access to methyl 3-trifluoro-2,2,3,3-
tetrafluoropropanoate, 9; however, we did have access to
methyl 4-trifluoroethenoxy-2,2,3,3,4,4-hexafluorobutanoate,
4. We synthesized the short-chain, protected carboxylic
acid 10 from the iodide 6 that was discussed above. It is
known that the iododifluoromethyl terminus of perfluo-
roalkyl iodides can be oxidized to the corresponding
carboxylic acid by sodium nitrite and zinc in dimethyl
sulfoxide (DMSO).18 Since we had already synthesized
1,2-dichloro-6-iodo-1,1,2,4,4,5,5,6,6-nonafluoro-3-oxahex-
ane, 6, we oxidized 6 using sodium nitrite and zinc in
DMSO at 110 °C. This reaction yielded 70% of the
desired, protected carboxylic acid 10, Scheme 11. This
carboxylic acid in turn could be employed in the sequence
depicted in Scheme 10 to produce the useful iodide
intermediate 11. In effect, the carbon chain of methyl
4-trifluoroethenoxy-2,2,3,3,4,4-hexafluorobutanoate, 4,
was shortened by two carbons using two consecutive iodo-
decarboxylation reactions. The synthesis of diethyl
1,1,2,2,4,5,5-heptafluoro-3-oxa-4-pentenylphosphonate, 2,
could be carried out directly from methyl 3-trifluoroet-
henoxy-2,2,3,3-tetrafluoropropanoate, 9, Scheme 10, or
indirectly by employing the oxidation of 1,2-dichloro-6-
iodo-1,1,2,4,4,5,5,6,6-nonafluoro-3-oxahexane, 6, to syn-
thesize carboxylic acid 10.
III. (EtO)2P (O)(CF 2)2OCF (CF 3)CF 2OCF dCF 2 (3).
Attempts to produce the longer, branched chain phos-
phonate ester, 3, using the reaction sequences described
above (Schemes 9 and 10) with methyl 6-trifluoroet-
henoxy-5-trifluoromethyl-4-oxa-2,2,3,3,5,6,6-heptafluoro-
hexanoate, 12, were complicated due to an isolation
problem. Scheme 12 demonstrates the reactions em-
ployed to produce the desired intermediate iodide, 13,
from carboxylate ester 12. Protection of the trifluorovinyl
ether functionality with excess chlorine and saponifica-
tion of the corresponding ester produced the chlorinated
acid, 14, in an excellent yield (86%). The protected
carboxylic acid, 14, could then be decarboxylated to
produce the corresponding iodide, 13. The decarboxyla-
tion produces a significant amount of iodobenzene from
the decarboxylation of benzoic acid, which arises from
the thermal decomposition of benzoyl peroxide. When
the shorter, linear chained iodides were synthesized, the
byproduct, iodobenzene, could be efficiently separated by
Sch em e 13. Syn th esis of Br a n ch ed -Ch a in Iod id e
13
distillation from the desired fluorinated iodide. However,
the iodide, 13, could not be separated from iodobenzene.
When the organic material from the reaction was distilled
at 90-92 °C at 60 mmHg, a 3:2 mixture of 13 and
iodobenzene distilled out. Sequential fractional distilla-
tions of this mixture using a 6 cm Vigreux column and
an 8 in. spinning band column failed to change the ratio
of iodobenzene to the desired iodide 13. It is surmised
that these two materials produce a low boiling azeotrope.
Attempts to rectify this problem using tert-butyl peroxide
in place of benzoyl peroxide proved unsuccessful due to
the incomplete decarboxylation of the carboxylic acid, 14.
It was concluded that a more efficient method was
required to produce the fluorinated iodide, 13.
In 1958, Krespan19 reported that perfluorinated acid
chlorides would thermally decarbonylate in the presence
of potassium iodide to yield the corresponding perfluori-
nated alkyl iodides. Conversion of carboxylic acid, 14,
to the acid chloride was accomplished using oxalyl
chloride and pyridine at 90 °C for 4 h, Scheme 13. The
acid chloride was distilled from the reaction mixture, and
placed in a Hastalloy-C pressure reactor with finely
ground potassium iodide. The mixture was heated at
210 °C until a constant pressure of 350-400 psi was
maintained in the pressure reactor (3-4 h). Workup and
distillation yielded 40% of the desired 1,2-dichloro-
(18) Chen, Q-Y.; Qiu, Z-M. Acta Chim. Sin. 1988, 46, 39.
(19) Krespan, C. G. J . Chem. Soc. 1958, 23, 2016.

8028 J . Org. Chem., Vol. 61, No. 23, 1996
Pedersen et al.
Sch em e 14. Syn th esis of Br a n ch ed -Ch a in
P h osp h on a te Ester 3
followed by iododesulfination of the alkylsulfinates to
produce alkyl iodides. These reactions have been used
to synthesize several fluorinated alkyl iodides.20 We
investigated the application of this synthetic methodology
to 16.
First, the sulfonyl fluoride was protected using excess
chlorine to produce the protected sulfonyl fluoride 17 in
a nearly quantitative yield. Following the methodology
of Hu and co-workers, the sulfonyl fluoride was reduced
to the potassium sulfinate salt, 18. The potassium
sulfonate 19 was found to be the major byproduct of this
reaction (Scheme 15). The amount of this sulfonate
byproduct must be minimized, since the sulfonate salt
does not undergo iododesulfination to form the corre-
sponding fluorinated alkyl iodide. Hu and co-workers
report that the most efficient solvent system for the
reduction reaction to synthesize potassium fluorosulfi-
nate salts is a mixture of dioxane and water. We found
that a 1:1 mixture of dioxane and water produced a 1:1
mixture of desired sulfinate 18 and undesired sulfonate
19. However, as the ratio of dioxane and water was
varied, the ratio of sulfinate salt to sulfonate salt was
improved. We found that production of the sulfinate salt
was maximized (85%) and production of sulfonate salt
was minimized (15%) when a 1:3 mixture of dioxane and
water was utilized as the solvent system for the reduction
of 17 to 18. The ratio of sulfinate salt 18 to sulfonate
salt 19 was easily determined by integration of the 19F
NMR signals of CF 2SO2K (-133.6 ppm) versus CF 2SO3K
(-117.5 ppm).
Sch em e 15. Syn th esis of Br a n ch ed -Ch a in Iod id e
13 fr om th e Su lfon yl F lu or id e 16
After the salt mixture was recrystallized and dried, the
mixture was treated with iodine in DMF solvent to
produce the fluorinated iodide 13 in 45% yield based on
protected sulfonyl fluoride 17. Again, once the fluori-
nated iodide, 13, was synthesized from the sulfonyl
fluoride, the iodide could be used as the starting material
for the photoreaction with TEPP as shown in Scheme 14.
The yield of iodide 13 was somewhat disappointing from
the starting sulfonyl fluoride; however, these reactions
were amenable to scale-up and allowed a large amount
of the desired branched iodide, 13, to be produced in
much shorter time than the corresponding synthesis that
utilized 12 as the starting material.
Con clu sion
1,1,2,4,4,5,7,7,8,8-decafluoro-5-trifluoromethyl-8-iodo-3,6-
dioxaoctane, 13.
Three novel fluorinated vinyl ethers were synthesized
for polymerization with tetrafluoroethylene. The vinyl
ethers all contained diethyl phosphonate ester groups.
These monomers allow the introduction of phosphonic
acid groups into perfluoropolymeric membranes. The
novel phosphonate esters mimic the commercially avail-
able monomers that are based on the sulfonyl fluoride
and carboxylic acid functionalities. It was shown that
the phosphonate ester moiety could be incorporated using
a series of reactions starting from the corresponding
iodides. The iodides were converted to the corresponding
phosphonites using a photoreaction with tetraethyl py-
rophosphite, followed by oxidation with hydrogen perox-
ide to prepare the desired diethyl phosphonate esters. It
was demonstrated that the intermediate iodides could be
synthesized either by decarboxylation of the carboxylic
acid functionalities or from the corresponding iododes-
Once the iodide, 13, had been cleanly synthesized and
isolated, it was photolyzed with TEPP to produce the
branched phosphonite 15, as shown in Scheme 14.
Phosphonite 15 could be dechlorinated with zinc in DMF,
and oxidized by hydrogen peroxide to yield 45% of diethyl
1,1,2,2,4,5,5,7,8,8-decafluoro-4-trifluoromethyl-3,6-dioxa-
7-octenylphosphonate, 3. Except for the change in the
synthesis of the branched iodide, 13, all three of the
phosphonate esters 1, 2, and 3 can be synthesized from
their corresponding starting methyl carboxylate esters
(4, 9, 12) via the corresponding iodides (6, 11, 13).
The somewhat disappointing yield of 13 and the
availability of 5-trifluoroethenoxy-4-trifluoromethyl-3-
oxa-1,1,2,2,4,5,5-heptafluoropentylsulfonyl fluoride, 16
(Scheme 15), prompted us to examine an alternative
synthetic route to the branched iodide 13. Hu and co-
workers20 have closely examined the conversion of flu-
orinated alkylsulfonyl fluorides to fluorinated alkylsul-
finate salts via reduction by sodium sulfite (K2SO3),
(20) (a) Hu, C-M.; Huang, W-Y.; Huang, B-N. J . Fluorine Chem.
1983, 23, 193. (b) Hu, C-M.; Huang, W-Y.; Huang, B-N. J . Fluorine
Chem. 1983, 23, 229.

Synthesis of Fluorinated Vinyl Ethers
J . Org. Chem., Vol. 61, No. 23, 1996 8029
200 mL), and water (3 × 200 mL). The organic layer was dried
over Na2SO4, and the ether was removed by ambient pressure
distillation. The residue was further distilled to yield 63.96 g
(87%) of CF2ClCFClO(CF2)3I, 6, bp 96 °C at 118 mmHg. GLPC
95%. 19F NMR (CFCl3, CDCl3) -59 (m, 2F), -71 (m, 2F), -77
(m, 1F), -82 (AB q, 2F), -117 (s, 2F) ppm. 13C NMR (TMS,
CDCl3) 92 (tt, J ) 320, 41 Hz), 107 (ttt, J ) 266, 32, 32 Hz),
115 (tt, J ) 291, 34 Hz), 116 (dt, J ) 300, 37 Hz), 122 (td, J )
300, 35 Hz) ppm. GCMS (m/e, rel.int.) 444, 446, 448 (M+, 0.69,
ulfination of a sulfonyl fluoride starting material. This
synthetic strategy produced moderate to good overall
yields of the desired fluorinated vinyl ethers containing
phosphonate ester groups.
Exp er im en ta l Section
Gen er a l. All of the boiling points are uncorrected. The
19F, 1H, 13C, and 31P NMR spectra were recorded in CDCl3
solvent. All of the chemical shifts are reported in parts per
million downfield (positive) of the standard: TMS for 1H and
13C, external 85% H3PO4 for 31P, and CFCl3 for 19F NMR. FT-
IR spectra were recorded as CCl4 solutions and are reported
in wavenumbers (cm-1). Gas chromatography/mass spectros-
copy (GC-MS) spectra were obtained at 70 eV in the electron-
impact mode. GLPC analyses were performed on a 5% OV-
101 column with a thermal conductivity detector. High-
resolution mass spectral determinations were made at the
University of Iowa High Resolution Mass Spectrometry Facil-
ity. A 1-ft, silvered, vacuum-jacketed spinning band apppa-
ratus with a Teflon band was employed for the final purifica-
tion of the phosphonates. All of the reactions were carried
out under an atmosphere of nitrogen in oven-dried glassware
with magnetic stirring, unless noted otherwise. Photochemical
reactions were carried out in a quartz Rotoflo tube in a
photoreactor equipped with 254 nm bulbs. DMF was distilled
at a reduced pressure from CaH2. Zinc (325 mesh, Aldrich)
was activated by washing with dilute HCl and then dried in
vacuo at room temperature. All of the reagents were obtained
from common commercial sources except CF2dCFO(CF2)3CO2-
CH3, 4 (Asahi Glass Co.), CF2dCFO(CF2)2CO2CH3, 9 (Dow
Chemical Co.), CF2dCFOCF2CF(CF3)O(CF2)2SO2F, 16 (Shan-
gai Institute of Organic Chemistry), and CF2dCFOCF2CF-
(CF3)O(CF2)2CO2CH3, 12 (E. I. du Pont de Nemours and Co.).
P r ep a r a tion of 6,7-Dich lor o-5-oxa -2,2,3,3,4,4,6,7,7-n on -
a flu or oh ep ta n oic Acid (5). A three-necked, round-bottomed
flask equipped with a dry ice condenser, a N2(g) inlet, a
magnetic stir bar, and an isopropyl alcohol bath was charged
with 150 g (490 mmol) of CF2dCFO(CF2)3CO2CH3, 4, and 100
mL of F-113 (CF2ClCFCl2). The isopropyl alcohol bath was
cooled to -10 °C, and gaseous chlorine was condensed into
the reaction flask until the solution remained bright yellow.
The flask was warmed to room temperature (approximately 3
h), adding additional gaseous chlorine as necessary to maintain
the yellow color. When the solution reached room temperature
and the yellow color persisted, the dry ice condenser was
removed, the reaction flask was fitted with a flash distillation
head, and the F-113 was removed in vacuo. The residue
remaining after the flash distillation was dissolved in 175 mL
of methanol and cooled to -5 °C in an ice/salt water bath, then
22 g (550 mmol) of NaOH was added with vigorous stirring.
The solution was warmed to room temperature and then
stirred for 16 h, and the methanol was removed under vacuum.
Total removal of the methanol was achieved after 2 days,
generally, leaving a solid residue which was dissolved in 150
mL of water and acidified with 100 mL of concd HCl. The
reaction mixture was stirred for 1 h, and the organic layer
was isolated. The aqueous layer was washed with diethyl
ether (3 × 200 mL). The organic layers were combined, dried
over Na2SO4, and concentrated to give a residue which was
distilled to afford 169 g (95%) of CF2ClCFClO(CF2)3CO2H, 5,
1H NMR purity 92%, bp 99 °C at 50 mmHg. 19F NMR (CFCl3,
CDCl3) -71 (s, 2F), -77 (s,1F), -84 (m, 2F), -119 (s, 2F), -127
(s, 2F) ppm. 1H NMR (TMS, CDCl3) 10.8 (1H) ppm. 13C NMR
(TMS, CDCl3) 109 (ttm, J ) 270, 35 Hz), 108 (tt, J ) 287, 32
Hz), 116 (dt, J ) 300, 37 Hz), 117 (tt, J ) 290, 32 Hz), 123 (td,
J ) 300, 35 Hz), 163 (t, J ) 30 Hz) ppm. FT-IR (CCl4) 3078
0.43, 0.06), 317, 319, 321 (M+ - I, 1.19, 0.76, 0.11), 227 (M+
-
CF2ClCFClO, 58.77), 177 (CF2I+, 49.31), 151, 153, 155 (CF2-
ClCFClO+, 100, 57.8, 9.12), 127 (I+, 23.85). HRMS (ZAB-HF)
calcd for C5F9OICl2 443.8227, obsd 443.8232. FT-IR (CCl4)
2361 (w), 1318 (m), 1252 (w), 1200 (s), 1184 (s), 1134 (s), 1016
(m) cm-1
.
Syn th esis of Dieth yl 1,1,2,2,3,3,5,6,6-Non a flu or o-4-oxa -
5-h exen ylp h osp h on a te (1). A 150 mL quartz Rotoflo tube
was charged with 40.7 g (73.3 mmol) of CF2ClCFClO(CF2)3I,
6, 25 g (100 mmol) of (EtO)2POP(OEt)2, and 25 mL of F-113.
The reaction mixture was irradiated in a Rayonet photochemi-
cal reactor at 254 nm for 20 h. After vacuum removal of F-113,
the residue was dissolved in dry DMF (75 mL) and treated
with zinc dust (9.8 g, 150 mmol) at 90 °C for 4 h. The residue
was then transferred to a three-necked, round-bottomed flask
and treated with 14 mL (150 mmol) of 30% H2O2 at -5 °C. On
warming to room temperature, the mixture was diluted with
150 mL of Et2O and washed with NH4Cl(aq) (3 × 200 mL),
NaHCO3(aq) (3 × 200 mL), and H2O (3 × 200 mL), and the
organic layer was dried over Na2SO4. After concentration, the
residue was purified by silica gel column chromatography
(methylene chloride eluent) to afford 19.58 g (51 mmol, 69%)
of (EtO)2P(O)(CF2)3OCFdCF2, 1. The monomer was further
purified by spinning band distillation. GLPC 99.96%. bp 51
°C at 0.1 mmHg. 19F NMR (CFCl3, CDCl3) -85 (s, 2F), -115
(m, 1F), -122 (m, 1F), -124 (s, 2F) ppm. 1H NMR (TMS,
CDCl3) 1.41 (t, J ) 7 Hz, 6H), 4.3 (q, J ) 7 Hz, 6H) ppm. 13C
NMR (TMS, CDCl3) 16 (d, J ) 5 Hz), 66 (d, J ) 7 Hz), 112 (tt,
J ) 275, 37 Hz), 115 (tt, J ) 275, 37 Hz), 117 (ttm, J ) 289,
33 Hz), 130 (ddd, J ) 268, 48, 48 Hz), 148 (ddd, J ) 278, 278,
54 Hz) ppm. 31P NMR (H3PO4, CDCl3) -0.02 (t, J ) 89 Hz)
ppm. GCMS (m/e, relative intensity) 356 (M+ - CH2CH2,
0.33), 328 (M+ - 2CH2CH2, 1.07), 231 (M+ - 153, 30.5), 109
(M+ - 275, 100), 81 (74.02). HRMS (ZAB-HF) calcd for
C7H6F9O4P 355.9860, obsd 355.9862. FT-IR (CCl4) 1335 (m),
1288 (m), 1166 (s), 1024 (s) cm-1
.
P r ep a r a t ion of 5,6-Dich lor o-4-oxa -2,2,3,3,5,6,6-h ep -
ta flu or oh exa n oic Acid (10) via Meth yl 4-Oxa -2,2,3,3,5,6,6-
h ep ta flu or o-5-h exen oa te (9). A three-necked, round-bot-
tomed flask equipped with a dry ice condenser, a N2(g) inlet,
a magnetic stir bar and an isopropyl alcohol bath was charged
with 123 g (480 mmol) of CF2dCFO(CF2)2CO2CH3, 9, and 100
mL of F-113. The isopropyl alcohol bath was cooled to -10
°C, gaseous chlorine was then condensed into the reaction flask
until the solution remained bright yellow. The flask was
warmed to room temperature (approximately 3 h), adding
additional gaseous chlorine as necessary to maintain the
yellow color. When the solution reached room temperature
and the yellow color persisted, the dry ice condenser was
removed, the reaction flask was fitted with a flash distillation
head, and the F-113 was removed in vacuo. The residue that
was remaining after the flash distillation was dissolved in 200
mL of methanol and 20 mL of H2O and cooled to -5 °C in an
ice/salt water bath, then 24 g (600 mmol) of NaOH was added
with vigorous stirring. The solution was warmed to room
temperature and stirred for 16 h, and the methanol was
removed under vacuum. Total removal of the methanol was
achieved after 2 days, generally, leaving a solid residue which
was dissolved in 150 mL of water and acidified with 80 mL of
concd HCl. The reaction mixture was stirred for 1 h, and the
organic layer was isolated. The aqueous layer was washed
with CH2Cl2 (3 × 200 mL). The organic layers were combined,
dried over MgSO4, and concentrated to give a residue which
was distilled to afford 110.5 g (74%) of CF2ClCFClO(CF2)2-
CO2H, 10, bp 75 °C at 15 mmHg. GLPC 93%. 19F NMR
(CFCl3, CDCl3) -71 (d, J ) 169 Hz, 1F), -72 (dd, J ) 170 Hz,
1F), -77 (m, 1F), -85 (d, J ) 142 Hz, 1F), -87 (d, J ) 142
(m), 1770 (s), 1150 (vs) cm-1
.
Syn th esis of 1,2-Dich lor o-6-iod o-1,1,2,4,4,5,5,6,6-n on -
a flu or o-3-oxa h exa n e (6). A 300 mL Rotoflo tube was
charged with 30 g (83 mmol) of CF2ClCFClO(CF2)3CO2H, 5,
21 g (83 mmol) of benzoyl peroxide, 20 g (83 mmol) of I2, and
15 mL of F-113. The mixture was degassed and heated at 120
°C for 4 h. The mixture was dissolved in 300 mL of diethyl
ether and washed with NaHSO3 (3 × 200 mL), NaHCO3 (3 ×

8030 J . Org. Chem., Vol. 61, No. 23, 1996
Pedersen et al.
Hz, 1F), -122 (s, 2F) ppm. 1H NMR (TMS, CDCl3) 10 (1H)
ppm. 13C NMR (TMS, CDCl3) 115 (dt, J ) 299, 38 Hz), 116
(tt, J ) 290, 33 Hz), 116 (tt, J ) 290, 34 Hz), 122 (td, J ) 300,
35 Hz), 161 (m) ppm.
obsd 335.0286. FT-IR (CCl4) 1329(m), 1281(m), 1168(s), 1139-
(s), 1123(s) cm-1
.
Syn th esis of 8,9-Dich lor o-2,2,3,3,5,6,6,8,9,9-d eca flu or o-
5-tr iflu or om eth yl-4,7-d ioxa n on a n oic Acid (14). A three-
necked, round-bottomed flask equipped with a dry ice con-
denser, a N2(g) inlet, a magnetic stir bar, a glass tube that
reached below the surface of the solution, and an ice/salt bath
was charged with 100 g (237 mmol) of CF2dCFOCF2CF-
(CF3)OCF2CF2CO2CH3, 12, and 100 mL of F-113 (CF2ClCFCl2).
The ice/salt bath was cooled to 0 °C, and gaseous chlorine was
bubbled into the reaction flask until the solution remained
bright yellow. The flask was warmed to room temperature
(approximately 4 h), adding additional gaseous chlorine as
necessary to maintain the yellow color. When the solution
reached room temperature and the yellow color persisted, 19F
NMR analysis of an aliquot showed that no vinyl fluorines
remained. The dry ice condenser was removed, the reaction
flask was fitted with a flash distillation head, and the F-113
was removed in vacuo. The residue that was remaining after
the flash distillation was dissolved in 175 mL of methanol and
cooled to -5 °C in an ice/salt water bath, then 12 g (300 mmol)
of NaOH was added with vigorous stirring. The solution was
warmed to room temperature and then stirred for 12 h, and
the methanol was removed in vacuo. The residue was then
dissolved in ethyl acetate and washed with brine (5 × 150 mL)
to remove any remaining MeOH. The ethyl acetate was then
removed via rotary evaporation and in vacuo. The remaining
solids were then dissolved in water and acidified with concd
HCl (60 mL) under vigorous stirring. The solution was then
transferred to a separatory funnel, and the organic layer was
isolated. The aqueous layer was washed with diethyl ether
(3 × 200 mL). The organic layers were combined, dried over
Na2SO4, and concentrated to give a residue which was distilled
to afford 98.2 g (86%) of CF2ClCFClOCF2CF(CF3)OCF2CF2-
CO2H, 14, bp 120-122 °C at 23 mmHg. GLPC 91%. 19F NMR
(CFCl3, CDCl3) -71.3 (m, 2F), -77.3 (m, 1F), -80.3 (m, 3F),
-82 through -86 (m, 4F), -122.3 (s, 2F), -145.7 (m, 1F) ppm.
1H NMR (TMS, CDCl3) 10.44 (s, 1H) ppm. 13C NMR (TMS,
CDCl3) 103.29 (dsex, J ) 269.76, 38.01 Hz), 106.89 (tt, J )
266.5, 36.1 Hz), 116.1 (tt, 259.6, 32.3 Hz), 116.14 (dt, J )
295.81, 34.0 Hz), 116.7 (td, J ) 290.2, 31.4 Hz), 118.8 (qd, J )
289.0, 31.9 Hz), 122.5 (td, J ) 300.2, 34.5 Hz), 164.7 (t, J )
P r ep a r a t ion of 5,6-Dich lor o-4-oxa -2,2,3,3,5,6,6-h ep -
t a flu or oh exa n oic Acid (10) via 1,2-Dich lor o-6-iod o-
1,1,2,4,4,5,5,6,6-n on a flu or o-3-oxa h exa n e (6). A 250 mL
three-necked, round-bottomed flask fitted with an oil bath, a
magnetic stir bar, a water condenser, an internal thermometer,
and a nitrogen source was charged with 21.5 g (41 mmol) of
CF2ClCFClO(CF2)3I, 6, 12.5 g (180 mmol) of sodium nitrite,
and 7.5 g (115 mmol) of zinc in 50 mL of dimethyl sulfoxide.
The reaction mixture was stirred at 110 °C for 10 h. After
the mixture was cooled, 19F NMR analysis showed a nearly
quantitative yield of CF2ClCFClO(CF2)2CO2H, 10. The reac-
tion mixture was then filtered through a medium frit glass
funnel to remove excess zinc. The solution was then acidified
with 60 mL (240 mmol) of 4 N HCl. The acidified mixture
was then extracted with diethyl ether (4 × 100 mL). The
combined organic layers were washed with water (3 × 75 mL)
and dried over MgSO4. Filtration and removal of the solvent
resulted in 14.05 g of crude CF2ClCFClO(CF2)2CO2H, 10, which
was then distilled at reduced pressure to yield 8.5 g (68%) of
CF2ClCFClO(CF2)2CO2H, 10. bp 53 °C at 1.5 mmHg. GLPC
96%. All of the spectroscopy data were identical to that noted
above.
Syn th esis of 1,2-Dich lor o-5-iod o-1,1,2,4,4,5,5-h ep ta flu -
or o-3-oxa p en ta n e (11). A 300 mL Rotoflo tube was charged
with 25 g (80 mmol) of CF2ClCFClO(CF2)2CO2H, 10, 21 g (83
mmol) of benzoyl peroxide, 20 g (83 mmol) of I2, and 50 mL of
F-113. The mixture was degassed and heated at 120 °C for 4
h. The mixture was dissolved in 500 mL of CH2Cl2 and washed
with NaHSO3 (3 × 200 mL), NaHCO3 (3 × 200 mL), and water
(3 × 200 mL). The organic layer was dried over MgSO4, and
the CH2Cl2 was removed by ambient pressure distillation. The
residue was further distilled to yield 27.2 g (63%) of CF2-
ClCFClO(CF2)2I, 11, bp ) 115-118 °C. GLPC 95%. 19F NMR
(CFCl3, CDCl3) -65 (m, 2F), -71 (d, J ) 170 Hz, 1F), -71
(dd, J ) 170, 7 Hz, 1F), -77 (m, 1F), -86 (ddm, J ) 141, 27
Hz, 1F), -88 (dd, J ) 143, 6 Hz, 1F) ppm. 13C NMR (TMS,
CDCl3) 89 (tt, J ) 320, 41Hz), 115 (tt, J ) 288, 31 Hz), 115
(dt, J ) 300, 37 Hz), 122 (dt, J ) 300, 35 Hz) ppm. GCMS
(m/e, relative intensity) 394, 396, 398 (M+, 1.91, 1.18, 0.16),
309, 311 (M+ - ClCF2, 0.59, 0.17), 267, 269, 271 (M+ - I, 2.26,
1.41, 0.23), 243 (2.01), 227 (ICF2CF2+, 100), 177 (42.11), 151,
153, 155 (22.81, 14.47, 2.44), 135, 137 (58.77, 19.08), 127 (I+,
17.98). HRMS (ZAB-HF) calcd for C4F7OICl2 393.8259, obsd
393.8252. FT-IR (CCl4) 1252(m), 1182(vs), 1155(s), 1127(s),
30.6 Hz) ppm. FT-IR (CCl4) 1763 (s), 1195 (s), 1020 (m) cm-1
.
Syn th esis of 1,2-Dich lor o-1,1,2,4,4,5,7,7,8,8-d eca flu or o-
5-tr iflu or om eth yl-8-iod o-3,6-d ioxa octa n e (13) via 8,9-
Dich lor o-2,2,3,3,5,6,6,8,9,9-d eca flu or o-5-tr iflu or om eth yl-
4,7-d ioxa n on a n oic Acid (14). A 300 mL Rotoflo tube was
charged with 40.63 g (85 mmol) of CF2ClCFClOCF2CF-
(CF3)OCF2CF2CO2H, 14, 21 g (85 mmol) of benzoyl peroxide,
22 g (86 mmol) of I2, and 30 mL of F-113. The mixture was
degassed and heated at 120 °C for 4 h. The mixture was
dissolved in 300 mL of diethyl ether and washed with NaHSO3
(3 × 200 mL), NaHCO3 (3 × 200 mL), and water (3 × 150 mL).
The organic layer was dried over Na2SO4 and the ether was
removed by simple distillation. The residue was further
distilled at reduced pressure to yield 69 g (73%) of a 40:60
mixture of iodobenzene and CF2ClCFClOCF2CF(CF3)O(CF2)2I,
13, bp 90 °C at 60 mmHg. GLPC 60%. 19F NMR (CFCl3,
CDCl3) -64 (s, 2F), -71 (AB q, 2F), -77 (m, 1F), -80 (m, 2F),
-83 (m, 1F), -84 (m, 3F), -146 (m, 1F) ppm. 13C NMR (TMS,
CDCl3) 90 (tt, J ) 320, 41Hz), 103 (dsex, J ) 270, 38 Hz), 116
(ttd, J ) 287, 31, 4 Hz), 116 (dt, J ) 300, 39 Hz), 117 (td, J )
291, 30 Hz), 118 (qd, J ) 288, 32 Hz), 123 (td, J ) 300, 35 Hz)
ppm. GCMS (m/e, relative intensity) 560, 562, 564 (M+, 1.69,
1.12, 0.18), 393 (M+ - CF2ClCFClO, 25.1), 227 (CF2CF2I+,
61.69), 177 (CF2I+, 50.98), 151, 153, 155 (CF2ClCFO+, 100,
92.55, 22.25), 127 (I+, 24.9), 100 (87.45), 69 (CF3+, 79.61). FT-
1061(m) cm-1
.
P r ep a r a tion of Dieth yl 1,1,2,2,4,5,5-Hep ta flu or o-3-oxa -
4-p en ten ylp h osp h on a te (2). A 150 mL quartz Rotoflo tube
was charged with 6.0 g (15.7 mmol) of CF2ClCFClO(CF2)2I,
11, 7.75 g (30 mmol) of (EtO)2POP(OEt)2, and 25 mL of F-113.
The reaction mixture was irradiated at 254 nm for 20 h in a
photochemical reactor. After vacuum removal of F-113, the
residue was dissolved in dry DMF (20 mL) and treated with
zinc dust (2.0 g, 30 mmol) at 90 °C for 4 h. The residue was
then transferred to a three-necked, round-bottomed flask and
treated with 4 mL (30 mmol) of 30% H2O2 at -5 °C. On
warming to room temperature, the mixture was diluted with
100 mL of Et2O and washed with NH4Cl(aq) (3 × 100 mL),
NaHCO3(aq) (3 × 100 mL), and H2O (3 × 100 mL), and the
organic layer was dried over MgSO4. After concentration, the
residue was purified by silica gel column chromatography
(methylene chloride eluent) to afford 2.8 g (8.5 mmol, 54%) of
(EtO)2P(O)(CF2)2OCFdCF2, 2. The monomer was further
purified by spinning band distillation, bp 95 °C at 5 mmHg.
GLPC 99.92%. 19F NMR (CFCl3, CDCl3) -86 (s, 2F), -115
(dd, J ) 85, 65 Hz, 1F), -123 (dd, J ) 109, 87 Hz, 1F), -125
(dt, J ) 117, 90 Hz, 2F), -135 (dd, J ) 112, 66 Hz, 1F) ppm.
1H NMR (TMS, CDCl3) 1.41 (t, J ) 7 Hz, 6H), 4.4 (m, 4H)
ppm. 13C NMR (TMS, CDCl3) 15 (s), 65 (s), 105 (m), 115 (m),
130 (dt, J ) 270, 48 Hz), 147 (td, J ) 280, 54 Hz) ppm. 31P
NMR (H3PO4, CDCl3) 0.89 (t, J ) 87 Hz) ppm. GCMS (m/e)
(333 M+ - H), 307, 279, 259, 234, 209, 181, 137, 109, 91, 81
(100), 65, 45. HRMS (ZAB-HF) calcd for C8H11F7O4P 335.0283,
IR (CCl4) 1296 (s), 1203 (s), 1187 (s), 913 (s) cm-1
.
Syn th esis of 7,8-Dich lor o-1,1,2,2,4,5,5,7,8,8-d eca flu or o-
4-tr iflu or om eth yl-3,6-dioxasu lfon yl Flu or ide (17). A three-
necked, round-bottomed flask equipped with a Teflon coated
magnetic stir bar, a dry ice-isopropyl alcohol bath, a dry ice-
isopropyl alcohol condenser, a low-temperature thermometer,
a nitrogen gas inlet, and an inlet for Cl2 was charged with
500 g (414 mmol) of CF2dCFOCF2CF(CF3)OCF2CF2SO2F, 16.
The solution was cooled to -5 °C via the dry ice-isopropyl

Synthesis of Fluorinated Vinyl Ethers
J . Org. Chem., Vol. 61, No. 23, 1996 8031
alcohol bath, and excess chlorine gas was bubbled into the
solution over 5 h. Once chlorine gas started to condense from
the dry ice-isopropyl alcohol condenser, the addition of
chlorine gas was stopped and the solution allowed to stir for
1 h. 19F NMR analysis showed no vinyl fluorines remained in
the mixture. Excess chlorine was then removed by flash
distillation at full vacuum to yield 532 g (86%) of CF2-
ClCFClOCF2CF(CF3)O(CF2)2SO2F, 17. GLPC 97%. 19F NMR
(CFCl3, CDCl3) 45.2 (s, 1F), -71.2 (d, J ) 21 Hz, 2F), -77.1
(m, 1F), -79.3 (m, 2F), -80.1 (d, J ) 8.4 Hz, 3F), -84.5 (m,
2F), -112.0 (s, 2F) ppm. 13C NMR (TMS, CDCl3) 103.7 (dsex,
J ) 271.6, 39 Hz), 113.7 (tt, J ) 302, 38 Hz), 116.0 (tt, J )
291, 30 Hz), 116.6 (dt, 301, 37.5 Hz), 117.3 (td, J ) 290, 29
Hz), 118.4 (qd, J ) 287, 31 Hz), 122.8 (td, J ) 300, 34.5 Hz)
ppm. GCMS (m/e, relative intensity) 349 (0.99), 263 (1.03),
169 (22.42), 153 (38.18), 151 (62.42), 67 (100). FT-IR (CCl4)
8.4 Hz, 3F), -81.0 through -85.5 (m, 4F), -116.6 (s, 2F),
-145.7 (s, 1F) ppm. A solution of 25 g (54 mmol) of CF2-
ClCFClOCF2CF(CF3)OCF2CF2COCl and 9.96 g (60 mmol) of
finely ground potassium iodide were then placed in a 250 mL
Parr Hastaloy-C pressure reactor equipped with a mechanical
stirrer, a temperature probe, a heating mantle, and a pressure
gauge. The reaction mixture was then heated to 210 °C.
When the pressure had reached a constant pressure (350-
400 psi), the reaction mixture was cooled, dissolved in 300 mL
of diethyl ether, and washed with NaHSO3(aq) (3 × 200 mL),
NaHCO3(aq) (3 × 200 mL), and H2O (3 × 200 mL). The ether
layer was dried over Na2SO4 and concentrated to give a residue
that was distilled at reduced pressure to yield 12.3 g (40%) of
CF2ClCFClOCF2CF(CF3)O(CF2)2I, 13, bp 95 °C at 65 mmHg.
GLPC 98%. All of the spectroscopy data were identical to that
noted above.
1463 (m), 1243 (s), 1207 (m) cm-1
.
P r ep a r a tion of Dieth yl 1,1,2,2,4,5,5,7,8,8-Deca flu or o-
4-tr iflu or om eth yl-3,6-d ioxa -7-octen ylp h osp h on a te (3). A
mixture of CF2ClCFClOCF2CF(CF3)O(CF2)2I, 13 (20 g, 35
mmol), (EtO)2POP(OEt)2 (12 g, 45 mmol), and F-113 (5 mL)
was irradiated in a Rayonet photochemical reactor in a quartz
tube at 254 nm for 20 h. After the F-113 was removed in
vacuo, the mixture was dissolved in DMF (60 mL) and treated
with zinc dust (3.0 g, 46 mmol) at 90 °C for 4 h. The solution
was then transferred to a round-bottomed flask and treated
with 14 mL (∼75 mmol) of 30% H2O2 at -10-0 °C. After the
mixture was warmed to room temperature (2 h), it was diluted
with 150 mL of Et2O and washed with NH4Cl(aq) (3 × 200
mL), NaHCO3(aq) (3 × 200 mL), and H2O (3 × 200 mL). The
Et2O fraction was then dried over Na2SO4 and concentrated
to give a residue that was purified by silica gel column
chromatography (methylene chloride eluent) to afford 10 g
(45%) of CF2dCFOCF2CF(CF3)O(CF2)2P(O)(OEt)2, 3. The
monomer was further purified by spinning band distillation,
bp 89 °C at 0.2 mmHg. GLPC 99.97%. 19F NMR (CFCl3,
CDCl3) -80 (s, 3F), -82 (m, 2F), -85 (s, 2F), -114 (dd, J )
85, 66 Hz, 1F), -122 (dd, J ) 124, 85 Hz, 1F), -125 (d, J ) 91
Hz, 2F), -136 (ddm, J ) 124, 66 Hz, 1F), -145 (t, J ) 22 Hz,
1F) ppm. 1H NMR (TMS, CDCl3) 1.4 (t, J ) 7 Hz, 6H), 4.3 (q,
J ) 7 Hz, 4H) ppm. 13C NMR (TMS, CDCl3) 16.3 (d, J ) 7
Hz), 66 (d, J ) 6.4 Hz), 103 (dsex, J ) 268, 35 Hz), 110 (tt, J
) 275, 36 Hz), 113 (tt, J ) 275, 36 Hz), 117 (tm, J ) 283 Hz),
118 (dqt, J ) 288, 312, 1 Hz), 130 (ddd, J ) 27, 48, 28 Hz),
147 (ddd, J ) 280, 280, 53 Hz) ppm. 31P NMR (H3PO4, CDCl3)
0 (t, J ) 91 Hz) ppm. GCMS (m/e, relative intensity) 500 (M+,
0.02), 347 (M+ - CF2dCFO-28, 6.63), 197 (4.11), 181 (21.43),
137 (66.63), 109 (100). HRMS (ZAB-HF) calcd for C11H11F13O5P
501.0137, obsd 501.0139. FT-IR (CCl4) 1335(m), 1287(m),
Syn th esis of 1,2-Dich lor o-1,1,2,4,4,5,7,7,8,8-d eca flu or o-
5-t r iflu or om et h yl-8-iod o-3,6-d ioxa oct a n e (13) via t h e
Su lfon yl F lu or id e (17). A mixture of CF2ClCFClOCF2CF-
(CF3)O(CF2)2SO2F, 17 (40 g, 80 mmol), K2SO3 (48 g, 308 mmol),
dioxane (60 mL), and water (180 mL) was stirred at 100 °C
for 14 h. The remaining solids were removed via vacuum
filtration. The filtrate was then dried under vacuum (3 days)
to form a solid that was extracted with hot isopropanol (2 ×
300 mL). Concentration and vacuum drying (3 days) of the
isopropyl alcohol solution gave 30.2 g of crude CF2ClCFClOCF2-
CF(CF3)O(CF2)2SO2K, 18 (contaminated with 15% CF2ClCFCl-
OCF2CF(CF3)O(CF2)2SO3K, 19). The crude sulfinate was
treated with iodine (20 g, 80 mmol) in DMF (47 mL) at 62 °C
for 3 h. The reaction mixture was then dissolved in 250 mL
of Et2O and washed with NaHSO3(aq) (3 × 200 mL), NaHCO3-
(aq) (3 × 200 mL), and H2O (3 × 200 mL). The ether layer
was dried over Na2SO4 and concentrated to give a residue that
was distilled at reduced pressure to yield 19 g (45%) of CF2-
ClCFClOCF2CF(CF3)O(CF2)2I, 13, bp 95 °C at 65 mmHg.
GLPC 98%. 19F NMR (CFCl3, CDCl3) -64 (s, 2F), -71 (AB q,
2F), -77 (m, 1F), -80 (m, 2F), -83 (m, 1F), -84 (m, 3F), -146
(m, 1F) ppm. 13C NMR (TMS, CDCl3) 90 (tt, J ) 320, 41 Hz),
103 (dsex, J ) 270, 38 Hz), 116 (ttd, J ) 287, 31, 4 Hz), 116
(dt, J ) 300, 39 Hz), 117 (td, J ) 291, 30 Hz), 118 (qd, J )
288, 32 Hz), 123 (td, J ) 300, 35 Hz) ppm. GCMS (m/e,
relative intensity) 560, 562, 564 (M+, 1.69, 1.12, 0.18), 393 (M+
- CF2ClCFClO, 25.1), 227 (CF2CF2I+, 61.69), 177 (CF2I+,
50.98), 151, 153, 155 (CF2ClCFO+, 100, 92.55, 22.25), 127 (I+,
24.9), 100 (87.45), 69 (CF3+, 79.61). HRMS (ZAB-HF) calcd
for C7F13O2ICl2 559.8112, obsd 559.8109. FT-IR (CCl4) 1464
(m), 1296 (s), 1203 (s), 1187 (s), 913 (s) cm-1
.
Syn th esis of 1,2-Dich lor o-1,1,2,4,4,5,7,7,8,8-d eca flu or o-
5-tr iflu or om eth yl-8-iod o-3,6-d ioxa octa n e (13) Utilizin g
th e Acid Ch lor id e of 8,9-Dich lor o-2,2,3,3,5,6,6,8,9,9-d e-
ca flu or o-5-tr iflu or om eth yl-4,7-d ioxa n on a n oic Acid (14).
A 500 mL three-necked, round-bottomed flask equipped with
a magnetic stir bar, a submersion thermometer, a water
condenser, a rubber septum, and a nitrogen inlet was charged
with 30 g (67 mmol) of CF2ClCFClOCF2CF(CF3)OCF2CF2-
CO2H, 14, and 10.5 g (130 mmol) of pyridine. An immediate
exothermic reaction occurred. After the mixture was cooled
to room temperature, 8.82 g (70 mmol) of oxalyl chloride was
slowly added via a syringe. The reaction mixture was then
heated to 90 °C for 4 h. The water condenser was then
1188(s), 1025(s), 908(vs) cm-1
.
Ack n ow led gm en t. We thank the National Science
Foundation, ARPA, and the Office of Naval Research
(ONR Contract N00014-92-J -1848) for financial support
of this work. S. D. Pedersen thanks the ONR for an
AASERT Fellowship (N00014-93-1-1070). We also thank
Asahi Glass, DuPont, and Dow Chemical for assistance
with monomer precursors.
Su p p or tin g In for m a tion Ava ila ble: Copies of 13C NMR
spectra for compounds 1, 2, 3, 5, 6, 10, 11, 13, 14, and 17 are
available (10 pages). This material is contained in libraries
on microfiche, immediately follows this article on the microfilm
version of the journal, and can be ordered from the ACS; see
any current masthead page for ordering information.
replaced with
a simple distillation apparatus, and CF2-
ClCFClOCF2CF(CF3)OCF2CF2COCl and some pyridinium salts
were crudely distilled under reduced pressure from the reac-
tion mixture, bp 130 °C at 40 mmHg. GLPC 98%. 19F NMR
(CFCl3, CDCl3) -71.2 (m, 2F), -77.3 (m, 1F), -80.1 (d, J )
J O961086A