Preparation of highly fluorinated cyclopropanes and ring-opening reactions with halogens

Article abstract of DOI:10.1021/jo030014y

Various highly fluorinated cyclopropanes 1 were prepared by reaction of the appropriate fluorinated olefins with hexafluoropropylene oxide (HFPO) at 180 °C. The fluorinated nitrile le was converted to the triazine derivatives 2a and 2b by catalysis with Ag₂O and NH₃/(CF₃CO)₂O, respectively. The fluorinated cyclopropanes reacted with halogens at elevated temperatures to provide the first useful, general synthesis of 1,3-dihalopolyfluoropropanes. At 150-240 °C, hexafluorocyclopropane and halogens X₂ produce XCF₂CF₂CF₂X (X = Cl, Br, I) in 50-80% isolated yields. Pentafluorocyclopropanes c-C₃F₅Y [Y = Cl, OCF₃, OC₃F₇ and OCF₂CF(CF₃)OCF₂CF₂Z; Z = SO₂F, CN, CO₂Me] react regiospecifically at 150 °C to give XCF₂CF₂CFXY, c-C₃F₅Br reacts regioselectively with Br₂ to give a 16.7:1 mixture of BrCF₂CF₂ CFBr₂:BrCF₂CFBrCF₂Br, whereas c-C₃F₅H reacts unselectively with I₂ to produce a statistical 2:1 mixture of ICF₂CF₂CFHI:ICF₂CFHCF₂I. Tri- and di(pentafluorocyclopropyl) derivatives 2 also undergo ring-opening reaction with halogens to give 16 and 17. Upon treatment of tetrafluorocyclopropanes 1j, 1k, and 1l with Br₂ or I₂, ring opening occurred exclusively at substituted carbons to give XCF₂CF₂CXY₂. Thermolysis of the ring-opened product ICF₂CF₂CFIOR_F at 240 °C gave R_FI and ICF₂CF₂COF in high yields.

Full text of DOI:10.1021/jo030014y

P r ep a r a tion of High ly F lu or in a ted Cyclop r op a n es a n d
Rin g-Op en in g Rea ction s w ith Ha logen s†
Zhen-Yu Yang
DuPont Central Research and Development, Experimental Station, Wilmington, Delaware 19880-0328
zhenyu.yang-1@usa.dupont.com
Received J anuary 13, 2003
Various highly fluorinated cyclopropanes 1 were prepared by reaction of the appropriate fluorinated
olefins with hexafluoropropylene oxide (HFPO) at 180 °C. The fluorinated nitrile 1e was converted
to the triazine derivatives 2a and 2b by catalysis with Ag2O and NH3/(CF3CO)2O, respectively.
The fluorinated cyclopropanes reacted with halogens at elevated temperatures to provide the first
useful, general synthesis of 1,3-dihalopolyfluoropropanes. At 150-240 °C, hexafluorocyclopropane
and halogens X2 produce XCF2CF2CF2X (X ) Cl, Br, I) in 50-80% isolated yields. Pentafluoro-
cyclopropanes c-C3F5Y [Y ) Cl, OCF3, OC3F7 and OCF2CF(CF3)OCF2CF2Z; Z ) SO2F, CN, CO2Me]
react regiospecifically at 150 °C to give XCF2CF2CFXY, c-C3F5Br reacts regioselectively with Br2
to give a 16.7:1 mixture of BrCF2CF2CFBr2:BrCF2CFBrCF2Br, whereas c-C3F5H reacts unselectively
with I2 to produce a statistical 2:1 mixture of ICF2CF2CFHI:ICF2CFHCF2I. Tri- and di(penta-
fluorocyclopropyl) derivatives 2 also undergo ring-opening reaction with halogens to give 16 and
17. Upon treatment of tetrafluorocyclopropanes 1j, 1k , and 1l with Br2 or I2, ring opening occurred
exclusively at substituted carbons to give XCF2CF2CXY2. Thermolysis of the ring-opened product
ICF2CF2CFIORF at 240 °C gave RFI and ICF2CF2COF in high yields.
In tr od u ction
preparation of 1,3-diiodofluoropropane derivatives by
ring-opening reaction of fluorinated cyclopropanes with
iodine and difluorodiiodomethane and by nickel-catalyzed
reaction of perfluoroepoxide with iodine.4b,c The ring-
opening reaction could be readily extended to make other
fluorinated 1,3-dihalides by reaction of fluorinated cy-
clopropanes with the corresponding halogens. More
interestingly, I have found the ring-opening reaction can
be used to make tri-, tetra-, and hexaiodides, which could
not be made by other means. Herein, I report my detailed
results of the preparation of highly fluorinated cyclo-
proanes and their reactions with halogens.
Perfluoroalkyl iodides are the most widely used flu-
orinated building blocks for introducing perfluoroalkyl
groups into organic molecules. These iodides are prepared
mainly through telomerization of short-chain perfluoro-
alkyl iodides such as CF3I and C2F5I with tetrafluoroet-
hylene.1 Although perfluoroalkylene diiodides have re-
cently been reported to be excellent telogens for the
synthesis of fluorinated thermoplastic elastomers and
other materials, preparation of the starting materials is
difficult and overall yields are low.2 The telomerization
of ICF2CF2I and tetrafluoroethylene yields the desired
diiodides along with significant amounts higher oligo-
mers.2e The diiodides with an odd number of CF2’s are
even more difficult to prepare and require expensive
starting materials and tedious experimental procedures.3
Reaction of halodifluoroacetate with iodine and CuI
provided the first practical method for the preparation
of CF2I2.4a We have developed a facile method for the
Resu lts a n d Discu ssion
I. P r ep a r a tion of F lu or in a ted Cyclop r op a n es 1.
Fluorinated cyclopropanes 1 are usually prepared by the
addition of a difluorocarbene to the appropriate alkenes.5
Although there are a number of sources to produce the
difluorocarbene, we used hexafluoropropylene oxide
(HFPO) as a carbene precursor since HFPO is a com-
mercial product and the byproduct CF3COF is readily
separated from the product and is useful for making other
fluoromonomers. In addition, the difluorocarbene from
HFPO is highly reactive to fluorinated alkenes and in
most cases gives the fluorinated cyclopropanes in high
yields.6 Hexafluorocyclopropane can be readily prepared
by heating HFPO at 180-185 °C. Other substituted
cyclopropanes were made by heating a mixture of HFPO
† Publication No. 8385.
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New York, 1994.
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A. R.; Chen, Q. Y. J . Fluorine Chem. 1997, 82, 151 (c) Li, A. R.; Chen,
Q. Y. Synthesis 1997, 333. (d) Li, A. R.; Chen, Q. Y. Synthesis 1997,
1481. (e) Baum, K.; Malik, A. A. J . Org. Chem. 1994, 59, 6804. (f) Yang,
Z. Y. J . Fluorine Chem. 2000, 102, 239.
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Soc. 1952, 74, 848. (b) Brel, V. K.; Uvarov, V. I.; Zefirov, N. S.; Stang,
P. J .; Caple, R. J . Org. Chem. 1993, 58, 6922.
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(5) Smart, B. E. Chemistry of Organic Fluorine Compounds II;
Hudlicky, M., Pavlath, Eds.; American Chemical Society: Washington,
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10.1021/jo030014y CCC: $25.00 © 2003 American Chemical Society
Published on Web 05/07/2003
4410
J . Org. Chem. 2003, 68, 4410-4416

Preparation of Highly Fluorinated Cyclopropanes
with the appropriate fluorinated alkenes as shown in the
Table 1. Although 1 equiv of HFPO should theoretically
be sufficient, a slight excess of HFPO gave higher yields
of the desired cyclopropanes. Various other perfluorovinyl
ethers also gave cyclopropane derivatives 1b-f in high
yields. The perfluorosulfonyl fluoride and ester-substi-
tuted cyclopropanes, 1d and 1f, were fairly tolerant to
the reaction conditions and could be prepared in greater
than 80% yields from the corresponding funtionalized
perfluorovinyl ethers, whereas the nitrile-substituted
vinyl ether gave the corresponding cyclopropane 1e in
44% yield. Chlorotrifluoroethylene and trifluoroethylene
gave good yields of 1g and 1h , respectively, while
bromotrifluoroethylene only produced bromopentafluo-
rocyclopropane, 1i, in modest to low yields. The observa-
tion of significant amounts of viscous oil indicated the
bromotrifluoroethylene thermally oligomerized at 180 °C.
It has been reported that bromotrifluoroethylene and
difluorocarbene from (CF3)3PF2 at 120 °C gave the
cyclopropane 1i in 61% yield.7 Interestingly, the oligo-
merization could be suppressed and the yield of 1i
improved by the addition of small amounts of a radical
inhibitor.
Multi(pentafluorocyclopropane) compounds 2 were pre-
pared from 1e. It has been well documented that fluori-
nated nitrile compounds can be trimerized into fluori-
nated s-triazines in high yields.8 When c-C3F5OCF2-
CF(CF3)OCF2CF2CN was treated with catalytic amounts
of Ag2O at 120-140 °C neat for 10 h, the corresponding
s-triazine 2a was formed in 80% isolated yield.
Di(pentafluorocyclopropanyl)triazine (2b) was also pre-
pared from 1e. 1e was first treated with excess NH3 at
-78 °C. After warming to room temperature over 2 h the
excess NH3 was evaporated under vacuum. The residue
was diluted with ether and 1 equiv of 1e was added. The
resulting mixture was stirred for 2 h. Finally, excess
trifluoroacetic anhydride was added, and the resulting
mixture was refluxed overnight to give the desired di-
(pentafluorocyclopropanyl)-substituted triazine 2b in 81%
overall yield.9
Difluorocarbene from HFPO also added to 1,1-difluor-
inated ethylenes under similar conditions. Reaction with
1,1-dichlorodifluoroethylene or vinylidene fluoride gave
good yields of the tetrafluorinated cyclopropanes, 1j and
1k , respectively, but 1,1-dibromodifluoroethylene gave
only low yields of tetrafluorodibromocyclopropane 1l.
TABLE 1. P r ep a r a tion of F lu or in a ted Cylcop r op a n es 1
compd no.
X
Y
yield (%)
1a
1b
1c
1d
1e
1f
1g
1h
1i
F
F
F
F
F
F
F
F
F
80
76
67
83
44
80
74
67
63
61
55
28
OCF3
OC3F7
OCF2CF(CF3)OCF2CF2CO2Me
OCF2CF(CF3)OCF2CF2CN
OCF2CF(CF3)OCF2CF2SO2F
Cl
H
Br
Cl
H
F
1j
1k
1l
Cl
H
Br
Br
II. Rin g-Op en in g Rea ction s of F lu or in a ted Cy-
With a mixture of cis- and trans-1,2-difluorodichloro-
ethylene, a mixture of cis- and trans-1,2-dichlorotet-
rafluorocyclopropane, 1m , was obtained in the same ratio
as starting material as reported in the literature.6a,13b
clop r op a n es w ith Ha logen s. Fluorine substituents
(9) Fluoropolymers; Wall, L. A., Ed.; Wiley-Interscience, New York,
1971.
(10) (a) Dolbier, W. R., J r. Advances in Strain in Organic Chemistry;
J AI Press Ltd.: Stamford, CT, 1993; Vol. 2, pp 1-58. (b) Smart, B. E.
Fluorocarbons. In Molecular Structure and Energetics; Liebman, J .,
Greenberg, A., Eds.; VCH Publishers: New York, 1986; Vol. 3. (c)
Dolbier, W. R., J r. Acc. Chem. Res. 1981, 14, 195.
(11) Atkinson, B.; McKeagan, D. J . Chem. Soc., Chem. Commun.
1966, 1890.
(12) (a) Liebmann, J . F.; Dolbier, W. R., J r.; Greenberg, A. J . Phys.
Chem. 1986, 90, 394. (b) Inagaki, S.; Ishitani, Y.; Kakefu, T. J . Am.
Chem. Soc. 1994, 116, 5954.
(6) (a) Sargeant, P. B.; Krespan, C. G. J . Am Chem. Soc. 1969, 91,
415. (b) Sargeant, P. B. J . Org. Chem. 1970, 35, 678. (c) Birchall, J .
M.; Fields, R.; Haszeldine, R. N.; McLean, R. J . J . Fluorine Chem. 1980,
15, 487. (d) Chepik, S. D.; Petrov, V. A.; Galakhov, M. V.; Belen’kii, G.
G.; Mysov, E. I.; German, L. S. Izv. Akad. Nauk SSSR, Ser. Khim.
1990, 8, 1844.
(7) Birchall, M. J .; Fields, R.; Haszeldine, R. N.; Kendall, N. T. J .
Chem. Soc., Perkin Trans. 1 1973, 1773.
(8) (a) Reilly, W. L.; Brown, H. C. J . Org. Chem. 1957, 22, 698. (b)
Brown, H. C.; Schuman, P. D. J . Org. Chem. 1963, 28, 112. (c),
Fedorova, G. B.; Dolgopolskii, I. M. J . Gen. Chem. USSR 1969, 39,
2710. (d) Young, J . A.; Dressler, R. L. J . Org. Chem. 1967, 32, 2237.
(13) (a) Haszeldine, R. N.; Rowland, R.; Speight, J . G.; Tipping, A.
E. J . Chem. Soc., Perkin Trans. 1 1980, 314. (b) Birchall, J . M.;
Haszeldine, R. N.; Roberts, D. W. J . Chem. Soc., Perkin Trans. 1 1973,
1071.
J . Org. Chem, Vol. 68, No. 11, 2003 4411

Yang
significantly affect both the structure and reactivity of
cyclopropanes.10 Hexafluorocyclopropane is much less
stable thermally than its hydrocarbon counterpart,11 and
its strain energy is about twice that of cyclopropane.10b,12
At 70-190 °C, it extrudes difluorocarbene (Ea ) 38.6 kcal/
mol),11b which can be trapped by alkenes to give difluo-
rocyclopropane derivatives.11,13 The CF2: extrusion pro-
cess is considered to be concerted, and in general there
is no direct evidence for homolytic cleavage of carbon-
carbon bonds in cyclopropanes. We discovered that highly
fluorinated cyclopropanes thermally undergo ring-open-
ing reactions with halogens to give 1,3-dihalofluoropro-
panes in good yields.4b
CFBr2:BrCF2CFBrCF2Br resulted, whereas pentafluoro-
cyclopropane reacted unselectively with I2 to give a 2:1
mixture of ICF2CF2CFHI:ICF2CFHCF2I.
When hexafluorocyclopropane 1a was heated with
halogens at 155 °C in a Shaker tube, the corresponding
1,3-dihalohexafluoropropanes were obtained in 50-80%
isolated yields. The trifluoroacetyl fluoride byproduct
produced in the preparation of F-cyclopropanes from
HFPO does not interfere with the ring-opening reactions
with halogens, and it is therefore unnecessary to purify
the fluorocyclopropane. The dihalides X(CF2)3X can thus
be prepared by first heating HFPO at 180-190 °C,
adding the halogen X2, and then heating to 150-190 °C.
With iodine and bromine, 3a and 3b were obtained in
80% and 83% yeilds, respectively. Reaction of 1a with
chlorine gave a modest yield of 3c, probably due to its
high volatility. The ring-opening reaction can also be
carried out with interhalogens such as I-X (X ) Br, Cl).
With I-Br and 1a at 240 °C, a 4.6:1:1.3 mixture of
I(CF2)3Br:Br(CF2)3Br:I(CF2)3I was isolated in 70% yield.
Similarly, the major product with I-Cl was Cl(CF2)3I
along with Cl(CF2)3Cl and I(CF2)3I (83% total yield).
Perfluoroalkoxycyclopropanes reacted with I2 at 240 °C
to form ICF2CF2COF and RFI in quantitative yields via
decomposition of the primary product RFOCFICF2CF2I.
This reaction pathway is supported by the observation
that authentic RFOCFICF2CF2I cleanly decomposed to
RFI and ICF2CF2COF at 240 °C. The possible mechanism
of this transformation is through a radical intermediate.
The iodine and carbon bond is readily cleaved to produce
an intermediate A at high temperature due to the
stabilization of the radical by an adjacent oxygen. The
intermediate A extrudes a perfluoroalkyl radical to form
the acyl fluoride 10. After heating a mixture of 1b with
iodine at 150-180 °C for 1 h and at 240 °C for 8 h, the
resulting mixture was treated with NH3 in ether to give
ICF2CF2CONH2 in 87% overall yield.
Substituted cyclopropanes readily undergo the ring-
opening reactions. With pentafluorocyclopropanes bear-
ing chlorine, bromine, and perfluoroalkoxy substituents,
the ring opening occurred under milder conditions. The
regiochemistry of the ring-opening reactions depends on
the substituents. Chlorine- and perfluoroalkoxy-substi-
tuted pentafluorocyclopropanes reacted with Br2 or I2 at
150-160 °C to give only XCF2CF2CFXY (X ) Br or I; Y
) Cl or RFO) in 58 to 80% yields, which indicates the
ring opening occurred exclusively at the substituted
carbons. Functional groups such as ester, sulfonyl fluo-
ride, and nitrile did not interfere with the ring-opening
reaction. The high regioselectivity can be attributed to
better stabilization of these substituents than that of
fluorine to the radical intermediates. However, bromine-
and hydrogen-substituted pentafluorocyclopropanes have
less regioselectivity. Upon reaction of bromopentafluo-
rocyclopropane and Br2, a 16.7:1 mixture of BrCF2CF2-
This chemistry was used to synthesize other more
complex functionalized iodides, which were used to make
functional materials as illustrated below.
In the presence of ethylene, the perfluorodiiodoether
5a was heated at 180 °C to give an excellent yield of the
4412 J . Org. Chem., Vol. 68, No. 11, 2003

Preparation of Highly Fluorinated Cyclopropanes
diadduct 13, which could then be treated with KOH to
form the diene 14.
The ring-opening products from perfluoroalkoxycyclo-
propanes and bromine decomposed much slowly than the
corresponding products from iodine, due to the stronger
bromine-carbon bond than that of iodine-carbon. After
a mixture of perfluoroalkoxycyclopropane and Br2 was
heated at 150 °C for 3 h and at 250 °C for 20 h, the ring-
opening product was found mostly unreacted and could
be isolated in 54% yield.
of ClCF2CF2CCl3 and ClCF2CClCF2Cl was obtained in a
3.2 to 1 ratio with chlorine. Similarly, upon treatment of
1,1-dibromotetrafluorocyclopropane with Br2, ring open-
ing occurred exclusively at the bromine-substituted
carbon. Reaction of tetrafluorocyclopropane with iodine
required a higher temperature to give ICF2CF2CH2I,
along with other byproducts such as ICF2CF2CF2CF2-
CH2I, at 260 °C. With bromine, only an insoluble black
solid was obtained at 260 °C.
The ring-opening reaction could be extended to multi-
(perfluorocyclopropane) derivatives, thus yielding various
materials which could not be prepared by other means.
For example, when the triazine derivative 2a was heated
with halogens such as iodine and bromine at 140-200
°C, the corresponding ring-opened products were ob-
tained in 88-96% yields. The reactions were carried out
neat or in perfluorinated solvents such as 2-perfluoro-
butyltetrahydrofuran.
When 1,2-dichlorotetrafluorocyclopropane was used as
a substrate, 1,3-dihalodichlorotetrafluoropropanes were
formed exclusively with bromine or iodine. The re-
giospecificity is due to the fact that chlorine stabilizes a
radical better than fluorine. In fact, thermal stereo-
mutation of trans-1m and related compounds to their cis
isomers has been reported.6b,14 The process was proposed
via the intermediacy of a trimethylene diradical. Thus,
in the presence of halogens, the trimethylene diradical
can be trapped to give 19.
Similarly, the bis(perfluorocyclopropane) compound 2b
also reacted with halogens to give the corresponding ring-
opened products in high yields.
In conclusion, I have synthesized various highly flu-
orinated cyclopropane derivatives in modest to high
yields from the reaction of the appropriate fluoroolefins
and hexafluoropropylene oxide (HFPO) at elevated tem-
peratures. The highly fluorinated cyclopropanes have
high strain and when heated with halogens or interh-
alogens, did not undergo the difluorocarbene extrusion
Although tetrafluorocyclopropanes have less strain
energy than hexafluorocyclopropane and substituted
pentafluorocyclopropanes, they decompose to difluoro-
carbene when heated above 200 °C.13 However, no ring-
opening reactions have been reported. I found tetra-
fluorocyclopropanes also underwent ring-opening reac-
tions with halogens at elevated temperatures. Reaction
of 1,1-dichlorotetrafluorocyclopropane with bromine gave
only one product BrCF2CF2CCl2Br, whereas a mixture
(14) (a) Ferrero, J . C.; de Staricco, E. A. R.; Staricco, E. H. J . Phys.
Chem. 1975, 79, 1242. (b) Ferrero, J . C.; Staricco, E. H. Int. J . Chem.
Kinet. 1979, 11, 1287. (c) Dolbier, W. R., J r.; Enoch, H. O. J . Am. Chem.
Soc. 1977, 99, 4532.
J . Org. Chem, Vol. 68, No. 11, 2003 4413

Yang
room temperature overnight and then 20.0 g of (CF3CO)2O was
added at 0 °C. The resulting reaction mixture was stirred at
room temperature for 2 h and at 40 °C overnight. After
evaporation of volatiles, the residue was distilled to give 15.7
g of 2b. Bp 88-89 °C/0.6 mmHg. 19F NMR δ -72.6 (s, 3F),
-80.3 (m, 6F), -82.2 (m, 4F), -85.6 (m, 4F), -118.6 (s, 4F),
-145.2 (t, J ) 21.7 Hz, 2F), -153.0 (ddm, J ) 196.8, 48.6 Hz,
4F), -155.7 (dm, J ) 196.1 Hz, 4F), -162.7 (t, J ) 8.8 Hz,
2F). Anal. Calcd for C20F33N3O4: C, 24.68; N, 4.32. Found: C,
24.87; N, 4.83.
reaction as described previously in the literature, but
instead, ring-opening reaction occurred to give 1,3-
dihalopropanes in good yields. Various functional groups
in the cyclopropanes such as nitrile, sulfonyl, ester, ether,
halogens, and triazine could be tolerated in the ring-
opening reaction. Thus, various fluorinated 1,3-di- and
polyhalides could be readily prepared which could not be
readily made by other means.
P r ep a r a tion of 1,3-Diiod oh exa flu or op r op a n e (3a ). A
shaker tube was charged with 38 g of iodine and 30 g of
hexafluorocyclopropane and heated at 155 °C for 20 h. After
the tube was cooled to room temperature, 56.4 g of liquid was
washed with aqueous Na2SO3 and brine. Distillation gave 48.3
g (80%) of product. Bp 75.5 °C/150 mmHg. 19F NMR δ -58.1
(t, J ) 5.0 Hz, 4F), -105.2 (t, J ) 5.0 Hz, 2F). Anal. Calcd for
C3F6I2: C, 8.92; F, 28.23; I, 62.85. Found: C, 9.13; F, 28.12; I,
61.45.
P r ep a r a t ion of 1,3-d ib r om oh exa flu or op r op a n e (3b ):
Bp 72-74 °C. 19F NMR δ -63.0 (s, 4F), -113.4 (s, 2F). Anal.
Calcd for C3F6Br2: C, 11.63; Br, 51.58. Found: C, 11.62; Br,
52.12.
Exp er im en ta l Section
All fluorinated starting materials are DuPont products
except CF2dCX2 (X ) Cl, Br) and CFCldCFCl, which were
obtained from SynQuest Laboratories Inc. CFCl3 is used as
an internal reference in 19F NMR.
Gen er a l P r ep a r a tion of F lu or in a ted Cyclop r op a n es
1. An autoclave was charged with the desired fluorinated olefin
and 1.1 to 1.4 equiv of hexafluoropropylene oxide (HFPO) and
heated at 180-190 °C for 8-10 h. After venting CF3COF, the
residue was distilled to give fluorinated cyclopropanes 1. If
the product was a gas, the reaction mixture was distilled at
low temperature to give product 1. Compounds 1a , 1b, 1c, 1g,
1h , 1i, 1j, 1l, and 1m are known.6,13
P r ep a r a t ion of c-C3F 5OCF 2CF (CF 3)OCF 2CF 2CO2CH 3
(1d ). Reaction of 425 g of CF2dCFOCF2CF(CF3)OCF2CF2CO2-
CH3 and 335 g of HFPO gave 391.6 g (83%) of 1d : Bp 83-84
°C/35 mmHg. 19F NMR δ -80.4 (s, 3F), -83.5 (m, 2F), -85.2
to -86.4 (m, 2F), -121.6 (s, 2F), -145.7 (t, J ) 22 Hz, 1F),
-152.9 9d, J ) 193.4 Hz, 2F), -155.7 (dm, J ) 194 Hz, 2F),
-162.4 (t, J ) 8.7 Hz, 1F). 1H NMR δ 3.97 (s). IR (neat): 1791
(s), 1308 (s), 1276 (s), 1239 (s), 1152 (s) cm-1. Anal. Calcd for
P r ep a r a tion of 1,3-d ich lor oh exa flu or op r op a n e (3c):
Bp 35-36 °C. 19F NMR δ -67.7 (s, 4F), -119.2 (s, 2F). Anal.
Calcd for C3F6Cl2: F, 51.60. Found: F, 51.91.
Rea ction of Hexa flu or ocyclop r op a n e (1a ) w ith Br o-
m in e Mon oiod id e. A shaker tube was charged with 52 g
(0.251 mol) of BrI and 40.0 g (0.25 mol) of 1a and heated at
240 °C for 20 h. After the tube was cooled to room temperature,
69.3 g of crude products was obtained. 19F NMR analysis
indicated a mixture of 3b and 3d (X ) Br) and 3a in a ratio of
1:4.6:1.3 (mol). Distillation gave 22.3 g of a mixture of 3b and
3d (X ) Br), bp 73-102 °C, 12.0 g of pure 3d (X ) Br), bp
103-104 °C, 17.0 g of a mixture of 3d (X ) Br) and 3a , bp
108-103 °C, and 8.4 g of pure 3a , bp 132 °C. 19F NMR for 3d
(X ) Br) δ -58.6 (m, 2F), -61.3 (m, 2F), -109.3 (m, 2F). Anal.
Calcd for C3F6BrI: C, 10.10; F, 31.95; Br, 22.39; I, 35.56.
Found: C, 1045; F, 31.77; Br, 21.72; I, 36.90.
Rea ction of Hexa flu or ocyclop r op a n e (1a ) w ith Ch lo-
r in e Mon oiod id e. A shaker tube was charged with 16.3 g
(0.1 mol) of ICl and 20.0 g (0.125 mol) of 1a and heated at 230
°C for 10 h. After the tube was cooled to room temperature,
29.2 g of crude products was obtained. 19F NMR analysis
indicated three main products, 3c and 3d (X ) Cl) and 3a in
a ratio of 1:1.75:1.5 (mol). Distillation gave 3.9 g of 3c, bp 34-
35 °C, 3.4 g of a mixture of 3c and 3d (X ) Cl), bp 40-79 °C,
3.0 g of pure 3d , bp 80-81 °C, 5.5 g of a mixture of 3d (X )
Cl) and 3a , bp 83-133 °C, and 9.8 g of pure 3a , bp 133-135
°C. 19F NMR for 3d (X ) Cl) δ 58.8 (tt, J ) 13.1, 5.0 Hz, 2F),
-66.9 (t, J ) 13.1 Hz, 2F), -112.1 (s, 2F).
P r epar ation 1,3-diiodo-1-ch lor oper flu or opr opan e (4a):
Bp 86-88 °C/50 mmHg. 19F NMR δ -51.7 (ddd, J ) 201.9,
9.0, 6.6 Hz, 1F), -55.8 (ddd, J ) 201.7, 24.8, 7.0 Hz, 1F), -72.8
(m, 1F), -94.6 (ddd, J ) 268.3, 13.7, 7.0 Hz, 1F), -102.9 (ddd,
J ) 268.3, 15.3, 9.2 Hz, 1F). Anal. Calcd for C3F5ClI2: C, 8.57;
F, 22.60; Cl, 8.44; I, 60.39. Found: C, 8.52; F, 22.53; Cl, 7.52;
I, 62.27.
P r ep a r a t ion 1,3-d ib r om o-1-ch lor op er flu or op r op a n e
(4b): Bp 114-115 °C. 19F NMR δ -58.5 (ddt, J ) 178.1, 10.8,
4.6 Hz, 1F), -60.0 (ddm, J ) 178, 16.6 Hz, 1F), -70.8 (m, 1F),
-106.7 (dm, J ) 268.7 Hz, 1F), -109.4 (dm, J ) 268.1 Hz,
1F). Anal. Calcd for C3F5ClBr2: C, 11.04; F, 29.11; halogen
calcd as Cl, 32.59. Found: C, 10.53; F, 29.33; halogen calcd as
Cl, 32.24.
C
10H3F15O4: C, 25.44; H, 0.64. Found: C, 26.19; H, 0.73.
P r ep a r a tion of c-C3F 5OCF 2CF (CF 3)OCF 2CF 2CN (1e):
Bp 119-120 °C. 19F NMR δ -80.3 (m, 3F), -84.6 (m, 2F),
-85.7 (m, 2F), -108.7 (t, J ) 5.0 Hz, 2F), -145.1 (t, J ) 19
Hz, 1F), -152.8 (dm, J ) 194.3 Hz, 2F), -155.5 (dm, J ) 194.3
Hz, 2F), -162.4 (t, J ) 9 Hz, 1F). IR (neat): 2270 (w), 1312-
(s), 1278 (s), 1248 (s), 1179 (s), 1157 (s), 1121 (s) cm-1. Anal.
Calcd for C9F15NO2: C, 24.62; F, 64.90; N, 3.19. Found: C,
25.03; F, 65.68; N, 2.93.
P r ep a r a tion of c-C3F 5OCF 2CF (CF 3)OCF 2CF 2SO2F (1f):
bp 91 °C/120 mmHg. 19F NMR δ +45.1 (m, 1F), -80.4 (m, 3F),
-85.2 (dm, J ) 143.1 Hz, 1F), -85.9 (dm, J ) 143 Hz, 1F),
-112.4 (s, 2F), -145.2 (t, J ) 21.5 Hz, 1F), -153.0 (dm, J )
201 Hz, 2F), -155.8 (dm, J ) 201 Hz, 2F), -162.7 (t, J ) 9
Hz, 1F). IR (neat): 1468 (s), 1278 (s), 1245 (s), 1158 (s), 1139
(s), 987 (s) cm-1
.
P r ep a r a tion of 1,1-d ibr om otetr a flu or ocyclop r op a n e
(1k ): Bp 81-82 °C. 19F NMR δ -136.4 (s). HRMS calcd for
C3F4Br2 269.8304, found 269.8257. Anal. Calcd for C3F4Br: C,
13.26. Found: C, 13.61.
P r ep a r a tion of c-C3F 5OCF 2CF (CF 3)OCF 2CF 2CN (2a ). A
mixture of 70 g of 1e and 0.8 g of Ag2O was stirred at 140 °C
for 20 h. The solids were removed by filtration through Celite
and washed with 1,1,2-trifluorotrichloroethane (CFC113).
After removal of CFC113, the filtrate was purified by chro-
matography on silica gel with use of a mixture of hexane and
ethyl acetate in a 90 to 10 ratio as eluent to give 55.3 g of 2a .
19F NMR δ -79.9 (m, 9F), -81.4 (m, 6F), -84.9 (s, 6F), -117.9
(d, J ) 13.8 Hz, 6F), -144.4 (t, J ) 22.1 Hz, 3F), -152.4 (ddm,
J ) 198, 34 Hz, 6F), -155.3 (dm, J ) 198 Hz, 6F), -162.5 (m,
3F). IR 1556 (s), 1314-1031 (vs), 985 (s), 869 (s) cm-1. Anal.
Calcd for C29F45N3O6: C, 24.62. Found: C, 24.78.
P r ep a r a tion of [c-C F 7OCF 2CF (CF 3)OCF 2CF 2]2C3N3CF 3
(2b). To a stirred solut3ion of 9.0 g of 1e and 20 mL of ether
was added excess NH3 at -40 °C. The resulting mixture was
stirred at -40 to -30 °C for 2 h and then warmed to 0 °C.
After removal of all volatiles at room temperature in a vacuum,
the residue was diluted with 10 mL of ether and an additional
8.6 g of 1e was added at -40 °C. The mixture was stirred at
P r ep a r a tion of 1,3-d iiod op en ta flu or op r op yl tr iflu or o-
m eth yl eth er (5a ): Bp 80-81 °C/100 mmHg. 19F NMR δ
-54.9 (d, J ) 10.7 Hz, 3F), -60.8 (ddm, J ) 180.4, 5.5 Hz,
1F), -62.8 (ddm, J ) 180.4, 21.1 Hz, 1F), -71.1 (m, 1F),
-111.8 (dd, J ) 274.2, 5.4 Hz, 1F), -112.9 (ddd, J ) 275, 7.5,
4.3 Hz, 1F). Anal. Calcd for C4F8I2O: C, 10.23; F, 32.35; I,
54.02. Found: C, 10.99; F, 32.01; I, 53.73.
4414 J . Org. Chem., Vol. 68, No. 11, 2003

Preparation of Highly Fluorinated Cyclopropanes
P r ep a r a tion of 1,3-d ibr om op en ta flu or op r op yl tr iflu o-
r om eth yl eth er (5b): Bp 99 °C. 19F NMR δ -54.9 (d, J )
10.7 Hz, 3F), -60.8 (ddm, J ) 180.4, 5.5 Hz, 1F), -62.8 (ddm,
J ) 180.4, 21.1 Hz, 1F), -71.1 (m, 1F), -111.8 (dd, J ) 274.2,
5.4 Hz, 1F), -112.9 (ddd, J ) 275, 7.5, 4.3 Hz, 1F). Anal. Calcd
for C4F8Br2O: C, 12.78; F, 40.44; Br, 42.52. Found: C, 12.72;
F, 42.67; Br, 42.73.
P r ep a r a t ion of 1,3-d iiod op en t a flu or op r op yl h ep t a -
flu or op r op yl eth er (6a ): Bp 85-86 °C/40 mmHg. 19F NMR
δ -55.3 (d, J ) 204.6 Hz, 1F), - 58.8 (ddd, J ) 204.6, 27, 6.3
Hz, 1F), -68.7 (m, 1F), -81.3 to -81.9 (m, 4F), -90.7 (d, J )
147.6 Hz, 1F), -102.4 (dt, J ) 276.7, 8 Hz, 1F), -104.4 (dt, J
) 276.6, 7.5 Hz, 1F), -130.4 (s, 2F). Anal. Calcd for C6F12I2O:
C, 12.65; F, 40.01; I, 44.54. Found: C, 12.57; F, 40.29; I, 45.06.
P r ep a r a tion of 1,3-d ibr om op en ta flu or op r op yl h ep -
ta flu or op r op yl eth er (6b). Bp 134 to 135 °C. 19F NMR δ
-61.0 (dt, J ) 180.3, 4.3 Hz, 1F), -63.1 (dd, J ) 180.8, 22.6
Hz, 1F), -71.0 (m, 1F), -81.6 (m, 3F), -83.2 (dm, J ) 146.5
Hz, 1F), -87.5 (dt, J ) 146.5, 7.6 Hz, 1F), -112.3 (m, 2F),
-130.3 (m, 2F). Anal. Calcd for C6F12Br2O: C, 15.14; F, 47.91;
Br, 33.58. Found: C, 14.78; F, 47.75; Br, 32.30.
Rea ction of c-C3F 7OCF 2CF (CF 3)OCF 2CF 2CO2CH3 (1d )
w ith Iod in e. 7a : Bp 107-110 °C/3 mmHg, 19F NMR δ -55.2
(d, J ) 205.1 Hz, 1F), -58.8 (dm, J ) 204.4 Hz, 1F), -69.0
(m, 1F), -80.0 (s, 3F), -79.6 to -80.7 (m, 1F), -82.5 to -84.0
(m, 2F), -89.9 (m, 0.5 F), -90.3 (m, 0.5F), -102.1 (d, J ) 277.1
Hz, 1F), -104.6 (dt, J ) 277, 8.4 Hz, 1F), -121.5 (s, 2F),
-145.7 (t, J ) 11.3 Hz, 0.5F), -146.0 (t, J ) 11.7 Hz, 0.5F).
1H NMR δ 4.01 (s). IR (neat): 1786 (s), 1243 (s), 1194 (s), 1152
(s) cm-1. Anal. Calcd for C10H3F15I2O4: C, 16.55; H, 0.42; I,
34.96. Found: C, 17.03; H, 0.51; I, 35.21.
P r epar ation of 3-Iodotetr aflu or opr opion yl Am ide (11).
An autoclave was charged with 254 g of iodine and 220 g of
trifluoromethoxypentafluorocyclopropane and heated at 150-
180 °C for 1 h and 240 °C for 8 h. After the tube was cooled to
room temperature and gas was vented, 426.8 g of crude
product 10 was obtained, which was dissolved in 800 mL of
ether, then NH3 has was added at -78 °C to room temperature
until the solution was basic. The reaction mixture was poured
into water and extracted with ether. The ether layer was
washed with water and dried over MgSO4. After removal of
the ether, the residue was re-crystallized from a mixture of
hexane and ether to give 244.6 g (87%) of ICF2CF2CO2NH2,
11: Mp 136-137 °C. 19F NMR δ -62.3 (t, J ) 5 Hz, 2F),
-112.1 (t, J ) 5 Hz, 2F). 1H NMR δ 7.99 (br, 1H), 7.69 (br,
1H). Anal. Calcd for C3H2F4NOI: C, 13.30; H, 0.74; F, 28.05;
I, 46.84. Found: C, 13.35; H, 0.78; F, 27.10; I, 46.87.
Rea ction of c-C3F 5OCF 2CF (CF 3)OCF 2CF 2CO2CH3 (1d )
w ith Iod in e a t 240 °C. A 0.4-L shaker tube was charged with
189 g of c-C3F5OCF2CF(CF3)OCF2CF2CO2CH3 and 100 g of I2
and heated at 150 °C for 3 h and 240 °C for 8 h. Distillation of
the reaction mixture gave 78.3 g of ICF2CF2COF (10), bp 57-
58 °C, and 129.3 g of ICF2CF(CF3)OCF2CF2CO2Me (12a ), bp
98-100 °C/60 mmHg. 19F NMR for 10 δ +28.0 (m, 1F), -62.1
(m, 2F), -111.4 (m, 2F). 19F NMR for 12a δ -58.8 (dm, J )
210 Hz, 1F), -59.9 (dm, J ) 210 Hz, 1F), -76.8 (m, 3F), -82.7
(dm, J ) 158.7 Hz, 1F), -83.7 (dm, J ) 158 Hz, 1F), -121.6
(t, J ) 3.3 Hz, 2F), -134.3 (m, 1F). IR for ICF2CF2COF 1768
(s), 1187 (s), 1150 (s) cm-1. IR for ICF2CF(CF3)CF2CF2CO2Me
1768 (s), 1342 9s), 1304 (s), 1232 to 1110 (s) cm-1. Anal. Calcd
for C7H3F10IO3: C, 18.60; H, 0.67; F, 42.03. Found: C, 18.24;
H, 0.52; F, 42.38.
Reaction of c-C3F5OCF2CF(CF3)OCF2CF2SO2F (1f) with
Iod in e a t 240 °C. A shaker tube was charged with 56 g of
c-C3F5OCF2CF(CF3)OCF2CF2SO2F and 25 g of I2 and heated
at 150 °C for 3 h and at 240 °C for 10 h. Distillation of the
reaction mixture gave 17.4 g of 10, bp 58-59 °C, and 44.3 g of
12b , bp100-104 °C/200 mmHg. 19F NMR for ICF2CF(CF3)-
OCF2CF2SO2F δ +45.5 (m, 1F), -58.7 (dm, J ) 213.7 Hz, 2F),
-60.0 (dm, J ) 214 Hz, 2F), -76.9 (m, 3F), -77.9 (dd, J )
139.2, 22.7 Hz, 1F), -79.7 (dm, J ) 139.2 Hz, 1F), -122.2 (s,
2F), -133.6 (m, 1F). Anal. Calcd for C5F11ISO3: C, 12.62; I,
26.66. Found: C, 12.68; I, 26.67.
Rea ction of c-C3F 5OCF 2CF (CF 3)OCF 2CF 2CN (1e) w ith
Iod in e. 7b: Bp 77 °C/5 mmHg. 19F NMR δ -55.4 (d, J ) 205.1
Hz, 1F), -58.8 (ddd, J ) 205.5, 27.3, 5.2 Hz, 1F), -69.4 (m,
1F), -79.1 to -80.4 (m, 4F), -84.1 to -85.2 (m, 2F), -89.9
(dm, J ) 152.5 Hz, 1F), 102.0 (dm, J ) 277.9 Hz, 1F), -104.5
(dm, J ) 278.4 Hz, 1F), -108.6 (s, 2F), -145.1 (t, J ) 21.2
Hz, 0.5F), -145.6 (t, J ) 21.3 Hz, 0.5F). IR (neat): 2269 (w),
1245 (s), 1180 (s) cm-1. Anal. Calcd for C9F15I2NO2: C, 15.60;
I, 36.63; N, 2.02. Found: C, 15.63; I, 37.50; N, 2.14.
Reaction of c-C3F5OCF2CF(CF3)OCF2CF2SO2F (1f) with
Iod in e. 7c: Bp 97 °C/4.8 mmHg. 19F NMR δ +45.3 (m, 1F),
-55.6 (d, J ) 204.7 Hz, 1F), -58.9 (ddd, J ) 204.7, 27.2, 6.3
Hz, 1F), -69.3 (m, 1F), -79.3 to -80.2 (m, 6F), -89.8 (dm, J
) 144.3 Hz, 1F), -101.9 (dm, J ) 277.9 Hz, 1F), -104.6 (dt, J
) 277.8, 7.7 Hz, 1F), -112.2 (m, 2F), -145.4 (m, 1F). IR
R ea ct ion of 1,3-Diiod op en t a flu or op r op yl Tr iflu or o-
m eth yl Eth er w ith Eth ylen e. A mixture of 50 g of ICF2CF2-
CFIOCF3 and 11.0 g of CH2dCH2 was heated at 180 °C for 4
h and then distilled to give 55.6 g of 13. 19F NMR δ -53.2 (d,
J ) 12.3 Hz, 3F), -114.3 (m, 2F), -123.0 (s, 3F), -126.3 (m,
(neat): 1465 (s), 1245 (vs), 1198 (s) cm-1. Anal. Calcd for C8F16
SO4I2: C, 12.81; F, 40.53; I, 33.84; S, 4.28.
-
1
2F). H NMR δ 3.20-3.64 (m, 4H), 2.61-2.87 (m, 4H). Anal.
Calcd for C8H8F8I2O: C, 18.27; H, 1.53; F, 28.90; I, 48.26.
Found: C, 18.59; H, 1.47; F, 29.25; I, 48.29.
Rea ction of Br om op en ta flu or ocyclop r op a n e (1j) w ith
Br om in e. 8a and 8b: Bp 92-93 °C/200 mmHg. 19F NMR for
8a δ -58.3 (d, J ) 15.2 Hz, 2F), -72.3 (tt, J ) 15.2, 13.7 Hz,
1F), -106.2 (d, J ) 13.7 Hz, 2F). 19F NMR for 8b δ - 54.7
(dm, J ) 178 Hz, 2F), -56.3 (dm, J ) 178.1 Hz, 2F), -123.4
(pent, J ) 15 Hz, 1F). Anal. Calcd for C3F5Br3: C, 9.72; F,
25.62. Found: C, 10.21; F, 24.95.
P r epar ation of CH2dCHCF2CF2CF(OCF3)CHdCH2 (14).
To a stirred solution of 21.0 g of 13 and 20 mL of EtOH was
added 6.7 g of KOH in 6 mL of water and 20 mL of EtOH at
75 °C. The resulting mixture was stirred for 2 h, and water
was added. The lower layer was separated and washed with
water and brine to give 8.3 g of 98.5% pure 14. Distillation
gave pure 14: Bp 117-119 °C. 19F NMR δ -53.4 (d, J ) 17
Hz, 3F), -112.7 (m, 2F), -125.2 (s, 2F), -129.1 (t, J ) 7.7 Hz,
Rea ction of P en ta flu or ocyclop r op a n e (1h ) w ith Io-
d in e. A shaker tube was charged with 25.4 g of I2 and 14 g of
pentafluorocyclopropane and heated at 190 °C for 3 h and 210
°C for 2 h. After the tube was cooled to room temperature, the
crude product was washed with aqueous Na2SO3 to give 24.3
g of material. 19F NMR and 1H NMR analysis indicated a
mixture of ICF2CF2CFHI (9a ) and ICF2CFHCF2I (9b) in a 2:1
1
1F). H NMR δ 5.7 to 6.10 (m). Anal. Calcd for C8H6F8O: C,
35.57; H, 2.24; F, 56.27. Found: C, 36.87; H, 2.23; F, 56.09.
Rea ction of [c-C3F 5OCF 2CF (CF 3)OCF 2CF 2]3C3N3 (2a )
w ith Br om in e. A mixture of 3.94 g of 2a , 2.1 g of Br2, and
1.5 mL of 2-perfluorobutyltetrahydrofuran was stirred in a
sealed tube at 160-170°C for 6 h. After removal of volatiles,
the crude product was purified by chromatography on silica
gel (hexane/ethyl acetate 90:10) to give 5.2 g (96%) of 16b: 19F
NMR δ -61.3 (d, J ) 181.1 Hz, 3F), -63.5 (dm, J ) 181 Hz,
3F), -71.5 (m, 3F), -80.4 (s, 9F), -82.0 (m, 3F), -82.4 (s, 6F),
-86.9 (m, 3F), -112.4 (m, J ) 277.8 Hz, 3F), -119.0 (m, 6F),
145.6 (m, 3F). Anal. Calcd for C27F45Br6N3O6: C, 18.05; N, 2.34;
Br, 26.68. Found: C, 18.27; N, 2.35; Br, 25.35.
1
ratio. H NMR for ICF2CF2CFHI δ 7.16 (ddd, J ) 47.6, 20.7,
1.5 Hz). 1H NMR for ICF2CFHCF2I δ 4.80 (dtt, J ) 42.1, 14.8,
3.3 Hz, 1H). 19F NMR for ICF2CF2CFHI δ -52.6 (dm, J ) 207.8
Hz, 1F), -54.8 (dm, J ) 207.8 Hz, 1F), -101.0 (ddt, J ) 273.1,
32.3, 6.3 Hz, 1F), -116.3 (dm, J ) 273.1 Hz, 1F), 165.7 (m,
1F). 19F NMR for ICF2CFHCF2I δ -57.9 (dm, J ) 207.8 Hz,
2F), -59.8 (dt, J ) 207.8, 6.5 Hz, 2F), -176.2 (m, 1F). HRMS
calcd for C3HCF5I2 385.8088, found 385.7962 for ICF2CF2CFHI
and 385.8171 for ICF2CFHCF2I. Anal. Calcd for C3F5HI2: C,
9.34; H, 0.26; F, 24.62. Found: C, 9.00; H, 0.22; F, 24.81.
Rea ction of [c-C3F 5OCF 2CF (CF 3)OCF 2CF 2]3C3N3 w ith
J . Org. Chem, Vol. 68, No. 11, 2003 4415

Yang
Iod in e. 16a : 19F NMR δ -55.3 (d, J ) 205.2 Hz, 3F), -59.0
(dm, J ) 205 Hz, 3F), -69.1 (m, 3F), -79.6 to 80.6 (m, 12F),
-82.2 (m, 6F), -89.7 (m, 3F), -101.9 (dm, J ) 277.8 Hz, 3F),
-104.6 (dm, J ) 277.8 Hz, 3F), -118.7 (m, 6F), 145.5 (m, 3F).
Anal. Calcd for C27F45I6N3O6: F, 41.13; N, 2.02; I, 36.62.
Found: F, 41.65; N, 2.11; I, 35.27.
Reaction of [c-C3F5OCF2CF(CF3)OCF2CF2]2C3N3CF3 (2b)
w ith Br om in e. 17a : 19F NMR δ -61.3 (d, J ) 180.8 Hz, 2F),
-63.5 (dt, J ) 181.0, 10.7 Hz, 2F), -71.3 (m, 2F), -72.1 (s,
3F), -80.2 (s, 6F), -81.7 to -82.5 (m, 6F), -86.6 (m, 2F),
-112.4 (m, 4F), -118.9 (m, 4F), -145.6 (m, 2F). Anal. Calcd
for C20F33N3O4Br4: C, 18.58; N, 3.25; Br, 24.72. Found: C,
18.51; N, 3.24; Br, 24.17.
Reaction of [c-C3F5OCF2CF(CF3)OCF2CF2]2C3N3CF3 (2b)
w ith Iod in e. 17b: 19F NMR δ -55.6 (d, J ) 205.1 Hz, 2F),
-59.2 (dm, J ) 205.7 Hz, 2F), -69.0 (m, 2F), -72.1 (s, 3F),
-80.2 to -80.7 (m, 8F), -82.5 (m, 4F), -89.7 (m, 2F), -102.0
(dm, J ) 277.8 Hz, 2F), -104.7 (dm, J ) 278 Hz, 2F), -118.8
(m, 4F), -145.8 (m, 2F). Anal. Calcd for C20F33N3O4I4: C, 16.22;
N, 2.84. Found: C, 17.02; N, 2.96.
Rea ction of 1,1-Dich lor otetr a flu or ocyclop r op a n e (1j)
w it h Br om in e. A mixture of 5.5.0 g of 1,1-dichlorotetra-
fluorocyclopropane and 4.8 g of Br2 was heated in a sealed tube
at 160 °C for 2 h and at 180 °C for 4 h. Distillation of the crude
product gave 8.0 g of BrCF2CF2CCl2Br (18a ), bp 153-154 °C.
19F NMR δ -55.5 (s, 2F), -102.0 (s, 2F). Anal. Calcd for C3F4-
Cl2Br2: C, 10.51; F, 22.17; halogen calcd as Cl, 41.37. Found:
C, 10.68; F, 22.20; halogen calcd as Cl, 42.03.
Rea ction of 1,1-Dibr om otetr a flu or ocyclop r op a n e (1l)
w ith Br om in e. A mixture of 2.72 g of 1,1-dibromotetrafluo-
rocyclopropane and 2.0 g of Br2 was heated in a sealed tube
at 170 °C for 5 h. The crude product was washed with aqueous
Na2SO3 solution and distilled to give 4.1 g of BrCF2CF2CBr3
(18b), bp 120-122 °C/80 mmHg. 19F NMR δ -53.4 (s, 2F),
-98.0 (s, 2F). HRMS calcd for C3F4Br4 427.6672, found
427.6706. Anal. Calcd for C3F4Br4: C,8.35. Found: C, 8.80.
Rea ction of 1,1-Dih yd r otetr a flu or ocyclop r op a n e (1k )
w it h Iod in e. A mixture of 30 g of 1,1-dihydrotetrafluoro-
cyclopropane and 25.4 g of I2 was heated in a sealed tube at
270 °C for 2.5 h. The reaction mixture was washed with
aqueous Na2SO3 to give 45.5 g of crude product, which was
distilled to give 5.6 g of 18a , bp 56-82 °C/10 mmHg, 5.8 g of
18b, bp 82-97 °C/100 mmHg, and 10.7 g of ICF2CF2CH2I
(18c), bp 97-102 °C/10 mmHg. 19F NMR δ -59.5 (t, J ) 4.0
Hz, 2F), -101.5 (tt, J ) 16.7, 4.0 Hz, 2F). HRMS calcd for
C3H2F4I2 367.8182, found 367.8142. One of the byproducts is
ICF2CF2CF2CF2CH2I with calcd C5H2F8I - I 340.9075, found
340.9076.
Rea ction of 1,1-Dich lor otetr a flu or ocyclop r op a n e (1j)
w ith Ch lor in e. After a mixture of 11.0 g of 1,1-dichlorotet-
rafluorocyclopropane and 7.0 g of Cl2 was heated in a shaker
tube at 260 °C for 10 h, 11.0 g of crude product was obtained,
which was distilled to give 7.1 g of product, bp 103-107 °C.
19F NMR indicated a mixture of ClCF2CF2CCl3, 18d , and
ClCF2CCl2CF2Cl, 18e, in a 3.2 to 1 ratio. 19F NMR for ClCF2-
CF2CCl3 δ -61.3 (s, 2F), -108.0 (s, 2F). 19F NMR for ClCF2-
CCl2CF2Cl δ -65.1 (s). HRMS calcd for C3F4Cl4 - Cl 216.9002,
found 216.9032 for ClCF2CF2CCl3 - Cl and 216.8995 for ClCF2-
CCl2CF2Cl - Cl.
Rea ction of 1,2-Dich lor otetr a flu or ocyclop r op a n e (1m )
w ith Br om in e. A mixture of 5.5 g of 1,2-dichlorotetrafluoro-
cyclopropane and 5.3 g of Br2 was heated in a sealed tube at
140 °C for 1 h, at 160 °C for 2 h, and at 165 °C for 1 h. After
being washed with aqueous Na2SO3, the organic layer was
distilled to give 8.4 g of BrCFClCF2CFClBr (19a ), bp89-92
°C/100 mmHg. 19F NMR indicated two diastereoisomers: first
isomer δ -65.1 (t, J ) 9 Hz, 2F), -102.7 (t, J ) 9 Hz, 2F);
second isomer δ -65.7 (t, J ) 9 Hz, 2F), -108.8 (dt, J ) 259,
10 Hz, 1F), -105.1 (dt, J ) 259, 9.3 Hz, 1F). HRMS calcd for
C3F4Cl2Br2 - Br 260.8497, found 260.8568.
Rea ction of 1,2-Dich lor otetr a flu or ocyclop r op a n e (1m )
w it h Iod in e. A mixture of 5.5 g of 1,2-dichlorotetrafluoro-
cyclopropane and 8.9 g of I2 was heated in a sealed tube at
140 °C for 1 h, at 160 °C for 2 h, and at 165 °C for 1 h. After
being cooled to room temperature, the reaction mixture was
washed with aqueous Na2SO3. After removal of CF2ClCFCl2,
the residue (9.6 g) was distilled to give 8.3 g of ICFClCF2CFClI
(19b), bp 120 °C/40 mmHg. 19F NMR indicated two diastere-
oisomers: first isomer δ -65.3 (t, J ) 14.6 Hz, 2F), - 91.6 (t,
J ) 15 Hz, 2F); second isomer δ -67.6 (t, J ) 14 Hz, 2F), -88.0
(dt, J ) 257, 13 Hz, 1F), -100.6 (dt, J ) 257, 13 Hz, 1F).
HRMS calcd for C3F4Cl2I2 435.7403, found 435.7402.
Ack n ow led gm en t. The author thanks Mr. R. E.
Smith, J r., for technical assistance, the High Pressure
Research Lab of DuPont for running all high-pressure
reactions, Drs. P. J . Krusic and B. E. Smart for helpful
discussions, and Dr. M. Hofmann for his comments on
the manuscript.
J O030014Y
4416 J . Org. Chem., Vol. 68, No. 11, 2003