2,2-Dihydroperfluoropentane (HFC 4310 mf) synthesis from HFP dimer

Article abstract of DOI:10.1016/S0022-1139(03)00145-3

The thermodynamic dimer of hexafluoropropene (HFP) may be used for the one pot synthesis of 2H-perfluoro-2-pentene, which is the starting compound for preparation of 2,2-dihydroperfluoropentane (HFC 4310 mf).

Full text of DOI:10.1016/S0022-1139(03)00145-3

Journal of Fluorine Chemistry 123 (2003) 227–231
2,2-Dihydroperfluoropentane (HFC 4310 mf) synthesis from
HFP dimer
Yuri Cheburkov*, George G.I. Moore
3M Company, 3M Center, St. Paul, MN, USA
Received 28 March 2003; received in revised form 6 May 2003; accepted 9 May 2003
Abstract
The thermodynamic dimer of hexafluoropropene (HFP) may be used for the one pot synthesis of 2H-perfluoro-2-pentene, which is the
starting compound for preparation of 2,2-dihydroperfluoropentane (HFC 4310 mf).
# 2003 Elsevier B.V. All rights reserved.
Keywords: Hexafluoropropene dimer; Perfluoroisobutene; HFC 4310 mf; HFC 236 fa
1. Introduction
2. Results and discussion
Reactions of perfluoro(2-methyl-2-pentene) (1), the ther-
modynamic dimer of hexafluoropropene (HFP), are some-
times impossible to explain without invoking isomerization
to terminally unsaturated perfluoro(2-methyl-1-pentene) (2)
[1–3]. One well-known incidence of such isomerization is
evident in the structure of thermodynamic HFP trimer. It
contains a normal propyl group (instead of isopropyl), which
is derived from the isomeric dimer 2 with the terminal
double bond [4] (Scheme 1).
Methylpentene (2) is a homolog of perfluoroisobutene
(PFIB) CF2¼C(CF3)CF3 and we anticipated its high reac-
tivity in nucleophilic additions like those of PFIB, the
chemistry of which is very well-known (see review [5]).
PFIB is a highly toxic gas resulting from processes where
perfluorinated compounds are exposed to high temperature.
PFIB is highly electrophilic and reacts with water to give
2H-hexafluoroisobutyric acid [6] and 2,2-dihydrohexafluor-
opropane (HFC 236 fa) as a result of decarboxylation of this
acid [7] (Scheme 2).
Hoechst AG chemists in 1976 [11] first studied the
reaction of HFP dimer 1 with water in the presence of
triethylamine. They found that water reacted easily to sub-
stitute the vinylic fluorine, forming triethylammonium per-
fluoro(2-methyl-2-pentene-2-olate) (Scheme 3).
Three years later, Nesmeyanov Institute chemists showed
that the reaction of this enolate with additional triethylamine
and water gives 2H-nonafluoro-2-pentene (3). This resulted
from enol rearrangement to the unsaturated acid fluoride and
subsequent substitution of COF group by hydrogen [12]
(Scheme 4).
We tried to combine both these reactions by reacting 1
with water and a two-fold excess of triethylamine to hopes of
preparing olefin 3. However, pentafluorobutanone (5) and
hexafluoropropane (6) were the main reaction products with
only a small amount (12% yield) of olefin 3. The inter-
mediate 2H-perfluoroisopropylpentafluoroethyl ketone (4)
or its triethylammonium enolate undergoes mainly haloform
degradation and hydrolysis, rather than rearrangement
(Scheme 5).
Water, being a small molecule, attacks the vinylic fluorine
in the HFP dimer very easily, and we could not find con-
ditions where the isomer with a terminal double bond is the
preferred reacting species.
2,2-Dihydrohexafluoropropane may be also prepared from
the adduct of PFIB with methanol [8,9], which has been a
byproduct of some industrial processes.
We decided to reinvestigate the reaction of the HFP dimer
with water and alcohols. In this case, one might expect to
obtain 2,2-dihydrodecafluoropentane (HFC 4310 mf), which
is known as a good candidate for replacing CFC 113 [10].
The situation is different when bulky tert-butanol is used
in place of water (see also [13]). The primary reaction
product, unstable 2H-perfluoro(2-methylpentyl)-tert-butyl
ether (7), may be isolated if pyridine is used as the catalyst.
A substantial amount of ester 8 is also produced, probably
* Corresponding author. Tel.: þ1-651-731-1452.
E-mail address: yche28@visi.com (Y. Cheburkov).
0022-1139/$ – see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-1139(03)00145-3

228
Y. Cheburkov, G.G.I. Moore / Journal of Fluorine Chemistry 123 (2003) 227–231
isomerization
HFP
(CF3)2C=CFC2F5
1
CF2=C(CF3)CF2CF2CF3
2
(CF3)2CFCF=C(CF3)CF2CF2CF3
HFP trimer
Scheme 1.
(CF3)2C=CF2 + H2O
(CF3)2CHCOOH
CF3CH2CF3
HFC 236fa
With triethylamine, the a-difluoroether (7) is easily (even
spontaneously) transformed into fluorinated 2-methylpenta-
noic (8) and 2-methylpentenoic (9) acid esters (Scheme 6).
A mixture of acids 10 and 11 was prepared from esters 8
and 9 by heating with p-toluenesulfonic acid. This acid
mixture undergoes decarboxylation in aqueous solution in
the presence of triethylamine. A sample of this mixture with
approximately 40% of acid 10 was decarboxylated in this
way and only C5HF9 pentene was obtained. There was none
of the desired C5H2F10 in the reaction product.
PFIB
Scheme 2.
-
o
+
(CF3)2C=CFC2F5 + H2O + Et3N
(CF3)2C=CC2F5 Et3NH
Scheme 3.
through the elimination of tert-butylfluoride, followed by
the reaction of the resulting 2H-perfluoro(2-methylpenta-
noic) acid fluoride with tert-butanol. In this particular case,
as in other reactions of the dimer 1 with water and tert-
butanol, some quantity of hydrogen fluoride is produced in
the form of its complex with tertiary amines. This HF is
captured by the HFP dimer to give 2H-perfluoro(2-methyl-
pentane) (CF3)2CHC3F7, which decreases the yield of the
desired ether 7 or esters 8 and 9. This is not a real loss,
because the methylpentane C6HF13 may be successfully
used in the synthesis of pentene 3 instead of HFP dimer
(see Section 3.8 for experimental details).
Decarboxylation of 2H-hexafluoroisobutyric acid (12)
(prepared from PFIB) thus differs from decarboxylation
of 2H-perfluoro(2-methylpentanoic) acid (10) (as a mixture
with the acid 11 prepared from HFP dimer). Only alkane 6
was obtained from PFIB. Only olefin 3 was obtained from its
C6 homolog (Scheme 7).
Preparation of 2H-pentafluoropropene (13) from hexa-
fluoroisobutyric acid is rather difficult. Tertiary amines do
not work, and thermal decarboxylation of the Na or K salts
of the acid requires exceptionally dry conditions [14]. In
contrast, the 2H-nonafluoropentene (3), and not the pentane
(HFC 4310 mf), is the only product from decarboxylation of
-
o
H2O
rearrangement
+
(CF3)2C=CC2F5 Et3NH
C2F5CF=C(CF3)COF
C2F5CF=CHCF3
3
CO
-
2
Scheme 4.
-
HF and hydrolysis
C2F5COCH(CF3)2 + Et3N
4
C2F5COCH(COOH)2
C2F5COCH3 + CO2
5
Haloform degradation
C2F5COOH + CF3CH2CF3
6
Scheme 5.
Py
C3F7CH(CF3)CF2Ot-Bu
7
t-BuOH
t-BuOH
C3F7C(CF3)=CF2
t-BuF
-
Et3N
C3F7CH(CF3)COOt-Bu + C2F5CF=C(CF3)COOt-Bu
9
8
TosOH
C3F7CH(CF3)COOH + C2F5CF=C(CF3)COOH
11
10
Scheme 6.

Y. Cheburkov, G.G.I. Moore / Journal of Fluorine Chemistry 123 (2003) 227–231
229
-CO2
and no
CF3C(CF3)=CF2
CF3C(C3F7)=CF2
CF3CH(CF3)COOH
12
CF3CH2CF3
6
CF2=CHCF3
13
-CO2 -HF
C2F5CF=CHCF3
3
CF3CH(C3F7)COOH
10
Scheme 7.
and weight percent concentrations for all the identified
components. CFCl3 was the solvent for 19F as well as for
1H NMR, unless otherwise noted. For analysis of acids 10
and 11 Varian UNITY plus 400 and Varian UNITY INOVA
500 FT-NMR spectrometer were used. Initial one-dimen-
sional (1D) 400 MHz 1H NMR and 376 MHz 19F NMR were
acquired. Additional two-dimensional correlated spectro-
scopy (2D-COSY) experiments were also performed to
facilitate assignment of some of the impurity components.
Specifically, a 19F/19F NMR homonuclear COSYexperiment
and a 19F/1H NMR heteronuclear HF-COSY experiment
were collected. GC/MS analyses were accomplished using
a 105 m ꢀ 0:32 mm Rtx-5 column to introduce the sample
into the Finnigan SSQ-700 mass spectrometer. The sample
components were ionized using chemical ionization with
methane as the reagent gas. The GC column was operated
from 40 to 300 8C with a temperature ramp of 108/min. With
the aid of GC/MS analysis results, the combined 1D and 2D
1H NMR spectral data were used to assign the major
component as the E-isomeric form of the acid 11. Two of
the other components including the Z-isomeric form and
acid 10 were also assigned. The 1D 19F NMR spectrum was
then used to calculate the relative weight percent concen-
trations of the three identified components. A gas chroma-
tograph HP 5890 Series 2 with J&W Scientific fused silica
capillary column DB 210 (30 m ꢀ 0:325 mm) with a FID
detector was used for both liquids and gases analysis. IR
spectra were recorded on Digilab FTS-40 FTIR spectro-
meter. Some well-known non-fluorinated compounds like
isobutene, tert-butanol, etc. were identified by comparison
of their GC retention time with the Aldrich samples.
.
.
CF3CH(CF3)COOR + Et3N
C3F7CH(CF3)COOR + Et3N
CF2=C(CF3)COOR + Et3N HF
Scheme 8.
CF2=C(C3F7)COOR + Et3N HF
.
C2F5CF=C(CF3)COOR + Et3N HF
Scheme 9.
the acid 10 in aqueous solution. The same difference is
observed when neat esters of the both acids are treated with
base. There is no visible reaction of 2H-hexafluoroisobutyric
acid methyl or ethyl ester with triethylamine, but we
observed immediate dehydrofluorination in case of ester
8. The explanation for the difference may be as follows:
dehydrofluorination of a hexafluoroisobutyrate is a reversi-
ble process because a very reactive terminal double bond
formed in the reaction (Scheme 8).
The same reversible process is possible for 2H-perfluoro-
2-methylpentanoic acid ester, but much less active internal
double bond can also be formed, rendering dehydrofluor-
ination irreversible (Scheme 9).
The synthesis of 2H-nonafluoropentene (3) from HFP
dimer may be accomplished as a one pot preparation (see
Section 3). The target compound C3F7CH2CF3 (HFC 4310
mf) was prepared by HF addition to the pentene 3 using
Olah’s reagent as a source of hydrogen fluoride or antimony
pentafluoride as a catalyst in anhydrous HF solution.
3.1. Reaction of HFP dimer with water and
triethylamine
3. Experimental details
Specialty Materials Manufacturing Division analytical
group at 3 M provided analytical data. The 1H and 19F
NMR spectra were acquired using a Bruker AC 270 spectro-
meter operating at 270.13 or 254.18 MHz frequency. The
samples were placed in an NMR tube, spiked with small
amount CFCl3 and TMS for both 19F and 1H chemical shifts
zero reference given in ppm, and spiked with small amount
of p-hexafluoroxylene (p-HFX) for use as a cross integration
standard. Use of the p-HFX facilitates the cross correlation
of various proton and fluorine signals intensities for quali-
tative purposes [15]. The cross integration measurement
technique was used to derive the overall relative mole
HFP dimer 1 (3.0 g, 10 mmol), triethylamine (3.03 g,
30 mmol), 3 ml H2O and 1.7 g CH3CN were heated in an
Ace-Glass Inc. pressure tube with stirring at 45–60 8C for
5 h. The cooled (ꢁ15 8C) reactor was opened and the
reaction mixture was distilled to give 0.96 g liquid with
bp up to 70 8C and 0.74 g of low boiling material in a trap
(ꢁ78 8C). The combined liquid was cooled to 0 8C and
washed with 15% HCl solution, and the organic layer was
separated by water freezing to get 1.4 g of the mixture (GC):
47% hexafluoropropane (6) (43% yield), 22% nonafluoro-
pentene (3) (12% yield) and 18% pentafluorobutanone (5)
(18% yield) (see NMR and MS in Section 3.7).

230
Y. Cheburkov, G.G.I. Moore / Journal of Fluorine Chemistry 123 (2003) 227–231
3.2. Reaction of HFP dimer with tert-butanol and
triethylamine
change. There was separated 1.71 g (99% yield) liquid pro-
duct which was pure (98.5% by GC) tert-butyl ester 9 of
perfluoro(2-methyl-2-pentenoic) acid (two isomers 16:1).
By Et3N: From 0.865 g of the esters mixture (74% of
saturated ester 8 and 23% of unsaturated ester 9) and 0.27 g
(50% excess) triethylamine for 30 min at 20 8C (after wash-
ing with water and drying) there was prepared 0.782 g (87%
yield) of the ester 9 with 92% (GC) purity.
HFP dimer perfluoro(2-methyl-2-pentene) (6.0 g, 20
mmol), triethylamine (2.05 g, 20 mmol) and tert-butanol
(3.7 g, 50 mmol) were heated in an Ace-Glass Inc. pressure
tube with Ace-Thred PTFE cap and with a magnetic bar
stirrer at 55–60 8C for 23 h. The initially clear liquid became
a suspension of white crystals in a slightly colored solution.
The tube was cooled to 0 8C, opened and water (5 ml) was
added to dissolve the solid material. The lower organic layer
washed with 15% HCl solution and water, dried MgSO4 to
give 9.69 g of a mixture consisting of (GC): 14% isobutene,
1% tert-butanol, 14% tert-butyl fluoride (CH3)3CF 19F anþd
1H NMR: ꢁ132.4 (CF dectet), 1.27 (CH3 d); MS: no M
was observed, 61 [(M ꢁ CH3)þ 7], 57 [(M ꢁ F)þ 100]; 4%
3.5. Perfluoro(2-methyl-2-pentanoic) acid (10) and
perfluoro(2-methyl-2-pentenoic) acid (11)
The above mixture of tert-butyl esters 8 and 9 (1.2 g) was
heated with 0.17 g of Aldrich p-toluenesulfonic acid mono-
hydrate at 150 8C for 30 min. The resulting water-insoluble
mixture of acids 10 and 11 was dissolved in potassium
bicarbonate solution, separated after acidification and dis-
tilled from the mixture with equal volume of conc. H2SO4 to
give 0.8 g (80%) acids 10 and 11 with bp 135–137 8C,
a
b
c
d
2H-perfluoro(2-methylpentane) (CF3 )2CHCF2 CF2 CF3
1
19F and H NMR: ꢁ62.1 (a, CF3 m), ꢁ112.4 (b, CF2 m),
ꢁ125.9 (c, CF2 dm), ꢁ80.9 (d, CF3 t), 3.80 (CH m); MS: no
Mþ was observed, 301 [(M ꢁ F)þ 100]; 17% ester 9
a
b
c
d
consisting of: 6.3% acid 10 CF3 CF2 CF2 CH(CF3 )COOH
19F and 1H NMR: ꢁ80.6 (a, CF3 t), ꢁ125.4 (CF2b m), ꢁ113.2
andꢁ114.6(c,CF2 Abq, J ¼ 284 Hz), ꢁ62.7(d,CF3 m),4.40
CF3 CF2 CFc¼C(CF3 )COOC(CH3 )3 19F and 1H NMR:
ꢁ83.6 (a, CF3 d), ꢁ120.2 (b, CF2 d), ꢁ117.4 (c, CF m),
ꢁ60.5 (d, CF3 d), 1.45 (e, CH3 s); MS: 333 [(M þ 1)þ 5],
317 (10), 277 (100), 259 (88); 37% tert-butyl ester 8
a
b
d
e
(CH qt or tq); acid 11 CF3 CF2 CFc¼C(CF3 )COOH 19F and
a
b
d
1H NMR: 87.4% E-isomer (Fc trans CF3 ), ꢁ83.3 (a, CF3 d),
d
a
b
c
d
f
CF3 CF2 CF2 CHe(CF3 )COOC(CH3 )3 19F and H NMR:
ꢁ80.86 (a, CF3 t), ꢁ125.7 (b, CF2 m), ꢁ113.5 and ꢁ115.8
(c, CF2 Abq, J ¼ 285 Hz), ꢁ62.9 (d, CF3 m), 3.82 (e, CH m),
1.45 (f, CH3 s); MS:353 [(M þ 1)þ 2], 325 (8), 297 (100), 279
(18). Themixturewasdistilled togive 6.87 g ofa fraction with
bp 120–135 8C ([6] bp 70–85 8C at 150 mmHg) consisted
of (GC): 32% ester 9 and 29% ester 8 with the combined
yield 88%.
ꢁ119.9 (b, CF2 d), ꢁ110.8 (c, CF m), ꢁ60.0 (d, CF3 d); 6.3%
1
d
Z-isomer (Fc cis CF3 ), ꢁ83.3(a, CF3), ꢁ119.0 (b, CF2 m),
ꢁ104.0 (c, CF m) ꢁ56.0 (d, CF3 m); acid 11 MS: 277
[(M þ 1)þ 100], 259 (36), 237 (96) 213 (40); IR (neat,
KBr, cmꢁ1): 1709 (C¼C), 1743 (CO), 2800–3300 (OH).
3.6. 2H-perfluoro-2-pentene (3)
The solution of 2.97 g (11 mmol) acid 11, 5 ml H2O and
1.5 g (15 mmol) triethylamine was heated at 64–80 8C until
a gas evolution was ceased. Combined organic material from
a receiver and a trap (ꢁ78 8C) was washed by 15% HCl
solution, then water, dried MgSO4 and distilled to give
1.88 g (8 mmol, 73% yield) pentene 3 with bp 32–33 8C
and purity (GC) 99% ([16] bp 32–33 8C). See NMR and MS
in Section 3.7.
3.3. Reaction HFP dimer with tert-butanol and pyridine
The same apparatus and procedure were used as in
Section 3.2 employing 6.0 g (20 mmol) HFP dimer, 3.2 g
(43 mmol) tert-butanol and 3.2 g (40 mmol) pyridine. After
the reaction was completed, an excess of pyridine was
washed out with water to give 6.2 g of organic material,
which after distillation with water gave 2.9 g (36% yield)
2H-perfluoro(2-methylpentane) with bp 55–65 8C (79%
pure) and 2.94 g of fraction with bp up to 101 8C consisting
of (GC): 39% tert-butyl ester 8 and 49% tert-butyl ether (7)
3.7. One pot synthesis 2H-perfluoro-2-pentene (3) from
HFP dimer
a
b
c
d
e
1
CF3 CF2 CF2 CH(CF3 )CF2 OC(CH3)3 19F and H NMR:
ꢁ80.97 (a, CF3 t), ꢁ125.3 (b, CF2 m), ꢁ111.2 and ꢁ112.3
(c, CF2 Abq, J ¼ 300 Hz), ꢁ61.7 (d, CF3 m), ꢁ58.2 (e, CF2
s broad), 3.60 (CH m), 1.40 (CH3 s); MS: 373 [(M ꢁ 1)þ 10],
359 (100), 301 (14).
The dimer 1 (400 g, 1.3 mol), triethylamine (170 g,
1.7 mol) and tert-butanol (224 g, 3 mol) were heated in a
glass pressure reactor at 55–60 8C for 20 h with stirring. The
reactor was cooled to 0 8C and opened (there was no pressure
inside) and the reaction mixture washed by water, 15% HCl
solution and water again to give 484 g organic material
consisting of (GC): 71% mixture of esters 8 and 9 along with
some low boiling compounds (same as in Section 3.2). The
mixture was heated at 110–115 8C for 3 h with 15 g
p-toluenesulfonic acid (TosOH) to give 365 g of crude acid
mixture. To this acid mixture 300 ml H2O was added and then
gradually 150 g of triethylamine to keep the temperature
3.4. Dehydrofluorination of 2H-perfluoro(2-
methylpentanoic) acid tert-butyl ester 8
By KOH: tert-Butyl esters 8 and 9 mixture (2.16 g) from
Section 3.2(41% for 8 and40%for9) was refluxed with 10 ml
15% KOH solution. The two layers mixture did not visually

Y. Cheburkov, G.G.I. Moore / Journal of Fluorine Chemistry 123 (2003) 227–231
231
below 65 8C. Decarboxylation started at 70 8C and the pro-
ductwithbp65 8C wasdistilledandcollectedina receiver and
a trap (ꢁ78 8C). The combined distillate washed by 15% HCl
solution, then water, dried MgSO4 and redistilled to give
199.6 g (63%) of two isomeric (Z:E ¼ 11:87) 2-hydroper-
fluoro-2-pentenes with bp 31–33 8C and purity 98%;
[(M ꢁ F)þ 100], 213 (10), 163 (2). The product yield was
58%.
In another experiment, 19.0 g pentene 3 and 8.1 g 10%
solution of SbF5 in anhydrous HF were heated in a stainless
steel tube at 240 8C for 20 h to give 15.3 g of the HFC 4310
mf with bp 46–47 8C and purity 96%. The yield was 71%.
CF3 CH¼CFbCF2 CF3 19F and 1H NMR: E-isomer,
ꢁ60.2 (a, CF3 dd), ꢁ113.3 (b, CF m), ꢁ123.3 (c, CF2
dm), ꢁ84.4 (d, CF3 dm), 5.81 (CH dq); Z-isomer (same
designation), ꢁ55.8 (a, CF3 m), ꢁ110.2 (b, CF m), ꢁ120.6
(c, CF2 p), ꢁ82.9 (d, CF3 s), 6.08 (CH dq); MS: 232 (Mþ, 8),
213 (100), 163 (50), 113 (32). The pentene contains less than
2% pentafluorobutanone (5) as an impurity, CF3CF2COCH3
19F and 1H NMR: ꢁ82.9 (CF3 s), ꢁ123.9 (CF2 s), 2.3 (CH3 s);
MS: 163 [(M þ 1)þ 100], 143 (5).
a
c
d
Acknowledgements
We thank John Hansen for FT-IR identification of gaseous
products and also Tom Kestner, Sheila Kromer, Rick Payfer
andJaySchulzofSpecialtyMaterialsDivisionAnalyticalLab
for GC/MS and FT-NMR measurements and interpretation.
3.8. Pentene 3 synthesis from 2H-perfluoro(2-
methylpentane)
References
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[2] D.D. Moldavsky, G.I. Kaurova, T.A. Bispen, G.G. Furin, J. Fluorine
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The same procedure was used as in Section 3.7. From
6.4 g (20 mmol) C6HF13 5.08 g (50 mmol) triethylamine
and 3.7 g (50 mmol) tert-butanol there was obtained
7.83 g organic material consisting of (GC): 14% i-C4H8,
19% tert-C4H9F, 2% starting C6HF13, 15% ester 8 and 42%
ester 9. This mixture and 0.45 g TosOH were heated at
115 8C for 3 h in a slow flow of nitrogen and in a trap
(ꢁ78 8C) was collected 1.66 g of low boiling material
including C6HF13. To 5.71 g of the residue was added
6 ml H2O and 2.5 g triethylamine and the crude pentene
was distilled out. It was washed, dried and redistilled to give
2.62 g (57%) of pentene 3 with bp 31–33 8C and purity 98%.
The product contained 2% ketone 5.
[3] A.A. Stepanov, G.Ya. Bekker, A.P. Kurbakova, L.A. Leites, I.N.
Rozhkov, Izv. Acad. Nauk SSSR, Ser. Khim. 12 (1981) 2285–2288.
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(1996) and 5594159 (1997).
3.9. 2,2-Dihydrodecafluoropentane (HFC 4310 mf)
[10] V.N.M. Rao, F.J. Weigert, C.G. Krespan, International Patent WO
93/05002.
In a stainless steel tube a mixture of 5.0 g pentene 3 (GC
purity 98%), 2.0 g Aldrich pyridinium poly(hydrogen fluor-
ide) and 1.6 g acetonitrile was heated at 280 8C for 17 h. The
reaction product was poured into ice water, the organic layer
(4.3 g) was separated and distilled from the mixture with
equal volume of conc. H2SO4 to give 3.79 g product with
a bp 42–47 8C ([10] bp 46–47 8C) and consisting of (GC)
13% pentene 3 and 81% 2,2-dihydroperfluoropentane
[11] T. Martini, C. Schumann, J. Fluorine Chem. 8 (1976) 535–540.
[12] I.L. Knunyants, M.D. Bargamova, E.I. Mysov, Izv. Akad. Nauk
SSSR, Ser. Khim. (1979) 2630–2631.
[13] V.F. Snegirev, K.N. Makarov, Izv. Akad. Nauk SSSR, Ser. Khim. 1
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(Chem. Abstr. 55 (1961) 6372h); see the procedure in I.L. Knunyants,
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[15] P.K. Isbester, J.L. Brandt, T.A. Kestner, E.J. Munson, Macromole-
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a
b
c
d
CF3 CH2CF2 CF2 CF3 19F and H NMR (CDCl3): ꢁ61.6
(a, CF3 pt), ꢁ115.2 (b, CF2 m), ꢁ128.3 (c, CF2 s), ꢁ81.0 (d,
CF3 t), 2.94 (CH2 m); MS: no Mþ was observed, 233
1
[16] G.G. Belen’kii, E.P. Lur’e, L.S. German, Izv. Acad. Nauk SSSR, Ser.
Khim. 12 (1975) 2728–2732.