Preparation of cis-1,1,1,4,4,4-hexafluorobut-2-ene by cis-selective semi-hydrogenation of perfluoro-2-butyne

Article abstract of DOI:10.1016/j.jfluchem.2011.06.004

Cis-1,1,1,4,4,4-hexafluorobut-2-ene has a zero ozone depletion potential (ODP), low global warming potential (GWP) and non-flammable properties, so it is believed to be a potential foam expansion agent. For the synthetic process of cis-1,1,1,4,4,4-hexafluorobut-2-ene, the process catalysts are the key factors for its yield and cost. In this paper, the catalysts of palladium attached to porous aluminum fluoride, to active carbon, to Al₂O₃, and the blends of palladium and bismuth to AlF₃ used to prepare cis-1,1,1,4,4,4-hexafluorobut-2-ene by cis-selective semi-hydrogenation of perfluoro-2-butyne were investigated. The performance of above-mentioned catalysts was compared in reaction process. The experimental results indicate that the additive of bismuth to palladium catalyst is useful for improving the activity and selectivity compared to Pd/C and Pd/Al₂O₃. The role of bismuth in the synthetic process is discussed based on the experimental results and theory analysis.

Full text of DOI:10.1016/j.jfluchem.2011.06.004

Journal of Fluorine Chemistry 132 (2011) 1188–1193
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Preparation of cis-1,1,1,4,4,4-hexafluorobut-2-ene by cis-selective
semi-hydrogenation of perfluoro-2-butyne
b
b
Xiaoqing Jia a, Xiaomeng Zhou b, Hengdao Quan b, , Masanori Tamura , Akira Sekiya
*
a Beijing Institute of Technology, Beijing 100081, China
b National Institute of Advance Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan
A R T I C L E I N F O
A B S T R A C T
Article history:
Cis-1,1,1,4,4,4-hexafluorobut-2-ene has a zero ozone depletion potential (ODP), low global warming
potential (GWP) and non-flammable properties, so it is believed to be a potential foam expansion agent.
For the synthetic process of cis-1,1,1,4,4,4-hexafluorobut-2-ene, the process catalysts are the key factors
for its yield and cost. In this paper, the catalysts of palladium attached to porous aluminum fluoride, to
active carbon, to Al2O3, and the blends of palladium and bismuth to AlF3 used to prepare cis-1,1,1,4,4,4-
hexafluorobut-2-ene by cis-selective semi-hydrogenation of perfluoro-2-butyne were investigated. The
performance of above-mentioned catalysts was compared in reaction process. The experimental results
indicate that the additive of bismuth to palladium catalyst is useful for improving the activity and
selectivity compared to Pd/C and Pd/Al2O3. The role of bismuth in the synthetic process is discussed
based on the experimental results and theory analysis.
Received 31 March 2011
Received in revised form 28 May 2011
Accepted 4 June 2011
Available online 13 June 2011
Keywords:
Cis-1,1,1,4,4,4-hexafluorobut-2-ene
Perfluoro-1,3-butadiene
Semi-hydrogenation
Pd-based catalyst
ß 2011 Elsevier B.V. All rights reserved.
Porous aluminum fluoride
1. Introduction
For the synthetic method of cis-1,1,1,4,4,4-hexafluorobut-2-ene,
some liquid phase methods have been developed. For example, Lui
In these years, much attention has been paid on the global
warming problem. The chlorofluorocarbons (CFCs) or hydro-
chlorofluorocarbons (HCFCs) are considered to be the main
compounds in the contribution to global warming. Hydrofluor-
oolefines (HFOs), as the prime alternatives of CFCs, HCFCs and
HFCs used as coolants, blowing agents, cleaners have been
studied and selected due to their low global warming potential
(GWP) and zero ozone depletion potential (ODP). Meanwhile, the
facile synthetic route for preparing HFOs has been investigated in
industry [1].
Cis-1,1,1,4,4,4-hexafluorobut-2-ene is a non-ozone depleting
compound with an acceptable GWP. Its short lifetime in
atmosphere indicates that it is not a long lived atmospheric
breakdown product. Furthermore, this compound is not a volatile
organic compound, and it is low toxicity and is non-flammable,
with a boiling point of 33 8C. Besides that, the study in DuPont
company shows that cis-1,1,1,4,4,4-hexafluorobut-2-ene is char-
acterized by good compatibility and chemical stability in generic
foam systems and foam processing materials. So it is used as
‘‘Fourth-Generation’’ foam expansion agent [2].
et al. [3] had developed a method that prepared 1,1,1,4,4,4-
hexafluorobut-2-ene from CF3–CH2–CHCl–CX3, in which the
individual radicals X independently of each other represent
chlorine and/or fluorine, by reaction with alkali metal fluoride in
an aprotic polar solvent. Aoyama et al. have prepared cis-1,1,1,4,4,4-
hexafluorobut-2-ene and trans-1,1,1,4,4,4-hexafluorobut-2-ene
using 1,1,1-trifluoro-2,2-dichloroethane, amine and copper as
raw materials [4]. However, by these liquid phase method, the
yield rate of cis-1,1,1,4,4,4-hexafluorobut-2-ene is low. The
synthetic process is a batch reaction and have a serious pollution
besides the synthesize apparatus is complex. For vapor phase
synthetic method of cis-1,1,1,4,4,4-hexafluorobut-2-ene, there is
rare report until now [5].
In our laboratory, a vapor-phase method in continuous process
to prepare cis-1,1,1,4,4,4-hexafluorobut-2-ene by cis-selective
semi hydrogenation of CF3CCCF3 is developed. We found that
the process catalyst is the key effect factor for the synthesis of cis-
CF3CHCHCF3. The catalysts of palladium attached to porous
aluminum fluoride, to active carbon, to Al2O3, the blends of
palladium and Bi attached to AlF3 to prepare cis-1,1,1,4,4,4-
hexafluorobut-2-ene by cis-selective semi-hydrogenation of per-
fluoro-2-butyne were investigated in this paper. The performance
of the catalysts and the catalytic mechanism of bismuth in the
synthetic process is discussed based on the experimental results
and theory analysis.
* Corresponding author. Tel.: +81 298 614657; fax: +81 298 614657.
E-mail address: Hengdao-quan@aist.go.jp (H. Quan).
0022-1139/$ – see front matter ß 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2011.06.004

X. Jia et al. / Journal of Fluorine Chemistry 132 (2011) 1188–1193
1189
2. Experimental
2.4.2. 3% Pd/AlF3
The PAF was impregnated into a sufficient amount of palladium
chloride solution overnight. The amount of palladium chloride in
the solution was adjusted to give a metal loading about 3 wt%. The
following treating procedure is as Section 2.4.1 shown.
2.1. Chemicals
CF255CFCF55CF2 (95% purity) was purchased from Kanto
Chemical Co. Porous aluminum fluoride (PAF) was obtained from
Xi an Modern Chemistry Research Institute, Xi’an, China. 5.0% Pd/C
(surface area 971.70 m2/g), 3% Pd/AlF3 (surface area 7.77 m2/g),
2.0% Pd + 0.1% Bi/PAF (surface area 9.02 m2/g), 4.5% Pd + 0.5% Ag/C
(surface area 918.86 m2/g), 1% Pd/(
35.58 m2/g), 0.5% Pd/C (surface area 1151.74 m2/g) are used in
experimental process.
2.4.3. 1% Pd/(
According to the procedure described in Section 2.4.1, about
1.0 wt% palladium was loading to -Al2O3 and was used to catalytic
g-Al2O3)
g
g
-Al2O3) (surface area
hydrogenation after the reduction of catalyst was run.
2.4.4. 2.0% Pd + 0.1% Bi/PAF
Bimetallic Pd–Bi/PAF catalyst containing 2.0% Pd and 0.1% Bi
were obtained from monometallic palladium catalysts by repeated
impregnation of these systems with water solution of
Bi(NO3)3Á5H2O according to the procedure described in Section
2.4.1.
2.2. Instrument
Apparatus for investigating the reaction process of CF3CCCF3
and H2 consist of N2 mass flow controllers, an electrically heated
tubular type-316 stainless-steel reactor, 12 mm in diameter and
300 mm in length.
2.4.5. 4.5% Pd + 0.5% Ag/C
The BET surface area of 5.0% Pd/C, 3% Pd/AlF3, 2.0% Pd + 0.1% Bi/
PAF, 4.5% Pd + 0.5% Ag/C, 1%Pd/(g-Al2O3), 0.5% Pd/C were
measured by means of low temperature adsorption of nitrogen
using a Micromeritics ASAP 2000. Samples were degassed under
vacuum at 573 K for 3 h before measurement.
Monometallic palladium catalyst was impregnated into an
amount of palladium AgNO3 solution overnight. AgNO3 in the
solution was adjusted to give a Pd–Ag alloy loading. The following
treating procedure is as Section 2.4.1 shown.
GC analysis was conducted on a Shimadzu GC-17 A. The
capillary column was a CP-PoraPLOT Q with 0.32 mm i.d. and 53 m
from J&W Scientific Inc. The column was programmed as follows:
the initial temperature was set at 100 8C for 5 min; then the
temperature was increased at the rate of 10 8C/min, and finally to
200 8C and held for 10 min.
MS (EI, 70 eV) spectra were measured using the Shimadzu
GCMS-QP2010 system equipped with GC-2010. And the column
type and the parameters were same as above mentioned GC
conditions.
2.5. Analytic results of intermediate and cis-CF3CH55CHCF3
2.5.1. CF255CF–CF55CF2
Boiling point, 6.5 8C. Spectral data, MS peaks m/z (%): 162 [M+],
143 [M+ÀF], 124 [M+À2F], 112 [M+ÀCF2], 93 [M+ÀCF3], 74
[M+ÀCF4], 69 [M+ÀC3F3], 31 [M+ÀC3F5].
NMR Chemical shifts: 19F (–CF–), À153.7 ppm. 19F (CF2–),
À120.9 ppm.
2.5.2. CF3C CCF3
1H NMR and 19F NMR of cis-CF3CH55CHCH3 and its intermediate
were recorded on a JNM-EX300 spectrometer (JEOL, 300 MHz) at
25 8C with Me4Si and CFCl3, respectively, as internal references in
CDCl3 solvent.
Boiling point, À24.6 8C. Spectral data, MS peaks m/z (%): 162
[M+], 143 [M+ÀF], 124 [M+À2F], 112 [M+ÀCF2], 93 [M+ÀCF3], 74
[M+ÀCF4], 69 [M+ÀC3F3], 31 [M+ÀC3F5].
NMR Chemical shifts: 19F (CF3–), À53.5 ppm.
2.3. Preparation of CF3CCCF3 from CF255CFCF55CF2
2.5.3. Cis-CF3CH55CHCF3
Boiling point, 33.5 8C. Spectral data, MS peaks m/z (%): 164[M+],
145 [M+ÀF], 113 [M+ÀCHF2], 95 [M+ÀCF3], 75 [M+ÀC2HF3], 69
[M+ÀC3H2F3].
CF3CCCF3 was prepared by CF255CFCF55CF2 using AlOClF as
catalyst (as Scheme 1 shown). By a series of measuring, it is shown
that at room temperature, the yield rate of CF3CCCF3 is up to 99.5%.
If the reaction temperature rises to 200 8C, cyclocompounds
appeared and the yield rate of CF3CCCF3 is decreased abruptly.
NMR Chemical shifts: 19F (CF3–), À60.6 ppm. 1H (–CH55),
6.65 ppm.
2.5.4. Trans-CF3CH55CHCF3
2.4. Preparation of above-mentioned catalysts
Boiling point, 8.5 8C. Spectral data, MS peaks m/z (%): 164 [M+],
145 [M+ÀF], 126 [M+À2F], 113 [M+ÀCHF2], 95 [M+ÀCF3], 75
[M+ÀC2HF3], 69 [M+ÀC3H2F3].
2.4.1. 0.5% Pd/C and 5.0% Pd/C
The activated charcoal was impregnated into a sufficient
amount of palladium chloride solution overnight. The amount of
palladium chloride in the solution was adjusted to give a final
metal loading to 0.5 wt% and 5.0 wt% respectively. The saturated
supporter was baked at 200 8C for 6 h and 300 8C for 6 h. The
reduction of catalyst was run in following procedure: 200 8C for
6 h; 300 8C for 6 h; and 350 8C for 5 h, the rate of hydrogen was
7.5 ml/min, 9 ml/min and 20 ml/min individually. The finished
catalyst was used to catalytic hydrogenation.
Chemical shifts: 19F (CF3–), À66.4 ppm. 1H (–CH55), 6.95 ppm.
2.5.5. CF3CH2CH2CF3
Boiling point, 24.6 8C. Spectral data, MS peaks m/z (%): 147
[M+ÀF], 127 [M+ÀHF2], 97 [M+ÀCF3], 77 [M+ÀCHF4], 69
[M+ÀC3H4F3], 51 [M+ÀC3H3F4], 27 [M+ÀC2HF6].
Chemical shifts: 19F (CF3–), À68.3 ppm. 1H (–CH2–), 2.49 ppm.
3. The experimental results
The experimental results show that there were four products in
semi-hydrogenation of perfluoro-2-butyne, CF3CCCF3, trans-
CF3CHCHCF3, CF3CH2CH2CF3 and cis-CF3CHCHCF3, respectively
(as Scheme 2 shown). The related factors of conversion of CF3CCCF3
and selectivity of cis-CF3CHCHCF3 with catalysts were investigated
in particularly.
Scheme 1. Route to prepare CF3CCCF3.

1190
X. Jia et al. / Journal of Fluorine Chemistry 132 (2011) 1188–1193
Scheme 2. Route to prepare cis-CF3CHCHCF3.
3.1. Effect of Pd wt% to catalytic activity
Pd + 0.5% Cu/C. Regardless of the content of additives in the studied
catalysts Pd/C and Pd/AlF3, the conversion and selectivity of target
product is improved greatly comparing the monometallic catalyst.
The results in Table 2 indicated that 2.0% Pd + 0.1% Bi/AlF3 own the
highest conversion and selectivity in the cis-selective semi-
hydrogenation of perfluoro-2-butyne.
Fig. 4 shows that the distribution of productions in different
reaction temperature. When the reaction temperature is from
150 8C to 200 8C, the yield of cis-CF3CHCHCF3 arrives to 90%.
Besides that, the conversion of CF3CCCF3 increased with the
temperature increasing. When the reaction temperature is more
than 200 8C, the conversion of CF3CCCF3 is quantitative. However,
the yield of by-product of trans-CF3CHCHCF3 is growing up with
the temperature increasing.
In this part, Al2O3, AlF3 and active carbon was used as catalyst
supporter respectively. From Table 1, it is known that the
conversion of CF3CCCF3 increased gradually and the yield of cis-
CF3CHCHCF3 (target products) decreased abruptly when the Pd
wt% increased to 5.0 wt% from 0.5 wt% in the active carbon. By
comparing the conversion of reactant and the selectivity of target
product in three catalyst supporters, it is known that AlF3 owns the
highest catalyst activity and Al2O3 owns the highest selectivity of
target product in 200 8C reaction temperature.
From Fig. 1, it is shown that the yield of production 3–5 have no
obvious change with the reaction temperature increase.
CF3CH2CH2CF3 is the mainly production in reaction process. The
yield of cis-CF3CHCHCF3 is below 30% among all productions. Fig. 2
shows that the conversion of CF3CCCF3 and the yield of cis-
CF3CHCHCF3 decreased with the temperature increase. It is
different between the catalyst using carbon and Al2O3 as catalyst
supporter.
Figs. 5 and 6 show that the conversion and selectivity of 4.5%
Pd + 0.5% Ag/C catalysts and 0.5% Cu + 4.5% Pd/C catalyst in the
70
60
Fig. 3 shows that the conversion of CF3CCCF3 and the yield of
cis-CF3CHCHCF3 are growing up with the temperature increase.
product 5
50
3.2. Effect of different additives to catalytic activity
product 4
product 3
40
Table 2 presents the conversion and selectivity of the following
catalysts: 2.0% Pd + 0.1% Bi/AlF3, 4.5% Pd + 0.5% Ag/C and 4.5%
product2
30
20
10
0
Table 1
The conversion of 2 and the selectivity of production 5 in different catalyst
supporter and Pd wt%.
Entry Catalyst
Reaction temp. (8C) Conversion (%) Selectivity (%)
1
2
3
4
5.0% Pd/C
0.5% Pd/C
3.0% Pd/AlF3
200
200
200
78.7
60.5
91.5
84.5
39.6
85.3
68.4
90.4
0
50
100
150
200
250
300
Reaction temperature / ˚C
1.0% Pd/Al2O3 200
Fig. 2. Catalyst 3.0% Pd/AlF3.
50
40
30
100
90
80
70
60
50
40
30
20
10
0
product 5
product 4
product 3
product 2
20
10
0
product 2
product 3
product 4
product 5
0
25 50 75 100 125 150 175 200 225 250 275 300
0
50
100
150
200
250
300
Reaction temperature / ˚C
Reaction temperature / ˚C
Fig. 1. Catalyst 5.0% Pd/C.
Fig. 3. Catalyst 1.0% Pd/(g-Al2O3).

X. Jia et al. / Journal of Fluorine Chemistry 132 (2011) 1188–1193
1191
70
Table 2
The conversion of 2 and the selectivity of production 5 using different additives.
product 5
product 4
product 3
product 2
60
50
40
30
20
10
0
Entry
Catalyst
Reaction
Conversion
(%)
Selectivity
(%)
temp. (8C)
5
6
7
Pd +0.1% Bi/AlF3
200
200
200
98.7
84.4
73.6
90.2
57.6
74.1
4.5% Pd + 0.5% Ag/C
0.5% Cu + 4.5% Pd/C
100
90
80
70
60
50
40
30
20
10
0
0
50
100
150
200
250
product 5
Reaction temperature / ˚C
product 4
product 3
product 2
Fig. 6. Catalyst 0.5% Cu + 4.5% Pd/C.
catalyst respectively, the results shown the conversion and
selectivity were improved obviously with the addition of Bi to
the Pd/PAF catalyst, the conversion of CF3CCCF3 reached 98.7% and
the selectivity of cis-CF3CHCHCF3 reached 90.2% at 250 8C. But the
improvement of the catalyst 4.5% Pd after adding 0.5% Ag and
catalyst 4.5% Pd after adding 0.5% Cu was not so obvious. So 2.0%
Pd + 0.1% Bi/AlF3 is believed to be a perfect catalyst for the
preparation of cis-CF3CHCHCF3 by cis-selective semi-hydrogena-
tion of perfluoro-2-butyne.
0
50
100
150
200
250
300
Reaction temperature / ˚C
Fig. 4. Catalyst (2.0% Pd + 0.1% Bi/AlF3).
different reaction temperature. With the reaction temperature
increasing, the conversion and selectivity is improved gradually.
When the temperature is arrived 200 8C, the effect of reaction
temperature to the conversion and selectivity is not sensitive.
Although it is improved greatly comparing with monometallic
palladium catalysts, the yield of target product using 4.5%
Pd + 0.5% Ag/C catalysts and 0.5% Cu + 4.5% Pd/C catalyst is quite
low. However, Bi/Pd systems, even containing a small amount of
bismuth are characterized by the highest activity and select in this
reaction.
4. Discussion
Comparison with Figs. 1–8, it shows that addition of appropri-
ate Bi to Pd catalyst improves the conversion and selectivity in
synthesis of cis-CF3CHCHCF3.
Cis-selective semi-hydrogenation of alkynes is an important
step in organic synthesis. Lindlar catalyst [6] is the most popular
catalyst for this reaction. The Lindlar catalyst is a Pd/CaCO3
catalyst treated with lead acetate solution and used in the
presence of 0.05–1 molar equivalent of quinoline. One well-
established action of the quinoline is to inhibit alkene surface
interactions, which results in an overall selectivity increase, a
general concept in selective hydrogenation reactions. An
undesired effect is that quinoline also competes with alkynes
for Pd surface interaction, which reduce the overall reaction rate
[7]. Besides that, quinoline owns strong odor and is very difficult
to remove in synthesize process. Cis-CF3CHCHCF3 could also be
prepared by perfluoro-2-butyne and H2 on Raney nickel [8], the
yield just contains cis-CF3CHCHCF3 and CF3CH2CH2CF3. The
3.3. The activity comparison of different catalysts
Figs. 7 and 8 show that the comparison of catalytic activity and
selectivity of different catalysts. It is shown that additives play an
important role for improving the activity and selectivity. When Bi
was added to the Pd/PAF catalyst and Ag was added to the Pd/C
50
45
40
product 5
110
100
90
product 4
35
product 3
product 2
30
25
20
15
10
5
80
5.0% Pd/C
3.0% Pd/AlF3
2.0% Pd+0.1% Bi/AlF3
4.5% Pd+0.5% Ag/C
1.0% Pd/ Al2O3
70
60
50
40
30
20
10
0
1.0% Pd/ γ-Al2O3
(treated with quinoline)
0.5% Pd/C
0.5% Cu+4.5% Pd/C
2% Pd( PdCl2) /AlF3
-10
0
50
100
150
200
250
0
50
100
150
200
250
Reaction temperature / ˚C
Reaction temperature / ˚C
Fig. 5. Catalyst (4.5% Pd + 0.5% Ag/C).
Fig. 7. Profile of conversion of 1 on different catalysts and reaction temperature.

1192
100
X. Jia et al. / Journal of Fluorine Chemistry 132 (2011) 1188–1193
90
80
70
60
50
40
30
20
10
0
0
50
100
150
200
250
Reaction temperature / ˚C
Fig. 8. Profiles of selectivity of 5 on different catalysts and at different temperature.
catalysts which prepared on borohydride exchange resin in
methanol show high selectivity [9]. But pyrophoric property of
Raney nickel and batch reaction makes it hard to get
quantitative products. Recently, the research on palladium
bimetallic systems characterized by higher activity and stability
than in the case of monometallic systems has started [10].
Therefore, Bi was attached to process catalyst in cis-1,1,1,4,4,4-
hexafluorobut-2-ene synthesis in our laboratory.
Bismuth is a well-established promoter of noble based catalysts
for the selective liquid phase oxidation of alcohols, aldehydes and
carbohydrates with molecular oxygen [11]. When it used alone,
Bismuth is not inactive for the concerned oxidation reactions, but
when associated with the noble metal, it considerable increase the
overall catalytic performances and the lifetime of catalysts. The
origin of the promoting role of bismuth on the activity of Pd is still a
matter discussion. However, the influence of the addition of a
second metal to Pd/support systems on catalytic properties in the
reaction of semi-hydrogenation of alkynes in the gas phase has not
been studied thoroughly yet.
Fig. 9. Possible reaction mechanism in synthesis of cis-CF3CHCHCF3 on Pd/AlF3
The interpretation to bimetallic palladium catalysts should
include following aspects: electronic effects, geometric effects, the
occurrence of mixed sites [12–14]. Thus the promoting effect of
addition of Bi on selectivity is interpreted as follows. When applied
to Pd–Bi alloys between an active component Pd and an inactive
one Bi, it indicate the dilution in ensembles of smaller size of the
active surface Pd by Bi. It is deduced that these smaller ensembles
of Pd is less facilitate to activate the reactant(s). Besides that, the
addition of Bi made Pd well-distributed in supporter AlF3 and
surface of AlF3 appeared more flat terrace. The flat terraces or
extended terraces were conductive to interaction of perfluoro-2-
butyne and hydrogen.
catalyst (a) without addition of Bi and (b) addition of Bi to Pd/AlF3.
5. Conclusion
The synthesis of cis-1,1,1,4,4,4-hexafluorobut-2-ene using
practical catalysts was introduced. We found that cis-selective
semi-hydrogenation of perfluoro-2-butyne proceeds with well
conversion of perfluoro-2-butyne and surprising selectivity of cis-
1,1,1,4,4,4-hexafluorobut-2-ene on catalyst (2.0% Pd + 0.1% Bi)/
AlF3. While, 5.0% Pd/C, 3.0% Pd/AlF3, 2.0% Pd + 0.1% Bi/AlF3, 4.5%
Pd + 0.5% Ag/C, 1.0% Pd/g-Al2O3, 0.5% Pd/C, 0.5% Cu + 4.5%Pd/C, 2%
Pd(PdCl2)/AlF3, did not show this effect. As an addition metal on
Pd-based catalyst, Bi was a good modifier for the cis-selective
semi-hydrogenation of perfluoro-2-butyne reaction. The plausible
catalysis mechanism of Pd–Bi/AlF3 in hydrogenation of perfluoro-
2-butyne reaction was proposed.
The effect process is as Fig. 9 shown.
According to the experimental results and theory discussion
with catalyst of 2.0% Pd + 0.1% Bi/PAF, we proposed the mechanism
of the improvement of conversion and selectivity for the addition
of Bi to Pd/AlF3 catalyst are as follows: A geometric effect which
results from the dilution of the Pd surface layer with Bi appeared
make surface of AlF3 more flat terrace, which enhanced the rate of
cis-CF3CHCHCF3 formation. The data in Figs. 7 and 8 are consistent
with this model.
References
[1] G. Loh, J.A. Creazzo, M.L. Robin, in: Proceedings of 12th Blowing Agents and
Faoming Process, Cologne, Germany, 2010.
[2] (a) G. Loh, J.A. Creazzo, M.L. Robin, DuPontTM Formacel WHITE PAPER, 2009;
(b) H.-D. Quan, H.-E. Yang, M. Tamura, A. Sekiya, J. Fluorine Chem. 128 (2007)
190–195.
Synthesis of cis-CF3CHCHCF3 could be divided into two steps,
the isomerization of perfluoro-2-butyne and then hydrogenation,
which is seen in Fig. 9. We deduced that
[3] N. Lui, A.M. Leverkusen, D. Bielefeldt, U.S. Patent 5,463,150 (1995).
[4] H. Aoyama, Osaka, U.S. Patent 5,516,951 (1996).
[5] E.L. Dupont, P.C.T./U.S. Patent 2,009,037,459 (2009).
[6] (a) H. Lindlar, Helv. Chim. Acta 35 (1952) 446–450;
(b) O. Isler, A. Ronco, W. Guex, N.C. Hindley, W. Huber, K. Dialer, M. Kofler, Helv.
Chim. Acta 32 (1949) 489–505;
molecule preferred to react with hydrogen molecule adopted
around palladium atoms located at flat terrace sites.
(c) J. Rajaram, A.P.S. Narula, H.P.S. Chawla, S. Dev, Tetrahedron 39 (1983)
2315–2322.

X. Jia et al. / Journal of Fluorine Chemistry 132 (2011) 1188–1193
1193
[7] R. Cosmo, T.W. Hambley, S. Sternhell, J. Org. Chem. 52 (1987) 3119–3123.
[8] A.L. Henne, W.G. Finnegan, J. Am. Chem. Soc. 71 (1949) 298–300.
[9] J. Choi, N.M. Yoon, Tetrahedron Lett. 37 (1996) 1057–1060.
[12] B. Coq, F. Figueras, J. Mol. Catal. A: Chem. 173 (2001) 117–134.
[13] J.C. Fuggle, F.U. Hillebrecht, R. Zeller, Z. Zolstroknierek, P.A. Bennett, C. Freiburg,
Phys. Rev. B 27 (1983) 2145.
[10] J. Petro, Contact Catalysis, Elsevier, Amsterdam, 1976.
[11] M.Wenkin,P.Ruiz,B.Delmon,M.Devillers,J.Mol.Catal.A:Chem.180(2002)141–159.
[14] A. Borodzinski, R. Dus, R. Frak, A. Janko, W. Palczewska, in: Proceedings of the 6th
International Congress on Catalysis, London, (1976), p. 151.