U.S. patent application number 12/689617 was filed with the patent office on 2010-07-22 for method for producing 1, 1-dichloro-2,2,3,3,3-pentafluoropropane.
This patent application is currently assigned to ASAHI GLASS COMPANY LIMITED. Invention is credited to Hidekazu OKAMOTO.
Application Number | 20100185028 12/689617 |
Document ID | / |
Family ID | 42337478 |
Filed Date | 2010-07-22 |
United States Patent
Application |
20100185028 |
Kind Code |
A1 |
OKAMOTO; Hidekazu |
July 22, 2010 |
METHOD FOR PRODUCING 1, 1-DICHLORO-2,2,3,3,3-PENTAFLUOROPROPANE
Abstract
To provide a method for producing
1,1-dichloro-2,2,3,3,3-pentafluoropropane (HCFC-225ca) at a high
content ratio, which is useful as e.g. a starting material to
obtain 1,1-dichloro-2,3,3,3-tetrafluoropropene (R1214ya). The
method comprises subjecting a starting material comprising one
isomer or a mixture of at least two isomers of
dichloropentafluoropropane (HCFC-225) and having a HCFC-225ca
content of less than 60 mol%, to an isomerization reaction in the
presence of a Lewis acid catalyst or a metal oxide catalyst so as
to increase the HCFC-225ca content in the product to be higher than
the content in the starting material.
Inventors: |
OKAMOTO; Hidekazu;
(Chiyoda-ku, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
ASAHI GLASS COMPANY LIMITED
Chiyoda-ku
JP
|
Family ID: |
42337478 |
Appl. No.: |
12/689617 |
Filed: |
January 19, 2010 |
Current U.S.
Class: |
570/151 ;
570/156 |
Current CPC
Class: |
C07C 17/23 20130101;
C07C 17/25 20130101; C07C 17/358 20130101; C07C 21/18 20130101;
C07C 17/358 20130101; C07C 17/23 20130101; C07C 17/25 20130101;
C07C 19/10 20130101; C07C 21/18 20130101; C07C 21/18 20130101 |
Class at
Publication: |
570/151 ;
570/156 |
International
Class: |
C07C 17/00 20060101
C07C017/00; C07C 17/23 20060101 C07C017/23 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 19, 2009 |
JP |
2009-009208 |
Claims
1. A method for producing
1,1-dichloro-2,2,3,3,3-pentafluoropropane, which comprises
subjecting a staffing material comprising one isomer or a mixture
of at least two isomers of dichloropentafluoropropane and having a
1,1-dichloro-2,2,3,3,3-pentafluoropropane content of less than 60
mol %, to an isomerization reaction in the presence of a Lewis acid
catalyst or a metal oxide catalyst so as to increase the
1,1-dichloro-2,2,3,3,3-pentafluoropropane content in the product to
be higher than the content in the starting material.
2. The method for producing
1,1-dichloro-2,2,3,3,3-pentafluoropropane according to claim 1,
wherein the starting material contains
1,3-dichloro-1,2,2,3,3-pentafluoropropane, and the
1,3-dichloro-1,2,2,3,3-pentafluoropropane is subjected to an
isomerization reaction to form
1,1-dichloro-2,2,3,3,3-pentafluoropropane.
3. The method for producing
1,1-dichloro-2,2,3,3,3-pentafluoropropane according to claim 2,
wherein the starting material further contains
2,2-dichloro-1,1,1,3,3-pentafluoropropane.
4. The method for producing
1,1-dichloro-2,2,3,3,3-pentafluoropropane according to claim 1,
wherein the isomerization reaction is carried out in a liquid phase
in the presence of a Lewis acid catalyst at a temperature of from 0
to 150.degree. C.
5. The method for producing
1,1-dichloro-2,2,3,3,3-pentafluoropropane according to claim 1,
wherein the isomerization reaction is carried out in a gas phase in
the presence of a metal oxide catalyst at a temperature of from 50
to 500.degree. C.
6. A method for producing 1,1-dichloro-2,3,3,3-tetrafluoropropene,
which comprises bringing the
1,1-dichloro-2,2,3,3,3-pentafluoropropane obtained by the method as
defined in claim 1 into contact with an aqueous alkali solution in
the presence of a phase transfer catalyst.
7. A method for producing 2,3,3,3-tetrafluoropropene, which
comprises reacting the 1,1-dichloro-2,3,3,3-tetrafluoropropene
obtained by the method as defined in claim 6 with hydrogen in the
presence of a catalyst.
8. The method for producing 2,3,3,3-tetrafluoropropene according to
claim 7, which is carried out in the presence of an inert gas.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing
1,1-dichloro-2,2,3,3,3-pentafluoropropane (HCFC-225).
BACKGROUND ART
[0002] Heretofore, various methods have been proposed as methods
for producing dichloropentafluoropropane (HCFC-225) represented by
a chemical formula C.sub.3HCl.sub.2F.sub.5. For example, a method
has been proposed which comprises contacting dichlorofluoromethane
with tetrafluoroethylene in the presence of a modified aluminum
chloride catalyst to obtain dichloropentafluoropropane, and a
technique to apply isomerization to a mixture of various isomers of
dichloropentafluoropropane obtained by this method, is disclosed
(Patent Document 1).
[0003] However, by the isomerization method disclosed in Patent
Document 1, it was not possible to obtain
1,1-dichloro-2,2,3,3,3-pentafluoropropane (HCFC-225ca) at a high
content ratio.
[0004] On the other hand, in recent years, it has been studied to
use 2,3,3,3-tetrafluoropropene (R1234yf) having a small ozone
depletion potential, as a cooling medium of next generation to be
substituted for 1,1,1,2-tetrafluoroethane (HFC-134a) being a
greenhouse gas. It is considered to use
1,1-dichloro-2,3,3,3-tetrafluoropropene (R1214ya) as a starting
material for preparing this R1234yf, and accordingly, usefulness of
HCFC-225ca is expected as a starting material to obtain R1214ya.
However, a method has not yet been found whereby HCFC-225ca can be
efficiently obtained by increasing the content ratio of HCFC-225ca
in the mixture of various isomers of HCFC-225.
[0005] Patent Document 1: U.S. Pat. No. 5,157,171.
SUMMARY OF THE INVENTION
Object to be Accomplished by the Invention
[0006] It is an object of the present invention to provide a method
for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane
(HCFC-225ca) useful as e.g. a starting material to obtain
1,1-dichloro-2,3,3,3-tetrafluoropropene (R1214ya) as a material to
prepare 2,3,3,3-tetrafluoropropene (R1234yf) being an excellent
cooling medium.
Means to Accomplish the Object
[0007] The present invention is to accomplish the above object and
provides the following. [0008] 1. A method for producing
1,1-dichloro-2,2,3,3,3-pentafluoropropane, which comprises
subjecting a starting material comprising one isomer or a mixture
of at least two isomers of dichloropentafluoropropane and having a
1,1-dichloro-2,2,3,3,3-pentafluoropropane content of less than 60
mol %, to an isomerization reaction in the presence of a Lewis acid
catalyst or a metal oxide catalyst so as to increase the
1,1-dichloro-2,2,3,3,3-pentafluoropropane content in the product to
be higher than the content in the starting material. [0009] 2. The
method for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane
according to the above 1, wherein the starting material contains
1,3-dichloro-1,2,2,3,3-pentafluoropropane, and the
1,3-dichloro-1,2,2,3,3-pentafluoropropane is subjected to an
isomerization reaction to form
1,1-dichloro-2,2,3,3,3-pentafluoropropane. [0010] 3. The method for
producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane according to
the above 2, wherein the starting material further contains
2,2-dichloro-1,1,1,3,3-pentafluoropropane. [0011] 4. The method for
producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane according to
any one of the above 1 to 3, wherein the isomerization reaction is
carried out in a liquid phase in the presence of a Lewis acid
catalyst at a temperature of from 0 to 150.degree. C. [0012] 5. The
method for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane
according to any one of the above 1 to 3, wherein the isomerization
reaction is carried out in a gas phase in the presence of a metal
oxide catalyst at a temperature of from 50 to 500.degree. C. [0013]
6. A method for producing 1,1-dichloro-2,3,3,3-tetrafluoropropene,
which comprises bringing the
1,1-dichloro-2,2,3,3,3-pentafluoropropane obtained by the method as
defined in any one of the above 1 to 5 into contact with an aqueous
alkali solution in the presence of a phase transfer catalyst.
[0014] 7. A method for producing 2,3,3,3-tetrafluoropropene, which
comprises reacting the 1,1-dichloro-2,3,3,3-tetrafluoropropene
obtained by the method as defined in the above 6 with hydrogen in
the presence of a catalyst. [0015] 8. The method for producing
2,3,3,3-tetrafluoropropene according to the above 7, which is
carried out in the presence of an inert gas.
Effects of the Invention
[0016] According to the present invention, it is possible to
obtain, at a high content ratio (molar ratio),
1,1-dichloro-2,2,3,3,3-pentafluoropropane (HCFC-225ca) useful as a
starting material to prepare 2,3,3,3-tetrafluoropropene (R1234yf)
being an excellent cooling medium.
BRIEF DESCRIPTION OF THE DRAWING
[0017] FIG. 1 shows the change with time of the gas composition at
the outlet of the reactor in Example 5 of the present
invention.
PREFERRED EMBODIMENTS OF THE INVENTION
[0018] The method according to an embodiment of the present
invention is characterized in that one isomer or a mixture of at
least two isomers of dichloropentafluoropropane (HCFC-225), which
has a 1,1-dichloro-2,2,3,3,3-pentafluoropropane (HCFC-225ca)
content of less than 60 mol %, particularly less than 50 mol %, is
used as a starting material, and this starting material is
subjected to an isomerization reaction in the presence of a
catalyst so as to increase the HCFC-225ca content in the reaction
product to be higher than the content in the starting material. The
HCFC-225ca content in the above mixture may be 0 mol %. The
isomerization reaction can be carried out in a liquid phase using a
Lewis acid as a catalyst. Otherwise, the isomerization reaction can
be carried out in a gas phase using a metal oxide as a
catalyst.
[0019] In the embodiment of the present invention, as the starting
material for the isomerization reaction, it is possible to use any
material so long as it is HCFC-225 (one isomer or a mixture of at
least two isomers) which has a HCFC-225ca content of less than 60
mol %. For example, it is possible to use a mixture of isomers of
HCFC-225 containing 1,3-dichloro-1,2,2,3,3-pentafluoropropane
(HCFC-225cb) as the main component.
[0020] In the present invention, in order to obtain
1,1-dichloro-2,3,3,3-tetrafluoropropene (R1214ya) as a material for
preparing 2,3,3,3-tetrafluoropropene (R1234yf) being a cooling
medium, a mixture of isomers of HCFC-225 which contains HCFC-225ca,
is contacted with an aqueous alkali solution in the presence of a
phase transfer catalyst to carry out a reaction for selective
dehydrofluorination of HCFC-225ca.
[0021] The mixture of isomers as the starting material for this
reaction contains HCFC-225cb,
2,2-dichloro-1,1,3,3,3-pentafluoropropane (HCFC-225aa), etc. in
addition to HCFC-225ca. And such HCFC-225cb, HCFC-225aa, etc. will
remain as they are without being reacted (dehydrofluorination). A
mixture of isomers such as remaining HCFC-225cb, HCFC-225aa, etc.
will be easily separated from the formed R1214ya by distillation.
Such a separated mixture of isomers such as HCFC-225cb, HCFC-225aa,
etc., can be used as a starting material for the isomerization
reaction of the present invention. As the mixture of the isomers as
the starting material for this reaction, a HCFC-225 product which
is industrially produced, can be used. When dehydrofluorination
reaction is carried out by using such a HCFC-225 product,
HCFC-225ca in the HCFC-225 product selectively undergoes a
dehydrofluorination reaction to form R1214ya. A mixture of HCFC-225
isomers remained as unreacted, can be used as a starting material
containing HCFC-225cb as the main component.
[0022] Further, when such a starting material containing HCFC-225cb
as the main component is isomerized, a mixture containing
HCFC-225ca and HCFC-225aa as the main components will be formed.
When a dehydrofluorination reaction is carried out by using this
mixture, HCFC-225ca selectively undergoes the dehydrofluorination
reaction to form R1214ya. A mixture of HCFC-225 isomers remained as
unreacted can be used as a starting material containing HCFC-225aa
as the main component.
[0023] In the embodiment of the present invention, the catalyst to
be used for the isomerization reaction in a liquid phase is not
particularly limited so long as it is a Lewis acid, but a halide
containing at least one element selected from the group consisting
of Al, Sb, Nb, Ta, W, Re, B, Sn, Ga, In, Zr, Hf and Ti, is
preferably used. For example, it is possible to use a chloride such
as GaCl.sub.2, GaCl.sub.3, ZrCl.sub.4, BCl.sub.3, AlCl.sub.3,
HfCl.sub.4, InCl.sub.3 or TiCl.sub.4, or one having such a compound
partially fluorinated, or a bromide or iodide such as GaBr.sub.3,
Gal.sub.a, HfBr.sub.4, InI.sub.3 or TiBr.sub.4, or one having such
a compound partially chlorinated or fluorinated, such as
TiCl.sub.2F.sub.2, TiClF.sub.3 or ZrCl.sub.2F.sub.2.
[0024] The amount of such a Lewis acid catalyst is preferably
within a range of from 1 to 100 mol %, more preferably from 5 to 50
mol %, to the total amount of isomers of dichloropentafluoropropane
(one isomer or a mixture of at least two isomers) as the starting
material.
[0025] In a case where the isomerization reaction is carried out in
a liquid phase, a solvent for the reaction may be added. The
reaction temperature is preferably within a range of from 0 to
150.degree. C., more preferably from 30 to 100.degree. C. The
reaction time is usually from 0.5 to 200 hours, preferably from 1
to 100 hours, although it depends also on the reaction temperature
or the type of the Lewis acid catalyst.
[0026] The catalyst to be used for the isomerization reaction in a
gas phase is not particularly limited so long as it is a metal
oxide, but an oxide of at least one element selected from the group
consisting of Al, Sb, Nb, Ta, W, Re, B, Sn, Ga, In, Zr, Hf and Ti,
is preferred, and alumina or zirconia is more preferred.
[0027] In the isomerization reaction in a gas phase, the reaction
temperature is preferably from 50 to 500.degree. C., more
preferably from 100 to 450.degree. C., further preferably from 200
to 400.degree. C. The reaction pressure is preferably within a
range of from 0 to 0.2 kg/cm.sup.2, particularly preferably within
a range of from 0 to 1 kg/cm.sup.2. The reaction time is usually
from 10 to 180 seconds, particularly preferably from 20 to 90
seconds, although it depends also on the reaction temperature or
the type of the metal oxide catalyst. In the isomerization
reaction, the mixture of isomers of HCFC-225 as the starting
material may be diluted with an inert gas such as nitrogen and then
supplied for the reaction. The molar ratio of the mixture of
isomers of HCFC-225 to the inert gas (the mixture of isomers of
HCFC-225: the inert gas) is preferably from 1:0.1 to 1:10, more
preferably from 1:0.1 to 1:5.
[0028] In the embodiment of the present invention, the starting
material comprising isomers of HCFC-225 (one isomer or a mixture of
at least two isomers) is subjected to an isomerization reaction in
the presence of the above-mentioned Lewis acid catalyst or metal
oxide catalyst under the above-mentioned reaction conditions,
whereby it is possible to form HCFC-225ca and it is possible to
substantially increase the HCFC-225ca content in the reaction
product over the content in the starting material. By the
isomerization reaction of the present invention, the HCFC-225ca
content is increased to be higher by at least 10 mol %, more
preferably by 30 mol %, than the content in the starting
material.
[0029] Particularly, in a case where the starting material contains
HCFC-225cb, this HCFC-225cb undergoes an isomerization reaction to
form a mixture of isomers containing HCFC-225ca as the main
component, whereby the HCFC-225cb content (molar ratio) in the
starting material decreases, and instead, the HCFC-225ca content
increases as compared with the content in the starting
material.
[0030] Further, in a case where the starting material contains
HCFC-225aa, and the content of HCFC-225aa present in the starting
material is larger than the equilibrium composition at the
isomerization reaction temperature, the HCFC-225aa content in the
starting material decreases, and instead, the HCFC-225ca content
increases. Further, in order to let HCFC-225ca form by the
isomerization reaction to increase the HCFC-225ca content (molar
ratio) in the reaction product over the content in the starting
material, the HCFC-225 ca content in the starting material must be
less than 60 mol % for the following reason.
[0031] That is, in a case where a mixture of various isomers of
HCFC-225 is subjected to an isomerization reaction, for example, at
25.degree. C., the HCFC-225ca content in an equilibrium state will
be from 78 to 80 mol %. If the reaction temperature becomes high,
the value of this content will decrease, but it will not be less
than 60 mol %. Accordingly, if the HCFC-225ca content in the
starting material is 60% or higher (for example 70 mol %), it is
likely that by the isomerization reaction, the HCFC-225ca content
becomes lower than the content in the starting material, but when
the HCFC-225ca content is less than 60 mol %, the HCFC-225ca
content in the product of the isomerization reaction will increase
as compared with the content in the starting material. That is, it
is possible to let HCFC-225ca form by the isomerization reaction of
the starting material thereby to increase the content to be higher
than in the starting material.
[0032] Thus, according to the embodiment of the present invention,
it is possible to obtain HCFC-225ca at a high content ratio among
various isomers of HCFC-225. And, HCFC-225ca thus obtained can be
used as a starting material to form R1214ya.
[0033] To form R1214ya by using HCFC-225ca as a starting material,
it is possible to employ, for example, a method which comprises
contacting the starting material with an aqueous alkali solution in
the presence of a phase transfer catalyst so that only the
HCFC-225ca be selectively dehydrofluorinated.
[0034] Here, the aqueous alkali solution is not particularly
limited so long as it is an aqueous solution of a basic compound
capable of carrying out the dehydrofluorination reaction. However,
it is preferred to employ an aqueous solution of sodium hydroxide,
potassium hydroxide or the like. The alkali concentration in the
aqueous alkali solution is not particularly limited, but it is
preferably from 0.5 to 40 mass %. Further, the amount of the
aqueous alkali solution is not particularly limited, but it is
preferably adjusted so that the amount of an alkali will be from
0.5 to 1.5 mol equivalent, more preferably from 0.8 to 1.2 mol
equivalent, to the amount of HCFC-225ca to be used for the
reaction. On the other hand, as the phase transfer catalyst, a
phase transfer catalyst which is commonly employed, can be used
without any particular restriction. Specifically, it is possible to
use, for example, a quaternary ammonium salt or quaternary
phosphonium salt substituted by a hydrocarbon group, or a crown
ether. The amount of the phase transfer catalyst is preferably from
0.001 to 5 mass %, more preferably from 0.01 to 1 mass %, to the
mass of HCFC-225ca as the starting material. Further, the reaction
temperature in the above dehydrofluorination reaction is not
particularly limited, but it is preferably from 0 to 80.degree. C.,
more preferably from 0 to 50.degree. C.
[0035] R1214ya thus obtained, is further reacted with hydrogen in
the presence of a catalyst (e.g. a Pd catalyst) to obtain
2,3,3,3-tetrafluoropropene (R1234yf) as a cooling medium to be
substituted for a greenhouse gas.
[0036] The above catalyst may, for example, be a catalyst having
palladium supported on a carrier, or a catalyst containing
palladium as the main component and having, supported on a carrier,
a mixture prepared by adding palladium and at least one member
selected from Group 10 elements other than palladium, Group 8
elements, Group 9 elements and gold. The Group 10 elements other
than palladium, Group 8 elements and Group 9 elements include,
iron, cobalt, nickel, ruthenium, rhodium, iridium, osmium and
platinum. Further, the amount of metals other than palladium to be
added to palladium, is preferably from 0.01 to 50 parts by mass per
100 parts by mass of palladium. Here, a composite catalyst having
other metals added to palladium has an effect such that the
catalyst durability tends to be higher than one made of palladium
alone.
[0037] As the carrier to support the above palladium or a metal
mixture containing palladium as the main component, activated
carbon or a metal oxide such as alumina, zirconia or silica may,
for example, be used. Among them, activated carbon is preferably
employed from the viewpoint of the activity, durability or
selectivity in the reaction. As the activated carbon, it is
possible to use one prepared from a material such as wood,
charcoal, fruit shell, coconut shell, peat, lignite or coal, and
one obtained from a plant material is preferred to one obtained
from a mineral material.
[0038] Particularly preferred is a coconut shell activated carbon.
With respect to the shape of the carrier, it is possible to employ
a molded carbon having a length of from about 2 to 5 mm, granulated
carbon of from about 4 to 50 mesh or pelletized carbon, but
granulated carbon of from 4 to 20 mesh or molded carbon is
preferred.
[0039] The reaction to form R1234yf is preferably carried out by a
gas phase reduction method wherein heated gasified R1214ya and
hydrogen are passed through a reactor packed with a catalyst at a
temperature of from 130 to 250.degree. C., preferably from 150 to
200.degree. C. to contact them with the catalyst. The molar ratio
of R1214ya to hydrogen supplied (R1214ya:H.sub.2) is preferably
from 1:0.5 to 1:10, more preferably from 1:0.5 to 1:5. The reaction
pressure is usually atmospheric pressure or natural pressure,
whereby R1234yf-forming reaction sufficiently proceeds. The contact
time with the catalyst may be set within a range of usually from 4
to 60 seconds, preferably from 8 to 40 seconds. Further, to control
an excessive increase of the temperature, the reaction may be
carried out by diluting the atmosphere with an inert gas such as
nitrogen. The molar ratio of hydrogen and the inert gas to be
supplied (H.sub.2: the inert gas) is preferably from 1:0.1 to 1:10,
more preferably from 1:0.5 to 1:4.
Examples
[0040] Now, the present invention will be described in detail with
reference to Examples, but it should be understood that the present
invention is by no means restricted to such Examples.
Example 1
[0041] Firstly, a Lewis acid catalyst was prepared as follows. That
is, a Dimroth condenser having a cooling medium cooled to
-20.degree. C., circulated, was set on a three-necked flask
(internal capacity: 500 mL), 50 g (0.375 mol) of aluminum
trichloride (AlCl.sub.3) was charged thereto and cooled to
0.degree. C., and then, 175 mL (262.5 g; 1.9 mol) of
trichlorofluoromethane (CFCl.sub.3) was slowly dropwise added with
stirring.
[0042] Isomerization of trichlorofluoromethane proceeded, while
accompanied by generation of a low boiling point gas. And, along
with the progress of isomerization, a halogen exchange reaction
proceeded between chlorofluoromethane as a substrate and aluminum
trichloride (AICl.sub.3) as a catalyst, to form a fluorinated
aluminum halide. The reaction was continued for one hour, whereupon
a volatile component was removed, and the catalyst was dried. Thus,
a partially fluorinated aluminum chloride was obtained.
[0043] Then, to a glass reactor (internal capacity: 1 L) provided
with a Dimroth condenser cooled to 0.degree. C., 10 g of the
partially fluorinated aluminum chloride obtained by the above
reaction was introduced as a catalyst, and 609 g (3.0 mol) of a
starting material liquid being a mixture of isomers of
chloropentafluoropropane (HCFC-225) was added thereto. The
composition of the starting material liquid (the molar ratio of
isomers) is shown in Table 1.
[0044] Here, this starting material liquid was a residue (the
residual product) obtained by reacting ASAHIKLIN AK225 (tradename
of Asahi Glass Company, Limited; comprising HCFC-225ca, HCFC-225cb
and other isomers) being a mixture of isomers of HCFC-225 in an
aqueous alkali solution in the presence of a phase transfer
catalyst (tetrabutylammonium bromide) to selectively dehydrogen
fluorinating HCFC-225ca, subjecting the obtained crude liquid to
liquid separation, then distilling the organic phase and recovering
R1214ya (boiling point: 45.degree. C.).
[0045] Then, after adding such a starting material liquid, the
temperature in the reactor was raised to 50.degree. C., and a
reaction was carried out for 20 hours with stirring. After the
reaction, the liquid was subjected to filtration to remove the
catalyst and to recover 600 g of the reaction product liquid. Then,
the obtained reaction product liquid was analyzed by gas
chromatography to obtain the composition of the reaction products.
The results are shown in Table 1. Here, in the Table, HCFC-225aa
represents 2,2-dichloro-1,1,3,3,3-pentafluoropropane.
TABLE-US-00001 TABLE 1 Molar ratio (%) Composition Composition of
starting of reaction material liquid product liquid HCFC-225ca 0 75
HCFC-225cb 99.5 1 HCFC-225aa 0 19 Other isomers 0.5 5
[0046] From the results in Table 1, it is evident that the
isomerization reaction of HCFC-225cb in the starting material
proceeded to form HCFC-225ca which was not present in the starting
material, whereby the content of this HCFC-225ca increased to at
least 70 mol %.
Examples 2 to 4
[0047] Firstly, a catalyst was prepared as follows. That is, a
catalyst of spherical activated alumina having a particle size of 2
mm (specific surface area: 280 m.sup.2/g, "ACBM-1", manufactured by
Catalysts & Chemicals Industries Co., Ltd.) was packed in a
reaction tube made of Inconel (registered trademark) 600 and having
an inner diameter of 2.54 cm and a length of 100 cm and immersed in
a salt bath. A gas mixture of nitrogen/Freon R-12
(CCl.sub.2F.sub.2) of 2/1 (mol/mol) heated to 250.degree. C. was
passed for a contact time of 20 seconds for 4 hours to activate the
catalyst.
[0048] Then, the temperature of the salt bath was raised to the
temperature identified in Table 2, and a mixture of isomers of
HCFC-225 prepared in the same manner as in Example 1 was passed
under the conditions shown in Table 2 to carry out the
isomerization reaction. The gas composition at the outlet of the
reactor was analyzed by gas chromatography to carry out the
analysis of the composition of the reaction products. The results
are shown in Table 2.
TABLE-US-00002 TABLE 2 Composition of starting material Ex. 2 Ex. 3
Ex. 4 Reaction Reaction -- 250.degree. C. 300.degree. C.
350.degree. C. conditions temperature Starting material -- 1/2 1/2
1/2 supply ratio (molar ratio) (HCFC-225/N.sub.2) Contact time --
20 20 20 seconds seconds seconds Composition
CClF.sub.2CF.sub.2CHClF 99.5 mol % 20 mol % 1 mol % 1 mol % of
crude gas (HCFC-225cb) CF.sub.3CF.sub.2CHCl.sub.2 0 mol % 58 mol %
64 mol % 60 mol % (HCFC-225ca) CF.sub.3CCl.sub.2CHF.sub.2 0 mol %
21 mol % 34 mol % 36 mol % (HCFC-225aa) Other isomers 0.5 mol % 1
mol % 1 mol % 3 mol %
Example 5
[0049] The reaction was carried out in the same manner as in
Example 3, and while the analysis of the gas composition at the
outlet of the reactor was carried out with time, the reaction was
continued for 940 hours. FIG. 1 shows the results obtained by
analyzing the change with time of the gas composition at the outlet
of the reactor.
[0050] From the results in FIG. 1, it was confirmed that no
deterioration of the catalyst was observed even after expiration of
940 hours.
Example 6
[0051] Using the reaction crude liquid recovered in Example 1,
1,1-dichloro-2,3,3,3-tetrafluoropropene (CF.sub.3CF.dbd.CCl.sub.2,
R1214ya) was produced by the following method.
[0052] To a glass reactor having an internal capacity of 1 L and
provided with a Dimroth condenser cooled to 0.degree. C., 3 g of
tetrabutylammonium bromide (TBAB) as a phase transfer catalyst, 129
g of potassium hydroxide (2.30 mol), 220 g of water and 600 g (2.96
mol) of the above-mentioned recovered composition were charged and
then gradually heated with stirring to carry out a reaction at
45.degree. C. for one hour. After completion of the reaction, a
part of the organic phase of the reaction crude liquid was
recovered, and the composition was analyzed by gas chromatography
(GC). The analytical results are shown in Table 3.
[0053] Further, after the GC analysis, the reaction crude liquid
separated into two phases of an organic phase and an aqueous phase
was subjected to liquid separation, and the organic phase was
charged and distilled in a distillation column having a capacity of
1 L and an ability of theoretical plate number of 10 plates. As a
result of the distillation, it was possible to recover 384 g (2.10
mol) of R1214ya having a purity of 99.5% (boiling point: 45.degree.
C.).
TABLE-US-00003 TABLE 3 Mol composition (%) Composition of
Composition of starting reaction material liquid crude liquid
HCFC-225ca 75 0 HCFC-225cb 1 1 HCFC-225aa 19 19 Other isomers of 5
5 HCFC-225 R1214ya 0 75
[0054] A catalyst of activated carbon having 2 mass % of palladium
supported (tradename: Shirasagi C2X, manufactured by Takeda
Pharmaceutical Company Limited) was packed into a reaction tube
made of Inconel (registered trademark) 600 having an inner diameter
of 2.54 cm and a length of 100 cm, and immersed in a salt bath.
Using 1,1-dichloro-2,3,3,3-tetrafluoropropene
(CF.sub.3CF.dbd.CCl.sub.2, R1214ya) obtained by the above-described
method, a reduction reaction was carried out under the reaction
conditions identified in Table 4 to produce
2,3,3,3-tetrafluoropropene (CF.sub.3CF.dbd.CH.sub.2, R1234yf).
[0055] Confirmation of the reaction products was carried out by
analyzing the gas discharged from the reactor by gas chromatography
and calculating the crude gas composition. The results are shown at
the lower portion in Table 4.
TABLE-US-00004 TABLE 4 Reaction Reaction 200.degree. C. conditions
temperature Starting material 1/2/2 supply ratio (molar ratio)
R1214ya/H.sub.2/N.sub.2 Contact time 53 seconds Composition
CF.sub.3CF = CCl.sub.2 0% of crude gas (R1214ya) CF.sub.3CF =
CH.sub.2 72% (R1234yf) Others 28%
Example 7
[0056] As the residue in the distillation to recover R1214ya in
Example 6, a composition shown in Table 5 was recovered. Using this
composition as a starting material, an isomerization reaction was
carried out by the same method as the method shown in Example 3.
The gas composition at the outlet of the reactor was analyzed by
gas chromatography thereby to carry out the analysis of the
composition of the reaction products. The results are shown in
Table 5.
TABLE-US-00005 TABLE 5 Mol composition (%) Composition Composition
of starting of reaction material liquid crude gas HCFC-225ca 0 62
HCFC-225cb 5 1 HCFC-225aa 76 35 Other isomers of 19 2 HCFC-225
INDUSTRIAL APPLICABILITY
[0057] From HCFC-225ca obtained by the present invention, it is
possible to efficiently produce R1234yf useful as a new cooling
medium, via R1214ya.
[0058] The entire disclosure of Japanese Patent Application No.
2009-009208 filed on Jan. 19, 2009 including specification, claims,
drawings and summary is incorporated herein by reference in its
entirety.
* * * * *