U.S. patent application number 09/789001 was filed with the patent office on 2001-11-01 for process for producing 1,1,1,-trifluoroacetone.
Invention is credited to Goto, Yoshihiko, Nadano, Ryo, Nishimiya, Takayuki, Sakaya, Takashi.
Application Number | 20010037041 09/789001 |
Document ID | / |
Family ID | 26585803 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010037041 |
Kind Code |
A1 |
Goto, Yoshihiko ; et
al. |
November 1, 2001 |
Process for producing 1,1,1,-trifluoroacetone
Abstract
A process for producing 1,1,1-trifluoroacetone includes the step
of conducting a hydrogenolysis of a halogenated trifluoroacetone,
which is represented by the general formula (1), by a hydrogen gas
in the presence of a catalyst containing a transition metal, 1
where X represents a chlorine, bromine or iodine, and n represents
an integer from 1 to 3. It is possible to obtain
1,1,1-trifluoroacetone with a high yield by using the special
catalyst.
Inventors: |
Goto, Yoshihiko; (Saitama,
JP) ; Nadano, Ryo; (Saitama, JP) ; Sakaya,
Takashi; (Saitama, JP) ; Nishimiya, Takayuki;
(Saitama, JP) |
Correspondence
Address: |
CROWELL & MORING LLP
Intellectual Property Group
P.O. Box 14300
Washington
DC
20044-4300
US
|
Family ID: |
26585803 |
Appl. No.: |
09/789001 |
Filed: |
February 21, 2001 |
Current U.S.
Class: |
568/394 |
Current CPC
Class: |
C07C 45/65 20130101;
C07C 45/65 20130101; C07C 49/167 20130101 |
Class at
Publication: |
568/394 |
International
Class: |
C07C 045/61 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2000 |
JP |
2000-043869 |
Oct 10, 2000 |
JP |
2000-309649 |
Claims
What is claimed is:
1. A process for producing 1,1,1-trifluoroacetone, comprising
conducting a hydrogenolysis of a halogenated trifluoroacetone,
which is represented by the general formula (1), by a hydrogen gas
in the presence of a catalyst comprising a transition metal, 4where
X represents a chlorine, bromine or iodine, and n represents an
integer from 1 to 3.
2. A process according to claim 1, wherein said transition metal is
selected from the group consisting of ruthenium, palladium,
platinum, iridium, rhodium, nickel, copper, and iron.
3. A process according to claim 2, wherein said transition metal is
selected from the group consisting of ruthenium, palladium,
platinum, iridium, and rhodium.
4. A process according to claim 1, wherein said catalyst further
comprises a support supporting thereon said transition metal.
5. A process according to claim 4, wherein said support is selected
from the group consisting of activated carbon, alumina,
silica-alumina, and silica.
6. A process according to claim 5, wherein said support is
activated carbon supporting thereon said transition metal that is
palladium or platinum.
7. A process according to claim 4, wherein said transition metal is
in an amount of 0.1-10 g per 100 ml of said support.
8. A process according to claim 1, wherein said hydrogenolysis is
conducted in the presence of water.
9. A process according to claim 1, wherein a hydrate of said
halogenated trifluoroacetone is used as a raw material for
conducting said hydrogenolysis.
10. A process according to claim 1, wherein an aqueous solution of
a hydrate of said halogenated trifluoroacetone is used as a raw
material for conducting said hydrogenolysis.
11. A process according to claim 1, wherein an aqueous solution of
said halogenated trifluoroacetone is used as a raw material for
conducting said hydrogenolysis.
12. A process according to claim 1, said hydrogenolysis is
conducted by a gas phase reaction.
13. A process according to claim 1, wherein said halogenated
trifluoroacetone is selected from the group consisting of
3-chloro-1,1,1-trifluoroacetone,
3,3-dichloro-1,1,1-trifluoroacetone, and
3,3,3-trichloro-1,1,1-trifluoroacetone.
14. A process according to claim 1, wherein said hydrogenolysis is
conducted at a temperature of 50-350.degree. C.
15. A process according to claim 1, wherein a molar ratio of said
halogenated trifluoroacetone to said hydrogen gas is 1.5 to 50.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a process for producing
1,1,1-trifluoroacetone that is useful as an intermediate of
pharmaceuticals and agricultural chemicals, or as a reagent for
introducing fluorine-containing groups.
[0002] 1,1,1-trifluoroacetone is known to be obtained by various
methods. It is described in J. Chem. Soc. (Lond.) 1956, 835 that
1,1,1-trifluoroacetone is synthesized by a Grignard reaction
between trifluoroacetic acid and magnesium methyliodide. This
Grignard reaction must be conducted in an anhydrous state. In
addition, it is also described in Tetrahedron, 20, 2163 (1964) that
trifluoroacetone can be synthesized by decarbonating
trifluoroacetoethyl acetate in sulfuric acid. It is described in
Tetrahedron Lett. Vol. 24 (No. 5), 507-510, 1983 that
difluoromethylketones are obtained at considerably high yield as a
result of reducing chlorodifluoroketones, which are represented by
CF.sub.2ClC(=O)R (wherein R is a group not containing halogen) by
zinc and methanol in tetrahydrofuran.
[0003] Japanese Patent Publication 2000-336057A, corresponding to
Japanese Patent Application 11-147670, discloses a process for
producing 1,1,1-trifluoroacetone by reacting
3,3-dichloro-1,1,1-trifluoroacetone with zinc in a solvent of a
proton donor. In this process, it is necessary to have a relatively
large amount of zinc.
SUMMARY OF THE INVENTION
[0004] It is an object of the present invention to provide a
process for producing 1,1,1-trifluoroacetone, which is suitable for
an industrial-scale production.
[0005] According to the present invention, there is provided a
process for producing 1,1,1-trifluoroacetone. This process
comprises conducting a hydrogenolysis of a halogenated
trifluoroacetone, which is represented by the general formula (1),
by a hydrogen gas in the presence of a catalyst comprising a
transition metal, 2
[0006] where X represents a chlorine, bromine or iodine, and n
represents an integer from 1 to 3.
[0007] According to the present invention, it is possible to obtain
1,1,1-trifluoroacetone with a high yield by using the above special
catalyst in hydrogenolysis of the halogenated trifluoroacetone
(e.g., 3,3-dichloro-1,1,1-trifluoroacetone) by a hydrogen gas.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0008] The hydrogenolysis can be conducted by a gas phase reaction
between the halogenated trifluoroacetone (gas) and a hydrogen gas
using a reactor for flow method.
[0009] The halogenated trifluoroacetone used as a starting material
in the process of the present invention may be a hydrate, alcohol
addition product, gem-diol, acetal or hemiacetal, or their aqueous
or alcohol solutions, of a halogenated trifluoroacetone represented
by the general formula (1), as indicated in the following formulas,
although an aqueous solution of the hydrate is preferable due to
its ease of handling: 3
[0010] where X and n are the same as previously defined in the
general formula (1), m represents an integer, R.sup.1 represents an
alkyl group, and each R.sup.2 independently represents a hydrogen
atom or alkyl group.
[0011] The halogenated trifluoroacetone can be
3-chloro-1,1,1-trifluorocet- one,
3,3-dichloro-1,1,1-trifluoroacetone, or
3,3,3-trichloro-1,1,1-trifluo- roacetone. These compounds can be
synthesized by known processes. For example, they can be obtained
by fluorinating pentachloroacetone by hydrogen fluoride in the
presence of a transition metal or the like as a catalyst.
Furthermore, decarboxylation of a trifluoroacetoacetic ester is
known.
[0012] As stated above, the halogenated trifluoroacetone used as a
starting material in the process of the present invention may be a
hydrate in which a halogenated trifluoroacetone represented by the
general formula (1) has hydrated to have an arbitrary number of
water molecules. In the process, it is preferable to use the
halogenated trifluoroacetone in the form of an aqueous solution,
since its handling is easy and thereby the reaction procedures can
be simplified. The existence of water is not an obstacle to the
reaction, but the existence of unnecessary water is not preferable
from the viewpoint of energy consumption.
[0013] As stated above, the catalyst used in the hydrogenolysis
comprises a transition metal. This transition metal is preferably a
noble metal such as ruthenium, palladium, platinum, iridium, and
rhodium. Further examples of the transition metal other than noble
metal are nickel, copper and iron. Of these, palladium and platinum
are preferable. The transition metal is preferably supported on a
support such as activated carbon, alumina, silica-alumina, and
silica. Of these, activated carbon is preferable. It is
particularly preferable to use a catalyst containing an activated
carbon supporting thereon palladium or platinum. The way of making
the transition metal to be supported on the support is not
particularly limited. For example, it is possible to immerse a
support in a solution of a transition metal compound or to spray
this solution to a support, followed by drying and then reduction
with hydrogen gas. The transition metal compound may be in the form
of chloride, bromide, fluoride, oxide, nitrate, sulfate or
carbonate. The transition metal may be in an amount of about 0.1-10
g, preferably 0.2-5 g, per 100 ml of the support. If it is less
than 0.1 g, both conversion of the halogenated trifluoroacetone and
yield of 1,1,1-trifluoroacetone may become too low. An amount of
greater than 5 g may not be preferable from the economical
viewpoint.
[0014] The reaction temperature may be 50.degree. C. or higher,
preferably 70.degree. C. or higher, more preferably 90.degree. C.
or higher, still more preferably 100.degree. C. or higher, further
preferably 105.degree. C. or higher. Furthermore, the reaction
temperature may be 350.degree. C. or lower, preferably 250.degree.
C. or lower, more preferably 200.degree. C. or lower, still more
preferably 150.degree. C. or lower, further preferably 120.degree.
C. or lower. Therefore, the reaction temperature range may be
50-350.degree. C., preferably 70-250.degree. C., more preferably
90-120.degree. C. If it is lower than 50.degree. C., both
conversion of the halogenated trifluoroacetone and yield of
1,1,1-trifluoroacetone may be lowered. If it is higher than
350.degree. C., fluorine atom hydrogenolysis and/or hydrogenation
of carbonyl group may proceed. With this, yield of
1,1,1-trifluoroacetone may be lowered.
[0015] The molar ratio of hydrogen (hydrogen gas) to the
halogenated trifluoroacetone may be varied depending on the number
of the halogen atoms (other than fluorine) of the halogenated
trifluoroacetone. This ratio may be in a range of 1.5-50,
preferably 2-10, more preferably 2.5-5. If it is less than 1.5,
conversion of the halogenated trifluoroacetone may not be
sufficiently high. Even if it is greater than 50, conversion of the
halogenated trifluoroacetone may not improve further. Furthermore,
this is not preferable from the economical viewpoint, due to the
necessity of recovering the unreacted hydrogen gas. It is optional
to make nitrogen gas coexistent with the other reagents in the
reaction system in order to adjust the reaction and to suppress the
catalyst deterioration.
[0016] It is preferable that the hydrogenolysis is conducted by
using a reactor made of a material lined with a lining material
selected from of borosilicate glasses, tetrafluoroethylene resins,
chlorotrifluoroethylene resins, vinylidene fluoride resins,
perfluoroalkyl vinyl ether (PFA) resins and carbon, when water
exists in the reaction system. When water does not exist in the
reaction system by using a halogenated trifluoroacetone that is not
hydrated, it is possible to use iron, stainless steel, nickel and
Hastelloy (trade name) for the reactor in addition to the
above-mentioned lining material.
[0017] The way of conducting the hydrogenolysis is not particularly
limited. For example, it can be conducted by the following flow
method. At first, a reactor for flow method, which is resistant
against the reaction conditions of the hydrogenolysis, is charged
with a transition metal supported catalyst. Then, the reactor is
heated from outside, and hydrogen gas is allowed to flow through a
reaction tube. When the reaction tube's inside temperature reaches
a predetermined temperature, the halogenated trifluoroacetone is
introduced into a vaporizer for vaporizing the same and then into
the reaction tube together with the hydrogen gas. A mixture of gas
and/or liquid flowing out of the reaction tube is absorbed into
water. Alternatively, it is cooled down and collected in the form
of liquid. It is optional to separately introduce the halogenated
trifluoroacetone and water into the reaction tube.
[0018] The resulting 1,1,1-trifluoroacetone can be purified by a
conventional purification method used for hydrogenolysis products
obtained from fluorinated compounds. For example, a reaction
product containing 1,1,1-trifluoroacetone (in the form of liquid or
gas), which has flowed out of the reactor together with hydrogen
chloride, is cooled down. After that, hydrogen chloride is removed
from the reaction product by distillation or gas-liquid phase
separation. Then, the remaining acid component is removed from the
product with a basic substance or the like. After that, the target
product, 1,1,1-trifluoroacetone of high purity, is obtained by
rectification.
[0019] The following nonlimitative catalyst preparations are
illustrative of the present invention.
Catalyst Preparation 1
[0020] At first, a 200-ml eggplant-type flask was charged with 35 g
of a granular activated carbon (a coconut husk carbon of a particle
diameter of 4-6 mm) made by Takeda Chemical Industries, Ltd. having
a trade name of GRANULAR SHIRO SAGI G2X-4/6. Then, about 120 ml of
an about 20% nitric acid aqueous solution was added to the flask.
After that, the flask was allowed to stand still for about 3 hr,
thereby to conduct a nitric acid treatment of the activated carbon.
Separately, 0.83 g of palladium (II) chloride, PdCl.sub.2, was
dissolved in 5 g of a 24% hydrochloric acid, to prepare a palladium
chloride solution. This palladium chloride solution was poured on
the activated carbon contained in the flask. Then, this flask was
allowed to stand still for 2 days. Then, the activated carbon,
impregnated with the palladium chloride solution, was subjected to
vacuum drying with an evaporator by increasing the bath temperature
to 150.degree. C. Then, the dried activated carbon was put into a
reaction tube having a diameter of 25 mm, an axial length of 400
mm, and a capacity of about 200 ml. Then, while nitrogen was
allowed to flow through the reaction tube at a rate of 200-300
ml/min, the reaction tube was heated from 150.degree. C. to
300.degree. C. by increasing the set temperature of the reaction
tube stepwise by 50.degree. C., in order to bake the activated
carbon. The reaction tube temperature was maintained at 300.degree.
C. for 1 hr in order to further bake the same, and then the set
temperature was decreased to 150.degree. C. After that, while
nitrogen and hydrogen were allowed to flow therethrough at
respective rates of 50 ml/min and 50 ml/min, the reaction tube
temperature was increased again to 300.degree. C. by increasing its
set temperature stepwise by 30.degree. C. for conducting reduction.
With this, there was prepared a first catalyst having an activated
carbon carrying thereon 0.5% of palladium, based on the weight of
the activated carbon.
Catalyst Preparation 2
[0021] At first, a 200-ml eggplant-type flask was charged with 35 g
of the same granular activated carbon as that of Catalyst
Preparation 1. Separately, 0.46 g of hexachloroplatinic (IV) acid
hexahydrate, H.sub.2PtCl.sub.6.6H.sub.2O, was dissolved in 100 ml
of 30% hydrochloric acid, to prepare a hexachloroplatinic acid
solution. This solution was poured on the activated carbon
contained in the flask. Then, this flask was allowed to stand still
for 2 days. Then, the same procedures as those of Catalyst
Preparation 1 were conducted, thereby preparing a second catalyst
having an activated carbon carrying thereon 0.5% of platinum, based
on the weight of the activated carbon.
[0022] The following nonlimitative examples are illustrative of the
present invention.
EXAMPLE 1
[0023] At first, a tubular reactor made of glass was charged with
50 ml of the first catalyst (0.5% Pd on activated carbon) obtained
in Catalyst Preparation 1. Then, the reactor was heated to
110.degree. C., while hydrogen gas was allowed to flow through the
reactor at a rate of 80 ml/min by downflow. A
3,3-dichloro-1,1,1-trifluoroacetone aqueous solution (water
content: 25%) was introduced into a vaporizer at a rate of 0.2
g/min, thereby vaporizing this solution. The resulting vapor was
mixed with hydrogen, and the mixture was introduced into the
reactor after the reactor's inside temperature became stable. Then,
the reaction was conducted for 5 hr. During the reaction, liquid
and gas flowing out of the reactor were introduced into 10 g of
water cooled at 0.degree. C., thereby collecting them. The
collected product in an amount of 47.2 g was found by Karl
Fischer's method to contain 52.4% of water. Furthermore, it was
found by gas chromatography to contain organic components of 98.4%
of 1,1,1-trifluoroacetone, 0.1% of 1,1-difluoroacetone, 0.5% of
1-fluoroacetone, 0.4% of acetone and others. These percentages are
areal percentages in chromatogram.
EXAMPLE 2
[0024] Example 1 was repeated except in that the flow rate of
hydrogen gas was 65 mmin, thereby collecting 53.8 g of a product.
The collected product was found by Karl Fischer's method to contain
42.3% of water. Furthermore, it was found by gas chromatography to
contain organic components of 97.7% of 1,1,1-trifluoroacetone, 0.4%
of 1,1-difluoroacetone, 1.3% of 1-fluoroacetone, 0.3% of acetone
and others.
EXAMPLE 3
[0025] Example 1 was repeated except in that the flow rate of
hydrogen gas was 100 ml/min, thereby collecting 49.1 g of a
product. The collected product was found by Karl Fischer's method
to contain 52.8% of water. Furthermore, it was found by gas
chromatography to contain organic components of 97.5% of
1,1,1-trifluoroacetone, 1.1% of 1,1-difluoroacetone, 0.5% of
1-fluoroacetone, 0.4% of acetone and others.
EXAMPLE 4
[0026] At first, a tubular reactor made of glass was charged with
50 ml of the first catalyst (0.5% Pd on activated carbon) obtained
in Catalyst Preparation 1. Then, the reactor was heated to
110.degree. C., while hydrogen gas was allowed to flow through the
reactor at a rate of 80 ml/min by downflow. An aqueous solution
(water content: 15%) of a raw material mixture containing 8.2% of
3-chloro-1,1,1-trifluoroacetone, 88.8% of
3,3-dichloro-1,1,1-trifluoroacetone, and 2.4% of
3,3,3-trichloro-1,1,1-trifluoroacetone was introduced into a
vaporizer at a rate of 0.2 g/min, thereby vaporizing this solution.
The resulting vapor was mixed with hydrogen, and the mixture was
introduced into the reactor after the reactor's inside temperature
became stable. Then, the reaction was conducted for 5 hr. During
the reaction, liquid and gas flowing out of the reactor were
introduced into 20 g of water cooled at 0.degree. C., thereby
collecting them. The collected product in an amount of 56.9 g was
found by Karl Fischer's method to contain 45.6% of water.
Furthermore, it was found by gas chromatography to contain organic
components of 97.9% of 1,1,1-trifluoroacetone, 0.4% of
1,1-difluoroacetone, 0.5% of 1-fluoroacetone, 0.6% of acetone and
others.
EXAMPLE 5
[0027] Example 1 was repeated except in that the first catalyst was
replaced with the second catalyst (0.5% Pt on activated carbon)
obtained in Catalyst Preparation 2 and that the water cooled at
0.degree. C. was in an amount of 14 g, thereby collecting 64.2 g of
a product. The collected product was found by Karl Fischer's method
to contain 46.3% of water. Furthermore, it was found by gas
chromatography to contain organic components of 99.0% of
1,1,1-trifluoroacetone, 0.1% of 1,1-difluoroacetone, 0.1% of
1-fluoroacetone, 0.3% of acetone and others.
EXAMPLE 6
[0028] At first, a tubular reactor made of glass was charged with
500 ml of the first catalyst (0.5% Pd on activated carbon) obtained
in Catalyst Preparation 1. Then, the reactor was heated to
95.degree. C., while hydrogen gas was allowed to flow through the
reactor at a rate of 500 ml/min by downflow. A raw material mixture
containing 9.6% of 3-chloro-1,1,1-trifluoroacetone, 84.0% of
3,3-dichloro-1,1,1-trifluoroace- tone, and 3.9% of
3,3,3-trichloro-1,1,1-trifluoroacetone was introduced into a
vaporizer at a rate of 1.5 g/min, thereby vaporizing the mixture.
The resulting vapor was mixed with hydrogen, and the mixture was
introduced into the reactor after the reactor's inside temperature
became stable. Then, the reaction was conducted for 6 hr. During
the reaction, liquid and gas flowing out of the reactor were
introduced into 500 g of water cooled at 0.degree. C., thereby
collecting them. The collected product in an amount of 909 g was
found by Karl Fischer's method to contain 55.0% of water.
Furthermore, it was found by gas chromatography to contain organic
components of 98.1% of 1,1,1-trifluoroacetone, 0.7% of
1,1-difluoroacetone, and others.
EXAMPLE 7
[0029] At first, a tubular reactor made of glass was charged with
10 ml of the second catalyst (0.5% Pt on activated carbon) obtained
in Catalyst Preparation 2. Then, the reactor was heated to
110.degree. C., while hydrogen gas was allowed to flow through the
reactor at a rate of 80 ml/min by downflow. An aqueous solution
(water content: 15%) of a raw material mixture containing 8.2% of
3-chloro-1,1,1-trifluoroacetone, 88.8% of
3,3-dichloro-1,1,1-trifluoroacetone, and 2.4% of
3,3,3-trichloro-1,1,1-trifluoroacetone was introduced into a
vaporizer at a rate of 0.16 g/min, thereby vaporizing the mixture.
The resulting vapor was mixed with hydrogen, and the mixture was
introduced into the reactor after the reactor's inside temperature
became stable. Then, the reaction was conducted for 1 hr. During
the reaction, liquid and gas flowing out of the reactor were
introduced into 10 g of water cooled at 0.degree. C., thereby
collecting them. The collected product in an amount of 16.1 g was
found by Karl Fischer's method to contain 61.2% of water.
Furthermore, it was found by gas chromatography to contain organic
components of 96.7% of 1,1,1-trifluoroacetone, 1.5% of
3-chloro-1,1,1-trifluoroacetone, and others.
EXAMPLE 8
[0030] At first, a tubular reactor made of glass was charged with
50 ml of the second catalyst (0.5% Pt on activated carbon) obtained
in Catalyst Preparation 2. Then, the reactor was heated to
110.degree. C., while hydrogen gas was allowed to flow through the
reactor at a rate of 80 ml/min by downflow.
3,3-dichloro-1,1,1-trifluoroacetone was introduced into a vaporizer
at a rate of 0.18 g/min, thereby vaporizing this compound. The
resulting vapor was mixed with hydrogen, and the mixture was
introduced into the reactor after the reactor's inside temperature
became stable. Then, the reaction was conducted for 1 hr. During
the reaction, liquid and gas flowing out of the reactor were
introduced into 10 g of water cooled at 0.degree. C., thereby
collecting them. The collected product in an amount of 17.4 g was
found by Karl Fischer's method to contain 55.9% of water.
Furthermore, it was found by gas chromatography to contain organic
components of 95.4% of 1,1,1-trifluoroacetone, 3.0% of
3-chloro-1,1,1-trifluoroacetone, and others.
[0031] The entire disclosure of each of Japanese Patent
Applications No. 2000-043869 filed on Feb. 22, 2000 and No.
2000-309649 filed on Oct. 10, 2000, including specification, claims
and summary, is incorporated herein by reference in its
entirety.
* * * * *