Technical Field
[0001] The present invention relates to a method for producing difluoroacetyl
chloride (hereinafter sometimes abbreviated as "DFAC") and, more particularly, to a
method for producing difluoroacetyl chloride by contact of a 1 -alkoxy-1,1,2,2-
tetrafluoroethane (hereinafter sometimes abbreviated as "ATFE") or a derivative
thereof with calcium chloride.
Background Art
[0002] It has been reported that difluoroacetyl chloride is useful as an
intermediate for pharmaceutical and agrichemical products and as a reaction reagent,
particularly a reagent for the introduction of a difluoromethyl group or
difluoroacetyl group into an organic compound, and can be produced by various
processes.
[0003] As a production method of a carboxylic acid chloride, there is generally
known a process of reacting a carboxylic acid or a salt, ester or anhydride thereof
with a chlorination agent such as chlorine, phosphorous pentachloride, phosphorous
trichloride, phosphoryl chloride or thionyl chloride. It has been reported that
difluoroacetyl chloride can be obtained by such a similar process. In this process,
however, the raw material such as difluoroacetic acid or derivative thereof is not
readily available.
[0004] By contrast, there is known a process of irradiating HCFC-132a (1,1-
difluoro-3,3,3-trichloroethane), together with oxygen and chlorine, by a high-
pressure mercury-vapor lamp under high-temperature conditions (Patent Document
1) as a method for producing a carboxylic acid chloride without going through
difluoroacetic acid as an intermediate. In this process, the raw material is a
substance that may cause ozone destruction. Further, this process is performed in a
photoreaction system and thus is not so suitable for long-term production.
[0005] On the other hand, a process of thermally decomposing a 1-alkoxy-
1,1,2,2-tetrafluoroethane (ATFE) in the presence of a metal oxide catalyst (Patent

Document 2) and a process of decomposing a l-alkoxy-l,l,2,2-tetrafluoroethane
(ATFE) in the presence of an antimony pentafluoride catalyst under low-temperature
conditions (Patent Document 3) are known as production methods of difluoroacetyl
fluoride (hereinafter sometimes abbreviated as "DFAC"). A process of converting a
perfluorocarboxylic acid fluoride to a corresponding acid chloride by halogen
exchange reaction with lithium chloride (Non-Patent Document 1) and a process of
forming benzoyl chloride by reaction of benzoyl fluoride with calcium chloride
(Patent Document 4) have been reported as methods for direct conversion from
carboxylic acid fluorides to carboxylic acid chlorides.
Prior Art Documents
Patent Documents
[0006] Patent Document 1: Japanese Laid-Open Patent Publication No. H8-53388
Patent Document 2: Japanese Laid-Open Patent Publication No. H8-92162
Patent Document 3: U.S. Patent No. 4,357,281
Patent Document 4: European Patent No. 293747
Patent Document 5: Japanese Laid-Open Patent Publication No. H6-277510
Non-Patent Documents
[0007] Non-Patent Document 1: J. Chem. Soc, Perkin Trans. 1, 1996, 915-920
Summary of the Invention
Problems to be Solved by the Invention
[0008] It is an object of the present invention to provide a method for producing
difluoroacetyl chloride efficiently from a l-alkoxy-l,l,2,2-tetrafluoroethane.
Means for Solving the Problems
[0009] The present inventors have made extensive researches on the method for
efficiently converting difluoroacetyl fluoride, which can be obtained by thermal
decomposition of a l-alkoxy-l,l,2,2-tetrafluoroethane (ATFE), to difluoroacetyl
chloride. As a result, the present inventors have found that it is possible to produce
difluoroacetyl chloride (DFAC) quantitatively, without causing chlorination of a
hydrogen atom in a difluoromethyl group, by contact of difluoroacetyl fluoride

(DFAF) and calcium chloride under heating conditions. The present inventors have
also found that the difluoroacetyl chloride can be obtained in one process step with
high selectivity and high yield, without the need to extract difluoroacetyl chloride as
an intermediate, by the application of a similar reaction process to ATFE. The
present invention is based on these findings.
[0010] Herein, it is conceivable to propose: an indirect reaction process that
uses ATFE as a starting material and goes through difluoroacetyl fluoride as an
intermediate; and a direct reaction process that obtains a target compound directly
from ATFE. In the indirect reaction process, a fluorine-containing organic
compound such as monofluoromethane is generated as a by-product. By contrast, a
chlorine-containing organic compound such as monochloromethane is generated as
a by-product in the direct reaction process. Even though both of these organic
compounds are useful and have a certain range of uses, the chlorine-containing
organic compound is easier to decompose and is preferred in terms of waste
management as compared to the fluorine-containing organic compound.
[0011] Namely, the present invention includes the following aspects.
[0012] [Inventive Aspect 1 ]
A production method of difluoroacetyl chloride, comprising a
chlorination step of bringing a raw material containing therein at least either a 1-
alkoxy-l,l,2,2-tetrafluoroethane or difluoroacetyl fluoride into contact with calcium
chloride at a reaction enabling temperature at which the at least either the 1-alkoxy-
1,1,2,2-tetrafluoroethane or difluoroacetyl fluoride can undergo reaction.
[Inventive Aspect 2]
The production method according to Inventive Aspect 1, wherein the raw
material contains at least the l-alkoxy-l,l,2,2-tetrafluoroethane.
[Inventive Aspect 3]
The production method according to Inventive Aspect 1 or 2, wherein the
raw material contains at least the l-alkoxy-l,l,2,2-tetrafluroethane and the
difluoroacetyl fluoride.

[Inventive Aspect 4]
The production method according to any one of Inventive Aspects 1 to 3,
wherein the chlorination step is performed in a gas-phase continuous-flow system.
[Inventive Aspect 5]
The production method according to any one of Inventive Aspects 1 to 4,
wherein the chlorination step is performed at a temperature of 50 to 400°C.
[Inventive Aspect 6]
The production method according to any one of Inventive Aspects 1 to 5,
further comprising a separation step of removing, from a product composition
obtained in the chlorination step and containing therein an alky! halide and
difluoroacetyl chloride, the alkyl halide.
[Inventive Aspect 7]
The production method according to any one of Inventive Aspects 1 to 6,
wherein the 1-alkoxy-1,1,2,2-tetrafluoroethane is l-methoxy-1,1,2,2-
tetrafluoroethane.
[Inventive Aspect 8]
The production method according to any one of Inventive Aspects 1 to 7,
wherein the difluoroacetyl fluoride is obtained by thermal decomposition of an 1-
alkoxy-l,l,2,2-tetrafluoroethane.
[Inventive Aspect 9]
A production method of 2,2-difluoroethyl alcohol, comprising a catalytic
reduction step of causing catalytic reduction of the difluoroacetyl chloride obtained
by the production method according to any one of Inventive Aspects 1 to 8.
[Inventive Aspect 10]
The production method according to Inventive Aspect 9, wherein the
catalytic reduction step is performed in the presence of a palladium catalyst.
[0013] The chlorination step of the present invention makes it possible that the
l-alkoxy-l,l,2,2-tetrafluoroethane and the difluoroacetyl fluoride can be efficiently
and selectively converted to the difluoroacetyl chloride by the same process

operation under substantially the same reaction conditions. Further, the adoption of
such a chlorination step makes it possible that the 2,2-difluoroethyl alcohol can be
obtained with high selectivity and high yield with the use of the 1-alkoxy-l,1,2,2-
tetrafluoroethane as the raw material.
Brief Description Of The Accompanying Drawings
[0014] FIG. 1 is a graph showing the reaction results of Example 1.
FIG. 2 is a graph showing the reaction results of Example 2.
FIG. 3 is a schematic view of a reaction device used in Examples 3 and 4.
FIG. 4 is a schematic view of a reaction device used in Thermal
Decomposition Examples 1 to 3 and Examples 7 and 8.
Detailed Description of the Embodiments
[0015] Hereinafter, the present invention will be described below in detail.
[0016] A production method of difluoroacetyl chloride according to the present
invention includes a reaction step (chlorination step) of bringing a raw material
containing at least either a l-alkoxy-l,l,2,2-tetrafluoroethane (ATFE) or
difluoroacetyl fluoride (DFAF) into contact with calcium fluoride at a reaction
enabling temperature at which the at least either the 1-alkoxy-l, 1,2,2-
tetrafluoroethaneor difluoroacetyl fluoride can undergo reaction.
[0017] In the present invention, each of reactions involved in the chlorination
step is quantitative. The respective reactions of the chlorination step are represented
by the following reaction schemes (1) and (2).
CHF2CF2OR + CaCl2 → CHF2COCI + RCI + CaF2 (1)
2CHF2COF + CaCI2 → 2CHF2COCl + CaF2 (2)
[0018] There is no particular limitation on R in the 1 -alkoxy-1,1,2,2-
tetrafluoroethane of the general formula: CHF2CF2OR (where R is a monovalent
organic group) used as the starting material of the reaction scheme (1) because R

serves as a leaving group. Examples of R are C1-C8 straight, branched or cyclic
alkyl group or fluorine-containing alkyl group and aryl group. Among others, the
alkyl group or fluorine-containing alkyl group is preferred. The alkyl group is more
preferred. Still more preferred is lower alkyl. Herein, the term "lower alkyl" refers
to an alkyl group of 1 to 4 carbon atoms.
[0019] Examples of the C1-C8 straight or branched alkyl group are methyl,
ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, n-pentyl and isopentyl. Of these,
methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl and t-butyl are categorized as the
lower alkyl group.
[0020] Examples of the C1-C8 cyclic alkyl group are cyclobutyl, cyclopentyl, 2-
methylcyclopentyl, 3-methylcyclopentyl, 2-ethylcyclopentyl, 3-ethylcyclopentyl,
cyclohexyl, 2-methylcyclohexyl, 3-methylcyclohexyl, 4-methyicyclohexyl, 2-
ethylcyclohexyl, 3-ethylcyclohexyl, 4-ethylcyclohexyl, cycloheptyl, 2-
methylcycloheptyl, 3-methylcycloheptyl and 4-methylcycloheptyl.
[0021] Examples of the aryl group are phenyl, 2-methylphenyl, 3-
methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-
dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 3,6-
dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 1-naphthyl
and 2-naphthyl.
[0022] Examples of the C1-C8 fluorine-containing alkyl group are fluoromethyl,
difluoromethyl, tritluoromethyl, chlorofluoromethyl, chlorodifluoromethyl,
bromofluoromethyl. bromodifluoromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl,
2,2,3,3,3-pentafluoropropyl, n-hexafluoropropyl and hexafluoroisopropyl.
[0023] It is feasible to obtain the l-alkoxy-l,l,2,2-tetrafluoroethane by a known
production process. One example of such production process is to react an alcohol
(R'OH) with tetrafluoroethylene in the presence of a base as represented by the
following reaction scheme (3).
CF2=CF2 + R'OH → CHF2CF2OR' (3)

[0024] More specifically, l -methoxy-1,1,2,2-tetrafluoroethane can be
synthesized by reaction of methanol and tetrafluoroethylene in the presence of
potassium hydroxide (see J. Am. Chem. Soc, 73, 1329 (1951)).
[0025] Specific examples of the l-alkoxy-l,l,2,2-tetrafluoroethane used in the
present invention include, but are not limited to, 1-methoxy-1,1,2,2-
tetrafluoromethane (also referred to as "CHF2CF2OMe" or "HFE-254pc"), 1-ethoxy-
1,1,2,2-tetrafluoroethane (also referred to as "CHF2CF2OEt,, or "HFE-374pc-f"), 1-
(n-propoxy)-1,1,2,2-tetrafluoroethane, 1 -isopropoxy-1,1,2,2-tetrafluoroethane, 1 -(n-
butoxy)-1,1,2,2-tetrafluoroethane, 1 -(s-butoxy)-1,1,2,2-tetrafluoroethane, 1 -(t-
butoxy)-1,1,2,2-tetrafluoroethane, 1 -trifluoromethoxy-1,1,2,2-tetrafluoroethane, 1 -
difluoromethoxy-1,1,2,2-tetrafluoroethane, 1 -(2,2,2-trifluoroethoxy)-1,1,2,2-
tetrafluoroethane, 1 -pentafluoroethoxy-1,1,2,2-tetrafluoroethane, 1 -(2,2,2,3,3-
pentafluoropropoxy)-1,1,2,2-tetrafluoroethane and 1 -hexafluoroisopropoxy-1,1,2,2-
tetrafluoroethane. Among others, preferred are HFE-254pc and HFE-374pc-f each
of which is low in molecular weight and easy to evaporate.
[0026] It is feasible to obtain the difluoroacetyl fluoride (DFAF) by any
production process. Any of the above-mentioned processes, such as: (1) thermal
decomposition of a l-alkoxy-l,l,2,2-tetrafluoroethane represented by CHF2CF2OR'
in the presence of sulfur trioxide and fluorosulfuric acid (Non-Patent Document 1);
and (2) production of difluoroacetyl fluoride by thermal decomposition of a 1-
alkoxy-l,l,2,2-tetrafluoroethane in the presence of a catalyst (Patent Document 4),
is applicable.
[0027] In the present invention, the difluoroacetyl fluoride is preferably
obtained by thermal decomposition of a l-alkoxy-l,l,2,2-tetrafluoroethane. This
thermal decomposition reaction is represented by the following reaction scheme (4)
where R' is an alkyl group.
CHF2CF2OR' → CHF2COF + R'F (4)

[0028] In the thermal decomposition reaction, metal oxide, partially fluorinated
metal oxide, metal fluoride, phosphoric acid or phosphate is used as a solid catalyst.
Specific examples of the catalyst are a metal oxide or partially fluorinated metal
oxide as disclosed in Patent Document 2 (Japanese Laid-Open Patent Publication
No. H8-92162) and a metal fluoride.
[0029] The thermal decomposition temperature is set depending on the kind of
the catalyst and the contact time and is generally in the range of 100 to 400°C,
preferably 110 to 350°C, more preferably 130 to 320°C, still more preferably 130 to
260°C, most preferably 140 to 200°C. The reaction time (contact time) is set
depending on the reaction temperature and is generally in the range of 0.1 to 1000
seconds, preferably 1 to 500 seconds, more preferably 10 to 300 seconds.
[0030] By the thermal decomposition of the 1 -alkoxy-1,1,2,2-tetrafluoroethane,
equivalent molar amounts of difluoroacetyl fluoride and alkyl fluoride (R'F) are
generated. Further, unreacted 1-alkoxy-1,1,2,2-tetrafloroethane may be contained in
the reaction product of the thermal decomposition. It is preferable to separate and
remove the alkyl fluoride from the difluoroacetyl fluoride, or at least reduce the
amount of the alkyl fluoride contained in the reaction product, in advance of the
chlorination step.
[0031 ] There is no particular limitation on the process for separation of the
alkyl fluoride. In view of the fact that not only the alkyl fluoride but also the
difluoroacetyl fluoride and unreacted ATFE are contained in the reaction product, a
distillation process using a difference between the boiling points of the alkyl fluoride
and the other components or a extraction process using a difference between the
solubility of the alkyl fluoride and the other components in water or solvent is herein
applicable.
[0032] The distillation process can be performed by any ordinary distillation
technique using a distillation column. In the case where there is a large boiling point
difference between the distillation target, that is, alkyl fluoride and the other

components such as difluoroacetyl fluoride (boiling point: 0°C) and unreacted
ATFE, it is feasible to easily separate the alkyl fluoride by simply cooling
liquefaction. For example, when the ATFE is HFE-254pc (boiling point: 40°C), the
alkyl fluoride is monofluoromethane (boiling point: -78°C) so that there is a large
boiling point difference between HFE-254pc and monofluoromethane. The
monofluoromethane can be thus easily separated as a low-boiling fraction from a
high-boiling fraction mixture of the difluoroacetyl fluoride and HFE-254pc by
cooling liquefaction at -20 to -78°C. In the case of using the distillation column, the
distillation process is performed with the use of a packed column, bubble-cap
column or empty column at a column top temperature of at around -78°C and a
column bottom temperature of about 0 to 50°C.
[0033] It is conceivable to further distillate the mixture of the difluoroacetyl
fluoride and ATFE so that the difluoroacetyl fluoride and ATFE can be separated as
respective components and used separately in the subsequent chlorination step.
However, the mixture of the difluoroacetyl fluoride and ATFE can be used, as it is
without separation, in chlorination step of the present invention. There is no
particular limitation on the component ratio of the mixture of the difluoroacetyl
fluoride and ATFE as the difluoroacetyl fluoride and ATFE undergo the chlorination
reaction under substantially the same reaction conditions. The difluoroacetyl
fluoride, the ATFE or the mixture thereof, even if containing monofluoromethane, is
used in the chlorination step of the present invention because the
monofluoromethane is stable in the chlorination step. Moreover, a hydrocarbon by-
product such as ethylene, propylene etc. may be contained in the thermal
decomposition product. It is preferable to remove such a hydrocarbon by-product
from the thermal decomposition product although the thermal decomposition
product can be used in the chlorination step without separation of the hydrocarbon
by-product.

[0034] [Chlorination Step]
In the chlorination step, the difluoroacetyl fluoride, the ATFE or the
mixture of the difluoroacetyl fluoride and ATFE is chlorinated with calcium
chloride so as to thereby convert the difluoroacetyl fluoride and the ATFE to the
difluoroacetyl chloride.
[0035] The calcium chloride (CaCl2) used in the chlorination step is preferably
in the form of an anhydride. The calcium chloride does not particularly need to be
high in purity. As the calcium chloride, there can be used any general-purpose
product available as a reagent, a chemical raw material or a drying agent. Further,
the calcium chloride can be in any shape. In the case of a flow-bed system or a
batch system, the calcium chloride is preferably in powdery form. In the case of a
continuous-flow system, the calcium chloride is preferably in granular form. There
is no particular limitation on the particle size of the calcium chloride. It is preferable
to use the calcium chloride of readily available size. For ease of handling, the
calcium chloride is particularly preferably in granular form mainly containing
particles with a maximum length of the order of 1 to 20 mm. In the case where
crystalline water is contained in the calcium chloride, it is preferable to obtain the
calcium chloride in substantially anhydrous form by pretreatment of filling the
calcium chloride into a reaction vessel and heating the calcium chloride in the
reaction vessel under the flow of an inert gas such as nitrogen. The temperature of
the pretreatment is set depending on the water content, treatment time, particle
shape, particle size etc. of the calcium chloride and is preferably in the range of 150
to 350°C.
[0036] It is preferable to perform the chlorination step in a continuous-flow
system although the chlorination step can be performed in either a continuous-flow
system or a batch system. Further, it is preferable to perform the chlorination step in
a gas phase for convenience and facilitation although the chlorination step can be
performed in either a gas phase or a liquid phase. In the continuous-flow system,
the difluoroacetyl fluoride and ATFE are quantitatively converted to the

difluoroacetyl chloride etc. as indicated in the reaction schemes (1) and (2) by
heating the granular calcium chloride packed in the reaction tube at a temperature
sufficient for conversion of the difluoroacetyl fluoride or ATFE to the difluoroacetyl
chloride, that is, a reaction enabling temperature at which the difluoroacetyl fluoride
or ATFE can undergo reaction, and then, feeding the difluoroacetyl fluoride, the
ATFE or the mixture thereof in gaseous form through the calcium chloride in the
reaction tube.
[0037] In such a gas-phase continuous-flow system, either a fixed bed or a flow
bed is applicable. In the case of using the granular calcium chloride, the fixed bed is
preferred for prevention of powdering and for ease of removal. In general, the
reaction between a gas and a solid occurs only at a surface of the solid. It is often
that the inside of the solid is not involved in the gas-solid reaction. In the
chlorination step of the present invention, by contrast, the granular calcium chloride
maintains its form after the reaction so that substantially the whole of the calcium
chloride can contribute to the reaction. When the residue meaning after the use of
the calcium chloride is analyzed by XDF (powder X-ray diffraction), the diffraction
peak pattern of the residue is in agreement with that of calcium fluoride (CaF2).
There is no peak attributed to the calcium chloride. It is thus apparent that even the
inside of the calcium chloride is involved in the reaction. The by-produced calcium
fluoride can be treated by contact with concentrated sulfuric acid in a kiln and used
as a raw material for production of hydrogen fluoride or optical crystal. Further, the
chlorination step may be performed in the presence of an inert gas. Examples of the
inert gas are nitrogen, argon and rare gas. For ease of handling and availability,
nitrogen, argon or helium is preferably used. In the case of using the inert gas, there
is no particular limitation on the ratio of the inert gas. However, the recovery rate of
the difluoroacetyl chloride may be deteriorated if the inert gas is present in too large
amount. Under normal conditions, the feeding rate of the inert gas is preferably
lower than the feeding rate of the organic raw material such as ATFE, difluoroacetyl
fluoride or mixture thereof.

[0038] In the chlorination step, the pressure is set arbitrarily and is generally of
the order of 0.05 to 1 MPa. It is preferable to perform the chlorination step
substantially at around atmospheric pressure. The reaction temperature is set
depending on the kind of the raw material, the retention time etc. of the chlorination
step and is preferably in the range of 50 to 400°C, more preferably 100 to 300°C,
still more preferably 100 to 250°C. If the reaction temperature is lower than 50°C,
the production efficiency of the difluoroacetyl chloride is unfavorably decreased due
to low reaction rate. If the reaction temperature exceeds 400°C, the yield of the
difluoroacetyl chloride is unfavorably decreased due to decomposition of
difluoroacetyl chloride. In the case where the generation of a chlorine-containing
organic compound e.g. monochloroethane as a by-product is not desired when HFE-
374pc-f is used as the raw material, the reaction temperature is preferably set to 250
to 300°C. The monochloroethane may not be sufficiently decomposed into ethylene
and hydrochloric acid under temperature conditions lower than 250°C.
[0039] The retention time is set depending on the reaction temperature and is
generally in the range of 1 to 1000 seconds, preferably 10 to 700 seconds, more
preferably 50 to 500 seconds. If the retention time is shorter than 1 second, the
reaction may not be completed. If the retention time exceeds 1000 seconds, the
reaction takes place but causes increase in equipment size so that the productivity of
the difluoroacetyl chloride relative to the equipment size becomes deteriorated. In
the case of using the reaction tube in the continuous-flow system, heat of 10 to 30°C
(called "heat spot") is locally generated in the vicinity of the inlet of the reaction
tube at an early stage after the initiation of the reaction. This heat spot gradually
shifts toward the outlet of the reaction tube. The conversion rate suddenly decreases
when the heat spot reaches the vicinity of the outlet of the reaction tube. By
monitoring such a phenomenon, the degree of consumption of the calcium chloride
can be checked so as to determine the time for replacement of the calcium chloride.
In the continuous-flow reaction system, it is preferable to set the retention time long
(i.e. set the feeding rate of the raw material low) because fresh calcium chloride is

present in a large excessive amount at the early stage of the reaction but decreases in
amount as the heat spot nears the vicinity of the outlet of the reaction tube. In order
to reduce the frequency of replacement of the calcium chloride, it is preferable to
use the equipment of larger size within the common sense of those skilled in the art.
The reaction tube is preferably formed of or with a lining of stainless steel, Monel
(trademark), Inconel (trademark), Hastelloy (trademark) or fluoro resin.
[0040] In addition to the difluoroacetyl chloride, unreacted raw material such as
ATFE or difluoroacetyl fluoride, alkyl halide (chlorine-containing organic
compound e.g. monochloromethane) and decomposition products thereof may be
contained in the product composition of the chlorination step. It is feasible to
separate these compounds by any ordinary purification process. For example, the
difluoroacetyl chloride (boiling point: 28°C) and monochloromethane (CH3Cl,
boiling point: -24°C) produced by chlorination of the raw material containing HFE-
254 can be separated by distillation etc. because of their large point difference. The
above explanation about the distillation separation of the alkyl fluoride from the
thermal decomposition product is applicable to the distillation separation of the alkyl
chloride. The operation conditions are different but can be easily adjusted by those
skilled in the art. Further, it is feasible to recover the alkyl halide such as
monochloromethane by separating the difluoroacetyl chloride by distillation and
removing an acid component from the distillation residue by treatment with water or
aqueous alkaline solution. The thus-obtained difluoroacetyl chloride composition
obtained in the chlorination step can be used, as it is without separation, as
difluoroacetyl chloride in various reactions.
[0041] When HFE-254pc is used as the ATFE, alkyl halide (RC1) such as
monofluoromethane is generated as a by-product. In the case where such a by-
product is not desired, HFE-374pc-f (CHF2CF2OCH2CH3) or the like can
alternatively be used as the raw material. In this case, there occur ethylene and
hydrochloric acid as by-products in place of the chlorine-containing organic
compound such as alkyl halide. This makes it possible to avoid the entry of the

chlorine-containing organic compound into the product and reduce the load of
purification operation of the difluoroacetyl chloride.
[0042] [Catalytic Reduction Step]
A production method of 2,2-difluoroethyl alcohol according to the
present invention includes a catalytic reduction step of causing catalytic reduction of
difluoroacetyl chloride. The catalytic reduction step can be performed in a gas
phase or liquid phase.
[0043] The reaction of the catalytic reduction step is represented by the
following reaction scheme (5).
CHF2COCI + 2H2 → CHF2CH2OH + HCl (5)
[0044] In the catalytic reduction step, it is feasible to use the difluoroacetyl
chloride obtained in the above chlorination step although difluoroacetyl chloride can
be obtained by any of the production processes mentioned in "Background Art". It
is preferable that the difluoroacetyl chloride does not substantially contain
difluoroacetyl fluoride. If the difluoroacetyl fluoride is contained in the
difluoroacetyl chloride, a stable salt is formed by fluorination of a noble metal of the
catalyst so as to cause a deterioration in the activity of the catalyst. As a result, the
yield and selectivity of the 2,2-difluoroethyl alcohol is decreased due to generation
of 2,2-difluoroethyl 2,2-difluoroacetate by reaction of the unreacted difluoroacetyl
fluoride with the produced 2,2-difluoroethyl alcohol.
[0045] The catalyst can be of any metal usable in any known catalytic reduction
by hydrogen in the catalytic reduction step. Preferably, a noble metal is used as the
catalyst. Preferred examples of the noble metal used as the catalyst are palladium
(Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru) and iridium (Ir). Among others,
Pd is more preferred. In order to efficiently utilize the noble metal, the noble metal
is preferably supported on a support such as activated carbon, alumina, barium
sulfate, calcium carbonate, strontium carbonate or silica gel. It is particularly

preferable to support the noble metal on the activated carbon. Specific examples of
the catalyst are: palladium supported on activated carbon; palladium hydroxide
supported on activated carbon; palladium supported on barium sulfate; palladium
supported on calcium carbonate; palladium supported on strontium carbonate;
palladium supported on silica gel; platinum supported on activated carbon;
ruthenium supported on activated carbon; and rhodium supported on activated
carbon. In particular, preferred is palladium supported on activated carbon (Pd/C).
The amount of the metal supported is generally 0.1 to 10 mass%, preferably 0.2 to 5
mass%, based on the total amount of the catalyst including the support.
[0046] In the gas-phase reaction system, it is preferable to use hydrogen in an
amount of 5 to 100 mol, more preferably 10 to 30 mol, per 1 mol of the
difluoroacetyl chloride. If the amount of the hydrogen used is less than 5 mol (i.e.
the reaction system is in a low-hydro gen-content state), not only deterioration of the
conversion rate but also deactivation of the catalyst may unfavorably occur. If the
amount of the hydrogen used exceeds 100 mol, the feeding rate of the difluoroacetyl
chloride is decreased so as to cause deterioration in productivity under the
conditions of the same reaction vessel and the same contact time.
[0047] The contact time is generally 1 to 200 seconds, preferably 10 to 60
seconds. If the contact time is shorter than 1 second, the conversion rate is
unfavorably deteriorated. If the contact time is longer than 200 second, the
productivity of the 2,2-difluoroethyl alcohol relative to the volume of the reaction
vessel is unfavorably deteriorated. The reaction temperature is preferably 150 to
300°C, more preferably 170 to 230°C. If the reaction temperature is lower than
150°C, the conversion rate is deteriorated. If the reaction temperature is higher than
300°C, there is a fear of not only sintering of the catalyst but also side reaction such
as hydrogenolysis. In the gas-phase reaction system, the reaction is performed
substantially at around atmospheric pressure. The reaction can alternatively be
performed at a pressure of about 0.05 to 1 MPa. Further, the reaction may be

performed upon introduction of an inert gas such as argon or nitrogen into the
reaction vessel.
[0048] In the liquid-phase reaction system, a heterogeneous catalyst is preferred
for easy separation of the catalyst although the catalyst can be either a homogeneous
catalyst or a heterogeneous catalyst. The above-mentioned supporting catalyst,
more specifically noble metal-supporting catalyst, is thus preferably used. The
amount of the catalyst used is set depending on the kind of the catalyst and is
generally 0.0001 to 1 mol%, more preferably 0.001 to 0.1 mol%.
[0049] Further, a reaction solvent can be used in the liquid-phase reaction
system. As the reaction solvent, alcohols, hydrocarbons, ethers, carboxylic acids,
esters, amides and water are usable. Specific examples of the reaction solvent are
methanol, ethanol, benzene, toluene, xylene, ethylbenzene, isopropylbenzene,
tetralin, mesitylene, tetrahydrofuran, diethyl ether, acetic acid, ethyl acetate and
dimethylformamide. The hydrocarbons and ethers are more preferred in view of the
fact that the alcohols are difficult to separate from the 2,2-difluoroethyl alcohol.
Further, the use of 2,2-difluoroetyl alcohol, which is the target compound, as the
solvent is preferred so as to omit the separation operation of the solvent. The use of
2,2-difluoroethyl 2,2-difluoroethylacetate (CHF2COOCH2CHF2), which may be
generated as a by-product, is acceptable under the above reaction conditions. These
solvents can be used solely or in combination of two or more kinds thereof.
[0050] The pressure of the hydrogen is set depending on the reaction conditions
such as the kinds of the solvent and catalyst and is generally about 1 to 10 MPa,
preferably 0.5 to 5 MPa. If the hydrogen pressure is lower than 0.5 MPa, the
reaction may become slow. If the hydrogen pressure exceeds 5 MPa, the equipment
needs to be pressure resistant. The reaction may be performed upon introduction of
an inert gas such as argon or nitrogen into the reaction vessel.

[0051 ] The reaction temperature is generally in the range from -20°C to a
boiling point of the solvent and is preferably about 0 to 50°C. The object of the
reaction can be sufficiently achieved even at a room temperature of 10 to 30°C.
[0052] It is unlikely that the catalyst will deteriorate in the case of using, as the
raw material, the difluoroacetyl chloride containing substantially no difluoroacetyl
fluoride. The activity of the catalyst may however become deteriorated with the
passage of time in the gas-phase reaction system. In such a case, it is feasible to
reactivate the catalyst by stopping the feeding of the difluoroacetyl fluoride and
feeding hydrogen to the catalyst at 250 to 350°C. At this time, the hydrogen may be
used while diluted with nitrogen or argon. In the liquid-phase reaction system, it is
feasible to, when the activity of the supported catalyst becomes deteriorated during
use, reactivate the catalyst by feeding hydrogen to the catalyst at 250 to 350°C in the
same manner as above. The hydrogen may also be used while diluted with nitrogen
or argon at this time.
Examples
[0053] The present invention will be described in more detail below by way of
the following examples. It should be noted that the following examples are not
intended to limit the present invention thereto. Unless otherwise specified, the
composition and purity of organic substances were analyzed by a gas chromatograph
with a FID detector; and each composition analysis value is in units of "area%
(hereinafter simply referred to as "%")". Further, a column according to "EPA
Method 624" was used in the analysis of the organic substance composition unless
otherwise specified.
[0054] [Reference Example 1: Sensitivity Check of FID Detector]
A gas chromatograph was equipped with a column according to "'EPA
Method 624". On the other hand, an equivalent molar composition was prepared
from samples of monofluoromethane and difluoroacetyl fluoride. The area of each
component in the prepared composition was measured by the gas chromatograph.

According to the measurement results, the area ratio was monofluoromethane:
CHF2COF = 2.41:1.00.
[0055] [Raw Material Preparation Example 1: Preparation of Difluoroacetyl
Fluoride]
An aluminum phosphate catalyst was prepared by compression molding
aluminum phosphate available from Aldrich Chemical Co. into pellets of 5 mm ϕ x
5 mm L and firing the pellets at 700°C for 5 hours under a nitrogen flow
atmosphere. Then, a stainless steel reaction tube (inner diameter ϕ: 37.1 mm, length
L: 500 mm) having a carburetor was packed with 200 cc of the prepared catalyst.
While flowing nitrogen at 15 cc/min into the reaction tube, the reaction tube was
heated externally by an electric furnace. When the temperature of the catalyst
reached 50°C, hydrogen fluoride (HF) was introduced at a rate of 0.6 g/min into the
reaction tube through the carburetor. The temperature of the catalyst was slowly
raised to 300°C while maintaining the flow of the HF. In this state, the catalyst was
held at 300°C for 5 hours. After that, the heater setting temperature was lowered to
200°C. When the temperature of the catalyst reached 200°C, the flow of the HF was
stopped; and the flow rate of the nitrogen was increased to 200 cc/min. The catalyst
was then held for 2 hours. Subsequently, l-methoxy-l,l,2,2-tetrafluoroethane
(HFE-254pc) was fed at a rate of 0.2 g/min into the reaction tube through the
carburetor. After a lapse of 30 minutes, the flow of the nitrogen was stopped so as
to feed only the HFE-254pc into the reaction tube. The resulting gas product was
sampled under a steady state and analyzed by the gas chromatograph. It was
confirmed by the analysis results that difluoroacetyl fluoride (CHF2COF) and
methyl fluoride (CH3F) were contained substantially quantitatively in the gas
sample. The above-obtained crude difluoroacetyl fluoride was subjected to
distillation, thereby obtaining purified difluoroacetyl fluoride with a purity of 99%
or higher.

[0056] [Catalyst Preparation Example 1: Activation of Pd/C Catalyst]
A stainless steel reaction tube having an inner diameter of 37 mm and a
length of 500 mm was packed with 2% Pd/activated carbon catalyst (280 cc)
available from Evonik Degussa Japan Co., Ltd. Nitrogen and hydrogen were mixed
together and fed into the reaction tube at 100 cc/min and 50 cc/min, respectively, at
room temperature. The reaction tube was heated so as to slowly raise the
temperature of the catalyst to 350°C over 8 hours and not to cause local heat
generation in the catalyst. When the temperature of the catalyst reached 350°C, the
flow rate of the hydrogen was increased by 50 cc/min every 30 minutes. The flow
rate of the hydrogen was finally maintained at 518 cc/min for 8 hours. After that,
the reaction tube was slowly cooled down to room temperature while only flowing
the nitrogen into the reaction tube. In the above catalyst activation operation, the
flow rate of the hydrogen was decreased to 10 cc/min or lower upon detection of
local heat generation (heat spot). After confirming that such local heat generation
settled down, the flow rate of the hydrogen gas was gradually returned to the
predetermined level.
[0057] [Example 1]
A stainless steel reaction tube having an inner diameter of 23 mm and a
length of 400 mm was packed with granular anhydrous calcium chloride (63 g, 120
cc; available from Junsei Chemical Co., Ltd. (particle size: about 2.5 to 3.5 mm)).
While flowing nitrogen at 50 cc/min into the reaction tube, the reaction tube was
heated at a setting temperature of 160°C. The flow of the nitrogen was stopped
simultaneously with feeding the difluoroacetyl fluoride, which had been obtained in
Raw Material Preparation Example 1, into the reaction tube at a rate of 0.3 g/min
(retention time: 66 seconds). It was observed that a heat spot of 10 to 20°C was
generated in the vicinity of the inlet of the reaction tube and shifted toward the outlet
of the reaction tube with the passage of time. The outlet gas was sampled and
analyzed over time by the gas chromatograph. It was confirmed by the experimental

results that difluoroacetyl chloride (DFAC) and difluoroacetyl fluoride (DFAF) were
contained in the gas sample. The experimental results are graphed in FIG. 1.
[0058] [Example 2]
Reaction experiment was performed in the same manner as in Example 1,
except that the temperature of the reaction tube was set to 100°C. The experimental
results are graphed in FIG. 2.
[0059] [Example 3]
As shown in FIG. 3, a stainless steel reaction tube I having an inner
diameter of 45 mm and a length of 1500 mm and having three tube-heating mantles
separately operable under PID (proportional-integral-derivative) control was packed
with granular calcium chloride (993 g, 2000 cc); and a reaction tube II was packed
with the Pd/C catalyst pretreated in Catalyst Preparation Example 1 and connected
to the outlet side of the reaction tube I. While flowing nitrogen (100 cc/min) into
the reaction tube I, the reaction tube I was heated by setting the temperatures of the
electric furnaces to 150°C, 160°C and 170°C, respectively, from the inlet side.
Further, the reaction tube II was heated to 185°C while flowing hydrogen (518
cc/min) into the reaction tube II from a branch line immediately upstream of the
inlet of the reaction tube II. A raw material (DFAC: 80%, DFAF 19.3%, others:
0.7%), which had been prepared by adding the DFAF obtained in Raw Material
Preparation Example 1 to the product (main components: DFAC, DFAF) of
repetition of Examples 1 and 2, was fed at a rate of 0.13 g/min into the reaction tube
I from the inlet side after a lapse of 3 hours from the stabilization of the
temperatures of both of the reaction tubes I and II. After a lapse of 1 hour, the flow
of the nitrogen was stopped. After a lapse of 750 hours, the gas product was
sampled at the sampling ports A and B and analyzed by the gas chromatograph
(FID). The experimental results are indicated in TABLE 1.
[0060] [Example 4]
Reaction experiment was performed in the same manner as in Example 3,
except for, after replacing the calcium chloride in the reaction tube I with the same

amount of the same kind of fresh calcium chloride, feeding the DFAF prepared in
Raw Material Preparation Example 1 as the raw material (DFAC: 99% or more,
others: 1% or less). After a lapse of 140 hours, the gas product was sampled at the
sampling ports A and B and analyzed by the gas chromatograph (FID). The
experimental results are indicated in TABLE 1.
[0061] [Comparative Example 1]
Reaction experiment was performed in the same manner as in Example 3,
except for feeding the raw material (DFAC: 80%, DFAF: 19.3%, others: 0.7%) into
the reaction tube II by bypassing the reaction tube I (CaCh tube). After a lapse of 4
hours and a lapse of 8 hours, the gas product was sampled at the sampling ports A
and B and analyzed by the gas chromatograph. The experimental results are
indicated in TABLE 1.

[0063] [Reference Example 2]
After the completion of the reaction experiment of Example 3, the
reaction tube I was cooled down to room temperature while flowing nitrogen at a
rate of 50 cc/min into the reaction tube I. The content of the reaction tube I was then
ground and analyzed by XRD. The analysis result was in agreement with the

diffraction pattern of CaF2. There was seen substantially no diffraction peak of
CaCl2.
[0064] [Example 5]
A stainless steel reaction tube having an inner diameter of 23 mm and a
length of 400 mm and externally equipped with an electric furnace was packed with
granular anhydrous calcium chloride (60 g, 0.541 mol, volume: 115 cc, particle size:
about 2.5 to 3.5 mm; available from Junsei Chemical Co., Ltd.)- While flowing
nitrogen into the reaction tube at a rate of 50 cc/min, the reaction tube was heated at
a setting temperature of 300°C for 2 hours. After that, the setting temperature was
controlled to 200°C. Simultaneously with feeding l-methoxy-1,1,2,2-
tetrafluoroethane (HFE-254pc) into the reaction tube at a rate of 0.2 g/min, the flow
of the nitrogen was stopped. The temperature in the vicinity of the inlet of the
reaction tube, the temperature in the center of the reaction tube and the temperature
in the vicinity of the outlet of the reaction tube were monitored by thermocouples. It
was observed that a heat spot of 10 to 20°C was generated in the vicinity of the inlet
of the reaction tube and shifted toward the outlet of the reaction tube with the
passage of time. The outlet gas was sampled and analyzed over time by the gas
chromatograph. The analysis results are indicated in TABLE 2.



CHF2Cl: chlorodifluoromethane
DFAF: difluoroacetyl fluoride
CH3Cl: methyl chloride
HFE-254pc: 1 -methoxy-1,1,2,2-tetrafluoroethane
DFAC1: difluoroacetyl chloride
n.d.: not detected
t.r.: trace amount detected
[0066] [Example 6]
After the completion of the reaction experiment of Example 5, the
calcium chloride was replaced with fresh one (63 g, 0.568 mol, volume: 120 cc).
While flowing nitrogen into the reaction tube at a rate of 50 cc/min, the reaction tube
was heated at a setting temperature of 300°C for 2 hours. After that, the setting
temperature was controlled to a temperature level as indicated in TABLE 3.
Simultaneously with feeding l-ethoxy-1,1,22-tetrafluoroethane (HFE-374pc-f) into
the reaction tube at a rate of 0.2 g/min, the flow of the nitrogen was stopped. The
temperature in the vicinity of the inlet of the reaction tube, the temperature in the
center of the reaction tube and the temperature in the vicinity of the outlet of the
reaction tube were monitored by thermocouples. It was observed that a heat spot of
several 10°C was generated in the vicinity of the inlet of the reaction tube and
shifted toward the outlet of the reaction tube with the passage of time. The outlet
gas was sampled and analyzed over time by the gas chromatograph. The analysis
results are indicated in TABLE 3.


[0068] [Catalyst Preparation Example 2]
A reaction tube of stainless steel (SUS315) having a length of 1.5 mm
and an inner diameter of 55 mm and surrounded by a heating mantle was packed
with 2 kg of y-alumina beads (KHS-46 available from Sumitomo Chemical Co.,

Ltd.). The temperature of the heating mantle was set to 50°C. While flowing
nitrogen (1000 cc/min) into the reaction tube, hydrogen fluoride (HF) was vaporized
by a carburetor and fed into the reaction tube at 4 g/min. It was observed that, due
to the heat of absorption of HF onto γ-alumina and the heat of reaction of γ-alumina
and HF, a heat spot was generated particularly in the vicinity of the reaction tube
and gradually shifted toward the outlet of the reaction tube. When the highest
temperature of the heat spot exceeded 300°C, the flow rate of the HF was decreased
to 1 g/min or lower so as to limit such local heat generation. After confirming that
the temperature reached the setting level, the flow rate of the HF was gradually
returned to 4 g/min. The fluorination treatment of the y-alumina beads was
performed repeatedly by increasing the mantle setting temperature by 50°C up to
250°C after the heat spot reached the vicinity of the outlet of the reaction tube.
Subsequently, the mantle setting temperature was controlled to 300°C; and the flow
rate of the HF was gradually increased to 20 g/min. At this time, the flow rate of the
HF was decreased to 1 g/min when the temperature of the heat spot exceeded 350°C.
When the heat spot was substantially no longer observed under the conditions of the
mantle setting temperature of 300°C and the HF flow rate of 20 g/min, the
fluorination treatment was continued under the same conditions for further 24 hours.
The reaction tube was cooled down by stopping the energization of the heating
mantle while only flowing nitrogen into the reaction tube. With this, fluorinated
alumina catalyst was obtained.
[0069] [Thermal Decomposition Example 1]
Thermal decomposition experiment was conducted using a thermal
composition device shown in FIG. 4.
[0070] In the device of FIG. 4, a reaction tube 71 of stainless steel having an
inner diameter of 37 mm and a length of 500 mm was provided. A sampling port 73
was located at the outlet side of the reaction tube 71. An electric furnace 72 was
externally located around the reaction tube 71. On the outlet side of the reaction
tube 71, an empty trap 74 of polyethylene, a coiled pipe 75, a separation column 78

(-15°C), an ice water trap 81, an aqueous basic solution trap 82 (50% aqueous KOH
solution cooled with ice) and a drying tube 84 were provided and connected together
by fluoro resin or polyethylene pipes. The coiled pipe 75 was held in a coolant bath
of-15°C. The separation column 78 had a reflux condenser 79 held at -78°C by a
dry ice-acetone bath on a top thereof and ajacketed high-boiling-compound
collector 76_held on a bottom thereof. A sampling port 84 was located at the outlet
side of the device. The drying tube 83 was packed with a drying agent containing
synthetic zeolite 4A. The outlet of the drying tube 83 was open to an abatement
system.
[0071] Before the initiation of reaction experiment, the pipe arrangement of the
device of FIG. 4 was changed so as to disconnect the reaction tube 71 from the
empty trap 74 and discharge the gas directly from the outlet of the reaction tube 71
to the abatement system. First, the reaction tube 71 was packed with 230 cc of the
catalyst obtained in Catalyst Preparation Example 1. While flowing nitrogen into
the reaction tube 71, the temperature of the electric furnace 72 was raised. When the
temperature of the catalyst reached 50°C, hydrogen fluoride (HF) was introduced at
1.0 g/min into the reaction tube 71 via a carburetor. While maintaining the flow of
the HF, the temperature of the catalyst was gradually raised to 350°C. Upon
detection of local heat generation during the temperature rise, the flow rate of the
HF was decreased to 0.1 g/min. The flow rate of the hydrogen gas was gradually
returned to 0.1 g/min after confirming that such local heat generation settled down.
When the temperature of the catalyst reached 350°C, the catalyst was maintained at
that temperature for 30 hours. After that, the How of the HF was stopped; and the
flow rate of the nitrogen was increased to 200 cc/min. In this state, the catalyst was
held for 2 hours. The temperature of the electric furnace 72 was subsequently
lowered to 180°C. Then, l-methoxy-l,l,2,2-tetrafluoroethane (HFE-254pc) was fed
at a rate of 0.2 g/min into the reaction tube 71 via a carburetor. The flow of the
nitrogen was stopped immediately afterwards. The setting temperature of the
electric furnace 72 was controlled in such a manner that the reaction temperature

became 150°C. When the reaction system reached a steady state, the device was
returned to that of FIG. 4 by connecting the outlet of the reaction tube 71 to the
empty trap 74. The resulting discharge gas was passed through the empty trap 74
and the coiled pipe 75, and then, fed into the separation column 78 (-15°C) so as to
condense a high-boiling component of the discharge gas by the reflux condenser 79.
The condensed high-boiling component was collected by the jacketed high-boiling-
compound collector 76 (-15°C). An uncondensed low-boiling component of the
discharge gas was passed through the ice cooling trap 81, the aqueous basic solution
trap 82 and the drying tube 83.
[0072] The sample taken at the sampling port 73 was analyzed by a gas
chromatograph (column according to "EPA Method 624") with a FID detector. It
was confirmed that the sample at the sampling port 73 had 54.291% of CH3F,
22.126% of CHF2COF, 23.101% of CHF2CF2OMe (Me: methyl, the same applies to
the following) and 0.482% of other compounds. Further, the sample taken at the
sampling port 84 was analyzed by a gas chromatograph (Silicon Plot column) with a
FID detector. It was confirmed that the sample at the sampling port 84 had less than
0.001% of CH4, 0.017% of C2H4, 0.009% of CHF3, 99.961% of CH3F, 0.008% of
C3H6 and 0.004% of other compounds. The experimental results are summarized in
TABLE 4.
[0073] [Thermal Decomposition Example 2]
Thermal decomposition experiment was conducted in the same manner as
in Thermal Decomposition Example 1, except that the reaction temperature was set
to 175°C. The sample taken at the sampling port 73 was analyzed by a gas
chromatograph (column according to "EPA Method 624") with a FID detector. It
was confirmed that the sample at the sampling port 73 had 69.644% of CH3F,
28.420% of CHF2COF, 1.351% of CHF2CF2OMe and 0.685% of other compounds.
Further, the sample taken at the sampling port 84 was analyzed by a gas
chromatograph (Silicon Plot column) with a FID detector. It was confirmed that the
sample at the sampling port 84 had 0.024% of CH4, 0.121% of C2H4, 0.126% of


[0075] [Example 7: Chlorination Step]
A stainless steel reaction tube having an inner diameter of 23 mm and a
length of 400 mm was packed with granular anhydrous calcium chloride (63 g.

volume: 120 cc, particle size: about 2.5 to 3.5 mm; available from Junsei Chemical
Co., Ltd.). While flowing nitrogen into the reaction tube at 50 cc/min, the reaction
tube was heated to 160°C. The flow of the nitrogen was stopped simultaneously
with feeding the organic substance (CHF2COF: 94.181%, CHF2CF2OMe: 4.569%),
which had been recovered by the jacketed high-boiling-compound collector 76 in
Thermal Decomposition Example 2, into the reaction tube at a rate of 0.3 g/min. It
was observed that a heat spot of 10 to 20°C was generated in the vicinity of the inlet
of the reaction tube and shifted toward the outlet of the reaction tube with the
passage of time. At the time when total 77.9 g of the organic substance was fed into
the reaction tube, the outlet gas was sampled and analyzed by a gas chromatograph
(column according to "EPA Method 624") with a FID detector. It was confirmed
that the gas sample had 1.105% of CHF2COF, 4.708% of CH3Cl, 0.001% of
CHF2CF2OMe, 93.769% of CHF2COCl and 0.417% of other compounds. The
experimental results are summarized in TABLE 5.


[0077] [Thermal Decomposition Example 3]
After the analysis of Example 7, the raw material was changed to
CHF2CF2OMe (99.9%); and the reaction temperature was changed to 330°C. The
outlet gas was sampled under a steady state (after a lapse of 30 hours) and analyzed
by a gas chromatograph (column according to "EPA Method 624") with a FID
detector. It was confirmed that the gas sample had 2.406% of C2H4, 68.486% of
CH3F, 20.460% of CHF2COF, 7.656% of CHF2CF2OMe and 0.992% of other
compounds. The experimental results are summarized in TABLE 4. After that, the
feeding of the raw material was stopped. The reaction tube was cooled down to
room temperature by stopping the energization of the electric furnace while flowing
nitrogen (100 cc/min) into the reaction tube. The content of the reaction tube was
slightly colored. The content of the reaction tube had the same shape as that before
the reaction with almost no powdering or aggregation. This content was ground by
an agate mortar and analyzed by XRD. The analysis result was in agreement with
the diffraction pattern of CaF2.
[0078] [Example 8: Chlorination Step]
A SUS reaction tube having an inner diameter of 23 mm and a length of
400 mm was packed with granular anhydrous calcium chloride (0.57 mol, 63 g,
volume: 120 cc). While flowing nitrogen into the reaction tube at 50 cc/min, the
reaction tube was heated to 200°C. The flow of the nitrogen was stopped
simultaneously with feeding the sample substance (CHF2CF2OMe, purity: 98.1%
(main impurity: CHF2COF, 1.1%)), which had been obtained by distilling the
organic substance recovered by the jacketed high-boiling-compound collector 76 in
Thermal Decomposition Example 1, into the reaction tube at a rate of 0.3 g/min.
The gas product was collected by a dry ice trap. It was observed that a heat spot of
10 to 20°C was generated in the vicinity of the inlet of the reaction tube and shifted
toward the outlet of the reaction tube with the passage of time. At the time when
total 68.5 g (0.52 mol) of the CHF2CF2OMe was fed into the reaction tube, total
83.8 g of the gas sample was recovered from the dry ice trap (recovery rate: 97.8%).

The recovered gas sample was analyzed by a gas chromatograph (column according
to "EPA Method 624") with a FID detector. It was confirmed that the gas sample
had 0.867% of CHF2COF, 68.877% of CH3C1, 0.341% of CHF2CF2OMe, 28.863%
of CHF2COCl and 1.062% of other compounds. The experimental results are
summarized in TABLE 5.
[0079] [Example 9: Chlorination Step]
A stainless steel reaction tube having an inner diameter of 37 mm and a
length of 500 mm and externally surrounded by an electric furnace was packed with
granular anhydrous calcium chloride (150 g, 1.35 mol, volume: 300 cc, particle size:
about 2.5 to 3.5 mm; available from Junsei Chemical Co., Ltd.). While flowing
nitrogen into the reaction tube at a rate of 50 cc/min, the reaction tube was heated at
a setting temperature of 300°C for 2 hours. After that, the setting temperature was
controlled to 200°C. Simultaneously with feeding l-methoxy-1,1,2,2-
tetrafluoroethane (HFE-254pc) into the reaction tube at a rate of 0.2 g/min, the flow
of the nitrogen was stopped. The temperature in the vicinity of the inlet of the
reaction tube, the temperature in the center of the reaction tube and the temperature
in the vicinity of the outlet of the reaction tube were monitored by thermocouples. It
was observed that a heat spot of 10 to 20°C was generated in the vicinity of the inlet
of the reaction tube and shifted toward the outlet of the reaction tube with the
passage of time. At the time when total 132 g (1 mol) of the HFE-254pc was fed
into the reaction tube, the outlet gas was sampled and analyzed. It was confirmed
that the gas sample had 70.3 % of methyl chloride (CH3C1) and 28.7% of
difluoroacetyl chloride (CHF2COCl, DFAC). After confirming these analysis
results, the feeding of the HFE-254pc was stopped. The whole of the product
collected by cooling with dry ice was transferred into a cylinder. By repeating 5
cycles of the above experimental reaction operation, total 642 g of the product was
obtained. The thus-obtained product was distillated, thereby yielding DFAC (501 g)
with a purity of 99.3%.

[0080] [Reference Example 3]
After performing one cycle of the reaction operation of Example 9, the
content of the reaction tube was cooled down to room temperature while flowing
nitrogen into the reaction tube at 50 cc/min. It was confirmed by observation that
the shape of the tube content was maintained with almost no powdering. Further,
the tube content (which was originally calcium chloride) was sampled from the inlet
of the reaction tube and from the center of the reaction tube and analyzed by XRD.
The analysis result was in agreement with the diffraction pattern of CaF2. There was
seen substantially no diffraction peak of CaCl2.
[0081] [Example 10: Catalytic Reduction Step]
The reaction tube, in which the catalyst prepared in Catalyst Preparation
Example 1 had remained packed, was heated to 185°C while flowing hydrogen (783
cc/min) into the reaction tube. After the temperature was stabilized, the DFAC
obtained in Example 9 was fed into the reaction tube at 0.05 g/min for 1 hour. The
feeding rate of the DFAC was slowly increased to 0.2 g/min over 2 hours. The
resulting product gas was sampled at the outlet of the reaction tube and analyzed by
a gas chromatograph at the time when 96 g of the DFAC was fed into the reaction
tube. It was confirmed that the gas sample had 99.17% of 2,2-difluoroethyl alcohol
(CHF2CH2OH), 0.03% of CHF2COOCH2CHF2 and and a trace amount of DFAC.
The above experimental operation was further continued. At the time when total
480 g of the DFAC was fed into the reaction tube, the product gas was sampled at
the outlet of the reaction tube and analyzed by the gas chromatograph. It was
confirmed that the gas sample had 99.14% of CHF2CH2OH, 0.02% of
CHF2COOCH2CHF2 and a trace amount of DFAC. The tendency of deterioration of
the catalyst was not seen.
[0082] It has been shown by the above Examples 1 to 10 that it is possible to
efficiently produce difluoroacetyl chloride by chlorination of 1-alkoxy-l,1,2,2-
tetrafluoroethane or difluoroacetyl fluoride with calcium chloride and further

possible to efficiently produce 2,2-difluoroethyl alcohol by catalytic reduction of the
obtained difluoroacetyl chloride.
Industrial Applicability
[0083] The production method of the present invention is useful for the
production of difluoroacetyl chloride, which is suitably usable as a reagent for the
introduction of a difluoro methyl group, and for the production of 2,2-difluoroethyl
alcohol.
[0084] Although the present invention has been described with reference to the
above embodiments, various modifications and variations of the above embodiments
can be made based on the knowledge of those skilled in the art without departing
from the scope of the present invention.
Description of Reference Numerals
[0085] 71: Reaction tube
72: Electric furnace
73: Sampling port
74: Empty trap
75: Coiled tube
76: Jacketed high-boiling-compound collector
77: Sampling port
78: Separation column
79: Reflux condenser
80: Sampling port
81: Ice water trap
82: Aqueous basic solution trap
83: Drying tube
84: Sampling port

WE CLAIM
1. A method for producing difluoroacetyl chloride, comprising a chlorination
step of bringing a raw material containing therein at least either a 1-alkoxy-1, 1,2,2-
tetrafluoro ethane or difluoro acetyl fluoride into contact with calcium chloride at a
reaction enabling temperature.
2. The method for producing difluoroacetyl chloride as claimed in claim 1,
wherein the raw material contains at least the l-alkoxy-l,l,2,2-tetrafluoroethane.
3. The method for producing difluoroacetyl chloride as claimed in claim 1 or 2,
wherein the raw material contains at least the l-alkoxy-l,l,2,2-tetrafluroethane and
the difluoroacetyl fluoride.
4. The method for producing difluoroacetyl chloride as claimed in any one of
claims 1 to 3, wherein the chlorination step is performed in a gas-phase continuous-
flow system.
5. The method for producing difluoroacetyl chloride as claimed in any one of
claims 1 to 4, wherein the chlorination step is performed at a temperature of 50 to
400°C.
6. The method for producing difluoroacetyl chloride as claimed in any one of
claims 1 to 5, further comprising a separation step of removing, from a product
composition obtained in the chlorination step and containing therein an alkyl halide
and difluoroacetyl chloride, the alkyl halide.
7. The method for producing difluoroacetyl chloride as claimed in any one of
claims 1 to 6, wherein the 1-alkoxy-l,1,2,2-tetrafluoroethane is 1-methoxy-l,1,2,2-
tetrafluoroethane.

8. The method for producing difluoroacetyl chloride as claimed in any one of
claims 1 to 7, wherein the difluoroacetyl fluoride is obtained by thermal
decomposition of an l-alkoxy-l,l,2,2-tetrafluoroethane.
9. A method of producing 2,2-difluoroethyl alcohol, comprising a catalytic
reduction step of causing catalytic reduction of the difluoroacetyl chloride obtained
by the production method according to any one of claims 1 to 8.
10. The method of producing the 2,2-difluoroethyl alcohol according to claim 9,
wherein the catalytic reduction step is performed in the presence of a palladium
catalyst.