Title of Invention	METHOD FOR RECOVERING A FLUOROALCOHOL FROM A LIQUID MIXTURE OF FLUOROALCOHOL AND WATER
Abstract	To provide a method for easily recovering a fluoroalcohol in a high concentration from a liquid mixture comprising the fluoroalcohol and water, which results from the production of CD-R or DVD-R. A method for recovering a fluoroalcohol, which comprises a step of separating a liquid mixture comprising a fluoroalcohol such as 2,2,3,3-tetrafluoropropanol and water, into two layers by adding an acid such as sulfuric acid to the liquid mixture, and preferably further includes a distillation step of distilling the lower layer obtained in the step of separating the liquid mixture into two layers.

Title of Invention

METHOD FOR RECOVERING A FLUOROALCOHOL FROM A LIQUID MIXTURE OF FLUOROALCOHOL AND WATER

Abstract

To provide a method for easily recovering a fluoroalcohol in a high concentration from a liquid mixture comprising the fluoroalcohol and water, which results from the production of CD-R or DVD-R. A method for recovering a fluoroalcohol, which comprises a step of separating a liquid mixture comprising a fluoroalcohol such as 2,2,3,3-tetrafluoropropanol and water, into two layers by adding an acid such as sulfuric acid to the liquid mixture, and preferably further includes a distillation step of distilling the lower layer obtained in the step of separating the liquid mixture into two layers.

Full Text	DESCRIPTION TECHNICAL FIELD The present invention relates to a technique to recover a fluoroalcohol from a liquid mixture comprising the fluoroalcohol and water. BACKGROUND ART A fluoroalcohol is used as a solvent for a dye for a recording layer in the production of an information recording medium such as CD-R or DVD-R, and it is indispensable for the production of high-capacity recording media. In the process for producing such a recording medium, a waste liquid of a fluoroalcohol containing watet results in a large amount. If the fluoroalcohol is recovered from such a waste liquid and reused, it is possible to reduce the load to the environment and to redube the production cost. Accordingly, a technique to remove water from a liquid mixture comprising a fluoroalcohol and water at a low cost, is desired. However, a liquid mixture of a fluoroalcohol and water may have an azeotropic composition, and it is very difficult to remove water by distillation. For example, the azeotropic composition of a liquid mixture of 2,2,3,3-tetrafluoropropanol (hereinafter referred to as TFPO) as one of fluoroalcohols and water, comprises 73 mass% of TFPO and 27 mass% of water. Patent Document 1 discloses a method for separating water by pervaporation to recover TFPO from a liquid mixture of TFPO and water. However, a more convenient and efficient method has been desired. Patent Document 1: JP-A-2001-187756 (Claim 5) DISCLOSURE OF THE INVENTION OBJECT TO BE ACCOMPLISHED BY THE INVENTION It is an object of the present invention to provide a me thod f or easily recovering a fluoroalcohol by separating water from a liquid mixture comprising the fluoroalcohol and water. MEANS TO ACCOMPLISH THE OBJECT The present invention provides a method for recovering a fluoroalcohol from a liquid mixture comprising the fluoroalcohol and water, which comprises a step of separating the liquid mixture into two layers by adding an acid to the liquid mixture. It is considered that in the present invention, by the addition of an acid, the dissociation (dissociation of proton from a hydroxyl group) equilibrium of the hydroxyl group of the fluoroalcohol moves substantially towards the non-dissociation side, whereby the solubility of water decreases so that the phase separation will take place. Such a phenomenon is considered to be related also with the facts that fluorine atoms are hydrophobic, hydrbxyl groups tend to be readily dissociable by the effects of the fluorine atoms, and the fluoroalcohol is a compound having a high specific gravity. The specific gravity of the fluoroalcohol is higher than water. Therefore, a layer mainly containing the fluoroalcohol is formed below, and a layer mainly containing water is formed above. EFFECTS OF THE INVENTION In the present invention, in the step of separating the liquid mixture into two layers, it is possible to separate the mixture into an upper layer mainly containing water and a lower layer mainly containing the fluoiroalcohol. By such a phase separation, the content of the fluoroalcohol in the lower layer can be made to be as high as at least 80 mass%, preferably at least 90 mass%. Therefore, when this lower layer is further purified by e.g. distillation, a high purity fluoroalcohol can easily be obtained without azeotropy with water. BEST MODE FOR CARRYING OUT THE INVENTION The fluoroalcohol in the present invention may, for example, be an alcohol having a perfluoroalkyl group, such as perfluoro-t-butanol, a fluoroalcohol such as 2,2,3,3,3-pentafluoropropanol, 1,1,1,3,3,3-hexafluoro-2- propanol or 2,2,2-trifluoroethanol, a fluorophenol, or a compound represented by the following formula 1: H-(CRfFCF2)n-CR1R2-OH Formula 1 wherein Rf is a fluorine atom or a C1-4 polyfluoroalkyl group, each of R1 and R2 which are independent of each other, is a hydrogen atom or a C1-3 alkyl group, and n is an integer of from 1 to 4. The compound represented by the formula 1 may specifically be H (CF2)2CH2OH (TFPO) , H (CF2) 4CF2OH, HCF2CF2CH(CH3)OH, HCF2CF2C(CH3)2OH, HC(CF3)FCF2CH2OH, HC(CF3)FCF2CH(CH3)OH or HC (CF3) FCF2C (CH3) 2OH . The content of water in the liquid mixture comprising the fluoroalcohol and water, to be treated in the present invention, is preferably at most 5 0 mass%, particularly preferably at most 25 mass%. If such a water content is too large, it will be required to add a larger amount of the acid, and it tends to take a longer time in the distillation step after the separation into two layers. Accordingly, in such a case, it is advisable to preliminarily remove water to some extent by carrying out e.g. simple distillation. The acid to be used in the present invention is preferably an inorganic acid, preferably a strong acid such as sulfuric acid, nitric acid, hydrochloric acid or hydrofluoric acid. Among them, sulfuric acid, nitric acid or hydrofluoric acid is preferred. Further, in a case where after the step of separation into two layers, the distillation step of further distilling the obtained lower layer is to be carried out, it is particularly preferred to employ sulfuric acid from such a viewpoint that it tends to scarcely corrode the distillation apparatus. In the present invention, it is preferred to add the acid in such an amount that proton (H+) would be at least 0.10, particularly preferably at least 0.15, more preferably at least 0.20, as calculated as the molar ratib to water in the liquid mixture comprising the fluoroalcohol and water (provided that the acid is regairded as dissociated 100%) . If the above molar ratio is less than 0.1, the content of water in the lower layer tends to be large, and the phase separation tends to be difficult. Further, usually, there is no particular merit in adding the acid in excess. Accordingly, the amount of the acid to be added should preferably be the minimum amount where the phase separation into two layers takes place, and the content of the fluoroalcohol in the lower layer will be at least a predetermined level. The addition of the acid to the liquid mixture comprising the fluoroalcohol and water may be carried out under atmospheric pressure at room temperature, and it is usually not necessary to carry out the temperature control, etc. Mixing is carried out by e.g. an agitator so that the added acid will be uniformly mixed with the above liquid mixture. To let the mixture separate into two layers, the mixture may be left to stand still. However, such separation may be carried out by means of a centrifugal separator or the like. When the mixture is left to stand still to let it separate into two layers, the time for leaving the mixture to stand still may be at a level of from 3 to 12 hours, although it may depend also on the thicknesses of the respective layers or the area of the interface. The content of the fluoroalcohol in the lower layer obtainable in the step of the separation into two layers in the present invention is preferably at least 80 mass%, particularly preferably at least 90 mass%, further preferably at least 92 mass%. The larger such a content of the fluoroalcohol, the better, since the load will thereby be smaller in the case of carrying out distillation in the subsequent step. In the upper layer obtainable in the step of the separation into two layers in the present invention, usually from about 10 to 3 0 mass% of the fluoroalcohol will be contained. Such fluoroalcohol contained in the upper layer may effectively be recovered by repeatedly using the obtained upper layer as a part of the acid to be used in the step of the separation into two layers for the subsequent batch. In the present invention, it is preferred to include a distillation step of further distilling the lower layer obtained in the step of separating the liquid mixture into two layers. It is thereby possible to further remove water from the lower layer thereby to obtain the fluoroalcohol having a smaller water concentration. The distillation conditions are not particularly limited, and water can be removed by a usual multistage distillation. The lower layer obtainable in the step of the separation into two layers in the present invention has a small content of water, and accordingly, the time required for this distillation step may be short. In the distillation step, it is preferred to obtain the fluoroalcohol having a water concentration of at most 1,000 ppm by distilling the above lower layer. Namely, in a case where the fluoroalcohol is used as a solvent for a dye to be used for an information recording medium, the lower the water concentration, the better. The water concentration is particularly preferably at most 500 ppm, more preferably at most 2 00 ppm. To bring the water concentration to the above range, in the present invention, after the distillation step, a step of removing water in the fluoroalcohol by means of a drying agent such as a zeolite, may further be preferably provided. EXAMPLES Now, the present invention will be described with reference to Examples (Examples 1 to 3). EXAMPLE 1 50 g of TFPO and 15 g of demineralized water were put into a separating funnel and shook, whereby the two were completely mixed to form a uniform liquid mixture. 11.5 g of 96 mass% concentrated sulfuric acid was slowly dropwise added thereto, and the mixture was shook and then left to stand still for 3 hours, whereby the liquid mixture was separated into two layers. The above amount of the concentrated sulfuric acid corresponds to 0.27 as calculated as the molar ratio of proton (H+) to water in the liquid mixture. The separated upper and lower layers were divided to obtain 24.6 g of the upper layer and 49.8 g of the lower layer. The concentration of TFPO in each of the upper and lower layers was quantified by NMR, whereby the TFPO concentration in the upper layer was 24.5 mass%, and the TFPO concentration in the lower layer was 93.7 mass%. The NMR measuring conditions are shown below. NMR MEASURING CONDITIONS Measuring apparatus: ECP-400, manufactured by JEOL Ltd. Measuring nuclei: 1H Measuring method: single pulse method Measuring solvent: nil (only the sample was put into a test tube.) Measuring temperature: room temperature Outer diameter of the sample tube: 5 mm EXAMPLE 2 In the same manner as in Example 1 except that the amount of 96 mass% concentrated sulfuric acid dropwise added, was changed to 9 g, mixing of TFPO and demineralized water and separation were carried out. The above amount of the concentrated sulfuric acid corresponds to 0.21 as calculated as the molar ratio of proton (H+) to water in the liquid mixture. After being left to stand still, the liquid mixture was separated into two layers. 23.0 g of the upper layer and 50.7 g of the lower layer were obtained, and the TFPO concentration in the upper layer was 18.3 mass%, and the TFPO concentration in the lower layer was 93.4 mass%. EXAMPLE 3 In the same manner as in Example 1 except that the amount of 96 mass% concentration sulfuric acid dropwise added, was changed to 4.5 g, mixing of TFPO and deionized water and separation were carried out. The above amount of the concentrated sulfuric acid corresponds to 0.11 as calculated as the molar ratio of proton (H+) to water in the liquid mixture. After being left to stand still, the liqulid mixture was separated into two layers. 15.7 g of the upper layer and 53.7 g of the lower layer were obtained, and the TFPO concentration in the upper layer was 115.5 mass%, and the TFPO concentration in the lower layer was 90.0 mass%. INDUSTRIAL APPLICABILITY The method for recovering a fluoroalcohol of the present invention is useful for a process of recovering and reusing a fluoroalcohol from a waste liquid resulting from the production process for CD-R or DVD-R. The entire disclosure of Japanese Patent Application No. 2005-037888 filed on February 15, 2005 including specification, claims, and summary is incorporated herein by reference in its entirety. WE CLAIM : 1. A method for recovering a fluoroalcohol from a liquid mixture comprising the fluoroalcohol and water, which comprises a step of separating the liquid mixture into two layers by adding an acid to the liquid mixture. 2. The method for recovering a fluoroalcohol as claimed in Claim 1, wherein the fluoroalcohol is a compound represented by the following formula 1: H-(CRfFCF2)n-CR1R2-OH Formula 1 wherein Rf is a fluorine atom or a C1-4 polyfluoroalkyl group, each of R1 and R2 which are independent of each other, is a hydrogen atom or a C1-3 alkyl group, and n is an integer of from 1 to 4. 3. The method for recovering a fluoroalcohol as claimed in Claim 1, wherein the fluoroalcohol is 2,2,3,3- tetrafluoropropanol. 4. The method for recovering a fluoroalcohol as claimed in Claim 1, 2 or 3, wherein the acid is added in such an amount that proton (H+) would be at least 0.10 as calculated as the molar ratio to the water in the liquid mixture (provided that the acid is regarded as dissociated 100%). 5. The method for recovering a fluoroalcohol as claimed in any one of Claims 1 to 4, wherein the acid is sulfuric acid. 6. The method for recovering a fluoroalcohol as claimed in any one of Claims 1 to 5, wherein the content of the fluoroalcohol in the lower layer obtained in the step of separating the liquid mixture into two layers, is at least 80 mass%. 7. The method for recovering a fluoroalcohol as claimed in any one of Claims 1 to 6, which further includes a distillation step of distilling the lower layer obtained in the step of separating the liquid mixture into two layers. 8. The method for recovering a fluoroalcohol as claimed in Claim 7, wherein by the distillation step, the fluoroalcohol having a water concentration of at most 1,000 ppm is obtained. 9. The method for recovering a fluoroalcohol as claimed in Claim 7 or 8, which includes, after the distillation step, a step of removing water in the fluoroalcohol by contacting the fluoroalcohol with a drying agent. 10. The method for recovering a fluoroalcohol as claimed in Claim 9, wherein the drying agent is a zeolite. ABSTRACT METHOD FOR RECOVERING A FLUOROALCOHOL FROM A LIQUID MIXTURE OF FLUOROALCOHOL AND WATER To provide a method for easily recovering a fluoroalcohol in a high concentration from a liquid mixture comprising the fluoroalcohol and water, which results from the production of CD-R or DVD-R. A method for recovering a fluoroalcohol, which comprises a step of separating a liquid mixture comprising a fluoroalcohol such as 2,2,3,3-tetrafluoropropanol and water, into two layers by adding an acid such as sulfuric acid to the liquid mixture, and preferably further includes a distillation step of distilling the lower layer obtained in the step of separating the liquid mixture into two layers.

Full Text

DESCRIPTION
TECHNICAL FIELD
The present invention relates to a technique to
recover a fluoroalcohol from a liquid mixture comprising
the fluoroalcohol and water.
BACKGROUND ART
A fluoroalcohol is used as a solvent for a dye for a
recording layer in the production of an information
recording medium such as CD-R or DVD-R, and it is
indispensable for the production of high-capacity
recording media.

In the process for producing such a recording

medium, a waste liquid of a fluoroalcohol containing
watet results in a large amount. If the fluoroalcohol is
recovered from such a waste liquid and reused, it is
possible to reduce the load to the environment and to
redube the production cost. Accordingly, a technique to
remove water from a liquid mixture comprising a
fluoroalcohol and water at a low cost, is desired.
However, a liquid mixture of a fluoroalcohol and
water may have an azeotropic composition, and it is very
difficult to remove water by distillation. For example,
the azeotropic composition of a liquid mixture of

2,2,3,3-tetrafluoropropanol (hereinafter referred to as
TFPO) as one of fluoroalcohols and water, comprises 73
mass% of TFPO and 27 mass% of water.
Patent Document 1 discloses a method for separating
water by pervaporation to recover TFPO from a liquid
mixture of TFPO and water. However, a more convenient
and efficient method has been desired.
Patent Document 1: JP-A-2001-187756 (Claim 5)
DISCLOSURE OF THE INVENTION
OBJECT TO BE ACCOMPLISHED BY THE INVENTION

It is an object of the present invention to provide
a me thod f or easily recovering a fluoroalcohol by

separating water from a liquid mixture comprising the
fluoroalcohol and water.

MEANS TO ACCOMPLISH THE OBJECT
The present invention provides a method for
recovering a fluoroalcohol from a liquid mixture
comprising the fluoroalcohol and water, which comprises a
step of separating the liquid mixture into two layers by
adding an acid to the liquid mixture.
It is considered that in the present invention, by
the addition of an acid, the dissociation (dissociation
of proton from a hydroxyl group) equilibrium of the
hydroxyl group of the fluoroalcohol moves substantially
towards the non-dissociation side, whereby the solubility
of water decreases so that the phase separation will take

place. Such a phenomenon is considered to be related
also with the facts that fluorine atoms are hydrophobic,
hydrbxyl groups tend to be readily dissociable by the
effects of the fluorine atoms, and the fluoroalcohol is a
compound having a high specific gravity.

The specific gravity of the fluoroalcohol is higher

than water. Therefore, a layer mainly containing the

fluoroalcohol is formed below, and a layer mainly
containing water is formed above.
EFFECTS OF THE INVENTION
In the present invention, in the step of separating
the liquid mixture into two layers, it is possible to
separate the mixture into an upper layer mainly
containing water and a lower layer mainly containing the
fluoiroalcohol. By such a phase separation, the content
of the fluoroalcohol in the lower layer can be made to be
as high as at least 80 mass%, preferably at least 90
mass%. Therefore, when this lower layer is further
purified by e.g. distillation, a high purity
fluoroalcohol can easily be obtained without azeotropy
with water.
BEST MODE FOR CARRYING OUT THE INVENTION
The fluoroalcohol in the present invention may, for
example, be an alcohol having a perfluoroalkyl group,

such as perfluoro-t-butanol, a fluoroalcohol such as
2,2,3,3,3-pentafluoropropanol, 1,1,1,3,3,3-hexafluoro-2-

propanol or 2,2,2-trifluoroethanol, a fluorophenol, or a
compound represented by the following formula 1:
H-(CRfFCF2)n-CR1R2-OH Formula 1
wherein Rf is a fluorine atom or a C1-4 polyfluoroalkyl
group, each of R1 and R2 which are independent of each

other, is a hydrogen atom or a C1-3 alkyl group, and n is
an integer of from 1 to 4.
The compound represented by the formula 1 may
specifically be H (CF2)2CH2OH (TFPO) , H (CF2) 4CF2OH,
HCF2CF2CH(CH3)OH, HCF2CF2C(CH3)2OH, HC(CF3)FCF2CH2OH,
HC(CF3)FCF2CH(CH3)OH or HC (CF3) FCF2C (CH3) 2OH .
The content of water in the liquid mixture
comprising the fluoroalcohol and water, to be treated in
the present invention, is preferably at most 5 0 mass%,
particularly preferably at most 25 mass%. If such a
water content is too large, it will be required to add a
larger amount of the acid, and it tends to take a longer
time in the distillation step after the separation into
two layers. Accordingly, in such a case, it is advisable
to preliminarily remove water to some extent by carrying
out e.g. simple distillation.
The acid to be used in the present invention is
preferably an inorganic acid, preferably a strong acid
such as sulfuric acid, nitric acid, hydrochloric acid or
hydrofluoric acid. Among them, sulfuric acid, nitric
acid or hydrofluoric acid is preferred. Further, in a
case where after the step of separation into two layers,

the distillation step of further distilling the obtained
lower layer is to be carried out, it is particularly
preferred to employ sulfuric acid from such a viewpoint
that it tends to scarcely corrode the distillation
apparatus.
In the present invention, it is preferred to add the
acid in such an amount that proton (H+) would be at least
0.10, particularly preferably at least 0.15, more
preferably at least 0.20, as calculated as the molar
ratib to water in the liquid mixture comprising the
fluoroalcohol and water (provided that the acid is
regairded as dissociated 100%) . If the above molar ratio
is less than 0.1, the content of water in the lower layer
tends to be large, and the phase separation tends to be
difficult.
Further, usually, there is no particular merit in
adding the acid in excess. Accordingly, the amount of
the acid to be added should preferably be the minimum
amount where the phase separation into two layers takes
place, and the content of the fluoroalcohol in the lower
layer will be at least a predetermined level.
The addition of the acid to the liquid mixture
comprising the fluoroalcohol and water may be carried out
under atmospheric pressure at room temperature, and it is
usually not necessary to carry out the temperature
control, etc. Mixing is carried out by e.g. an agitator
so that the added acid will be uniformly mixed with the

above liquid mixture.
To let the mixture separate into two layers, the
mixture may be left to stand still. However, such
separation may be carried out by means of a centrifugal
separator or the like. When the mixture is left to stand
still to let it separate into two layers, the time for
leaving the mixture to stand still may be at a level of
from 3 to 12 hours, although it may depend also on the

thicknesses of the respective layers or the area of the
interface.
The content of the fluoroalcohol in the lower layer
obtainable in the step of the separation into two layers
in the present invention is preferably at least 80 mass%,
particularly preferably at least 90 mass%, further
preferably at least 92 mass%. The larger such a content

of the fluoroalcohol, the better, since the load will

thereby be smaller in the case of carrying out
distillation in the subsequent step.
In the upper layer obtainable in the step of the
separation into two layers in the present invention,
usually from about 10 to 3 0 mass% of the fluoroalcohol
will be contained. Such fluoroalcohol contained in the
upper layer may effectively be recovered by repeatedly
using the obtained upper layer as a part of the acid to
be used in the step of the separation into two layers for
the subsequent batch.
In the present invention, it is preferred to include

a distillation step of further distilling the lower layer
obtained in the step of separating the liquid mixture
into two layers. It is thereby possible to further
remove water from the lower layer thereby to obtain the
fluoroalcohol having a smaller water concentration.
The distillation conditions are not particularly
limited, and water can be removed by a usual multistage
distillation. The lower layer obtainable in the step of
the separation into two layers in the present invention
has a small content of water, and accordingly, the time
required for this distillation step may be short.
In the distillation step, it is preferred to obtain
the fluoroalcohol having a water concentration of at most
1,000 ppm by distilling the above lower layer. Namely,
in a case where the fluoroalcohol is used as a solvent
for a dye to be used for an information recording medium,
the lower the water concentration, the better. The water
concentration is particularly preferably at most 500 ppm,
more preferably at most 2 00 ppm. To bring the water

concentration to the above range, in the present
invention, after the distillation step, a step of

removing water in the fluoroalcohol by means of a drying
agent such as a zeolite, may further be preferably
provided.
EXAMPLES
Now, the present invention will be described with
reference to Examples (Examples 1 to 3).

EXAMPLE 1
50 g of TFPO and 15 g of demineralized water were
put into a separating funnel and shook, whereby the two
were completely mixed to form a uniform liquid mixture.
11.5 g of 96 mass% concentrated sulfuric acid was slowly
dropwise added thereto, and the mixture was shook and
then left to stand still for 3 hours, whereby the liquid
mixture was separated into two layers. The above amount
of the concentrated sulfuric acid corresponds to 0.27 as
calculated as the molar ratio of proton (H+) to water in
the liquid mixture. The separated upper and lower layers
were divided to obtain 24.6 g of the upper layer and 49.8
g of the lower layer. The concentration of TFPO in each
of the upper and lower layers was quantified by NMR,
whereby the TFPO concentration in the upper layer was
24.5 mass%, and the TFPO concentration in the lower layer
was 93.7 mass%. The NMR measuring conditions are shown
below.
NMR MEASURING CONDITIONS
Measuring apparatus: ECP-400, manufactured by JEOL

Ltd.
Measuring nuclei: 1H

Measuring method: single pulse method
Measuring solvent: nil (only the sample was put into
a test tube.)
Measuring temperature: room temperature
Outer diameter of the sample tube: 5 mm

EXAMPLE 2
In the same manner as in Example 1 except that the
amount of 96 mass% concentrated sulfuric acid dropwise
added, was changed to 9 g, mixing of TFPO and
demineralized water and separation were carried out. The

above amount of the concentrated sulfuric acid

corresponds to 0.21 as calculated as the molar ratio of
proton (H+) to water in the liquid mixture. After being
left to stand still, the liquid mixture was separated
into two layers. 23.0 g of the upper layer and 50.7 g of
the lower layer were obtained, and the TFPO concentration

in the upper layer was 18.3 mass%, and the TFPO
concentration in the lower layer was 93.4 mass%.
EXAMPLE 3
In the same manner as in Example 1 except that the
amount of 96 mass% concentration sulfuric acid dropwise
added, was changed to 4.5 g, mixing of TFPO and deionized
water and separation were carried out. The above amount
of the concentrated sulfuric acid corresponds to 0.11 as
calculated as the molar ratio of proton (H+) to water in
the liquid mixture. After being left to stand still, the
liqulid mixture was separated into two layers. 15.7 g of
the upper layer and 53.7 g of the lower layer were
obtained, and the TFPO concentration in the upper layer
was 115.5 mass%, and the TFPO concentration in the lower
layer was 90.0 mass%.

INDUSTRIAL APPLICABILITY
The method for recovering a fluoroalcohol of the
present invention is useful for a process of recovering
and reusing a fluoroalcohol from a waste liquid resulting
from the production process for CD-R or DVD-R.
The entire disclosure of Japanese Patent Application
No. 2005-037888 filed on February 15, 2005 including

specification, claims, and summary is incorporated herein
by reference in its entirety.

WE CLAIM :
1. A method for recovering a fluoroalcohol from a liquid
mixture comprising the fluoroalcohol and water, which
comprises a step of separating the liquid mixture into two
layers by adding an acid to the liquid mixture.
2. The method for recovering a fluoroalcohol as claimed in
Claim 1, wherein the fluoroalcohol is a compound represented
by the following formula 1:
H-(CRfFCF2)n-CR1R2-OH Formula 1
wherein Rf is a fluorine atom or a C1-4 polyfluoroalkyl group,
each of R1 and R2 which are independent of each other, is a
hydrogen atom or a C1-3 alkyl group, and n is an integer of
from 1 to 4.
3. The method for recovering a fluoroalcohol as claimed in
Claim 1, wherein the fluoroalcohol is 2,2,3,3-
tetrafluoropropanol.
4. The method for recovering a fluoroalcohol as claimed in
Claim 1, 2 or 3, wherein the acid is added in such an amount
that proton (H+) would be at least 0.10 as calculated as the
molar ratio to the water in the liquid mixture (provided that
the acid is regarded as dissociated 100%).
5. The method for recovering a fluoroalcohol as claimed in
any one of Claims 1 to 4, wherein the acid is sulfuric acid.
6. The method for recovering a fluoroalcohol as claimed in
any one of Claims 1 to 5, wherein the content of the

fluoroalcohol in the lower layer obtained in the step of
separating the liquid mixture into two layers, is at least 80
mass%.
7. The method for recovering a fluoroalcohol as claimed in
any one of Claims 1 to 6, which further includes a
distillation step of distilling the lower layer obtained in
the step of separating the liquid mixture into two layers.
8. The method for recovering a fluoroalcohol as claimed in
Claim 7, wherein by the distillation step, the fluoroalcohol
having a water concentration of at most 1,000 ppm is
obtained.
9. The method for recovering a fluoroalcohol as claimed in
Claim 7 or 8, which includes, after the distillation step, a
step of removing water in the fluoroalcohol by contacting the
fluoroalcohol with a drying agent.
10. The method for recovering a fluoroalcohol as claimed in
Claim 9, wherein the drying agent is a zeolite.

ABSTRACT

METHOD FOR RECOVERING A FLUOROALCOHOL FROM A LIQUID MIXTURE
OF FLUOROALCOHOL AND WATER
To provide a method for easily recovering a fluoroalcohol
in a high concentration from a liquid mixture comprising the
fluoroalcohol and water, which results from the production of
CD-R or DVD-R.
A method for recovering a fluoroalcohol, which comprises
a step of separating a liquid mixture comprising a
fluoroalcohol such as 2,2,3,3-tetrafluoropropanol and water,
into two layers by adding an acid such as sulfuric acid to
the liquid mixture, and preferably further includes a
distillation step of distilling the lower layer obtained in
the step of separating the liquid mixture into two layers.

METHOD FOR RECOVERING A FLUOROALCOHOL FROM A LIQUID MIXTURE OF FLUOROALCOHOL AND WATER

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