Title of Invention	METHOD FOR RECOVERY OF FLUORINATED ALCOHOL
Abstract	The invention discloses a method for recovering a fluoroalcohol 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, which comprises a step of separating a liquid mixture comprising said fluoroalcohol and water, into two layers by adding an inorganic salt which is a hydrochloride or a sulfate of an alkali metal salt to the liquid mixture, wherein the inorganic salt is added in such an amount that the total of inorganic ions to be formed would be at least 0.10 as calculated as the molar ratio to the water in the liquid mixture (provided that the inorganic salt is regarded as dissociated 100%).

Title of Invention

METHOD FOR RECOVERY OF FLUORINATED ALCOHOL

Abstract

The invention discloses a method for recovering a fluoroalcohol 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, which comprises a step of separating a liquid mixture comprising said fluoroalcohol and water, into two layers by adding an inorganic salt which is a hydrochloride or a sulfate of an alkali metal salt to the liquid mixture, wherein the inorganic salt is added in such an amount that the total of inorganic ions to be formed would be at least 0.10 as calculated as the molar ratio to the water in the liquid mixture (provided that the inorganic salt is regarded as dissociated 100%).

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 water 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 reduce 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 method for easily recovering a fluoroalcohol by separating water from a liquid mixture comprising the fluoroalcohol and water, which results e.g. in the process for the production of CD-R or DVD-R. MEANS TO ACCOMPLISH THE OBJECT The present invention provides a method for recovering a fluoroalcohol, which comprises a step of separating a liquid mixture comprising the fluoroalcohol and water, into two layers by adding an inorganic salt to the liquid mixture. It is considered that in the present invention, by the addition of an inorganic salt to the liquid mixture comprising the fluoroalcohol and water, the solubility of the fluoroalcohol in 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, hydroxyl 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. The present invention provides the following: (1) A method for recovering a fluoroalcohol, which comprises a step of separating a liquid mixture comprising the fluoroalcohol and water, into two layers by adding an inorganic salt to the liquid mixture. (2) The method for recovering a fluoroalcohol according to the above (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 according to the above (1), wherein the fluoroalcohol is 2,2,3,3 -tetrafluoropropanol. (4) The method for recovering a fluoroalcohol according to any one of the above (1) to (3), wherein the inorganic salt is added in such an amount that the total of inorganic ions to be formed would be at least 0.10 as calculated as the molar ratio to the water in the liquid mixture (provided that the inorganic salt is regarded as dissociated 100%). (5) The method for recovering a fluoroalcohol according to any one of the above (1) to (4), wherein the inorganic salt is sodium chloride. (6) The method for recovering a fluoroalcohol according to any one of the above (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 according to any one of the above (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 according to the above (7), wherein by the distillation step, the fluoroalcohol having a water concentration of at most 1,000 ppm is obtained. 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 fluoroalcohol in a short time. 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 85 mass%/ more preferably at least 90 mass%. Therefore, when this lower layer is further purified by e.g. distillation, a high purity fluoroalcohol can easily and efficiently be obtained. BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a preferred fluoroalcohol may, for example, be a C2-7 fluoroalcohol such as perfluoro-t-butanol, 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 fluoroalkyl 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. A preferred specific example of the compound represented by the formula 1 may, for example, be H(CF2)2CH2OH (2,2,3,3-tetrafluoropropanol, 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 50 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 inorganic salt, 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 inorganic salt to be used in the present invention is preferably an alkali metal salt, particularly preferably a salt of a strong acid such as a hydrochloride or a sulfate, from the viewpoint of dissociation efficiency. Specifically, the inorganic salt may, for example, be sodium chloride, sodium sulfate, sodium carbonate, sodium hydrogencarbonate, sodium fluoride or potassium sulfate. Among them, sodium chloride or sodium sulfate is preferred, and sodium chloride is particularly preferred, since it is inexpensive and readily soluble in the liquid mixture of the fluoroalcohol and water. In the present invention, it is preferred to add the inorganic salt in such an amount that the total of inorganic ions to be formed would be at least 0.10, particularly preferably at least 0.13, as calculated as the molar ratio to water in the liquid mixture comprising the fluoroalcohol and water (provided that the inorganic salt is regarded as dissociated 100%). If the above molar ratio is less than 0.10, the content of water in the lower layer tends to be large, and the phase separation tends to be difficult. The above inorganic ions are meant for both anions and cations to be formed by dissociation of the inorganic salt. A method for calculation of the molar amount of inorganic ions will be exemplified. In a case where 1 mol of NaCl is added, it will be dissociated into 1 mol of Na+ and 1 mol of Cl-, whereby inorganic ions will be 2 mols in total. In a case where 1 mol of Na2SO4 is added, it will be dissociated into 2 mols of Na+ and 1 mol of SO42-, whereby inorganic ions will be 3 mols in total. Further, usually, there is no particular merit in adding the inorganic salt in excess. Accordingly, the amount of the inorganic salt 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 inorganic salt 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. agitator so that the added inorganic salt 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 85 mass%, further preferably at least 90 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 5 to 10 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 inorganic salt 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 the separation 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 e.g. a zeolite, may further be preferably provided. EXAMPLES Now, the present invention will be described with reference to Examples (Examples 1 and 2). EXAMPLE 1 50 g of 2,2,3,3-tetrafluoropropanol (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. 3.5 g of sodium chloride was 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 sodium chloride corresponds to 0.14 as calculated as the molar ratio of inorganic ions to water in the liquid mixture. The separated upper and lower layers were divided to obtain 13.9 g of the upper layer and 54.2 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 5.8 mass%, and the TFPO concentration in the lower layer was 89.3 mass%. The NMR measuring conditions are shown below. NMR MEASURING CONDITIONS Measuring apparatus: ECP-400, manufactured by JEOL Ltd. Measuring nuclei: XH 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 2,2,3,3-tetrafluoropropanol (TFPO) was changed to 35 g, and the amount of sodium chloride added was changed to 9 g, mixing of TFPO and demineralized water and separation were carried out. The above amount of the sodium chloride corresponds to 0.16 as calculated as the molar ratio of inorganic ions to water in the liquid mixture. After being left to stand still, the liquid mixture was separated into two layers. 16.1 g of the upper layer and 37.3 g of the lower layer were obtained, and the TFPO concentration in the upper layer was 5.5 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. 2005-53596 filed on February 28, 2005 including specification, claims, and summary is incorporated herein by reference in its entirety. WE CLAIM: 1. A method for recovering a fluoroalcohol 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, which comprises a step of separating a liquid mixture comprising said fluoroalcohol and water, into two layers by adding an inorganic salt which is a hydrochloride or a sulfate of an alkali metal salt to the liquid mixture, wherein the inorganic salt is added in such an amount that the total of inorganic ions to be formed would be at least 0.10 as calculated as the molar ratio to the water in the liquid mixture (provided that the inorganic salt is regarded as dissociated 100%) . 2. The method for recovering a fluoroalcohol as claimed in Claim 1, wherein the fluoroalcohol is 2,2,3,3- tetrafluoropropanol. 3. The method for recovering a fluoroalcohol as claimed in any one of Claims 1 or 2, wherein the inorganic salt is sodium chloride. 4. The method for recovering a fluoroalcohol as claimed in any one of Claims 1 to 3, 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%. 5. The method for recovering a fluoroalcohol as claimed in any one of Claims 1 to 4, which optionally comprises a distillation step of distilling the lower layer obtained in the step of separating the liquid mixture into two layers. 6. The method for recovering a fluoroalcohol as claimed in Claim 5, wherein by the distillation step, the fluoroalcohol having a water concentration of at most 1,000 ppm is obtained. ABSTRACT METHOD FOR RECOVERY OF FLUORINATED ALCOHOL The invention discloses a method for recovering a fluoroalcohol 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, which comprises a step of separating a liquid mixture comprising said fluoroalcohol and water, into two layers by adding an inorganic salt which is a hydrochloride or a sulfate of an alkali metal salt to the liquid mixture, wherein the inorganic salt is added in such an amount that the total of inorganic ions to be formed would be at least 0.10 as calculated as the molar ratio to the water in the liquid mixture (provided that the inorganic salt is regarded as dissociated 100%).

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
water 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
reduce 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 method for easily recovering a fluoroalcohol by
separating water from a liquid mixture comprising the
fluoroalcohol and water, which results e.g. in the
process for the production of CD-R or DVD-R.
MEANS TO ACCOMPLISH THE OBJECT
The present invention provides a method for
recovering a fluoroalcohol, which comprises a step of
separating a liquid mixture comprising the fluoroalcohol
and water, into two layers by adding an inorganic salt to
the liquid mixture.
It is considered that in the present invention, by
the addition of an inorganic salt to the liquid mixture
comprising the fluoroalcohol and water, the solubility of
the fluoroalcohol in 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, hydroxyl 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.
The present invention provides the following:
(1) A method for recovering a fluoroalcohol, which
comprises a step of separating a liquid mixture
comprising the fluoroalcohol and water, into two layers
by adding an inorganic salt to the liquid mixture.
(2) The method for recovering a fluoroalcohol
according to the above (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
according to the above (1), wherein the fluoroalcohol is
2,2,3,3 -tetrafluoropropanol.
(4) The method for recovering a fluoroalcohol
according to any one of the above (1) to (3), wherein the

inorganic salt is added in such an amount that the total
of inorganic ions to be formed would be at least 0.10 as
calculated as the molar ratio to the water in the liquid
mixture (provided that the inorganic salt is regarded as
dissociated 100%).
(5) The method for recovering a fluoroalcohol
according to any one of the above (1) to (4), wherein the
inorganic salt is sodium chloride.
(6) The method for recovering a fluoroalcohol
according to any one of the above (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
according to any one of the above (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
according to the above (7), wherein by the distillation
step, the fluoroalcohol having a water concentration of
at most 1,000 ppm is obtained.
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

fluoroalcohol in a short time. 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 85 mass%/ more preferably at least 90
mass%. Therefore, when this lower layer is further
purified by e.g. distillation, a high purity
fluoroalcohol can easily and efficiently be obtained.
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, a preferred fluoroalcohol
may, for example, be a C2-7 fluoroalcohol such as
perfluoro-t-butanol, 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 fluoroalkyl 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.
A preferred specific example of the compound
represented by the formula 1 may, for example, be
H(CF2)2CH2OH (2,2,3,3-tetrafluoropropanol, 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 50 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 inorganic salt, 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 inorganic salt to be used in the present
invention is preferably an alkali metal salt,
particularly preferably a salt of a strong acid such as a
hydrochloride or a sulfate, from the viewpoint of
dissociation efficiency.
Specifically, the inorganic salt may, for example,
be sodium chloride, sodium sulfate, sodium carbonate,
sodium hydrogencarbonate, sodium fluoride or potassium
sulfate. Among them, sodium chloride or sodium sulfate
is preferred, and sodium chloride is particularly
preferred, since it is inexpensive and readily soluble in
the liquid mixture of the fluoroalcohol and water.
In the present invention, it is preferred to add the
inorganic salt in such an amount that the total of
inorganic ions to be formed would be at least 0.10,
particularly preferably at least 0.13, as calculated as
the molar ratio to water in the liquid mixture comprising
the fluoroalcohol and water (provided that the inorganic

salt is regarded as dissociated 100%). If the above
molar ratio is less than 0.10, the content of water in
the lower layer tends to be large, and the phase
separation tends to be difficult. The above inorganic
ions are meant for both anions and cations to be formed
by dissociation of the inorganic salt.
A method for calculation of the molar amount of
inorganic ions will be exemplified. In a case where 1
mol of NaCl is added, it will be dissociated into 1 mol
of Na+ and 1 mol of Cl-, whereby inorganic ions will be 2
mols in total. In a case where 1 mol of Na2SO4 is added,
it will be dissociated into 2 mols of Na+ and 1 mol of
SO42-, whereby inorganic ions will be 3 mols in total.
Further, usually, there is no particular merit in
adding the inorganic salt in excess. Accordingly, the
amount of the inorganic salt 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 inorganic salt 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. agitator so that the added inorganic salt 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 85 mass%, further
preferably at least 90 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 5 to 10 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 inorganic
salt 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 the separation 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 e.g. a
zeolite, may further be preferably provided.
EXAMPLES
Now, the present invention will be described with
reference to Examples (Examples 1 and 2).
EXAMPLE 1
50 g of 2,2,3,3-tetrafluoropropanol (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. 3.5 g of sodium chloride was
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
sodium chloride corresponds to 0.14 as calculated as the
molar ratio of inorganic ions to water in the liquid
mixture. The separated upper and lower layers were
divided to obtain 13.9 g of the upper layer and 54.2 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 5.8 mass%,
and the TFPO concentration in the lower layer was 89.3
mass%. The NMR measuring conditions are shown below.
NMR MEASURING CONDITIONS
Measuring apparatus: ECP-400, manufactured by JEOL
Ltd.
Measuring nuclei: XH
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 2,2,3,3-tetrafluoropropanol (TFPO) was changed

to 35 g, and the amount of sodium chloride added was
changed to 9 g, mixing of TFPO and demineralized water
and separation were carried out. The above amount of the
sodium chloride corresponds to 0.16 as calculated as the
molar ratio of inorganic ions to water in the liquid
mixture. After being left to stand still, the liquid
mixture was separated into two layers. 16.1 g of the
upper layer and 37.3 g of the lower layer were obtained,
and the TFPO concentration in the upper layer was 5.5
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. 2005-53596 filed on February 28, 2005 including
specification, claims, and summary is incorporated herein
by reference in its entirety.

WE CLAIM:
1. A method for recovering a fluoroalcohol 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,
which comprises a step of separating a liquid mixture
comprising said fluoroalcohol and water, into two layers by
adding an inorganic salt which is a hydrochloride or a
sulfate of an alkali metal salt to the liquid mixture,
wherein the inorganic salt is added in such an amount that
the total of inorganic ions to be formed would be at least
0.10 as calculated as the molar ratio to the water in the
liquid mixture (provided that the inorganic salt is regarded
as dissociated 100%) .
2. The method for recovering a fluoroalcohol as claimed in
Claim 1, wherein the fluoroalcohol is 2,2,3,3-
tetrafluoropropanol.
3. The method for recovering a fluoroalcohol as claimed in
any one of Claims 1 or 2, wherein the inorganic salt is
sodium chloride.
4. The method for recovering a fluoroalcohol as claimed in
any one of Claims 1 to 3, 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%.
5. The method for recovering a fluoroalcohol as claimed in
any one of Claims 1 to 4, which optionally comprises a
distillation step of distilling the lower layer obtained in
the step of separating the liquid mixture into two layers.
6. The method for recovering a fluoroalcohol as claimed in
Claim 5, wherein by the distillation step, the fluoroalcohol
having a water concentration of at most 1,000 ppm is
obtained.

ABSTRACT

METHOD FOR RECOVERY OF FLUORINATED
ALCOHOL
The invention discloses a method for recovering a
fluoroalcohol 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, which comprises a step of separating a
liquid mixture comprising said fluoroalcohol and water, into
two layers by adding an inorganic salt which is a
hydrochloride or a sulfate of an alkali metal salt to the
liquid mixture, wherein the inorganic salt is added in such
an amount that the total of inorganic ions to be formed
would be at least 0.10 as calculated as the molar ratio to
the water in the liquid mixture (provided that the inorganic
salt is regarded as dissociated 100%).

METHOD FOR RECOVERY OF FLUORINATED ALCOHOL

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