Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-11-22
2001-11-06
O'Sullivan, Peter (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06313357
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for recovering a fluoroalcohol.
BACKGROUND ART
Fluoroalcohols have high solubility in water. When water is accidentally introduced into the fluoroalcohol or water is formed during the production process of the fluoroalcohols, water and fluoroalcohols are mixed together and thus difficult to separate water from the fluoroalcohols. In addition, since the fluoroalcohols have higher coefficient of global warming than carbon dioxide, it is desirable that the alcohols are recovered after use and recycled. The fluoroalcohols, however, are highly hygroscopic and absorb moisture in the air when handled or left in the open system. Therefore, water is likely to enter into fluoroalcohols by the time it is recycled. When the fluoroalcohols are used as solvents to dissolve dyes for producing information recording media such as CD-R and DVD-R, wherein recording layers capable of writing and/or reading are provided on their substrate by means of a laser, the water contained therein may cause deterioration and impaired solubility of the dyes, leading to degraded quality of the information recording media. Consequently, when the fluoroalcohols contain water, particularly when the fluoroalcohols are recycled, the alcohols have to be purified to a level substantially free of water.
An object of the present invention is to provide a method for recovering a fluoroalcohol which is substantially free of water by separating water from a mixture comprising a fluoroalcohol and water.
DISCLOSURE OF THE INVENTION
The inventors found the followings: By the distillation of water-containing fluoroalcohol, water is distilled off as an azeotropic or azeotrope-like composition; the remaining fluoroalcohol has a very low water content; and thus a fluoroalcohol which is substantially free of water can be easily recovered.
In addition, the inventors found that a fluoroalcohol substantially free of water can also be obtained by pervaporation to separate a fluoroalcohol and water. The present invention has been accomplished based on the findings.
The present invention provides the processes and a fluoroalcohol listed below:
1. A method for recovering a fluoroalcohol from a mixture comprising a fluoroalcohol and water, wherein the fluoroalcohol is recovered by distilling the mixture of a fluoroalcohol and water to separate water as an azeotropic or azeotrope-like composition.
2. The method according to item
1
, wherein the distillation is carried out under reduced pressure.
3. The method according to item
1
, wherein the fluoroalcohol is represented by the formula (1)
H(CFR
1
CF
2
)
n
CH
2
OH (1)
wherein n=1 or 2; when n=1, R
1
represents F or CF
3
; when n=2, R
1
represents F.
4. A fluoroalcohol obtained by the method of item
1
, the fluoroalcohol containing not more than 2,000 mass ppm of water.
5. A method for recovering a fluoroalcohol from a mixture comprising a fluoroalcohol and water, wherein water is separated by pervaporation to recover the fluoroalcohol.
6. The method according to item
5
, wherein the mixture comprising the fluoroalcohol and water is an azeotropic or azeotrope-like composition of a fluoroalcohol and water.
7. The method according to item
5
, wherein the pervaporation is carried out by using a membrane made of a polyamide, polyvinyl alcohol, polyacrylic ester, cellulose, perfluorosulfonic acid ionomer, chitosan, polyimide, PDMS, PBAA, PTFE, PEBA, silica or zeolite.
8. The method according to item
5
, wherein the fluoroalcohol is represented by the formula (1)
H(CFR
1
CF
2
)
n
CH
2
OH (1)
wherein n=1 or 2; when n=1, R
1
represents F or CF
3
; when n=2, R
1
represents F.
9. A fluoroalcohol obtained by the method of item
5
, the fluoroalcohol containing not more than 2,000 mass ppm of water.
10. A process for recovering a fluoroalcohol comprising the steps of recovering the fluoroalcohol by distilling the mixture comprising the fluoroalcohol and water to separate water as an azeotropic or azeotrope-like composition; and separating the water contained in the separated azeotropic or azeotrope-like composition by pervaporation to recover the fluoroalcohol contained in the composition.
The fluoroalcohol is not specifically limited insofar as the alcohol has at least one fluorine atom. Examples of the preferably fluoroalcohols are those represented by the formula (1) H(CFR
1
CF
2
)
n
CH
2
OH (wherein n =1 or 2; when n=1, R
1
represents F or CF
3
; when n=2, R
1
represents F).
The amount of the fluoroalcohol contained in the mixture subjected to distillation is more than the amount of the fluoroalcohol in the azeotropic or azeotrope-like composition of the fluoroalcohol and water. The content of fluoroalcohol is typically 80 mass % or more, preferably 90 mass % or more, based on the total weight of the mixture. When the mixture is separated into two phases (i.e., aqueous phase and organic phase), the organic phase may be subjected to distillation.
For example, when the fluoroalcohol is HCF
2
CF
2
CH
2
OH (in the formula (1), n=1 and R
1
=F), HCF
2
CF
2
CH
2
OH and water form a homogeneous solution. The azeotropic composition of HCF
2
CF
2
CH
2
OH : water has a ratio of 72.5:27.5 (by weight) (azeotropic point: 92.5° C., at atmospheric pressure). Therefore, by the distillation of the mixture containing more than 72.5 mass %, preferably more than 90 mass % of HCF
2
CF
2
CH
2
OH, water is distilled off with the fluoroalcohol as an azeotropic or azeotrope-like composition. Thus, HCF
2
CF
2
CH
2
OH free of water is recovered from the mixture.
As to HCF
2
CF
2
CF
2
CF
2
CH
2
OH (in the formula (1), n=2 and R
1
=F), HCF
2
CF
2
CF
2
CF
2
CH
2
OH and water is separated into two phases when the content of HCF
2
CF
2
CF
2
CF
2
CH
2
OH in the mixture is at least 2.9 mass % and not more than 94.2 mass %. HCF
2
CF
2
CF
2
CF
2
CH
2
OH and water are uniformly mixed when the content of HCF
2
CF
2
CF
2
CF
2
CH
2
OH is outside the above range (at 25° C.). The azeotropic composition of HCF
2
CF
2
CF
2
CF
2
CH
2
OH : water has a ratio of 62.0:38.0 (by weight) (azeotropic point: 97.8° C., at an atmospheric pressure). Therefore, by the distillation of the mixture (including the separated organic phase) wherein HCF
2
CF
2
CF
2
CF
2
CH
2
OH and water are uniformly mixed, water is distilled off with the fluoroalcohol as an azeotropic or azeotrope-like composition. Thus, HCF
2
CF
2
CF
2
CF
2
CH
2
OH free of water is recovered from the mixture.
As to CF
3
CHFCF
2
CH
2
OH (in the formula (1), n=1 and R
1
=CF
3
), CF
3
CHFCF
2
CH
2
OH and water is separated into two phases when content of CF
3
CHFCF
2
CH
2
OH in the mixture is at least 7.5 mass % and not more than 90.4 mass %. CF
3
CHFCF
2
CH
2
OH and water are uniformly mixed when the content of CF
3
CHFCF
2
CH
2
OH is outside the above range (at 25° C.). The azeotropic composition of CF
3
CHFCF
2
CH
2
OH: water has a ratio of 75.0:25.0 (by weight) (azeotropic point: 94.2° C., at an atmospheric pressure). Therefore, by the distillation of the mixture (including the separated organic phase) wherein CF
3
CHFCF
2
CH
2
OH and water are uniformly mixed, water is distilled off with the fluoroalcohol as an azeotropic or azeotrope-like composition. Thus, CF
3
CHFCF
2
CH
2
OH free of water is recovered from the mixture.
An azeotropic composition herein means a composition whose vapor, being in equilibrium with a liquid mixture, has the same ratio as the liquid mixture. An azeotrope-like composition means a composition whose vapor, being in equilibrium with a liquid mixture, has a similar ratio as the liquid mixture.
Distillation is carried out at ambient pressure or under reduced pressure, for example, about 0.001-0.1 MPa. Furthermore, the distillation under determined pressure is carried out at an azeotropic temperature, typically at about 30-98° C.
After being separated by distillation, a fluoroalcohol substantially free of water can be obtained by collecting the fluoroalcohol remaining in t
Katsube Toshiyuki
Yamaguchi Fumihiko
Daikin Industries Ltd.
Larson & Taylor PLC
O'Sullivan Peter
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