Process for producing fluoroalcohol

Details Process for producing fluoroalcohol Process for producing fluoroalcohol

1999-09-13

2001-02-13

O'Sullivan, Peter (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S904000

Reexamination Certificate

active

06187969

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a process for producing a fluoroalcohol of the general formula (1):
H(CFR
1
CF
2
)
n
CH
2
OH  (1)
(n=1 or 2, wherein R
1
represents F or CF
3
when n=1; R
1
represents F when n=2).
BACKGROUND ART
Regarding the technology of producing H(CF
2
CF
2
)
n
CH
2
OH (n=1 or 2), Japanese Unexamined Patent Publication No. 154707/1979 and U.S. Pat. No. 2,559,628 disclose that a mixture of telomers comprising H(CF
2
CF
2
)
n
CH
2
OH (n=12 at a maximum) is prepared by reacting methanol with tetrafluoroethylene in the presence of t-butyloctyl peroxide.
However, even if the telomer mixture obtained by the process is purified by distillation, the evaporation residue of the order of about a few hundreds of ppm can not be eliminated. When it is used as a solvent in the manufacture of an information recording medium comprising a substrate sheet and as built thereon a recording layer adapted for laser information writing and/or reading, such as CD-R and DVD-R, the disadvantage is inevitable that a high quality information recording medium can not be obtained owing to the influence of said evaporation residue.
DISCLOSURE OF THE INVENTION
It is an object of the invention to provide a process for producing a fluoroalcohol of the following general formula (1)
H(CFR
1
CF
2
)
n
CH
2
OH  (1)
(wherein n and R
1
are as defined above), which is substantially free of impurities such as an evaporation residue and UV-absorbing substances.
The inventors found that when the fluoroalcohol of general formula (1) is distilled after elimination, by decomposition, of the remaining initiator in the reaction mixture, the above object is accomplished. The present invention has been completed based on this novel finding.
The invention relates to the following processes.
1. A process for producing a fluoroalcohol of the following formula (1)
H(CFR
1
CF
2
)
n
CH
2
OH  (1)
(n=1 or 2, wherein R
1
represents F or CF
3
when n=1; R
1
represents F when n=2) comprising reacting methanol with tetrafluoroethylene or hexafluoropropylene in the presence of an initiator, wherein the fluoroalcohol of formula (1) is distilled after decomposing the remaining initiator contained in the reaction mixture.
2. The process according to item 1 above wherein the decomposition of the remaining initiator is carried out using at least one means selected from the group consisting of decomposition of the remaining initiator by heating the reaction mixture, decomposition of the remaining initiator by contact with an acid catalyst, decomposition of the remaining initiator by contact with a reducing agent, decomposition of the remaining initiator by UV irradiation and decomposition of the remaining initiator by contact with a base.
3. The process according to item 1 above wherein the distillate containing the fluoroalcohol of formula (1) is further distilled either in the presence of a base or after contact of said distillate with a base.
In the reaction of methanol with tetrafluoroethylene or hexafluoropropylene in the presence of an initiator, methanol is used in excess over tetrafluoroethylene or hexafluoropropylene. The reaction temperature is about 40-140° C., the reaction time is about 3-12 hours, and the reaction pressure is about 0.2-1.2 MPa. The reaction may be conducted in a high pressure reactor such as autoclave. The reaction system is preferably subjected to inert gas purge using nitrogen, argon or the like gas. The reaction is generally carried out batchwise.
Examples of initiator include peroxides and azo compounds. It is preferable to use an initiator with a half-life of about 0.5-10 hours at a reaction temperature.
Preferred examples of initiator include di-t-butyl peroxide (available under the tradename “perbutyl D”, manufacture of NOF Corp.), t-butylperoxy-2-ethyl hexanoate (available under the tradename “perbutyl O”, manufacture of NOF Corp.), t-butylperoxyisopropyl carbonate (available under the tradename “perbutyl I”, manufacture of NOF Corp.) and like peroxides; and azobisisobutyronitrile, azobiscyclohexanenitrile and like azo compounds.
The amount of the initiator is generally about 0.005-0.1 mole per mole of tetrafluoroethylene or hexafluoropropylene.
The above reaction may be carried out in the presence of an acid acceptor. Examples of acid acceptor include calcium carbonate, magnesium carbonate, sodium carbonate, potassium carbonate, barium carbonate, sodium bicarbonate, potassium bicarbonate and like carbonates and bicarbonates of alkali metals or alkaline earth metals; calcium oxide, calcium hydroxide and soda lime. Preferred acid acceptors are substances capable of capturing the acid generated during the reaction (e.g., HF) without imparting strong basicity to the reaction mixture.
The amount of the acid acceptor is not specifically limited to, but may be about 0.001-0.1 mole per mole of tetrafluoroethylene or hexafluoropropylene.
The process of the invention optionally includes a distillation step for removing any excess of methanol from the reaction mixture after completion of the reaction.
The means for decomposing the undecomposed initiator remaining in the reaction mixture is not specifically limited to, and the examples of the means include following (i)-(v).
In the following (ii), (iii) and (v), “contact” is carried out by adding an acid catalyst, reducing agent or base to the reaction mixture.
(i) Decomposition by Heating
The temperature to heat the reaction mixture can be suitably selected according to the kind of the initiator, and is generally about 100-200° C. Heating is performed, either in an open system or in a closed system, for about 0.5-10 hours.
(ii) Decomposition by Contact with an Acid Catalyst
The acid catalyst may be an inorganic acid, an organic acid or a solid acid catalyst.
Examples of inorganic acid include sulfuric acid, hydrochloric acid, nitric acid, hydroiodic acid and hydrobromic acid. Examples of organic acid include acetic acid and trifluoromethanesulfonic acid. Examples of solid acid catalyst include silica alumina, silica magnesia and ion exchange resins or ion exchange membranes having sulfonic, carboxyl and like acidic groups. A preferred example of the ion exchange membrane is NAFION (tradename, manufacture of E.I.duPont de Nemours and Company, perfluorosulfonic acid ionomer).
These acid catalysts can be used singly or in combination.
The amount of the acid catalyst can be suitably selected according to the amount of the initiator added to the reaction system and the reaction conditions, but is generally about 1-500 parts by weight based on 100 parts by weight of the initiator added.
The condition for decomposing the remaining initiator by the acid catalyst can be suitably selected according to the kind of the initiator and the acid catalyst. The decomposition by the acid catalyst is generally carried out at about 0-100° C. for about 0.5-20 hours, either in an open system or in a closed system.
(iii) Decomposition by Contact with a Reducing Agent
Examples of reducing agent include Fe(II) salts, Cr(II) salts, Cu(I) or Cu(II) salts, Ag(I) salts and like salts of transition metals, and thiosulfates. More specifically, FeSO
4
, CrCl
2
, CuCl, Cu(OCOCH
3
)
2
, [Ag(NH
3
)
2
]OH and Na
2
S
2
O
3
can be mentioned. These reducing agents can be used singly or in combination.
The amount of the reducing agent can be suitably selected according to the amount of the initiator added to the reaction system and the reaction conditions, but is generally about 0.001-5 moles per mole of the initiator added.
The condition for decomposing the remaining initiator by the reducing agent can be suitably selected according to the kind of the initiator and the reducing agent. The decomposition by the reducing agent is generally carried out at about 20-100° C. for 0.5-10 hours, either in an open system or in a closed system.
(iv) Decomposition by UV Irradiation
The UV decomposition may be carried out by irradiating the reaction mixture with UV light (at about 100-

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