WO2002018306A1

WO2002018306A1 - Process for producing fluoroalcohol

Info

Publication number: WO2002018306A1
Application number: PCT/JP2001/006072
Authority: WO
Inventors: Fumihiko Yamaguchi; Shouji Takaki; Toru Yoshizawa; Kazuyoshi Ichihara
Original assignee: Daikin Industries, Ltd.
Priority date: 2000-08-28
Filing date: 2001-07-13
Publication date: 2002-03-07
Also published as: TWI250975B; CN1438980A; JP2002069017A

Abstract

A process for producing a fluoroalcohol represented by the general formula (1) from methanol and tetrafluoroethylene or the like as starting materials in the presence of a free-radical generator and an acid acceptor, characterized by comprising the steps of: (i) reacting methanol with tetrafluoroethylene or the like; (ii) removing both a product of the reaction of the acid acceptor and the acid acceptor remaining unreacted from the crude reaction product obtained; (iii) introducing the crude reaction product treated in the step (ii) into a distillation column to distill off the methanol through the column top together with the free-radical generator remaining in the crude reaction product and take out a bottom containing the fluoroalcohol represented by the general formula (1) through the column bottom; (iv) returning the distillate obtained through the column top to the reactor to reuse it; and (v) purifying the bottom to recover the fluoroalcohol represented by the general formula (1).

Description

Specification

Method for producing fluoroalcohol

Technical field

The present invention provides a compound represented by the general formula (1)

H (CFR ¹ CF ₂ ) _n CH ₂ OH (1)

(n = l or 2. When n = 1, R ¹ represents F or CF _3. When n = 2, R ¹ represents F.)

Background art

Regarding the method for producing H (CF ₂ CF ₂ ) _n CH ₂ OH (n = l, 2), JP-A-54-154707 and U.S. Pat.No. 2,596,628 disclose methanol and tetrafluoroethylene as radical generators. It is described that a telomer mixture of H (CF ₂ CF ₂ ) _n CH ₂ OH (n is up to 12) can be obtained by reacting in the presence of butyl octyl peroxide.

Since this method uses an excessive amount of methanol, it is desirable to recover and reuse the methanol contained in the crude reaction product. For example, Japanese Patent No. 302804 discloses a method for producing a fluorine-containing alcohol including a step of recycling methanol. On the other hand, when the radical generator remains unreacted in the crude reaction product, or when the unreacted acid acceptor remains in the crude reaction product when an acid acceptor is used in the reaction, the telomer When the desired fluoroalcohol is to be obtained by distilling the mixture, impurities such as evaporation residue, UVP, and components are included in the recovered fluoroalcohol. Therefore, when used as a solvent when manufacturing an information recording medium having a recording layer capable of writing and / or reading information with a laser on a substrate such as a CD-R or DVD-R, There is a disadvantage that it is not suitable for manufacturing a quality information recording medium.

An object of the present invention is to provide a general formula (1) containing substantially no impurities and capable of reusing methanol.

H (CFR ¹ CF ₂ ) _n CH ₂ OH (1)

(n = l or 2. When n = 1, R ¹ represents F or CF _3. When n = 2, R ¹ represents F.) . Disclosure of the invention

The present invention relates to a method for producing a fluoroalcohol shown in each of the following items. Item 1 Starting from methanol and tetrafluoroethylene or hexafluoropropylene in the presence of a radical generator and an acid acceptor, the following general formula (1)

H (CFR'CF,) _n CH ₂ OH (1)

(n = l or 2. When n = l, R ¹ represents F or CF _3. When n = 2, R ¹ represents F.) In the method for producing a fluoroalcohol represented by the following (i) ) To (v): a method comprising:

(ii) removing the reaction product of the acid acceptor and the unreacted acid acceptor from the obtained reaction crude product,

(iii) introducing the crude reaction product treated in the above (ii) step to a distillation column, and distilling methanol together with a radical generator remaining in the crude reaction product from the top of the column;

Removing the bottom component containing the fluorine alcohol represented by the general formula (1) from the bottom of the column,

(iv) a step of returning the fraction obtained from the top of the column to the reactor for reuse, and

(V) a step of purifying the bottom component to recover a fluoroalcohol represented by the general formula (1).

Item 2 A method for producing HCF ₂ CF ₂ CH ₂ OH using methanol and tetrafluoroethylene as starting materials in the presence of a radical generator and an acid acceptor, comprising the following steps (i) to (vi): Features method:

(0 a step of reacting methanol with tetrafluoroethylene,

(ii) removing the reaction product of the acid acceptor and the residue of the acid acceptor from the obtained reaction crude product,

(iii) guiding the reaction crude product treated in the above (ii) step to the first distillation column, and distilling methanol together with the radical generator remaining in the reaction crude product from the top of the column;

General formula from the bottom (2)

H (CF ₂ CF ₂ ), CH ₂ OH (2) (1 = an integer from 1 to 5) taking out a bottom component containing fluoroalcohol represented by

(iv) a step of returning the fraction obtained from the top of the column to the reactor for reuse,

(v) The bottom component obtained in the step (iii) is led to a second distillation column, and HC F ₂ CF ₂ CH ₂ OH is distilled off from the top of the column, and 1 in the general formula (2) is obtained from the bottom of the column. Removing the bottom component containing two or more fluoroalcohols; and

(vi) The HCF ₂ CF ₂ CH ₂ OH distilled from the top of the column in the above step (V) is contacted with a base or distilled in the presence of a base to obtain HCF ₂ CF ₂ CH ₂ 〇H The process of collecting

Item 3. In the method of Item 2, the method of recovering HCF ₂ CF ₂ CH ₂ OH by distillation in the step (vi) is to distill the components containing HCF ₂ CF ₂ CH ₂ 〇H to remove low boiling components. after, in the resulting H CF _{_₂} CF ₂ CH ₂ 0 method by again distilling the component containing H recovering HCF _{_₂} CF ₂ CH ₂ 〇_H as Potomu component of Aru HCF _{_₂} CF ₂ CH ₂ 0 H Production method. In the step of reacting methanol with tetrafluoroethylene or hexafluoropropylene in the presence of a radical generator, an excess amount of methanol is used with respect to tetrafluoroethylene or hexafluoropropylene. The reaction temperature is about 40 to 140, the reaction time is about 3 to 12 hours, and the reaction pressure is about 0.2 to 1.2 MPa. The reaction can be performed in a high-pressure reactor such as an autoclave. It is preferable to replace the inside of the reaction system with an inert gas such as nitrogen or argon. As the radical generator, one that can be distilled together with methanol when distilled is used. These radical generators need only be able to be distilled off together with methanol, and may be those that decompose in the course of distillation.

Specifically, t-butyl peroxide (boiling point: 109 to: L10) (available as trade name "Perbutyl D" (manufactured by NOF Corporation)), t-butyl peroxy-1-ethylhexanoate ( Available under the trade name "Perbutyl II" (made by NOF Corporation), t-butyl peroxyisopropyl carbonate (available under the trade name "Perbutyl I" (made by NOF Corporation)), etc. Is preferably exemplified. This Among them, it is preferable to use di-t-butyl peroxide.

The amount of the radical generator used is usually about 0.005 to 0.1 mol per 1 mol of tetrafluoroethylene or hexafluoropropylene.

The above reaction is performed in the presence of an acid acceptor. Examples of the acid acceptor include calcium carbonate, magnesium carbonate, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, carbonates and hydrogencarbonates of alkaline metal or alkaline earth metal such as potassium lime, calcium oxide, calcium oxide, 7K calcium oxide, soda lime, barium carbonate and the like. The acid acceptor is preferably capable of trapping an acid such as HF generated during the reaction without making the reaction system strongly alkaline.

The amount of the acid acceptor used is not particularly limited, but may be about 0.001 to 0.1 mol per 1 mol of tetrafluoroethylene or hexafluoropropylene. Is usually performed in a batch process, but the process after the reaction may be a batch process or a continuous process.

The crude reaction product obtained by the above-described method is guided from the reactor to a distillation column as shown in FIG. 1, and the distillation column is heated to distill methanol from the top. When the reaction is carried out under the above conditions, a part of the radical generator usually remains undivided in the crude reaction product, but the radical generator used in the present invention is distilled together with methanol when distilled. Since it is a radical generator that can be released, the still distillation is performed while controlling the normal distillation conditions of methanol, for example, the pressure in the distillation column to about 0.05 to 0.5 MPa (a gauge pressure is shown. The same applies hereinafter). Is heated and distilled, and if methanol is distilled off at about 40 to 90 ° C., the radical generator remaining in the reaction crude product is distilled off together with methanol. Thus, the radical generator remaining undecomposed can be removed from the crude reaction product.

In the present invention, it is only necessary that the undecomposed radical generator remaining in the reaction crude product can be removed from the reaction crude product.The radical generator itself may be distilled together with methanol, and the radical generator may be generated during the distillation process. The agent may decompose, and the decomposed product may be distilled off together with methanol. Therefore, the fraction containing methanol may contain an undecomposed radical generator or a decomposed product of a radical generator. Yes, or both of them may be included. For example, among the radical generators exemplified above, when t-butyl peroxide is used, it hardly decomposes in the course of distillation, so that t-butyl peroxide is distilled off together with methanol. . The crude product may contain HF and water, which are concentrated in the middle stage of the distillation column. The layer enriched in HF and water can be withdrawn from the distillation column as a side-lot fraction as shown in FIG. The temperature of the side cut fraction is about 80 to 120 ° CZ0.

In the present invention, before the reaction crude product is introduced into the distillation column, CaF ₂ ,

The reaction product of the acid acceptor such as NaF and the unreacted acid acceptor are removed. This operation is not particularly limited as long as it can remove the reaction product of the acid acceptor and the unreacted acid acceptor from the crude reaction product.For example, as shown in FIG. 1, a centrifuge is used. By using, it can be efficiently removed.

The distillate obtained from the top is returned to the reactor and reused as shown in Figs. When a radical generator is contained in the fraction without being decomposed, the radical generator can also be reused. Even if the fraction contains a decomposition product of a radical generator, the fraction can be returned to the reactor as it is and reused. After distillation of methanol, it is preferable that all remaining radical generators are removed from the potom component containing the mixture of the fluoroalcohol remaining in the still, but the amount of the radical generator contained in the bottom component is 1%. , 00 Omass ppm or less, desirably 5 Omass ppm or less.

The bottom component is taken out from the bottom of the column and led to a purification step by distillation as shown in Figs. 1 and 2, where H (CF ₂ CF ₂ ) _x CH ₂ OH (x is 3 or more) present in the crude reaction product. ), H (CF (CF ₃ ) CF ₂ ) _y CH ₂ OH (y is 2 or more), etc. to remove the general formula (1) H (CFR ¹ CF ₂ ) _n CH ₂ OH (1) ( n = l or 2. When n = l, R ¹ represents F or CF _3. When n = 2, R ¹ represents F.) is recovered. When tetrafluoroethylene was used as a raw material, HCF ₂ CF ₂ CH ₂ OH and H (CF ₂ CF ₂ ) ₂ CH ₂ Since OH is contained, HCF ₂ CF ₂ CH ₂ OH and H (CF ₂ CF ₂ ) ₂ CH ₂ 〇H may be sequentially separated from the bottom component in the purification step.

In the method of the present invention, after the above-mentioned purification step, the general formula (1)

H. (CFR ^ Fa) _n CH ₂ OH (1) (where n and R ¹ are as defined above), after contacting a fraction containing a fluoroalcohol with a base, or May be recovered by distillation in the presence of. By performing a powerful operation, a fluoroalcohol of the general formula (1) having a lower impurity content can be obtained. At this time, the base may be added directly to the middle part or the still of the distillation column, or a treatment tank (base treatment tank) may be provided before the distillation column. When a base treatment tank is provided, the operation conditions in the treatment tank are not particularly limited, but usually, it is sufficient to add the base and then contact it at about 20 to 15 Ot for about 0.5 to 3 hours. Using methanol and tetrafluoroethylene as raw materials for 11 days? ₂ (： 11 ₂ 〇 ^^ When manufacturing, remove the acid acceptor, etc. from the crude reaction product obtained by reacting methanol and tetrafluoroethylene, and remove methanol and residual radicals in the first distillation column. The generator is distilled off from the top of the column, and the bottom component represented by the general formula (2) H (CF ₂ CF ₂ ) iCHsOH (2) (1 = 1 to 5) is taken out from the bottom of the column. The potato component containing the fluorine alcohol represented by the formula (2) is led to the second distillation column for distillation, and HCF ₂ CF ₂ CH ₂ CHH is distilled off from the top of the column, and the fraction is separated with a base. HCF ₂ CF ₂ CH ₂ OH can be recovered after the contact or by further distillation in the presence of a base. The bottom component containing is extracted.

As the base, a base having a pKb of 2 or less is preferable. Examples of such a base include carbonates of alkaline metals such as sodium carbonate and carbon dioxide; sodium hydrogen carbonate such as sodium bicarbonate and hydrogen carbonate; sodium methylate, sodium ethylate, sodium Alkali metal alcoholates such as propylate, potassium t-butoxide, lithium methylate; alkali metal hydroxides such as sodium oxide, lithium hydroxide, lithium hydroxide, lithium hydroxide; calcium hydroxide, calcium hydroxide Hydroxides of alkaline earth metals such as gnesium and barium hydroxide; 7J aluminum oxide, soda lime and the like. These bases may be used alone or in combination of two or more. These may be used in combination. The base is usually used as a solution of an alcohol such as methanol.

The amount of the base to be used can be appropriately set, but is usually about 0.05 to 1.0 mol per kg of the fluorine alcohol of the general formula (1) brought into contact with the base, preferably 0.1 to 0.1 mol. It is about 0.5 mol.

When treating with a base, alcohols, water, etc. are produced as reaction products depending on the type of the base used, and the reaction products and low-boiling components such as alcohols used as a solvent for the base are converted into the general formula (1) )). Therefore, in order to obtain a high-purity fluoroalcohol of the general formula (1), first, as a distillation operation in the first step, low-boiling components such as alcohol and water are separated and removed from the fluoroalcohol of the general formula (1) Then, as a second step, the component containing the fluoroalcohol of the general formula (1) obtained as the bottom component by the distillation operation of the first step is distilled to obtain the compound of the general formula (1) Preferably, the fluoroalcohol is recovered. One embodiment of the present invention including such a distillation method is shown in FIG. According to such a distillation method, it is possible to obtain a fluorine alcohol of the general formula (1) which is substantially free from impurities by containing no alcohol or water.

In addition, instead of such a two-stage distillation operation, low-boiling components such as alcohol and water are sequentially removed by distillation, and then the fluoroalcohol of the general formula (1) is recovered from the top or middle stage of the distillation column. Is also possible.

In the method of the present invention, any of the distillation methods may be employed, but the two-stage distillation method can easily recover high-purity fluoroalcohol of the general formula (1). According to the production method of the present invention, a fluorine alcohol of the general formula (1) having an evaporation residue of 50 mass ppm or less, preferably 25 mass ppm or less, more preferably 1 Omass ppm or less is obtained.

The evaporation residue can be determined as follows. That is, the weight of the residue obtained when the fluoroalcohol was evaporated at 40 ° (5 mmHg (0.665 kPa)) was measured and expressed in mass ppm relative to the fluoroalcohol.

The UVP and luminous intensity of the fluoroalcohol of the general formula (1) obtained in the present invention in methanol at 205 nm is not more than 0. It is preferably at most 0.2 abs. The UVPJ luminosity in methanol is measured using 1 ml of fluoroalcohol of the general formula (1) and 3 ml of methanol as a measurement sample, and using methanol as a reference.

The fluorine alcohol obtained by the production method of the present invention is `` substantially free of impurities '', and (i) the evaporation residue of the fluorine alcohol is 50 mass ppm or less, preferably 25 mass ppm or less, more preferably 1 Omass ppm or less. And / or (ii) means that the UVP luminous intensity (205 nm) in methanol is 0.1 abs or less, preferably 10 labs or less, more preferably -0.2 abs or less. . An information recording medium comprising a substrate and a recording layer on which information can be written and Z or readable by a laser is provided is a solvent containing a fluoroalcohol of the general formula (1) of the present invention, and preferably contains the fluoroalcohol. According to a conventional method such as dissolving a dye in a fluorinated solvent, applying the obtained solution on a substrate, and drying, a recording layer containing the dye can be formed to manufacture. Examples of the dye include a cyanine dye, a phthalocyanine dye, a pyrylium dye, a thiopyrylium dye, a squarylium dye, an azurenium dye, an indophenol dye, an indoline phosphorus dye, a triphenyl methane dye, and a quinone dye. Amide dyes, dimonium dyes, metal complex salt dyes, and the like. Examples of the substrate include plastics such as polypropionate, polymethyl methacrylate, epoxy resin, amorphous polyolefin, polyester, and polyvinyl chloride, glass, and ceramics. An undercoat layer may be provided between the recording layer and the substrate for the purpose of improving flatness, improving adhesive strength, preventing deterioration of the recording layer, and a protective layer may be provided on the recording layer. .

According to the present invention, an information recording medium (an optical disc such as a CD-R or a DVD-R) in which a recording layer capable of writing and reading or reading information by a laser on a substrate is provided, and a photosensitive film. HCF ₂ CF ₂ CH ₂ OH, H (CF ₂ CF ₂ ) ₂ CH ₂ OH and HCF (CF ₃ ) CF ₂ CH ₂ which are substantially free of impurities and suitable for the production of

OH can be easily produced, and the recovered methanol-containing fraction and the radical generator contained in the fraction can be effectively used.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing one embodiment of the present invention. FIG. 2 is a view showing one embodiment of the present invention including a step of extracting a side cut fraction.

FIG. 3 is a diagram showing one embodiment of the present invention including a two-stage alkali distillation step.

In these figures, reference numeral 1 denotes a reaction vessel, reference numeral 2 denotes a distillation column, reference numeral 3 denotes a centrifuge, reference numeral 4 denotes a first distillation column, reference numeral 5 denotes a second distillation column, reference numeral 6 denotes a base treatment tank, reference numerals 7 and 8. Indicates an alkali distillation column, respectively.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 11

A high-pressure reactor was charged with methanol (1500 g), perbutyl D (di-tert-butyl peroxide, 31.25 g) and calcium carbonate (6.5 g). After the reactor was replaced with nitrogen, the temperature was raised to 125, and tetrafluoroethylene was reacted for 2.6 hours while charging at a controlled pressure of 0.85 MPa. After cooling the reaction crude, the weight was measured to be 2270 g, and analysis by gas chromatography revealed that 15.5 g of perbutyl D remained undecomposed. The obtained reaction crude product was treated by the following method according to the flow chart shown in FIG. '

First, the reaction crude product was guided from the reaction vessel 1 to the centrifugal separator 3, and after removing the reaction product of the acid acceptor and the unreacted acid acceptor by centrifugation, the reaction crude product was introduced to the first distillation column 4.

Then, the still was calo-heated while controlling the pressure of the distillation column at 0.1 IMP a. From the top of the first distillation column 4, methanol was distilled at a distillation temperature of 80 to 90 ° C. The obtained fraction was 1261.5 g. Analysis of this fraction showed that 13.0 g of perbutyl D was contained, and that perbutyl D remaining in the crude reaction product together with methanol was distilled out with almost no decomposition. The bottom component did not contain any protein D.

Next, the bottom component was taken out from the bottom of the first distillation column 4 and led to a purification step by distillation. The bottom component is led to the second distillation column 5, where HCF ₂ CF ₂ CH ₂ OH (648.3 g) is distilled from the top, and H (CF ₂ CF ₂ ) and CH ₂ OH (1 is 2 or more) From the column bottom. A part (150 g) 'of the obtained HCF ₂ CF ₂ CH ₂ 〇H was taken out, led to a base treatment tank 6, and the fraction was treated with sodium methylate (6 g, about 0.03 mol; as a 28% methanol solution). ) Was added. Then, leads to H CF _{_₂} CF ₂ CH ₂ OH which are processed with a base to Al force Li distillation column 7 and distilled to distill the methanol and water from the top, Potomu containing HCF ₂ CF ₂ CH ₂ OH The components were sent to distillation column 8. Finally, by distilling in the alkaline distillation column 8, the middle stage fraction was reduced to 112 ₂ ? ₂ (:. 11 ₂ 0 ^ 1 was collected resulting HCF ₂ CF ₂ CH ₂ 〇 H evaporation residue of a 1 Omass ppm, UV absorbance (205 nm) were _0 2Abs less..

Example 11

1261.5 g of methanol containing perbutyl D (13.0 g) recovered in Example 1-1 was returned to the reactor 1 and reused. That is, 254 g of fresh methanol was added to the collected methanol, and perbutyl D (15.75 g) and calcium carbonate (6′.5 g) were charged. The reaction was carried out in the same manner as in Example 1-1. The reaction time was 2.7 hours. After completion of the reaction, the reaction crude was cooled and weighed to be 2265 g. Analysis by gas chromatography revealed that 15.1 g of perbutyl D remained without decomposition.

The obtained crude reaction product was also processed according to the flowchart shown in FIG. 3 in the same manner as in Example 1-1.

That is, first, the reaction crude product was led from the reaction vessel 1 to the centrifugal separator 3 to remove the reaction product of the acid acceptor and the unreacted acid acceptor, and then to the first distillation column 4.

Then, the still was heated while controlling the pressure of the distillation column at 0.1 IMPa. Methanol was distilled from the top of the first distillation column 4 at a distillation temperature of 80 to 90 ° C. The obtained fraction was 1222.3 g. Analysis of this fraction revealed that it contained 12.6 g of perbutyl D, and the perbutyl D remaining in the crude reaction product together with methanol was distilled out with almost no decomposition. The bottom component contained no D.

Next, the bottom component was taken out from the bottom of the first distillation column 4 and led to a purification step by distillation. The bottom component is led to the second distillation column 5, and from the top, HCF ₂ CF ₂ CH ₂ OH (644. 1 g) was distilled off, and a bottom component containing H (CF ₂ CF ₂ ) iCH ₂ 〇H (1 is an integer of 2 or more) was taken out from the bottom of the column. A part (150 g) of the obtained HCF ₂ CF ₂ CH ₂ 〇H was taken out, led to a base treatment tank 6, and 28% sodium methylate (6 g, about 0.03 mol) was added to the fraction. . Then, the HCF _{_₂} CF ₂ CH ₂ 〇 H which is treated with a base leads to alkali distillation column 7 and distilled to distill the methanol and water from the top, the bottom component containing HCF _{_₂} CF ₂ CH ₂ 〇_H Was sent to the alkali distillation column 8. Finally, HCF ₂ CF ₂ CH ₂ OH was recovered as a middle-stage fraction by distillation in an alkali distillation column 8. 11〇 obtained? ₂ . ₂ . The evaporation residue of ^ 1 ₂ 〇11 was 10 mass ppm, and the UV absorbance (205 nm) was less than _0.2 abs.

Claims

The scope of the claims

1. Starting from methanol and tetrafluoroethylene or hexafluoropropylene in the presence of a radical generator and an acid acceptor, the following general formula (1)

H (CFR ¹ CF ₂ ) _n CH ₂ OH (1)

[N = l or 2. When n = l, R ¹ represents F or CF ₃ . when n = 2, R ¹ shows a F. A method for producing a fluoroalcohol represented by the following method, comprising the following steps (i) to (v):

(v) a step of purifying the bottom component to recover the fluoroalcohol represented by the general formula (1).

2. A process for producing HCF ₂ CF ₂ CH ₂ 〇H starting from methanol and tetrafluoroethylene in the presence of a radical generator and an acid acceptor, including the following steps (i) to (vi): Method characterized by:

(i) reacting methanol with tetrafluoroethylene,

General formula from the bottom (2)

[1 = Integer of 1 to 5] Take out the potom component containing fluoroalcohol represented by Process,

(v) The bottom component obtained in the step (iii) is led to a second distillation column, and HCF ₂ CF ₂ CH ₂ OH is distilled from the top of the column, and 1 in the general formula (2) is obtained from the bottom of the column. Removing the bottom component containing two or more fluoroalcohols; and

(vi) The HCF ₂ CF ₂ CH ₂ OH distilled from the top of the column in the above step (V) is contacted with a base or distilled in the presence of a base to obtain HCF ₂ CF ₂ CH ₂ 〇H Collect

3. The method according to claim 2, wherein the method of recovering HCF ₂ CF ₂ CH ₂ 〇H by distillation in the step (vi) comprises distilling a component containing HCF ₂ CF ₂ CH ₂ OH to remove a low boiling component. After the removal, the component containing HCF ₂ CF ₂ CH ₂ OH obtained as the bottom component is again distilled to recover HCF ₂ CF ₂ CH ₂ 〇H, thereby producing HCF ₂ CF ₂ CH ₂ OH. .