JP3403770B2 - Method for producing hydrofluorocarbon - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing hydrofluorocarbon.

[0002]

2. Description of the Related Art Hydrofluorocarbons are 1, 1,
It is a compound that substitutes for a chlorofluorocarbon compound such as 2-trichloro-1,2,2-trifluoroethane and does not destroy the ozone layer.

[0003]

2. Description of the Related Art The following reports have been made on a method for synthesizing a hydrofluorocarbon using iodofluorocarbon as a starting material.

(1) Method of reduction in the presence of zinc (J. Flu
orine Chem., 6,297,1975). (2) Method of synthesis by reaction using Grignard reagent (J. Fluorine Chem., 3,247,1973).

(3) Method of synthesis by liquid phase reduction reaction using hydrogen and Raney nickel catalyst (Ger. Offen. 2,060,04)
1, J. Chem. Soc., 3761, 1953). (4) Method of synthesis by reduction reaction using sodium hypophosphite and palladium or platinum catalyst (J. Fluorine Ch
em., 55, 101, 1991).

(5) Method of reacting with alcoholic-potassium-hydroxide (J. Chem. Soc., 3761, 1953). (6) A method of reacting with an alkali metal hydroxide in methanol (EP 0,449,516A1).

[0007]

The method (1) has a problem of handling and treating zinc and zinc slurry produced by the reaction. In the method (2), the Grignard reagent may be ignited by moisture or the like. Further, since a low boiling point ether solvent is used as a solvent, there is a high risk, and there is a problem in waste liquid treatment. Method (3) is
Since the reaction must be performed under high temperature and high pressure conditions of 65 ° C. and 60 to 80 atm, there is a high risk. The method (4) has a problem that an expensive catalyst is required.

The method (5) uses alcoholic-potassium-hydroxide at a high temperature of 100 to 130 ° C., but has a problem of low yield.

According to the method (6) using only methanol,
The conversion rate of the raw material iodofluorocarbon was actually 99.9.
% Or more is difficult, and there is a problem in obtaining high-purity hydrofluorocarbon. Further, when an inexpensive aqueous solution of an alkali metal hydroxide which is usually used for industry is used as the alkali metal hydroxide, the conversion rate is further lowered.

Further, although the reaction using only isopropyl alcohol is described in (6), both the conversion and the selectivity are low, and the yield is low at 22.6%. There is also a problem that tar-like substances are produced as by-products.

Further, when a hydrofluorocarbon synthesized by using only methanol or isopropyl alcohol as a solvent was used as a polymerization solvent without distillation, there were problems such as the reaction not being aimed at or the polymer being colored.

[0012]

Means for Solving the Problems The present inventor has conducted extensive studies on a method for efficiently producing a hydrofluorocarbon using iodofluorocarbon as a starting material. As a result, by reacting iodofluorocarbon with an alkali metal hydroxide under the action of an alcohol mixture consisting of a primary alcohol and a secondary alcohol, it is possible to safely and at a high conversion rate, a high selectivity and a high rate. It has been found that a pure hydrofluorocarbon can be obtained.

That is, the present invention provides the general formula I _n R _f I (wherein n is 0 or 1, and when n is 0, R
_f is a linear or branched polyfluoroalkyl group having 2 to 12 carbon atoms, and when n is 1, R _f is 2 to 2 carbon atoms.
It is 12 linear or branched polyfluoroalkylene groups. ) Is reacted with an alkali metal hydroxide under the action of an alcohol mixture consisting of a primary alcohol and a secondary alcohol, and a general formula H _n R _f H (however, In the formula, n and R _f are the same as those described above.).

The iodofluorocarbon which is the raw material of the present invention is a compound represented by the general formula I _n R _f I. However, in the formula, n is 0 or 1. When n is 0, R _f
Is a straight-chain or branched polyfluoroalkyl group having 2 to 12 carbon atoms, preferably 3 to 8 carbon atoms, and particularly CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ —. preferable. When n is 1, R _f has 2 to 1 carbon atoms
Two linear or branched polyfluoroalkylene groups are preferred, but ones having 3 to 8 carbon atoms are preferable, and especially -C
It is preferably F ₂ CF ₂ CF ₂ CF ₂ —.

Specific examples of the iodofluorocarbon include 1-iodo-1,1,2,2,2-pentafluoroethane and 1-iodo-1,1,2,2,3,3,4.
4,4-nonafluorobutane, 1-iodo-1,1,
2,2,3,3,4,4,5,5,6,6,6-tridecafluorohexane, 1-iodo-1,1,2,2
3,3,4,4,5,5,6,6,7,7,8,8,8
-Heptadecafluorooctane, 2-iodo-1,1,
1,2,3,3,3-heptafluoropropane, 4-iodo-1,1,1,2,3,3,4,4-octafluoro-2-trifluoromethylbutane, 6-iodo-1,
1,1,2,3,3,4,4,5,5,6,6-dodecafluoro-2-trifluoromethylhexane, 1,2-
Diiodo-1,1,2,2-tetrafluoroethane,
1,4-diiodo-1,1,2,2,3,3,4,4-
Octafluorobutane, 1,6-diiodo-1,1,
2,2,3,3,4,4,5,5,6,6-dodecafluorohexane and the like can be mentioned, but not limited thereto.

[0016] The present invention is characterized by reacting a basis in A alkali metal hydroxide effects of alcohol mixture of the iodofluorocarbon and a primary alcohol and a secondary alcohol.

The primary alcohol and the secondary alcohol are not particularly limited, and known or known alcohols can be used. In the usual case, it is preferable to use methanol, ethanol, propyl alcohol, butyl alcohol or the like as the primary alcohol, and particularly preferable is methanol. As the secondary alcohol, isopropyl Al <br/> calls are preferred.

The ratio of primary alcohol to secondary alcohol is
Although not particularly limited, in general, the weight ratio of primary alcohol: secondary alcohol is 0.5: 1 to 100.
A range of about 0: 1 is preferable, and particularly 1: 1 to 200:
A range of 1 is preferred. If the ratio of the secondary alcohol becomes too large, the amount of the high boiling point compound produced may increase. On the other hand, when the ratio of secondary alcohol is too small,
The reaction speed may slow down.

In general, the amount of the primary alcohol is preferably about 0.1 to 10 parts by weight with respect to 1 part by weight of the raw material iodofluorocarbon. It is preferable to use the primary alcohol in an amount larger than that in which the alkali metal hydroxide is completely dissolved.

As the alkali metal hydroxide, sodium hydroxide, potassium hydroxide and the like are usually preferred.
Further, in the present invention, since the alkali metal hydroxide can be used as an aqueous solution, an inexpensive aqueous alkali metal hydroxide solution which is commercially available for industrial use can be directly used.

The amount of the alkali metal hydroxide is usually 1.5 mol or more, preferably about 1.5 to 3 mol, per 1 mol of the iodofluorocarbon as a raw material. Since the reaction rate of the alkali metal hydroxide is increased when it is used in excess, it is preferable that the concentration of the alkali metal hydroxide is as high as possible within the range where it can be dissolved in the reaction system.

The conditions of the above reaction can be appropriately changed depending on the kinds and amounts of the reactant and alcohol. If the reaction temperature is too low, the reaction becomes difficult, and if the reaction temperature is too high, it is dangerous. Therefore, the reaction temperature is preferably adjusted to a temperature at which the reaction solution is refluxed, and is usually about 40 to 70 ° C. The reaction pressure may be normal pressure, reduced pressure or increased pressure, and normal pressure is preferred. The reaction time is usually about 1 to 10 hours. There is no problem even if the reaction is carried out under pressure and at high temperature.

In the method of the present invention, a highly pure product can be obtained by washing the reaction crude product with water. According to the method of the present invention, since the conversion rate of the raw material iodofluorocarbon is extremely high, it should be used without distillation purification except for special applications where it is necessary to remove an extremely small amount of iodine compounds of the order of several ppm. The advantage is that

The hydrofluorocarbon produced by the above reaction is a compound represented by the general formula H _n R _f H. However, in the formula, n is 0 or 1. When n is 0, R _f is a linear or branched polyfluoroalkyl group having 2 to 12 carbon atoms, preferably 3 to 8 carbon atoms, particularly CF ₃ CF ₂ CF ₂ CF ₂ CF. ₂ CF ₂
It is preferably −. When n is 1, R _f is a linear or branched polyfluoroalkylene group having 2 to 12 carbon atoms, preferably 3 to 8 carbon atoms, particularly —CF ₂ CF ₂ CF ₂ CF. _It is preferably _2- .

Specific examples of the hydrofluorocarbon are 1,1,1,2,2-pentafluoroethane, 1,
1,1,2,2,3,3,4,4-nonafluorobutane, 1,1,1,2,2,3,3,4,4,5,5,5
6,6-tridecafluorohexane, 1,1,1,2,
2,3,3,4,4,5,5,6,6,7,7,8,8
-Heptadecafluorooctane, 1,1,1,2,3
3,3-heptafluoropropane, 1,1,1,2,
3,3,4,4-octafluoro-2-trifluoromethylbutane, 1,1,1,2,3,3,4,4,5
5,6,6-dodecafluoro-2-trifluoromethylhexane, 1,1,2,2-tetrafluoroethane,
1,1,2,2,3,3,4,4-octafluorobutane, 1,1,2,2,3,3,4,4,5,5,6,6
-Dodecafluorohexane and the like.

According to the present invention, hydrofluorocarbon can be obtained from iodofluorocarbon with extremely high conversion and high selectivity. Therefore, the amount of unreacted iodofluorocarbon or the like remaining in the product is extremely small, and the product can be used for various purposes without distilling and purifying the product. For example, the polymerization reaction can be carried out using the hydrofluorocarbon produced by the present invention as a polymerization solvent, and in that case also, the reaction can be carried out without coloring the polymer.

The polymer in this case is not particularly limited, but polytetrafluoroethylene, polyperfluoro
( Butenyl vinyl ether ) , a copolymer of tetrafluoroethylene and perfluoro ( alkyl vinyl ether ), a copolymer of tetrafluoroethylene and ethylene, and other fluorine-based polymers can be exemplified.

[0028] Conventionally, chlorofluorocarbon compounds have been used as the polymerization solvent, although adverse effects on the ozone layer has become a problem, hydrofluorocarbons produced by the present invention, there is no risk of destroying the ozone layer Therefore, by using these as a polymerization solvent, they are also very excellent compounds in that adverse effects on the environment can be avoided.

Further, the hydrofluorocarbon of the present invention can be used for applications such as a foaming agent, a refrigerant and a cleaning agent, like the conventionally used chlorinated hydrocarbon or chlorinated fluorinated hydrocarbon.

Further, even when bromofluorocarbon or the like is synthesized using the hydrofluorocarbon synthesized by the method of the present invention as a starting material and used as an artificial blood or a contrast agent, a coloring phenomenon presumed to be derived from an iodine compound is not recognized. There are advantages.

[0031]

In the present invention, the function and function of the alcohol mixture are not always clear, but the primary alcohol and the secondary alcohol interact with each other, which results in a high conversion and a high selectivity which were not achieved by their individual use. It is considered that the effect of suppressing the production of high boiling point compounds such as tar is produced.

[0032]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[Example 1] In a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer,
256 g of methanol, 3 of isopropyl alcohol
g, and 46.4 g (1.16 mol) of sodium hydroxide were charged. After heating the reactor to an internal temperature of 60 ° C., C ₆
223 g (0.5 mol) of F ₁₃ I was added dropwise over 1 hour.
After completion of dropping, heating and refluxing were continued for 6 hours. The conversion rate is 99.
It was 9% or more. After cooling the reactor to room temperature, 300 g of water was added to dissolve the precipitated sodium iodide.
The reaction crude liquid was separated into two layers, and the fluorocarbon layer (lower layer) was further washed twice with 300 g of water, and C ₆ F ₁₃ H was added to 145
g (purity 99.9%) was obtained. No tar was found in the reactor.

Example 2 In a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer,
256 g of methanol, 30 of isopropyl alcohol
g, and 74.3 g (1.13 mol) of 85% potassium hydroxide was charged. After heating the reactor to an internal temperature of 60 ° C., 223 g (0.5 mol) of C ₆ F ₁₃ I was added dropwise over 1 hour. After the dropping was completed, heating and refluxing were continued for 5 hours. The conversion rate was 99.9% or more. After cooling the reactor to room temperature, 300 g of water was added to dissolve the precipitated potassium iodide. The reaction crude liquid was separated into two layers, and the fluorocarbon layer (lower layer) was further washed with 300 g of water. When the fluorocarbon layer was analyzed by gas chromatography, C ₆
The purity of F ₁₃ H was 99.5%, and C ₆ F ₁₃ I was not detected. The amount of C ₆ F ₁₃ H obtained was 154 g.
No tar was found in the reactor.

Example 3 In a 20-liter Hastelloy C autoclave equipped with a stirrer, a reflux condenser and a thermometer, 5130 g of methanol, 60 g of isopropyl alcohol and 1485 g of 85% potassium hydroxide (22.
5 mol) was charged. After heating the reactor to an internal temperature of 50 ° C., 4460 g (10 mol) of C ₆ F ₁₃ I was fed in 2 hours. Keeping the internal temperature of the reactor at 50 to 55 ° C,
Stirring was continued for 10 hours. The conversion rate was 99.9% or more. After cooling the reactor to room temperature, 3200 g of water was added to dissolve the precipitated potassium iodide. The reaction crude liquid is separated into two layers, and the fluorocarbon layer (lower layer) is further separated into 320 layers.
It was washed twice with 0 g of water to obtain 2975 g (purity 99.9%) of C ₆ F ₁₃ H. No tar was found in the reactor.

Example 4 In a 500 ml four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer,
256 g of methanol, 1. of isopropyl alcohol.
5 g and 74.3 g (1.13 mol) of 85% potassium hydroxide were charged. 113.5 g (0.25 mol) of IC ₄ F ₈ I was added to the reactor while maintaining the reactor internal temperature at 30 to 35 ° C.
Dropped over time. After the dropping was completed, stirring was continued at 35 ° C. for 3 hours. The conversion rate was 99.9% or more. After cooling the reactor to room temperature, 300 g of water was added to dissolve the precipitated potassium iodide. The reaction crude liquid was separated into two layers, and the fluorocarbon layer (lower layer) was further washed with 300 g of water.
When the fluorocarbon layer was analyzed by gas chromatography, the purity of HC ₄ F ₈ H was 99.5%.
C ₄ F ₈ I was detected. The obtained HC ₄ F ₈ H
Was 39 g. No tar was found in the reactor.

Example 5 In a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer,
256 g of methanol, 3 of isopropyl alcohol
g, and 74.3 g (1.13 mol) of 85% potassium hydroxide was charged. After heating the reactor to an internal temperature of 60 ° C., 273 g (0.5 mol) of C ₈ F ₁₇ I was added dropwise over 1 hour. After completion of dropping, heating and refluxing were continued for 8 hours. The conversion rate was 99.9% or more. After cooling the reactor to room temperature, 300 g of water was added to dissolve the precipitated potassium iodide. The reaction crude liquid was separated into two layers, and the fluorocarbon layer (lower layer) was further washed with 300 g of water. When the fluorocarbon layer was analyzed by gas chromatography,
The purity of C ₈ F ₁₇ H was 99.6%, and C ₈ F ₁₇ I was not detected. The amount of C ₈ F ₁₇ H obtained was 199 g. No tar was found in the reactor.

[Example 6] 20 equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer
In a liter Hastelloy C autoclave, 7700 g of methanol, 60 g of isopropyl alcohol, 8
1980 g (30 mol) of 5% potassium hydroxide was charged. After heating the reactor to an internal temperature of 55 ° C., C ₆ F ₁₃ I
Of 4460 g (10 moles) were fed in 2 hours. The reactor was maintained at 55 ° C and stirring was continued for 10 hours. The conversion rate was 99.9% or more. 3200 g of water was added to dissolve the precipitated potassium iodide. The reaction crude liquid was separated into two layers, and the fluorocarbon layer (lower layer) was further washed twice with 3200 g of water to obtain 2951 g of C ₆ F ₁₃ H (purity: 9
9.9%. C ₆ F ₁₃ I was detected 3.9 ppm. ) Got. No tar was found in the reactor.

[Example 7] A 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer was used.
128 g of methanol, 64 of isopropyl alcohol
g, 131 g of a 48% aqueous potassium hydroxide solution (1.1
(2 mol). After heating the reactor to an internal temperature of 55 ° C., 223 g (0.5 mol) of C ₆ F ₁₃ I was added dropwise over 1 hour. The reaction conversion rate after 5 hours from the end of dropping was 99.
It was 9% or more. No potassium iodide was deposited in the reactor. After cooling the reactor to room temperature, 3
00 g of water was added, the reaction crude liquid was separated into two layers, and the fluorocarbon layer (lower layer) was further washed with 300 g of water three times. When the fluorocarbon layer was analyzed by gas chromatography, the purity of C ₆ F ₁₃ H was 99.5%,
C ₆ F ₁₃ I was detected. The obtained C ₆ F ₁₃ H was 135 g. No tar was found in the reactor.

[Comparative Example 1] In a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer,
510 g of methanol and 99 g of 85% potassium hydroxide
(1.5 mol) was charged. Heat the reactor to an internal temperature of 6
After the temperature was 5 ° C., 446 g (1 mol) of C ₆ F ₁₃ I was added dropwise over 1 hour. 2 hours after the end of the dropping, the internal temperature of the reactor was 60
It was ℃. The conversion rate was low at 74% or less. After adding 300 g of water to the reaction crude liquid to dissolve the precipitated potassium iodide, two layers were separated, and the fluorocarbon layer (lower layer) was further washed with 300 g of water. A large amount of C ₆ F ₁₃ I was detected in the obtained fluorocarbon layer.

COMPARATIVE EXAMPLE 2 256 g of methanol and 131 g of 48% aqueous potassium hydroxide solution were added to a 1 liter four-necked flask equipped with a stirrer, a reflux condenser with a distillation device, a dropping funnel and a thermometer. (1.12 mol) was charged.
After heating the reactor to an internal temperature of 55 ° C., 2 of C ₆ F ₁₃ I was added.
23 g (0.5 mol) was added dropwise over 1 hour. The reaction conversion rate after heating and refluxing for 5 hours was 45.8%.

Comparative Example 3 510 g of isopropyl alcohol and 85 g of isopropyl alcohol were placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser with a distillation device, a dropping funnel and a thermometer.
% Potassium hydroxide 49.5 g (0.75 mol) was charged. After heating the reactor to an internal temperature of 65 ° C., C ₆ F ₁₃ I
223 g (0.5 mol) of was added dropwise over 1 hour. After completion of the dropping, heating and refluxing were continued for 1 hour. The reaction conversion rate is 99.9.
%, But a large amount of black, tar-like residue was left in the reactor after the reaction crude liquid was distilled to recover the fraction.

Reference Example 1 A stainless steel reaction vessel having an internal volume of 1.2 liter was degassed, 1200 g of C ₆ F ₁₃ H synthesized in Example 6 and 0.8 g of n-pentane as a chain transfer agent. Then, 45 g of tetrafluoroethylene, 3.7 g of ethylene, and 0.8 g of ( perfluorobutyl ) ethylene were charged, and the temperature was maintained at 65 ° C. to obtain 10% by weight of t as a polymerization initiator.
ert- butyl peroxyisobutyrate 1,1,2
-3 cc of trichloro-1,2,2-trifluoroethane solution was added to start the reaction. During the reaction, a mixed gas of tetrafluoroethylene and ethylene (molar ratio 53/4
7) was introduced and the reaction pressure was maintained at 17.5 g / cm ₂ . After 6 hours, 85 g of a white copolymer was obtained in a slurry state. The obtained polymer had a melting point of 270 ° C. and a thermal decomposition starting point of 340 ° C. When the polymer was molded at 300 ° C., a compression molded product with no coloration was obtained. 250 ° C
No coloration was observed even after holding for 3 days.

Reference Example 2 The reaction crude liquid of Comparative Example 1 was distilled to obtain C ₆ F ₁₃ H containing 200 ppm of C ₆ F ₁₃ I. When this was used as a polymerization solvent and polymerized in the same manner as in Reference Example 1, after 10 hours, 63 g of a white copolymer was obtained in a slurry state. The melting point of the polymer is 269 ° C.,
The starting point of thermal decomposition was 313 ° C. When the polymer was molded at 300 ° C., remarkable coloring was observed.

[0045]

According to the present invention, hydrofluorocarbons can be produced from iodofluorocarbons with high conversion and high selectivity. Further, the present invention is a method which has a fast reaction rate, is efficient and safe, and is industrially very advantageous.

In particular, according to the present invention, since the conversion rate of the raw material is very high and the selectivity is also high, a high-purity hydrofluorocarbon can be obtained without performing a distillation operation. Furthermore, unreacted raw material iodofluorocarbon,
And various inconveniences derived from various iodine compounds generated from iodofluorocarbon can be avoided.

In the reaction of the present invention, an inexpensive aqueous alkali metal hydroxide solution for industrial use can be adopted as the alkali metal hydroxide. When the aqueous solution is used, the alkali metal iodide does not precipitate, which is advantageous in terms of post-treatment and the like.

The obtained hydrofluorocarbon is a useful compound which does not adversely affect the ozone layer, and a blowing agent as a substitute compound for the chlorofluorocarbon compound,
It can also be used for refrigerants, detergents and the like.

Particularly when it is used as a polymerization solvent, it is possible to prevent the unnecessary molecular weight distribution from being widened by the iodofluorocarbon having a high chain transfer property and the coloring of the polymerization product due to the mixing of unreacted iodofluorocarbon. .

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) C07C 17/23 C07C 19/08

Claims (4)

(57) [Claims] 1. A compound represented by the general formula I _n R _f I (wherein n is 0 or 1, and when n is 0, R _f is a linear or branched polyfluoroalkyl having 2 to 12 carbon atoms). The base,
When n is 1, R _f is a linear or branched polyfluoroalkylene group having 2 to 12 carbon atoms. ) Is reacted with an alkali metal hydroxide under the action of an alcohol mixture consisting of a primary alcohol and a secondary alcohol, and a general formula H _n R _f H (however, In the formula, n and R _f are the same as above.) The method for producing a hydrofluorocarbon. 2. When n is 0, R _f is a linear or branched polyfluoroalkyl group having 3 to 8 carbon atoms , and n is
When 1, the manufacturing method according to claim 1 R _f is a linear or branched polyfluoroalkylene group having 3 to 8 carbon atoms. 3. When n is 0, R _f is CF ₃ CF ₂ CF ₂ CF.
₂ CF ₂ CF ₂ -, and, if n is 1, R _f is -CF ₂ C
The process according to claim 1 in which - F ₂ CF ₂ CF _2. 4. A primary alcohol is Ri Oh with methanol, secondary
Claim 1 alcohol Ru Ah with isopropyl alcohol,
The manufacturing method according to 2 or 3 .