JP3265434B2 - Method for producing gem-difluoroalkanes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing gem-difluoroalkanes.

[0002]

2. Description of the Related Art Conventionally, so-called specific CFCs have been awarded as detergents and refrigerants, but it has been internationally determined that the use of such CFCs should be restricted in recent years with increasing interest in the problem of destruction of the global environment. Fluorocarbon alternatives are being actively developed.

[0003] Fluorine compounds can be expected as materials for high-performance materials in various fields including the electronics industry and the medical field by themselves or as polymers.

Under such circumstances, the general formula RCF ₂
The gem-difluoroalkanes represented by R ′ (R and R ′ represent a hydrogen atom and a hydrocarbon residue which may have a substituent) are a substitute for fluorocarbon, a synthetic intermediate of a substitute for fluorocarbon, and furthermore fluorine. It is expected to be used as a raw material for the synthesis of polymer series. For example, 2,2-difluoropropane is used as a substitute for CFCs such as a foaming agent and a refrigerant (Japanese Patent Publication No. 3903336, Japanese Patent Application Laid-Open No.
17139).

As described above, gem which is expected to be developed in the future
-Difluoroalkanes, the production method of which,
At present, there is no practically satisfactory one. For example, a method is known in which an alkyne is reacted with hydrogen fluoride in the absence of a solvent (US Patent No. 228).
No. 7934, Journal of American Chemical Society, 64, 2289, (194)
2)), this method has a problem that the yield of gem-difluoroalkanes is low. On the other hand, a method has been proposed in which the reaction is carried out in the presence of a polar solvent such as acetone, ether, pyridine, etc.
American Chemical Society, 65, 58
7, (1943), Journal of Organic Chemistry, 44, 3872, (1979)), and the improvement in yield was not yet satisfactory.

[0006]

The inventors of the present invention have made intensive studies to solve the problems of the prior art, and as a result, by reacting alkynes with hydrogen fluoride in the presence of a non-polar solvent, a high degree of reaction has been achieved. The inventors have found that gem-difluoroalkanes can be obtained with a high yield, and have completed the present invention based on this finding.

[0007]

Thus, according to the present invention, alkynes (excluding those containing a polymerizable olefin as impurities) and hydrogen fluoride are converted into a non-polar solvent or a fluorine-substituted aliphatic hydrocarbon. Characterized in that it is reacted in the presence of a compound or a fluorine-substituted cycloaliphatic hydrocarbon.
-A process for the production of difluoroalkanes is provided.

The alkynes used in the present invention are a general term for hydrocarbons having a carbon-carbon triple bond in the molecule or at the terminal of the molecule, or hydrocarbons which may have a substituent inert to the reaction. . Specific examples of such a hydrocarbon having a carbon-carbon triple bond include acetylene, propyne, 1-butyne, 2-butyne, and 3-methyl-
1-butyne, 1-pentine, 2-pentyne, 4-methyl-2-pentyne, 1-heptin, 2-heptin, 3-heptin, 1-octyne and the like.

The substituent inert to the reaction includes a halogen atom, an alkoxy group, a carbonyl group, an alkoxycarbonyl group, a cyano group and a nitro group.

[0010] Hydrogen fluoride may be either an anhydride or an aqueous solution, but the anhydride is awarded in terms of reactivity and operability.
The amount of hydrogen fluoride is usually 2 to 1 mole of alkyne.
10 to 10 mol, preferably 2 to 5 mol.

In the present invention, the reaction is carried out in the presence of a non-polar solvent or a hydrogen-substituted aliphatic hydrocarbon or a fluorine-substituted alicyclic hydrocarbon. As such a non-polar solvent, aliphatic hydrocarbons, alicyclic hydrocarbons and the like are used. Examples of the aliphatic hydrocarbons include n-butane, isobutane, n-pentane, 2-methylbutane, n-hexane, 2-methylpentane, n-heptane, n-octane and the like. Among them, aliphatic hydrocarbons having 6 or less carbon atoms are awarded in terms of reactivity.

The alicyclic hydrocarbons include, for example, cyclopentane, methylcyclopentane, cyclohexane and the like. Among them, cyclopentane is awarded for its reactivity.

Examples of the fluorine-substituted aliphatic hydrocarbons include 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, 2,2-difluoropropane,
1,2-trifluoropropane, 1,1,1,2,2
3,3-heptafluoropropane, 2,2-difluorobutane, 2,2,3-trifluorobutane, 1,1,
1,2,3,4,4,5,5,5-decafluoropentane, perfluorobutane, perfluoropentane, perfluorohexane, 3,3-difluorohexane, 2,
2-difluorooctane and the like. Examples of the fluorine-substituted alicyclic hydrocarbons include, for example, fluorocyclopentane, 1,1-difluorocyclopentane, 1,2-difluorocyclopentane, 1,1,2, 2,3,3-hexafluorocyclopentane, 1,1,2,2,3,3
4,5-octafluorocyclopentane, nonafluorocyclopentane, perfluorocyclopentane, fluorocyclohexane, 1,1-difluorocyclohexane and the like can be mentioned. Among them, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, 2,2-
Difluorobutane, perfluoropentane, perfluorohexane and the like are awarded because they are readily available industrially.

The amount of the non-polar solvent, the fluorine-substituted aliphatic hydrocarbon and the fluorine-substituted alicyclic hydrocarbon is usually 0.1 to 100 times by weight, preferably 0.5 to 100 times, the weight of hydrogen fluoride.
It is appropriately selected in a range of 50 times by weight.

[0015] The reaction temperature is usually -70 to 100 ° C, preferably -30 to 30 ° C. The reaction time depends on the type of raw material,
It varies depending on the amount used, the reaction temperature, etc., and is usually 0.5 to
10 hours, preferably 0.5 to 5 hours.

The reaction is also different depending on the kind of the raw material, the reaction temperature and the like.
It is performed under a pressure of 0 kg / cm ² or less. Although the reaction method is not particularly limited, for example, hydrogen fluoride and a non-polar solvent, or a fluorine-substituted aliphatic hydrocarbon or a fluorine-substituted alicyclic hydrocarbon are charged into a closed reactor such as an autoclave, and the reaction is carried out at a predetermined temperature. When the temperature has reached, an alkyne is added while maintaining the temperature, then the set temperature is maintained for a certain period of time, and then the temperature is maintained at room temperature or higher to complete the reaction.

After completion of the reaction, gem-difluoroalkanes can be isolated by separating excess hydrogen fluoride from the reaction solution and then distilling it.

Thus, according to the present invention, gem-difluoroalkanes can be obtained in a higher yield than in the prior art.

[0019]

The present invention will be described more specifically with reference to the following examples. Parts and% in Examples and Comparative Examples are based on weight unless otherwise specified.

Example 1 An autoclave was charged with 18.6 grams of anhydrous hydrogen fluoride.
The mixture was cooled to −19 ° C. with stirring, and 11.4 g of 98.9% pure propyne and 1,1-difluoroethane 1 were added.
A mixture with 1.8 grams was slowly introduced in the gas phase.
Next, the internal temperature was raised to room temperature, and the mixture was stirred for 1 hour. After removal of anhydrous hydrogen fluoride from the reaction solution, distillation yielded a purity of 9
There were obtained 21.4 g (93% yield) of 9.2% of 2,2-difluoropropane.

Example 2 A reaction was carried out in the same manner as in Example 1 except that 1,1,1,2-tetrafluoroethane was used instead of 1,1-difluoroethane. 20.7 grams (90% yield) of difluoropropane were obtained.

Example 3 An autoclave was charged with 17.7 g of anhydrous hydrogen fluoride and 20.8 g of n-pentane, cooled to −19 ° C. with stirring, and added with 14.8% propyne having a purity of 98.9%. Grams were gradually introduced in the gas phase. Next, the internal temperature was raised to room temperature, and the mixture was stirred for 1 hour. After removing anhydrous hydrogen fluoride from the reaction solution, distillation was performed to obtain 26.1 g (yield: 89%) of 2,2-difluoropropane having a purity of 98.8%.

Example 4 The reaction was carried out in the same manner as in Example 3 except that 2,2-difluoropropane was used instead of n-pentane. As a result, 26.4% of 2,8.8-difluoropropane having a purity of 98.8% was obtained.
Grams (90% yield) were obtained.

Comparative Example 1 The reaction was carried out according to Example 3 except that acetone was used instead of n-pentane. As a result, the yield of 2,2-difluoropropane was 47%.

Comparative Example 2 The reaction was carried out according to Example 3 except that melamine was used instead of n-pentane. As a result, the yield of 2,2-difluoropropane was 75%.

Example 5 The reaction was carried out according to Example 3 except that 2-butyne was used instead of propyne. As a result, the yield of 2,2-difluorobutane was 89%.

Example 6 The reaction was carried out according to Example 5 except that cyclopentane was used instead of n-pentane. As a result, the yield of 2,2-difluorobutane was 83%.

Example 6 The reaction was carried out according to Example 5 except that 2,2-difluorobutane was used instead of n-pentane.
The yield of 2-difluorobutane was 80%.

Comparative Example 3 The reaction was carried out according to Example 5 except that ethyl ether was used instead of n-pentane. As a result, the yield of 2,2-difluorobutane was 12%.

Comparative Example 4 The reaction was carried out according to Example 5 except that acetone was used instead of n-pentane. As a result, the yield of 2,2-difluorobutane was 8.5%.

Comparative Example 5 The reaction was carried out according to Example 5 except that toluene was used instead of n-pentane. As a result, the yield of 2,2-difluorobutane was 42.0%.

Comparative Example 6 The reaction was carried out according to Example 5 except that dichloromethane was used instead of n-pentane. As a result, the yield of 2,2-difluorobutane was 68.0%.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-255143 (JP, A) JP-A-5-221892 (JP, A) JP-A-52-51304 (JP, A) 16767 (JP, B1) JP 48-24367 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 19/08 C07C 17/08

Claims (1)

(57) [Claims] 1. An alkyne (excluding those containing a polymerizable olefin as an impurity) and hydrogen fluoride, a non-polar solvent, or a fluorine-substituted aliphatic hydrocarbon or a fluorine-substituted alicyclic hydrocarbon. A method for producing gem-difluoroalkanes, characterized by reacting in the presence of: