JP2734672B2 - Method for producing 1,1-difluoroethane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] In recent years, it has been feared that chemically stable chlorofluorocarbons may destroy the ozone layer when released into the atmosphere. Therefore, the production and use of so-called specific CFCs such as CFC-11 and CFC-12 are being regulated or abolished internationally. Freon-12
As an alternative candidate substance (chemical formula: CCl ₂ F ₂ , boiling point: −29.8 ° C.), HFC-134a (chemical formula: CF ₃ CH ₂ F, boiling point: −26.5 ° C.)
Has been proposed. However, the physical properties of HFC-134a and Freon-12 are not always the same. Therefore, CFC-12
It is said that a HFC-134a cannot be directly replaced with a refrigerator using, and a newly designed refrigerator is required. Therefore, 1,1-difluoroethane (HFC-152) is used as an alternative refrigerant for refrigerators currently using Freon-12.
a, a mixed refrigerant containing a chemical formula: CH ₃ CHF ₂ , boiling point: 25.0 ° C.) has been proposed.

The present invention relates to a method for producing 1,1-difluoroethane, which is expected to be used as a substitute for CFC-12.

[Prior art and problems] As a method for producing 1,1-difluoroethane, a method for fluorinating acetylene or vinyl fluoride is known. However, this process requires a large amount of equipment investment for ensuring safety, and has a problem that a high reaction yield cannot always be easily obtained.

[Means for Solving the Problems] The present inventor has proposed 1-chloro-1,1-difluoroethane (HCFC-1) as a reaction route for obtaining 1,1-difluoroethane.
(42b, chemical formula: CClF ₂ CH ₃ , boiling point: -9.8 ° C.) The inventors have made intensive studies and found that 1,1-difluoroethane can be obtained in high yield, and have provided the present invention. It is. Hereinafter, details of the present invention will be described together with examples.

HCFC-142b as a raw material can be easily obtained by a method such as fluorination of methyl chloroform.
In the reduction of HCFC-142b, chlorine in the molecule is replaced with a hydrogen atom as shown in the following formula.

CClF ₂ CH ₃ → CHF ₂ CH ₃ + HCl (HCFC-142b) (HFC-152a) In general, for a C—X (X = F, C1, Br, I) bond, CI>C—Br> C—C1≫ Reduction becomes difficult in the order of CF. (See table below) Therefore, a reduction reaction of 1,1-difluoroethane including a process of breaking a CF bond having a strong binding energy is unlikely to occur, and 1,1-difluoroethane can be selectively obtained by the method of the present invention.

The reduction can be performed using various reduction methods, such as a method under light irradiation, a method using zinc, and a method using hydrogen in the presence of a catalyst. When the reduction is performed under light irradiation, the compound used as a proton source is not particularly limited as long as it is an organic compound to which a hydrogen atom is bonded.For example, methanol, ethanol, isopropyl alcohol, alcohols such as sec-butyl alcohol, hexane , Alkanes such as heptane, and aromatic compounds such as toluene and xylene are preferable, and secondary alcohols such as isopropyl alcohol are particularly preferable. Moreover, these mixed solvents can also be used. The reaction temperature is suitably from -20 ° C to + 300 ° C, and the stoichiometric amount or more of the reducing agent is preferably used.

The solvent used for the reduction using zinc is not particularly limited, but includes alcohols such as methanol, ethanol, and isopropyl alcohol; organic acids such as acetic acid and formic acid; ethers such as tetrahydrofuran; water; and mixtures thereof. Preferably, alcohols such as methanol, ethanol, and isopropyl alcohol are used. As zinc, any shape such as powder, granules and shavings can be used, but zinc powder is most preferably used. It is not necessary to perform a special activation treatment or the like before use. The amount of zinc used is not particularly limited, but usually it is preferable to use an equimolar amount based on the starting material. Reaction temperature is -20 ° C ~ +
300 ° C is appropriate. The pressure is not particularly limited, but is usually 0.
The pressure is preferably in the range of 1010 kg / cm ² G, preferably 1-3 kg / cm ² G.

When the reduction is performed using hydrogen in the presence of a catalyst, the liquid phase,
Any system in the gas phase is possible. As the reduction catalyst, any of noble metal catalysts such as platinum, palladium, rhodium and ruthenium and nonmetal catalysts such as nickel can be used, and among them, it is particularly preferable to use noble metal catalysts. When the reduction is performed in the liquid phase, the reduction may be performed without a solvent, or a solvent inert to the reaction, for example, an alcohol such as methanol, ethanol, or isopropyl alcohol may be used. The reaction temperature is suitably from room temperature to 400 ° C., and the stoichiometric amount or more of hydrogen is suitable. The reaction pressure may be normal pressure or a pressure higher than normal pressure. When the reaction is carried out in a gas phase, the contact time is usually 0.1 to 300 ° C., particularly 2 to 60 seconds.

The catalyst needs to have sufficient stability against hydrogen chloride produced as a by-product. Moreover, as a result of examining the reaction behavior using various catalysts, it was found that a relatively high reaction temperature was required. Therefore, the catalyst is required to have high activity and high heat resistance. That is, a platinum group element catalyst or a catalyst mainly containing an alloy obtained by adding an iron group element or rhenium mainly to a platinum group element can be used. Further, by appropriately adding titanium, zirconium, hafnium, lanthanum, other lanthanide elements, tantalum, niobium, molybdenum, tungsten, and group IB elements, the heat resistance of the catalyst can be improved and a long-life catalyst can be obtained. Is obtained. As a method for supporting the catalyst component, a method in which a simple salt or a complex salt of the above element is used and supported by an impregnation method, an ion exchange method or the like can be applied. As a method for reducing the supported catalyst component,
A method of reducing in a liquid phase with hydrogen, hydrazine, formaldehyde, sodium borohydride, or the like, a method of reducing in a gas phase with hydrogen, and the like can be applied. As the carrier, for example, activated carbon, alumina, zirconia and the like are suitable.
Before using the catalyst, it is desirable to perform a hydrogen reduction treatment in advance to obtain stable characteristics.

As described above, the present invention provides a method for producing 1,1-difluoroethane in a high yield by reducing 1-chloro-1,1-difluoroethane.

[Example] An example of the present invention will be described below.

Example 1 A reaction tube made of Inconel 600 having an inner diameter of 2.6 cm and a length of 100 cm filled with 300 cc of a commercially available platinum catalyst supported on activated carbon (supporting amount: 0.5%) was immersed in a salt bath furnace.

Hydrogen and 1-chloro-1,1-difluoroethane were introduced into the reaction tube in a 4: 1 molar ratio. The flow rates of hydrogen and starting material were 200 cc / min and 50 cc / min, respectively. The reaction temperature was 300 ° C. Gas chromatography was used for the analysis of the produced gas. Table 1 shows the results.

Example 2 A commercially available palladium catalyst supported on activated carbon (supporting amount 0.5
%) Except that the reaction was carried out in the same manner as in Example 1.
The results are shown in Table 1.

Example 3 The reaction was carried out in the same manner as in Example 1 except that the catalyst was rhodium, a commercially available activated carbon carrier (amount supported: 0.5%). First result
It is shown in the table.

Example 4 The catalyst was a commercially available activated carbon carrier ruthenium (loading amount: 0.5%)
The reaction was carried out in the same manner as in Example 1 except for the above. The results are shown in Table 1.

Example 5 Activated carbon was immersed in pure water to impregnate the water into the pores. Ammonia was added to an aqueous solution in which palladium chloride and nickel chloride were dissolved by a ratio of 50:50 by weight of the metal component and 2.0% by the total weight of the metal component with respect to the weight of the activated carbon to make it weakly alkaline. The activated carbon was introduced into the aqueous solution to adsorb the ionic components on the activated carbon. An aqueous solution of sodium borohydride was added dropwise thereto to reduce the catalyst component. After washing with distilled water, it was dried at 150 ° C. for 5 hours. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 6 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH using hydrochloric acid, palladium chloride and potassium perrhenate were added in a weight ratio of 90:10 for the heavy metal component, and 1.0% for the total weight of the heavy metal component based on the weight of the activated carbon.
An aqueous solution in which only the ionic components were dissolved was added dropwise little by little, and the ionic components were adsorbed on activated carbon. After washing with pure water,
Dry at 5 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 300 ° C. for 5 hours. Using the catalyst thus prepared, the reaction temperature was 33
The reaction was carried out in the same manner as in Example 1 except that the temperature was changed to 0 ° C. The results are shown in Table 1.

Example 7 Palladium chloride and copper chloride were mixed in a weight ratio of metal components of 90:10.
Of the total weight of the metal component with respect to the weight of the activated carbon
After adding 1% of aqueous ammonia to the aqueous solution in which only% was dissolved, activated carbon was added to adsorb the catalyst component. After hydrazine was added dropwise to this and reduced, it was washed with water and dried at 140 ° C. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 8 Activated carbon was immersed in pure water to impregnate water to the inside of the pores. After adjusting the pH with hydrochloric acid, an aqueous solution in which palladium chloride and chloroauric acid are dissolved by a ratio of 80:20 by weight of the metal component and 2.0% by the total weight of the metal component with respect to the weight of the activated carbon is gradually added. The ionic component was adsorbed on the activated carbon by dropping.
After washing with pure water, it was dried at 150 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 250 ° C. for 5 hours. Using the catalyst thus prepared, the reaction was carried out in the same manner as in Example 1 except that the reaction temperature was set to 320 ° C. The results are shown in Table 1.

Example 9 Activated carbon was immersed in pure water to impregnate water into the pores. An aqueous solution in which palladium sulfate and silver diammine sulfate were dissolved at a weight ratio of the metal component of 80:20 to the weight of the activated carbon by only 1.0% based on the total weight of the metal component was added dropwise little by little, and the ionic component was adsorbed on the activated carbon. . Add ammonia and pH
Was reduced to a weak alkali, hydrazine was added dropwise, reduced, washed with water, and dried at 140 ° C. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 10 Activated carbon was immersed in pure water to impregnate water into the inside of the pores. After adjusting the pH with hydrochloric acid, an aqueous solution in which palladium chloride and lanthanum chloride are dissolved by a ratio of 90:10 by weight of the metal component and 2.0% of the total weight of the metal component with respect to the weight of the activated carbon is added dropwise little by little. The ionic components were adsorbed on activated carbon. After washing with pure water, it was dried at 150 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 300 ° C. for 5 hours. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 11 Activated carbon was immersed in pure water to impregnate water to the inside of the pores. An aqueous solution in which chloroplatinic acid and potassium perrhenate are dissolved at a ratio of 70:30 by weight of the heavy metal component and 2.0% of the total weight of the heavy metal component with respect to the weight of the activated carbon is added dropwise little by little, and the ionic component is adsorbed on the activated carbon. I let it. After adding ammonia to make the pH weak alkali, sodium borohydride was added dropwise and reduced. After washing with distilled water, it was dried at 140 ° C. Using the catalyst thus prepared, the reaction temperature was set at 34.
The reaction was carried out in the same manner as in Example 1 except that the temperature was changed to 0 ° C. The results are shown in Table 1.

Example 12 60: 4 chloroplatinic acid and nickel chloride in a weight ratio of the metal component
0%, the total weight of the metal component is 2.0% based on the weight of activated carbon
Ammonia is added dropwise to the aqueous solution that has just been dissolved to make the pH slightly alkaline. Into this aqueous solution, activated carbon immersed in pure water and impregnated with water to the inside of the pores was introduced, and the ionic components were adsorbed on the activated carbon. This was reduced with hydrazine, washed with pure water, and dried at 150 ° C. for 5 hours. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 13 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH with hydrochloric acid, ammonia was added to an aqueous solution in which chloroplatinic acid and copper chloride were dissolved in a weight ratio of metal components of 90:10 and 1.0% by weight of the total weight of the metal components to the weight of the activated carbon. 1% was added dropwise to make it slightly alkaline. The activated carbon described above was added thereto, and the ionic components were adsorbed on the activated carbon.
After reducing with formaldehyde and washing with pure water,
It was dried at 150 ° C. for 5 hours. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 14 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH with hydrochloric acid, slightly dissolve an aqueous solution in which chloroplatinic acid and chloroauric acid are dissolved in a weight ratio of the metal component of 80:20 and only 2.0% by the total weight of the metal component to the weight of the activated carbon. The ionic components were adsorbed on the activated carbon by dropping each time. After washing with pure water, it was dried at 150 ° C. for 5 hours.
Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced,
Reduction was carried out at 300 ° C. for 5 hours. Example 1 was repeated except that the catalyst thus prepared was used and the reaction temperature was 340 ° C.
The reaction was carried out in the same manner as in. The results are shown in Table 1.

Example 15 Activated carbon was immersed in pure water to impregnate water into the inside of the pores. After adjusting the pH with hydrochloric acid, slightly dissolve an aqueous solution in which chloroplatinic acid and potassium tungstate are dissolved in a weight ratio of the heavy metal component of 90:10 and 1.0% by the total weight of the heavy metal component to the weight of the activated carbon. The ionic components were adsorbed on the activated carbon by dropping each time. After washing with pure water,
For 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 300 ° C. for 5 hours.
Using the catalyst thus prepared, the reaction temperature was 340 ° C.
The reaction was carried out in the same manner as in Example 1 except for the above. The results are shown in Table 1.

Example 16 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH with hydrochloric acid, an aqueous solution in which rhodium chloride and nickel chloride are dissolved in a weight ratio of metal components of 60:40 and only 1.0% of the total weight of metal components with respect to the weight of activated carbon is added dropwise. The ionic components were adsorbed on activated carbon. After washing with pure water, it was dried at 150 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 300 ° C. for 5 hours. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 17 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH using hydrochloric acid, an aqueous solution in which palladium chloride and chloroplatinic acid are dissolved in a ratio of 90:10 by weight of the metal component and 0.5% of the total weight of the metal component with respect to the weight of the activated carbon is added little by little. The ionic component was adsorbed on the activated carbon by dropping. After washing with pure water, it was dried at 150 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 300 ° C. for 5 hours. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 18 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH with hydrochloric acid, an aqueous solution in which palladium chloride and rhodium chloride are dissolved in a weight ratio of the metal component of 80:20 and only 0.5% of the total weight of the metal component with respect to the weight of the activated carbon is added dropwise little by little. The ionic components were adsorbed on activated carbon. After washing with pure water, it was dried at 150 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 300 ° C. for 5 hours. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 19 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH using ammonia, palladium sulfate, tetraammineplatinum sulfate, and silver diamine sulfate were added in a weight ratio of the metal component of 80: 5: 15, and only 0.5% of the total weight of the metal component with respect to the weight of the activated carbon. The dissolved aqueous solution was added dropwise little by little, and the ionic components were adsorbed on the activated carbon. After washing with pure water, it was dried at 150 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 300 ° C. for 5 hours. The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 340 ° C. using the catalyst thus prepared. The results are shown in Table 1.

Example 20 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH with hydrochloric acid, palladium chloride and chloroplatinic acid and chloroauric acid were added in a weight ratio of metal components of 80: 5: 15.
0.5% of the total weight of the metal components based on the weight of the activated carbon
% Of the aqueous solution was gradually added dropwise, and the ionic component was adsorbed on activated carbon. After washing with pure water,
Dry at 5 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced and reduced at 300 ° C. for 5 hours. Using the catalyst thus prepared, the reaction temperature was set at 34.
The reaction was carried out in the same manner as in Example 1 except that the temperature was changed to 0 ° C. The results are shown in Table 1.

Example 21 300 g of methanol and 400 g of zinc dust were added to a 1000 ml Inconel 600 autoclave, and stirred at 0 ° C. for 1 hour.
400 g of chloro-1,1-difluoroethane were injected. After the injection, stirring was continued at 0 ° C. for another 8 hours. 350 g of the organic layer was collected and analyzed using gas chromatography and ¹⁹ F-NMR. The results are shown in Table 1.

[Effects of the Invention] As will be understood from the examples, the present invention has an excellent effect in improving the reaction activity and selection.

Claims (5)

(57) [Claims] 1. A method for producing 1,1-difluoroethane, comprising reducing 1-chloro-1,1-difluoroethane. (2) 1-chloro-1,1-difluoroethane is
A method for producing 1,1-difluoroethane, comprising reducing with hydrogen in the presence of a catalyst containing a platinum group element as a main component. 3. The method according to claim 2, wherein the catalyst is a hydrogenation catalyst in which a catalyst component is supported on an activated carbon carrier. 4. A method according to claim 1, wherein 1-chloro-1,1-difluoroethane is
A method for producing 1,1-difluoroethane, characterized in that reduction is carried out by irradiation with light or zinc in the presence of an organic compound having a hydrogen atom bonded thereto. 5. The method according to claim 4, wherein the organic compound having a hydrogen atom bonded thereto is an alcohol.