JPH0115000B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing triphenylphosphine in high yield using an electrolytic reaction. Triphenylphosphine is used as a catalyst in the oxo process and as an intermediate in various organic syntheses. The method for producing triphenylphosphine is a method in which phenyl alkali synthesized from chlorobenzene and sodium is reacted with phosphorus trihalide in the presence of a solvent (Japanese Patent Publication No. 57-26676).It is prepared by reacting chlorobenzene and magnesium. A method in which phenylmagnesium chloride is reacted with phosphorus trichloride in tetrahydrofuran (British Patent No. 1495246), and in the presence of anhydrous aluminum chloride, phosphorus trichloride and benzene in an amount more than three times the molar amount thereof are reacted under pressure. A heating reaction method (Japanese Patent Publication No. 46-39337) is known. However, although the yield is high in the method and, since metallic sodium or metallic magnesium is used, there is a drawback that complete dehydration of the raw materials and the solvent is required. Furthermore, since the reaction between chlorobenzene and metallic sodium or metallic magnesium is a heterogeneous system, the reaction does not start smoothly and sometimes even poses a risk of explosion. Therefore, both methods have operational difficulties and are problematic to implement industrially. Another method uses the Friedel-Crafts reaction,
Although there are no operational disadvantages as described above, the yield of the target triphenylphosphine is low, the cost is higher than that of the method, and the purity of the produced triphenylphosphine is also low. The reason for the low yield of this method is that triphenylphosphine strongly binds to aluminum chloride to form a complex, which must be decomposed with water, but this decomposition produces phosphine oxide as a by-product. There are things to do. However, so far, there has been no method that does not produce phosphine oxide as a by-product. The present inventors have conducted various studies to overcome the drawbacks of conventional methods for producing triphenylphosphine, and as a result, a reaction solution containing triphenylphosphine produced using the Friedel-Crafts reaction has been developed. It has been found that by electrolytically reducing and then hydrolyzing, the yield of triphenylphosphine can be significantly improved and the above object can be satisfied. The present invention has been made based on this knowledge. That is, the present invention provides a method for producing triphenylphosphine, which is characterized by reacting halogenodiphenylphosphine or dihalogenophenylphosphine with benzene in the presence of anhydrous aluminum chloride, and then electrolytically reducing the reaction product. The present invention provides a method. The halogenodiphenylphosphine or dihalogenophenylphosphine used in the present invention can be easily prepared by reacting benzene and phosphorus trihalide in the presence of anhydrous aluminum chloride. Examples of halogens in the halogenodiphenylphosphine or dihalogenophenylphosphine include chlorine, bromine, and iodine. In the present invention, triphenylphosphine is obtained as a complex with anhydrous aluminum chloride by reacting halogenodiphenylphosphine or dihalogenophenylphosphine with benzene in the presence of anhydrous aluminum chloride. The reaction product containing the complex of triphenylphosphine and anhydrous aluminum chloride thus obtained is subjected to an electrolytic reduction treatment either as a reaction solution or after removing unreacted substances. Electrolysis is performed using an electrolytic cell having a nitrogen gas inlet pipe, a gas outlet, and a diaphragm, and placing the reaction product together with an organic solvent in a cathode chamber. As the electrode in this case, platinum, carbon, lead dioxide, lead, titanium, mercury, etc. are used. Examples of electrolytic solvents include methylene chloride, chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, halogenated hydrocarbons such as trichloroethylene, acetone, ketones such as methyl ethyl ketone and methyl isobutyl ketone, diethyl ether, tetrahydrofuran, Ethers such as dioxane, methanol, ethanol,
Alcohols such as isopropanol, nitriles such as acetonitrile, propionitrile, phenylacetonitrile, benzonitrile, carbon disulfide, nitrilomethane, nitrobenzene, dimethylformamide, dimethylacetamide, benzene, toluene, xylene, chlorobenzene, dichlorobenzene, etc. Used alone or in combination. As a supporting electrolyte, the general formula (R ₁ ) ₄ NX,
A compound represented by MX, (R ₂ ) ₃ N·HX, (R ₃ ) ₃ PR ₄ Y or a part of the Friedel-Crafts reaction solution to be subjected to electrolysis is used. here,
R ₁ represents hydrogen, methyl, ethyl, propyl, or butyl, R ₂ represents ethyl, propyl, or butyl, and (R ₂ ) ₃ N also includes pyridine, piperidine, and the like. Also, R ₃ is butyl, phenyl,
tolyl, R ₄ represents methyl and ethyl, M is an alkali metal, X is chloro, bromine,
Iodine, benzene sulfonate

[Formula] p-toluenesulfone to

[Formula] Methanesulfonate (CH ₃ SO ₃ ), Y consists of chlor, bromo, and iodo. Further, as the diaphragm, an unglazed cylinder, an ion exchange membrane, a glass filter, etc. are used. The reaction temperature of the electrolytic reaction is set within the range of 0 to 100°C and below the boiling point of the solvent. Preferably 5~
It is in the range of 20℃. There is no particular limit to the concentration of the complex of triphenylphosphine and anhydrous aluminum chloride in the cathode chamber, but
A range of 5 to 50% by weight is preferred. In this way, after the electrolytic reaction is carried out by applying an amount of electricity of 1 faraday per mole of substrate, the resulting electrolyte in the cathode chamber can be hydrolyzed to produce the target triphenylphosphine in high yield. . Triphenylphosphine can be separated and recovered from this reaction solution by a known method such as vacuum distillation. According to the method of the present invention, triphenylphosphine can be produced in high yield and with high purity by the Friedelkrack reaction. The method of the present invention is suitable for industrial implementation because it is free from the operational troubles and dangers of conventional methods using sodium metal or magnesium metal. Next, the present invention will be explained in more detail based on examples. In addition, % in the following examples represents weight %. Example 1 A 300 ml autoclave was charged with 25 g of dichlorophenylphosphine, 100 g of benzene, and 18.7 g of anhydrous aluminum chloride, and after purging with nitrogen, the autoclave was reacted at 220° C. for 3 hours. Next, platinum electrode, diaphragm, thermometer, nitrogen introduction tube,
Put 25 ml of the above reaction solution and 50 ml of acetonitrile into the cathode chamber of an electrolytic cell equipped with a gas outlet, put 40 ml of acetonitrile, 20 ml of methylene chloride, and 1 g of tetraethylammonium p-toluenesulfonate into the anode chamber, and heat for 10 to 20 minutes under a nitrogen stream. 0.3A constant current electrolysis was performed at ℃. After 2 hours, the electrolyte in the cathode chamber was hydrolyzed and analyzed by gas chromatography, which revealed 73% triphenylphosphine (hereinafter referred to as TPP), 12% diphenylphosphine (hereinafter referred to as DPP), and triphenyl. The amount of phosphine oxide (hereinafter referred to as TPPO) was 3%. Comparative Example 1 The reaction solution of Example 1 without electrolytic treatment was directly hydrolyzed and analyzed by gas chromatography.
TPP was 43%, DPP was 26%, and TPPO was 30%. Example 2 A Friedel-Crafts reaction was carried out in the same manner as in Example 1 to prepare a reaction solution having a composition of 52% TPP, 14% DPP, and 30% TPPO. Using the same electrolytic cell as in Example 1, put 25 ml of this reaction solution and 50 ml of methylene chloride into the cathode chamber, put 20 ml of acetonitrile, 5 ml of methylene chloride, and 1 g of tetraethylammonium p-toluenesulfonate into the anode chamber, and conduct 0.3A constant current electrolysis. I went there. After 2 hours, the reaction solution was hydrolyzed and analyzed by gas chromatography, and it was found that TPP79
%, DPP 10%, and TPPO 5%. Example 3: Includes reflux condenser, thermometer and nitrogen inlet pipe
10.9 g of benzene, 45.8 g of phosphorus trichloride, and 14.9 g of anhydrous aluminum chloride were placed in a 100 ml four-necked flask, and the mixture was refluxed for 2 hours under a nitrogen atmosphere. After the reaction, excess benzene and phosphorus trichloride were distilled off under reduced pressure.
This concentrated residue and 115 g of benzene were charged into a 300 ml autoclave, and the autoclave was purged with nitrogen and reacted at 220° C. for 5 hours. This reaction solution was electrolytically reduced using the same electrolytic cell as in Example 1. First, 25 ml of the reaction solution and 50 ml of acetonitrile are placed in the cathode chamber, and 10 ml of acetonitrile, 10 ml of methylene chloride, and 1 g of tetraethylammonium p-toluenesulfonate are placed in the anode chamber, and electrolysis is performed at a constant current of 0.3 A under a nitrogen stream. After 2.5 hours, the electrolyte in the cathode chamber was hydrolyzed and analyzed by gas chromatography, and it was found that TPP80% and DPP4
%, TPPO3%. Comparative Example 2 The reaction solution before being subjected to the electrolytic treatment of Example 3 was directly hydrolyzed and analyzed by gas chromatography, and it was found that TPP was 64%, DPP was 7%, and TPPO was 26%. Example 4 A Friedel-Crafts reaction was performed in the same manner as in Example 1, and TPP50%, DPP12%, TPPO27%
A reaction solution having the composition was prepared. 50 ml of this reaction solution and 25 ml of acetonitrile were placed in the cathode chamber, and 10 ml of acetonitrile, 10 ml of methylene chloride, and 1 g of tetrabutylammonium bromide were placed in the anode chamber, and 0.3A constant current electrolysis was performed. After 5 hours, the reaction solution was hydrolyzed and analyzed by gas chromatography.
TPP was 78%, DPP was 10%, and TPPO was 2%. Example 5 Electrolysis was carried out in the same manner as in Example 4, except that 1 ml of Friedel-Crafts reaction solution was used instead of 1 g of tetrabutylammonium bromide.
TPP was 81%, DPP was 9%, and TPPO was 2%.

Claims (1)

[Claims] 1. A method for producing triphenylphosphine, which comprises reacting halogenodiphenylphosphine or dihalogenophenylphosphine with benzene in the presence of anhydrous aluminum chloride, and then electrolytically reducing the reaction product.