JP4901174B2 - Method for producing 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl - Google Patents

Description

  In the present invention, 2,2′-bis (trifluoromethyl) -4,4, which is useful as a raw material for polyimide resins and the like, is obtained by sequentially carrying out a reduction reaction and a benzidine rearrangement reaction using m-nitrobenzotrifluoride as a starting material. The present invention relates to a method for producing '-diaminobiphenyl.

  Conventionally, using m-nitrobenzotrifluoride as a raw material, a two-step reduction reaction and a benzidine rearrangement reaction are carried out in order, and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (hereinafter referred to as “three steps”). , Which may be abbreviated as TFMB) is known (see, for example, Non-Patent Documents 1 and 2). That is, in the former document, as shown by the following formula, m-nitrobenzotrifluoride (1) is reduced with zinc in the presence of an aqueous sodium hydroxide solution in a methanol solvent to give 3,3′-bis (trifluoro). Methyl) azobenzene (2) (hereinafter sometimes abbreviated as azo isomer) is produced, and azo isomer (2) is separated from the reaction mixture by solvent removal, chloroform extraction and concentrated crystallization. This is reduced with zinc and ammonium chloride in an acetone solvent, the reaction mixture is poured into aqueous ammonia, extracted with chloroform, desolvated, and 3,3′-bis (trifluoromethyl) hydrazobenzene (3) ( Hereinafter, it may be abbreviated as a hydrazo body). Subsequently, the obtained hydrazo compound (3) is dissolved in ethanol, and an ethanol solution of concentrated hydrochloric acid is added dropwise at 0 ° C. to carry out a benzidine rearrangement reaction to synthesize TFMB (4). In order to separate TFMB from the reaction mixture obtained by the rearrangement reaction, the reaction mixture was treated with alkali, and the free TFMB was extracted with chloroform, separated by column, concentrated to dryness, recrystallized and separated. The above reduction reaction is carried out in two stages including the operation of isolating the azo form, and the process is very complicated. In addition, the separation process of TFMB from the rearrangement reaction mixture is complicated and cannot be said to be an industrial method. Furthermore, the yield of TFMB is as low as 17% based on the hydrazo form, which is not an industrially attractive method.

  In the latter document, m-nitrobenzotrifluoride (1) is synthesized by reduction with zinc and sodium hydroxide or electrolytic reduction to azo compound (2), and then reduced with sodium amalgam to give hydrazo compound (3). Is synthesized. The hydrazo compound (3) is dissolved in alcohol and dropped into sulfuric acid water (volume ratio 1/1) to cause a benzidine rearrangement reaction to produce TFMB. The yield based on the hydrazo form is as low as 10%, the production process is complicated, and it cannot be said that it is an industrial method.

Journal of Polymer Science: Part A: Polymer Chemistry 37, 937-957 (1999) Journal of Chemical Society 1994-1998 (1953)

  According to the method described in the above document, the reduction process has two steps, and a very complicated operation is required. In addition, as described in the latter document, disproportionation is likely to occur in the benzidine rearrangement reaction, and the reaction yield is low because the trifluoromethyl group inhibits the smooth reaction. It was. Accordingly, the present inventors have developed a method for producing 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl in a simpler method and in a high yield from m-nitrobenzotrifluoride as a raw material. We examined to find out. Specifically, first, a method for further simplifying the reduction step of m-nitrobenzotrifluoride was examined. Secondly, a method for increasing the reaction yield in the benzidine rearrangement was also examined. As a result, the inventors have found a two-step process using m-nitrobenzotrifluoride as a raw material.

That is, according to the present invention, m-nitrobenzotrifluoride is converted into zinc in the presence of an organic solvent immiscible with water, an alcohol or an organic solvent that is a mixed solvent thereof, and an alkaline aqueous solution in a nitrogen atmosphere. Reduction is carried out using 3 to 8 moles per mole of nitrobenzotrifluoride to directly produce 3,3′-bis (trifluoromethyl) hydrazobenzene, and the resulting 3,3′-bis ( 2,2 ′ comprising the step of rearranging (trifluoromethyl) hydrazobenzene in the presence of an organic solvent and an inorganic acid to produce 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl. A process for producing -bis (trifluoromethyl) -4,4'-diaminobiphenyl is provided. In this method, it is preferable to use an organic solvent immiscible with water as the organic solvent used for the rearrangement reaction of 3,3′-bis (trifluoromethyl) hydrazobenzene. Further, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl is isolated as an acid salt from the reaction mixture obtained by the rearrangement reaction, and 2,2′-bis (trimethyl) is obtained by treating with alkali. Fluoromethyl) -4,4'-diaminobiphenyl is preferably liberated and isolated.

  According to the present invention, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl useful as a raw material for a polyimide resin can be produced with a simple process and in a high yield. In particular, 3,3′-bis (trifluoromethyl) hydrazobenzene produced in the first step does not need to be isolated and can be used in the rearrangement reaction in the form of a solution, so that it is inexpensive and industrial. In particular, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl can be produced.

  In the present invention, m-nitrobenzotrifluoride is reduced with zinc in the presence of an organic solvent and an aqueous alkali solution to directly produce 3,3'-bis (trifluoromethyl) hydrazobenzene. As the organic solvent used in this reduction reaction, it is preferable to use an organic solvent immiscible with water, an alcohol, or a mixed solvent thereof. Examples of water-immiscible organic solvents include aliphatic hydrocarbons such as pentane, hexane, heptane, and octane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, and aromatic carbons such as benzene, toluene, xylene, and ethylbenzene. And hydrocarbons such as hydrogen; halogenated hydrocarbons such as methylene chloride, ethyl chloride, and chlorobenzene; ethers such as isopropyl ether and butyl ether. Among these, it is preferable to use hydrocarbons, particularly aromatic hydrocarbons. Moreover, as alcohol, it is good to use C1-C8 alcohol, Preferably lower alcohols, such as methanol, ethanol, and propanol, Especially preferably, methanol or ethanol is used. In this reduction reaction, an organic solvent immiscible with water, preferably a mixed solvent of hydrocarbon and alcohol, may be used. In this mixed solvent, the mixing ratio of the water-immiscible organic solvent and the alcohol is arbitrary, but considering the rearrangement reaction in the next step, the alcohol is 0.1 to 1 per 1 part by weight of the hydrocarbon. It is preferable to use a ratio of parts by weight, particularly 0.2 to 0.5 parts by weight. The amount of the organic solvent used in the reduction reaction may be such that m-nitrobenzotrifluoride can be efficiently stirred, and is usually 1 to 20 parts by weight, preferably 3 to 1 part by weight of m-nitrobenzotrifluoride. About 10 times the weight.

  As the alkaline aqueous solution used in the reduction reaction, an aqueous solution of sodium hydroxide or potassium hydroxide is preferably used, and its concentration is preferably 10 to 60% by weight, particularly 25 to 50% by weight. The aqueous alkali solution is preferably used as an alkali hydroxide in a proportion of 0.1 to 1.0 mol, particularly 0.25 to 0.8 mol, with respect to 1 mol of m-nitrobenzotrifluoride.

Zinc used for the reduction of m-nitrobenzotrifluoride is preferably used in an amount of 3 to 8 mol per 1 mol of m-nitrobenzotrifluoride in consideration of the reaction rate and economy.

The reduction reaction using the above raw materials can be performed by intimately mixing m-nitrobenzotrifluoride, an organic solvent, an alkaline aqueous solution, and zinc. The reaction is preferably performed in a nitrogen atmosphere, and is preferably performed with stirring. The reaction temperature is, for example, 40 to 110 ° C, preferably 50 to 70 ° C. Although reaction time changes also with reaction conditions, it is about 4 to 6 hours, for example.

  After completion of the reaction, the zinc oxide produced by the reaction, unreacted zinc and the like are filtered off to neutralize the alkali hydroxide. In the rearrangement reaction of 3,3′-bis (trifluoromethyl) hydrazobenzene, it is necessary to particularly isolate 3,3′-bis (trifluoromethyl) hydrazobenzene from the reaction solution thus obtained. Instead, it may be recovered and used as a solution of an organic solvent used for the rearrangement reaction. As the organic solvent used in the rearrangement reaction, it is preferable to use an organic solvent immiscible with water, and it is particularly preferable to use the above-described hydrocarbons, particularly aromatic hydrocarbons alone. By using such an organic solvent immiscible with water for the rearrangement reaction, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl can be produced with high yield. Therefore, in the reduction reaction, when an organic solvent immiscible with water is used as the solvent, the reaction solution subjected to the above filtration and neutralization can be used as it is for the rearrangement reaction. In the reduction reaction, when a mixed solvent of water and an immiscible organic solvent and alcohol is used as the solvent, the one obtained by removing the alcohol from the reaction solution that has been filtered and neutralized must be used for the rearrangement reaction. Can do. In any case, it is needless to say that concentration or a new addition of an organic solvent immiscible with water may be optionally performed. Furthermore, when alcohol is used as a solvent in the reduction reaction, the alcohol is removed from the reaction solution after the above filtration and neutralization, and an organic solvent immiscible with water is added to the rearrangement reaction. can do.

  In the rearrangement reaction of 3,3′-bis (trifluoromethyl) hydrazobenzene, a solution as described above prepared by adding post-operation as necessary from a reaction solution obtained by a reduction reaction is dropped into an inorganic acid. Can be done. The dropping may be performed sequentially or may be added at once. The 3,3'-bis (trifluoromethyl) hydrazobenzene solution used for the rearrangement reaction preferably has a concentration of about 5 to 40% by weight. As the inorganic acid, concentrated hydrochloric acid or sulfuric acid is preferably used, and it is particularly preferable to use a sulfuric acid aqueous solution having a concentration of about 10 to 80% by weight, preferably about 20 to 60% by weight. The amount of the inorganic acid used is suitably in the range of 1 to 20 mol, particularly 2 to 10 mol, per mol of 3,3'-bis (trifluoromethyl) hydrazobenzene. The reaction temperature is preferably −10 to + 80 ° C., particularly preferably −5 to + 50 ° C. The reaction time is usually about 2 to 10 hours until the reaction is completed.

  After completion of the reaction, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl is crystallized and separated from the reaction mixture of the rearrangement reaction as an acid salt, and then subjected to alkali treatment to give 2,2 '-Bis (trifluoromethyl) -4,4'-diaminobiphenyl can be recovered. According to this method, it is possible to obtain high-quality 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl without additional purification operations. From the rearrangement reaction mixture, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl was separated as an aqueous acid salt solution and then treated with alkali to give 2,2′-bis (trifluoro). Methyl) -4,4′-diaminobiphenyl can be recovered, but in this case, purification by means such as recrystallization may be required as necessary.

Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, the concentration indicates% by weight, and the yield indicates mol%. The analysis was performed by high performance liquid chromatography under the following conditions, and the quantification was performed by an absolute calibration curve method using a reagent manufactured by Tokyo Chemical Industry Co., Ltd. as a standard substance.
Measurement conditions Column: Intersil ODS 80A (manufactured by GL Sciences Inc.) Length 250 mm, inner diameter 4.2 mm
Mobile phase: methanol / 0.1% phosphoric acid water Detector: UV (254 nm)

[Example 1]
A 500 ml glass reaction vessel equipped with a reflux condenser, a temperature measuring tube and an electromagnetic stirrer was charged with 35.4 g of m-nitrobenzotrifluoride, 66.5 g of toluene and 51.2 g of methanol under a nitrogen atmosphere, and 40% water. 13.6 g of aqueous sodium oxide solution was charged. After raising the internal temperature to 65 ° C., 47.3 g of zinc powder was added over 2 hours. Then, it was made to react at this temperature for 5 hours. After the reaction, the solid was filtered off to obtain a reaction filtrate. After neutralizing sodium hydroxide in the filtrate, the methanol in the filtrate was removed and washed with water to separate 95.3 g of the toluene layer. As a result of analyzing the toluene layer, the concentration of 3,3′-bis (trifluoromethyl) hydrazobenzene was 31.0%. The yield of 3,3′-bis (trifluoromethyl) hydrazobenzene based on m-nitrobenzotrifluoride was 99.8%.

  95.3 g of the toluene layer obtained by the reduction reaction was dropped into 90.3 g of a 50% aqueous sulfuric acid solution at 0 ° C., and after the dropwise addition, the mixture was reacted at 0 ° C. for 5 hours. After the reaction, the reaction mixture was heated to 70 ° C., the toluene layer was removed, the sulfuric acid aqueous layer was cooled, and the precipitated crystals were collected by filtration. The obtained crystals were added to water, neutralized with sodium hydroxide, and extracted with toluene. The toluene layer was separated and concentrated and crystallized to separate 9.50 g of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl having a purity of 99.9%. The yield based on m-nitrobenzotrifluoride was 32.1%.

[Example 2]
Under a nitrogen atmosphere, 20.00 g of m-nitrobenzotrifluoride and 152 g of methanol were charged in a 300 ml glass reaction vessel equipped with a reflux condenser, a temperature measuring tube and an electromagnetic stirrer, and 46.37 g of 40% sodium hydroxide aqueous solution was added. After the addition, 36.0 g of zinc dust was charged. The internal temperature was raised to 65 ° C., and the reaction was carried out at this temperature for 5 hours. After the reaction, the solid was filtered off to obtain a reaction filtrate. After neutralizing sodium hydroxide in the filtrate, methanol was removed and washed with water, extracted with toluene, and then the solvent was removed to obtain 16.76 g of a pale yellow liquid. As a result of analyzing this pale yellow liquid, 3,3′-bis (trifluoromethyl) hydrazobenzene having a purity of 96.4% was isolated in a yield of 96.4% based on m-nitrobenzotrifluoride.

  4.19 g of a pale yellow liquid obtained by the reduction reaction was dissolved in 14.0 g of toluene, dropped into 15.0 g of a 50% aqueous sulfuric acid solution at 25 ° C., and reacted for 5 hours after the dropping. After the reaction, the solution was neutralized and extracted with toluene to obtain 41.4 g of a toluene layer. As a result of analyzing the toluene layer, the concentration of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl was 3.11%, and the yield based on m-nitrobenzotrifluoride was 30.6%. Met. The separated toluene solution was concentrated and crystallized to separate 2,8'-bis (trifluoromethyl) -4,4'-diaminobiphenyl having a purity of 98.8%. Subsequently, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl having a purity of 99.9% was separated by recrystallization purification with toluene. The yield based on m-nitrobenzotrifluoride was 29.1%.

[Example 3]
The reaction vessel used in Example 2 was charged with 5.04 g of m-nitrobenzotrifluoride and 37.49 g of toluene in a nitrogen atmosphere, and 11.41 g of 40% aqueous sodium hydroxide solution, and then 9.06 g of zinc dust. Was charged. The internal temperature was raised to 65 ° C., and the reaction was carried out at this temperature for 5 hours. After the reaction, the solid was separated by filtration and washed with toluene to obtain 45.0 g of a reaction filtrate. As a result of analyzing the reaction filtrate, the concentration of 3,3′-bis (trifluoromethyl) hydrazobenzene was 8.91%, and the yield based on m-nitrobenzotrifluoride was 95.0%.

  The reaction filtrate was washed with water, concentrated to 17.94 g, and added dropwise to 7.36 g of 50% aqueous sulfuric acid while maintaining 25 ° C. After dripping, it was made to react at 25 degreeC for 5 hours. After the reaction, it was neutralized and extracted with toluene to obtain 10.4 g of a toluene layer. As a result of analyzing the toluene layer, the concentration of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl was 11.5%, and the yield based on m-nitrobenzotrifluoride was 28.3%. Met.

[Example 4]
8.71 g of the pale yellow liquid obtained in the reduction step of Example 1 was dissolved in 29.0 g of toluene, and dropped into 22.1 g of concentrated hydrochloric acid while maintaining at 25 ° C. After the dropwise addition, the mixture was reacted at 25 ° C. for 3 hours. It was. After the reaction, the mixture was neutralized and extracted with toluene to obtain 86.1 g of a toluene layer. As a result of analyzing the toluene layer, the concentration of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl was 2.48%, and the yield based on m-nitrobenzotrifluoride was 24.6%. Met.

  The above results are summarized in Table 1.

＊：ｍ−ニトロベンゾトリフルオリド基準

*: M-nitrobenzotrifluoride standard

Claims (6)

In a nitrogen atmosphere, m-nitrobenzotrifluoride is dissolved in 1 mol of m-nitrobenzotrifluoride in the presence of an organic solvent immiscible with water, an organic solvent that is immiscible with water, an alcohol or a mixed solvent thereof, and an aqueous alkaline solution. Reduction using 3 to 8 moles to directly produce 3,3′-bis (trifluoromethyl) hydrazobenzene, and the obtained 3,3′-bis (trifluoromethyl) hydrazobenzene 2,2′-bis (trifluoromethyl) comprising a step of producing 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl by rearrangement in the presence of an organic solvent and an inorganic acid A method for producing -4,4'-diaminobiphenyl.   The 2,2'-bis (trifluoromethyl) according to claim 1, wherein the organic solvent used for rearrangement of 3,3'-bis (trifluoromethyl) hydrazobenzene is an organic solvent immiscible with water. ) -4,4′-diaminobiphenyl production method.   The inorganic acid used for rearrangement of 3,3′-bis (trifluoromethyl) hydrazobenzene is a sulfuric acid aqueous solution or concentrated hydrochloric acid having a concentration of 10 to 80%, and 3,3′-bis (trifluoromethyl) hydra The method for producing 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl according to claim 1 or 2, wherein 1 to 20 mole times of zobenzene is used.   In the reduction reaction of m-nitrobenzotrifluoride, 3,3′-bis (trifluoromethyl) hydrazobenzene is recovered as a solution of an organic solvent immiscible with water and used in the rearrangement reaction. The method for producing 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl according to claim 2 or 3, characterized by the above.   The method for producing 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl according to any one of claims 1 to 4, wherein the organic solvent immiscible with water is a hydrocarbon.   2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl is isolated as an acid salt from the reaction mixture obtained by the rearrangement reaction of 3,3′-bis (trifluoromethyl) hydrazobenzene, The 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl is liberated by subjecting it to an alkali treatment, and this is isolated. Of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl.