Method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene

Abstract

To provide a method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene with minimal coloration at a high yield.SOLUTION: A method includes the step of subjecting 9-fluorenone to a condensation reaction with 2-fluoroaniline at a molar ratio of at least 7.5 times and at most 12.5 times relative to the 9-fluorenone, in the presence of aromatic sulfonic acid, thereby yielding a reaction solution including 9,9-bis(4-amino-3-fluorophenyl)fluorene.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene. [Background technology]

[0002] Because 9,9-bis(4-amino-3-fluorophenyl)fluorene contains electron-withdrawing fluorine atoms in its structure, polyimides, polyamides, and epoxy resins that use this compound as a starting material are expected to have lower dielectric constants and improved heat resistance, making them suitable for a wide range of industrial applications, including electronic information materials and composite materials.

[0003] 9,9-bis(4-amino-3-fluorophenyl)fluorene is obtained by condensing 9-fluorenone with 2-fluoroaniline. However, the resulting 9,9-bis(4-amino-3-fluorophenyl)fluorene has the problem of being easily colored.

[0004] In particular, 9,9-bis(4-amino-3-fluorophenyl)fluorene with little coloring is required for use in optical applications that require transparency, such as liquid crystal display substrates and flexible display substrates.

[0005] In Patent Document 1, in the reaction of 9-fluorenone with 2-fluoroaniline, a condensation reaction is carried out using 7.0 moles of 2-fluoroaniline and 1.3 moles of trifluoromethanesulfonic acid relative to the moles of 9-fluorenone.

[0006] In Patent Document 2, in the reaction of 9-fluorenone and 2-fluoroaniline, a condensation reaction is carried out using 0.9 molar amounts of hydrochloric acid or 2-fluoroaniline hydrochloride relative to the 9-fluorenone in the presence of 15 molar amounts of 2-fluoroaniline relative to the 9-fluorenone, and the resulting 9,9-bis(4-amino-3-fluorophenyl)fluorene is decolorized using activated carbon.

[0007] In Patent Document 3, in the reaction of 9-fluorenone and 2-fluoroaniline, a condensation reaction is carried out using 8.0 moles of 2-fluoroaniline relative to 9-fluorenone and a titanium-based solid acid catalyst.

[0008] Patent Document 1 describes a method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene using trifluoromethanesulfonic acid as an acid catalyst. However, the yield is low at 45%, and there is no mention of coloration of the resulting 9,9-bis(4-amino-3-fluorophenyl)fluorene. Furthermore, trifluoromethanesulfonic acid is a volatile liquid, so there is a concern that it may corrode equipment.

[0009] Patent Document 2 describes a method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene using hydrochloric acid as an acid catalyst. Hydrochloric acid forms a salt with 2-fluoroaniline, and some of the salt precipitates during the condensation reaction, making the mixture difficult to stir. In addition, using activated carbon to decolorize the resulting 9,9-bis(4-amino-3-fluorophenyl)fluorene complicates the production process, and no examples are given regarding the decolorization process.

[0010] The reaction in Patent Document 3 uses a titanium-based solid superacid as an acid catalyst. Trace amounts of metal dissolve from this titanium-based acid catalyst, and the metal remains in the resulting 9,9-bis(4-amino-3-fluorophenyl)fluorene, which may adversely affect the properties of polyamides, polyimides, epoxy resins, etc. that use 9,9-bis(4-amino-3-fluorophenyl)fluorene. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 2-261524 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-84502 [Patent Document 3] Chinese Patent No. 104926667 Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to provide a production method capable of producing 9,9-bis(4-amino-3-fluorophenyl)fluorene with little coloration in high yield. [Means for solving the problem]

[0013] The method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene of the present invention includes a step of subjecting 9-fluorenone and 2-fluoroaniline in an amount of 7.5 to 12.5 times by mole relative to the 9-fluorenone to a condensation reaction in the presence of an aromatic sulfonic acid to obtain a reaction solution containing 9,9-bis(4-amino-3-fluorophenyl)fluorene. [Effects of the Invention]

[0014] The method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene of the present invention includes a step of condensing 9-fluorenone and a specific amount of 2-fluoroaniline in the presence of an aromatic sulfonic acid to obtain a reaction solution containing 9,9-bis(4-amino-3-fluorophenyl)fluorene, thereby producing 9,9-bis(4-amino-3-fluorophenyl)fluorene with low coloration in high yield. After obtaining the reaction solution containing 9,9-bis(4-amino-3-fluorophenyl)fluorene, the method simply involves a neutralization treatment and cooling crystallization, which are common purification steps, resulting in an industrially excellent production method that produces 9,9-bis(4-amino-3-fluorophenyl)fluorene with low coloration in high yield. When a 10 mg / mL tetrahydrofuran solution of the 9,9-bis(4-amino-3-fluorophenyl)fluorene obtained by the production method of the present invention is prepared, the light transmittance over the entire wavelength range of 400 to 900 nm is 97% or more, and the 9,9-bis(4-amino-3-fluorophenyl)fluorene obtained by the production method of the present invention is low in coloration, and can be used in electronic information materials, optical materials, composite materials, and the like. The upper limit of the light transmittance is theoretically 100%, so there is no particular limitation. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a graph comparing the light transmittance of tetrahydrofuran solutions of 9,9-bis(4-amino-3-fluorophenyl)fluorene synthesized by changing the type of acid catalyst used in the condensation reaction in the Examples. [Figure 2] FIG. 2 is a graph comparing the light transmittance of tetrahydrofuran solutions of 9,9-bis(4-amino-3-fluorophenyl)fluorene synthesized by varying the amount of 2-fluoroaniline used in the examples. [Figure 3] FIG. 1 is a graph comparing the light transmittance of tetrahydrofuran solutions of 9,9-bis(4-amino-3-fluorophenyl)fluorene synthesized by varying the amount of p-toluenesulfonic acid used in an example. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail below. The 9,9-bis(4-amino-3-fluorophenyl)fluorene produced in the present invention is produced by a condensation reaction between 9-fluorenone and 2-fluoroaniline.

[0017] The amount of 2-fluoroaniline used in the condensation reaction of the present invention is 7.5 to 12.5 times the number of moles of 9-fluorenone. By using 7.5 to 12.5 times the number of moles of 2-fluoroaniline, a 9,9-bis(4-amino-3-fluorophenyl)fluorene compound with little coloration can be produced. In particular, when a 10 mg / mL tetrahydrofuran solution of the obtained 9,9-bis(4-amino-3-fluorophenyl)fluorene is prepared, the light transmittance is 97% or more over the entire wavelength range of 400 to 900 nm, and the compound is little colored.

[0018] The condensation reaction of 9-fluorenone and 2-fluoroaniline is carried out in the presence of an aromatic sulfonic acid. Aromatic sulfonic acid is an acid catalyst soluble in 2-fluoroaniline, and the salt of aromatic sulfonic acid and 2-fluoroaniline also dissolves in 2-fluoroaniline. Therefore, salt precipitation does not occur during the condensation reaction, preventing stirring. On the other hand, the use of liquid, volatile sulfonic acids such as methanesulfonic acid and trifluoromethanesulfonic acid can be difficult to handle due to concerns about corrosion of equipment. Furthermore, aromatic sulfonic acids do not readily oxidize 2-fluoroaniline during the condensation reaction, making them less likely to produce colored compounds. When an oxidizing acid catalyst, such as a heteropolyacid such as phosphotungstic acid or silicotungstic acid, is used, the reaction solution turns reddish-purple. This is thought to be due to the oxidation of 2-fluoroaniline by the acid catalyst, resulting in the production of colored compounds. Consequently, the use of aromatic sulfonic acid offers the advantage of reducing the color of the resulting 9,9-bis(4-amino-3-fluorophenyl)fluorene.

[0019] Examples of aromatic sulfonic acids include p-toluenesulfonic acid, benzenesulfonic acid, m-xylene-4-sulfonic acid, p-xylene-2-sulfonic acid, 2-naphthalenesulfonic acid, and hydrates thereof. These aromatic sulfonic acids may be used in combination. More preferred are p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, and benzenesulfonic acid.

[0020] The amount of aromatic sulfonic acid is preferably 0.1 to 5.0 times by mole, more preferably 1.0 to 3.0 times by mole, relative to the number of moles of 9-fluorenone. By using 0.1 or more times by mole of aromatic sulfonic acid, the condensation reaction can be efficiently carried out. Furthermore, by using 3.0 or less times by mole of aromatic sulfonic acid, expensive aromatic sulfonic acid can be efficiently used.

[0021] In the condensation reaction of 9-fluorenone and 2-fluoroaniline, water is produced, and it is preferable to carry out the reaction while removing this water. For this purpose, a method is used in which an inert gas is passed through the reaction system while the produced water is entrained therein, or an azeotropic solvent is used to continuously remove the produced water. Nitrogen is preferably used as the inert gas. As the azeotropic solvent, a solvent inert to the reaction system is used, such as cyclohexane, methylcyclohexane, benzene, toluene, or xylene. Toluene or xylene is preferably used. The amount of the azeotropic solvent used is preferably 0.5 to 10 times the mass of 9-fluorenone.

[0022] The condensation reaction is preferably carried out in an oxygen-free inert atmosphere. Specifically, it can be carried out by passing substantially oxygen-free nitrogen gas through the reaction system. If the reaction is carried out in the presence of oxygen, 2-fluoroaniline is oxidized to produce colored substances, which may cause coloration of 9,9-bis(4-amino-3-fluorophenyl)fluorene.

[0023] The reaction temperature is preferably 80 to 170°C, more preferably 120 to 160°C. If the reaction temperature is lower than 80°C, a long time will be required for the reaction to be completed, and if it is higher than 170°C, the temperature will exceed the boiling point of 2-fluoroaniline, resulting in the discharge of 2-fluoroaniline together with water out of the system. Furthermore, while the recovery and reuse of unreacted 2-fluoroaniline is important for reducing production costs, if 2-fluoroaniline is discharged out of the system, the recovery rate of 2-fluoroaniline will decrease, leading to a worsening of the unit consumption and an increase in waste.

[0024] The reaction time depends on the reaction temperature, but is preferably 3 to 100 hours, more preferably 5 to 80 hours. The reaction end point can be set, in liquid chromatography analysis of the reaction solution, when the total peak area of ​​9-fluorenone and the imine intermediate formed by condensing one molecule of 2-fluoroaniline with 9-fluorenone is preferably 5.0 area % or less, more preferably 2.0 area % or less of the peak area obtained by subtracting the total peak area of ​​2-fluoroaniline and aromatic sulfonic acid from the total peak area.

[0025] After the reaction is complete, the reaction mixture contains 9,9-bis(4-amino-3-fluorophenyl)fluorene, excess 2-fluoroaniline, aromatic sulfonic acid, and impurities. The aromatic sulfonic acid can be removed by washing the reaction mixture with an alkaline aqueous solution. This reduces the aromatic sulfonic acid content in the 9,9-bis(4-amino-3-fluorophenyl)fluorene obtained by the crystallization procedure. In other words, the aromatic sulfonic acid content in the crystallized 9,9-bis(4-amino-3-fluorophenyl)fluorene can be substantially reduced to 30 ppm or less.

[0026] After the reaction is complete, the reaction solution is preferably diluted with 2-fluoroaniline. The solubility of 9,9-bis(4-amino-3-fluorophenyl)fluorene in 2-fluoroaniline is 17% by mass at 100°C. Therefore, if the concentration is below this level, precipitation of 9,9-bis(4-amino-3-fluorophenyl)fluorene can be avoided during the washing process with an aqueous alkaline solution. While there is essentially no lower limit to the concentration of 9,9-bis(4-amino-3-fluorophenyl)fluorene when diluting the reaction solution, for example, diluting the 9,9-bis(4-amino-3-fluorophenyl)fluorene to 5% by mass increases the amount of 2-fluoroaniline used and reduces the crystallization rate of 9,9-bis(4-amino-3-fluorophenyl)fluorene in the subsequent crystallization process, resulting in reduced productivity. Therefore, the concentration of 9,9-bis(4-amino-3-fluorophenyl)fluorene in the reaction solution is preferably 11 to 17% by mass.

[0027] Examples of the alkaline aqueous solution include an aqueous solution of an alkali metal hydroxide, an aqueous solution of an alkali metal carbonate, an aqueous solution of an alkali metal hydrogen carbonate, and an aqueous solution of an alkali metal sulfite. Examples of the aqueous solution of an alkali metal hydroxide include an aqueous solution of lithium hydroxide, an aqueous solution of sodium hydroxide, and an aqueous solution of potassium hydroxide. Examples of the aqueous solution of an alkali metal carbonate include an aqueous solution of sodium carbonate, an aqueous solution of lithium carbonate, and an aqueous solution of potassium carbonate. Examples of the aqueous solution of an alkali metal hydrogen carbonate include an aqueous solution of sodium hydrogen carbonate. Examples of the aqueous solution of an alkali metal sulfite include an aqueous solution of sodium sulfite.

[0028] The molar amount of the base in the alkaline aqueous solution is preferably in excess of the molar amount of the aromatic sulfonic acid used in the reaction, and more preferably 1.1 to 2.0 times the molar amount of the aromatic sulfonic acid.

[0029] The mass of the alkaline aqueous solution is preferably 0.25 to 4 times, more preferably 0.5 to 2 times, the mass of the reaction solution. By making the mass of the alkaline aqueous solution 0.5 times or more, the separability between the organic phase and the aqueous layer is improved. Furthermore, by making the mass of the alkaline aqueous solution 2 times or less, the amount of wastewater can be reduced.

[0030] Since a small amount of alkali metal ions remain in the solution after washing with an alkaline aqueous solution, it is preferable to remove the remaining alkali metal ions by washing with water. The mass of water is preferably 0.25 to 4 times, more preferably 0.5 to 2 times, the mass of the solution after washing with an alkaline aqueous solution.

[0031] After washing with an alkaline aqueous solution, or an alkaline aqueous solution and water, the organic phase is cooled to 0-10°C, causing 9,9-bis(4-amino-3-fluorophenyl)fluorene to precipitate. This is then filtered and rinsed with a poor solvent, allowing for the production of low-colored 9,9-bis(4-amino-3-fluorophenyl)fluorene in high yield.

[0032] The poor solvent used for washing may be an alcohol solvent, an aromatic hydrocarbon solvent, an ether solvent, an ester solvent, or an amide solvent, but an alcohol solvent is preferably used as the solvent for rinsing. Examples of the alcohol solvent include methanol, ethanol, and isopropyl alcohol. The mass of the poor solvent used for washing is preferably 0.1 to 10 times the mass of 9-fluorenone. [Example]

[0033] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. The analytical values ​​of 9,9-bis(4-amino-3-fluorophenyl)fluorene obtained in this specification were measured by the following methods.

[0034] (conversion rate, reaction yield, chemical purity) The fraction of the 9-fluorenone peak area (HPLC area%) relative to the total peak area excluding the peak areas of 2-fluoroaniline and p-toluenesulfonic acid was measured using liquid chromatography (Shimadzu LC-20A) under the following conditions, and the value obtained by subtracting this value from 100% was used as the 9-fluorenone conversion rate (%). Similarly, the fraction of the peak area (HPLC area%) of 9,9-bis(4-amino-3-fluorophenyl)fluorene was measured and used as the reaction yield (%).

[0035] In addition, the 9,9-bis(4-amino-3-fluorophenyl)fluorene obtained after purification was measured by liquid chromatography (Shimadzu Corporation LC-20A) under the following conditions, and the peak area fraction of 9,9-bis(4-amino-3-fluorophenyl)fluorene was taken as the chemical purity (LC area %). Column: YMC-Pack ODS-AM 4.6φ×250mm Column temperature: 40℃ Mobile phase: 0.1% (v / v) phosphoric acid aqueous solution (A) and acetonitrile (B) were used, and the composition was changed according to the gradient (A / B) shown below. Gradient Time (min) Composition (A / B) 0 60 / 40 10 45 / 55 15 20 / 80 25 20 / 80 30 10 / 90 40 10 / 90 45 40 / 60 60 40 / 60 ·Flow rate: 1ml / min ·Injection volume: 10μl Detection: UV 254nm ·Analysis time: 45 minutes Analytical sample preparation: Weigh out 0.02 g of sample and dilute it in approximately 40 ml of acetonitrile. However, the analytical conditions are not limited to these as long as the same analytical results as those based on the above analytical conditions are obtained.

[0036] (p-toluenesulfonic acid content) The content of p-toluenesulfonic acid in the resulting 9,9-bis(4-amino-3-fluorophenyl)fluorene was measured by liquid chromatography (Shimadzu Corporation, LC-20A) under the above conditions, except that the detection UV wavelength was changed to 225 nm.

[0037] The p-toluenesulfonic acid content was quantified using the internal standard method. p-Toluenesulfonic acid monohydrate (Nacalai Tesque, Inc., Grade 1) was used as the standard for p-toluenesulfonic acid, and diphenyl ether (Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the internal standard. The diphenyl ether concentration was fixed at 134 mg / L, and acetonitrile solutions with p-toluenesulfonic acid monohydrate concentrations of 0.2, 0.6, and 1.0 mg / L were prepared, and a calibration curve was created.

[0038] For the p-toluenesulfonic acid measurement sample, a 4 mg / mL acetonitrile solution of the obtained 9,9-bis(4-amino-3-fluorophenyl)fluorene was prepared and used for the measurement. However, the analytical conditions are not limited to these as long as the same analytical results as those based on the above analytical conditions are obtained.

[0039] (Light transmittance measurement) For the light transmittance measurement sample, a 10 mg / mL tetrahydrofuran solution of the obtained 9,9-bis(4-amino-3-fluorophenyl)fluorene was prepared and measured using an ultraviolet-visible spectrophotometer (Shimadzu Corporation UV-1900) under the following conditions. ·Measurement wavelength 400-900nm Measurement cell: Quartz cell (optical path length 1.0 cm) Scan speed: Medium Sampling pitch 1.0nm Photometric value type: Transmittance Baseline measurement: Baseline measurement with tetrahydrofuran

[0040] Example 1 A 300 mL four-neck flask equipped with a thermometer, condenser, and stirrer was charged with 6.3 g (35 mmol) of 9-fluorenone, 38.9 g of 2-fluoroaniline (10 mol / 9-fluorenone), and 6.7 g of p-toluenesulfonic acid monohydrate (1.0 mol / 9-fluorenone). The liquid temperature was raised to 150°C under stirring in a nitrogen atmosphere to initiate the reaction. The condensation reaction was carried out by aging for 19 hours while distilling off water. After completion of the reaction, the conversion of 9-fluorenone was 100% (LC area %), and the reaction yield of 9,9-bis(4-amino-3-fluorophenyl)fluorene was 93.7%.

[0041] To the resulting reaction solution, 77.8 g of 2-fluoroaniline (20 moles / 9-fluorenone, 9,9-bis(4-amino-3-fluorophenyl)fluorene concentration after dilution: 11 mass%) was added. Then, 124.2 g of a 5 mass% aqueous sodium carbonate solution (1.7 moles / p-toluenesulfonic acid monohydrate) was added and washed at 90 ° C. The aqueous layer was removed, and 124.2 g of pure water was added and washed at 90 ° C. The aqueous layer was removed, and the washed organic layer was allowed to cool to obtain a slurry containing 9,9-bis(4-amino-3-fluorophenyl)fluorene. This slurry was filtered to obtain a cake. This cake was vacuum-dried overnight at 60 ° C and a reduced pressure of 0.01 kPa or less, and 10.1 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield: 75.1 mass% / based on 9-fluorenone) was obtained as a white solid. The chemical purity determined by liquid chromatography analysis was 98.9% (LC area %), and the p-toluenesulfonic acid content determined by the liquid chromatography internal standard method was less than 30 ppm.

[0042] Example 2 In Example 1, 38.9 g of 2-fluoroaniline (10 mol times / 9-fluorenone) was changed to 29.2 g of 2-fluoroaniline (7.5 mol times / 9-fluorenone), except that the reaction was completed in 10 hours, and the reaction yield was 93.5%. Purification was carried out in the same manner as in Example 1, except that 77.8 g of 2-fluoroaniline (20 mol times / 9-fluorenone, 9,9-bis(4-amino-3-fluorophenyl)fluorene concentration after dilution was 11% by mass) was changed to 87.5 g of 2-fluoroaniline (23 mol times / 9-fluorenone, 9,9-bis(4-amino-3-fluorophenyl)fluorene concentration after dilution was 11% by mass). As a result, 10.2 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield 76.0% / based on 9-fluorenone) was obtained as a white solid. The chemical purity determined by liquid chromatography analysis was 99.0% (LC area %), and the p-toluenesulfonic acid content determined by the liquid chromatography internal standard method was less than 30 ppm.

[0043] Example 3 In Example 1, 38.9 g of 2-fluoroaniline (10 mol times / 9-fluorenone) was changed to 48.6 g of 2-fluoroaniline (12.5 mol times / 9-fluorenone), except that the reaction was carried out in the same manner as in Example 1. The reaction was completed in 20 hours, and purification was carried out in the same manner as in Example 1, except that 77.8 g of 2-fluoroaniline (20 mol times / 9-fluorenone, diluted 9,9-bis (4-amino-3-fluorophenyl) fluorene concentration 11 mass%) was changed to 68.1 g of 2-fluoroaniline (18 mol times / 9-fluorenone, 9,9-bis (4-amino-3-fluorophenyl) fluorene concentration 11 mass%). As a result, 10.6 g of 9,9-bis (4-amino-3-fluorophenyl) fluorene (isolation yield 78.9% / 9-fluorenone basis) was obtained as a white solid. The chemical purity determined by liquid chromatography analysis was 98.9% (LC area %), and the p-toluenesulfonic acid content determined by the liquid chromatography internal standard method was less than 30 ppm.

[0044] Example 4 The reaction was carried out in the same manner as in Example 1, except that 6.7 g of p-toluenesulfonic acid monohydrate (1.0 mol / 9-fluorenone) was replaced with 10.0 g of p-toluenesulfonic acid monohydrate (1.5 mol / 9-fluorenone). The reaction was completed in 10 hours, with a reaction yield of 94.3%. Purification was carried out in the same manner as in Example 1. As a result, 10.7 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield 79.2% / based on 9-fluorenone) was obtained as a white solid. The chemical purity by liquid chromatography analysis was 99.2% (LC area %), and the p-toluenesulfonic acid content by the liquid chromatography internal standard method was less than 30 ppm.

[0045] Example 5 The reaction was carried out in the same manner as in Example 1, except that 6.7 g of p-toluenesulfonic acid monohydrate (1.0 mol times / 9-fluorenone) was changed to 20.0 g of p-toluenesulfonic acid monohydrate (3.0 mol times / 9-fluorenone). The reaction was completed in 8 hours, and the reaction yield was 92.5%. Purification was carried out in the same manner as in Example 1, except that 124.2 g of 5% by mass aqueous sodium carbonate solution (1.7 mol times / p-toluenesulfonic acid monohydrate) was changed to 124.2 g of 10% by mass aqueous sodium carbonate solution (1.1 mol times / p-toluenesulfonic acid monohydrate). As a result, 9.3 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield 69.4% / based on 9-fluorenone) was obtained as a white solid. The chemical purity determined by liquid chromatography analysis was 99.2% (LC area %), and the p-toluenesulfonic acid content determined by the liquid chromatography internal standard method was less than 30 ppm.

[0046] (Comparative Example 1) The reaction was carried out in the same manner as in Example 1, except that 6.7 g of p-toluenesulfonic acid monohydrate (1.0 mol / 9-fluorenone) was replaced with 3.7 g of 35% hydrochloric acid (1.0 mol / 9-fluorenone). The reaction was not complete even after 47 hours, at which point the reaction was terminated. Purification was carried out in the same manner as in Example 1. As a result, 7.2 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene was obtained as a pale purple solid. This solid was placed in a 300 mL four-neck flask equipped with a thermometer, condenser, and stirrer, and 120.0 g of toluene was added. The mixture was heated to reflux and then allowed to cool, thereby recrystallizing 9,9-bis(4-amino-3-fluorophenyl)fluorene. The resulting mixture was filtered to obtain a cake. The cake was dried overnight at 60°C under a reduced pressure of 0.01 kPa or less to obtain 5.6 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolated yield 41.8% based on 9-fluorenone) as a pale purple solid. The chemical purity by liquid chromatography was 99.4% (LC area %).

[0047] (Comparative Example 2) The reaction was carried out in the same manner as in Example 1, except that 6.7 g of p-toluenesulfonic acid monohydrate (1.0 mol / 9-fluorenone) was replaced with 3.4 g of sulfuric acid (1.0 mol / 9-fluorenone). The reaction was not complete even after 75 hours, at which point the reaction was terminated. Purification was carried out in the same manner as in Example 1. As a result, 6.8 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield 50.5% based on 9-fluorenone) was obtained as a pale purple solid. The chemical purity by liquid chromatography analysis was 98.1% (LC area %).

[0048] (Comparative Example 3) The reaction was carried out in the same manner as in Example 1, except that 6.7 g of p-toluenesulfonic acid monohydrate (1.0 mol / 9-fluorenone) was replaced with 1.2 g of phosphotungstic acid hydrate (0.01 mol / 9-fluorenone). Immediately after adding the phosphotungstic acid hydrate, the reaction solution turned reddish purple. The reaction was completed in 24 hours, and purification was carried out in the same manner as in Example 1. As a result, 10.2 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield 76.1% based on 9-fluorenone) was obtained as a pale purple solid. The chemical purity by liquid chromatography analysis was 99.4% (LC area %).

[0049] Comparative Example 4 The reaction was carried out in the same manner as in Example 1, except that 6.7 g of p-toluenesulfonic acid monohydrate (1.0 mol / 9-fluorenone) was replaced with 1.2 g of tungstosilicic acid hydrate (0.01 mol / 9-fluorenone). Immediately after adding the tungstosilicic acid hydrate, the reaction solution turned reddish purple. The reaction was completed in 24 hours, and purification was carried out in the same manner as in Example 1. As a result, 9.7 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield 71.8% based on 9-fluorenone) was obtained as a pale purple solid. The chemical purity determined by liquid chromatography analysis was 99.4% (LC area %).

[0050] (Comparative Example 5) In Example 1, 38.9 g of 2-fluoroaniline (10 mol times / 9-fluorenone) was changed to 19.4 g of 2-fluoroaniline (5.0 mol times / 9-fluorenone), except that the reaction was completed in 7 hours, and the reaction yield was 91.4%. Purification was carried out in the same manner as in Example 1, except that 77.8 g of 2-fluoroaniline (20 mol times / 9-fluorenone, 9,9-bis(4-amino-3-fluorophenyl)fluorene concentration after dilution was changed to 97.2 g of 2-fluoroaniline (25 mol times / 9-fluorenone, 9,9-bis(4-amino-3-fluorophenyl)fluorene concentration after dilution was 11% by mass). As a result, 10.0 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield 74.5% / based on 9-fluorenone) was obtained as a white solid. The chemical purity determined by liquid chromatography analysis was 99.1% (LC area %), and the p-toluenesulfonic acid content determined by the liquid chromatography internal standard method was less than 30 ppm.

[0051] (Comparative Example 6) In Example 1, 38.9 g of 2-fluoroaniline (10 mol times / 9-fluorenone) was changed to 58.3 g of 2-fluoroaniline (15.0 mol times / 9-fluorenone), except that the reaction was completed in 21 hours, and the reaction yield was 93.1%. Purification was carried out in the same manner as in Example 1, except that 77.8 g of 2-fluoroaniline (20 mol times / 9-fluorenone, 9,9-bis(4-amino-3-fluorophenyl)fluorene concentration 11% by mass) was changed to 58.3 g of 2-fluoroaniline (15 mol times / 9-fluorenone, 9,9-bis(4-amino-3-fluorophenyl)fluorene concentration 11% by mass). As a result, 10.1 g of 9,9-bis(4-amino-3-fluorophenyl)fluorene (isolation yield 75.3% / 9-fluorenone basis) was obtained as a white solid. The chemical purity determined by liquid chromatography analysis was 98.8% (LC area %), and the p-toluenesulfonic acid content determined by the liquid chromatography internal standard method was less than 30 ppm.

[0052] Table 1 summarizes the above-mentioned Examples 1 to 5, and Table 2 summarizes Comparative Examples 1 to 6. Regarding light transmittance, measurement results showing a transmittance of 97% or more over the entire wavelength range of 400 to 900 nm are indicated as ◯, and results other than this are indicated as ×. The results of light transmittance measurements for Examples 1 to 5 and Comparative Examples 1 to 6 are shown in Figures 1 to 3.

[0053] Figure 1 is a graph comparing the light transmittance at wavelengths of 400 to 900 nm of a 10 mg / mL tetrahydrofuran solution of 9,9-bis(4-amino-3-fluorophenyl)fluorene, synthesized using 10 moles of 2-fluoroaniline relative to 9-fluorenone and various acid catalysts.

[0054] FIG. 2 is a graph comparing the light transmittance at wavelengths of 400 to 900 nm of a 10 mg / mL tetrahydrofuran solution of 9,9-bis(4-amino-3-fluorophenyl)fluorene synthesized using 1.0 mole of p-toluenesulfonic acid relative to 9-fluorenone and 5.0 to 15 moles of 2-fluoroaniline relative to 9-fluorenone.

[0055] FIG. 3 is a graph comparing the light transmittance at wavelengths of 400 to 900 nm of a 10 mg / mL tetrahydrofuran solution of 9,9-bis(4-amino-3-fluorophenyl)fluorene synthesized using 10 molar equivalents of 2-fluoroaniline relative to 9-fluorenone and 1.0 to 3.0 molar equivalents of p-toluenesulfonic acid relative to 9-fluorenone.

[0056] When non-oxidizing p-toluenesulfonic acid was used, 9,9-bis(4-amino-3-fluorophenyl)fluorene was obtained in high yield with a transmittance of over 97%. On the other hand, when hydrochloric acid or sulfuric acid was used, the transmittance and yield decreased. Furthermore, when phosphotungstic acid and silicotungstic acid, which have oxidizing properties, were used, the yield was high but the transmittance was less than 97%.

[0057] [Table 1]

[0058] [Table 2] [Industrial Applicability]

[0059] According to the method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene of the present invention, 9-fluorenone and 2-fluoroaniline are subjected to a condensation reaction in the presence of an aromatic sulfonic acid to obtain a reaction solution containing 9,9-bis(4-amino-3-fluorophenyl)fluorene, and then, by carrying out a neutralization treatment and cooling crystallization, which are common purification steps, 9,9-bis(4-amino-3-fluorophenyl)fluorene can be obtained in high yield with little coloration. The method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene of the present invention is an industrially excellent production method.

[0060] The 9,9-bis(4-amino-3-fluorophenyl)fluorene compound obtained by the production method of the present invention can be used in electronic information materials, optical materials, composite materials, and the like.

Claims

1. A method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene, comprising the step of subjecting 9-fluorenone to a condensation reaction with 2-fluoroaniline in an amount of 7.5 to 12.5 times by mole relative to the 9-fluorenone in the presence of an aromatic sulfonic acid, to obtain a reaction solution containing 9,9-bis(4-amino-3-fluorophenyl)fluorene.

2. The method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene according to claim 1, wherein the aromatic sulfonic acid is any one of p-toluenesulfonic acid, benzenesulfonic acid, m-xylene-4-sulfonic acid, p-xylene-2-sulfonic acid, and 2-naphthalenesulfonic acid, or a hydrate thereof, or a mixture thereof.

3. 3. The method for producing 9,9-bis(4-amino-3-fluorophenyl)fluorene according to claim 1 or 2, wherein the aromatic sulfonic acid is used in an amount of 1.0 to 3.0 times by mole relative to the 9-fluorenone in the condensation reaction.

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