2,7-dibromo-9-fluorenone and producing method thereof

Abstract

To provide high-purity 2,7-dibromo-9-fluorenone with improved reactivity and hue and a producing method thereof.SOLUTION: The 2,7-dibromo-9-fluorenone is characterized by a transmittance of 85% or more at 500 nm when in a 5% tetrahydrofuran solution, and the conductivity of the treated water obtained by the method below is 1.0 mS / m or less. Conductivity of the treated water; adding 5 g of 2,7-dibromo-9-fluorenone to 50 g of distilled water and subjecting it to ultrasonic irradiation for 30 minutes, then measuring the conductivity (mS / m) of the distilled water from which 2,7-dibromo-9-fluorenone has been filtered out, minus the conductivity (mS / m) of the distilled water itself.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to 2,7-dibromo-9-fluorenone and a method for producing the same. [Background technology]

[0002] 2,7-Dibromo-9-fluorenone is a useful compound as a raw material for agricultural chemicals, pharmaceuticals, highly functional polymers (highly functional resins), dyes, pigments, photosensitizers, etc., and in recent years has been used especially as a raw material for highly functional resins.

[0003] Thermoplastic resins such as polycarbonate, polyester, and polyester carbonate, which are given as examples of highly functional resins, are attracting attention as optical components such as optical lenses and optical sheets due to their excellent optical properties, heat resistance, and moldability. In particular, polyester carbonate resins developed for optical lenses use aromatic dialcohol compounds having substituents at the 2,7-positions of the fluorene ring in order to improve the optical properties of the resin, such as transparency, heat resistance, refractive index, and birefringence, and these aromatic dialcohol compounds use 2,7-dibromo-9-fluorenone as a raw material.

[0004] For example, Patent Document 1 discloses an aromatic dialcohol compound having a phenyl group or a 2-naphthyl group at the 2,7 positions of the fluorene ring of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (BPEF), and Patent Document 2 discloses an aromatic dialcohol compound having a phenyl group at the 2,7 positions of the fluorene ring of 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]fluorene (BNEF). However, depending on the quality of the 2,7-dibromo-9-fluorenone used as a raw material, it may cause deterioration in transparency and hue required for optical lens applications, making it unsuitable as a raw material for such applications.

[0005] In the conventional method for producing 2,7-dibromo-9-fluorenone from 2,7-dibromofluorene (Patent Document 3), an ammonium salt is used as a phase transfer catalyst, and any trace of the ammonium salt remaining may impair the hue or transparency of the target aromatic dialcohol compound or a high-performance resin using the same.

[0006] On the other hand, in the method for producing 2,7-dibromo-9-fluorenone from 9-fluorenone using bromine (Non-Patent Document 1), although it is a catalyst-free, it is a heterogeneous reaction using water, and therefore when scaled up, inorganic salts (e.g., neutralization salts) after the reaction are incorporated into the crystals of 2,7-dibromo-9-fluorenone, and when the target aromatic dialcohol compound is synthesized using this as a raw material, the reaction rate decreases and the hue of the target compound decreases, which can impair the hue and transparency of the high-performance resin, so there is still room for improvement for industrial production. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2019 / 044214 [Patent Document 2] JP 2020-186220 A [Patent Document 3] JP 2004-115385 A [Non-patent literature]

[0008] [Non-Patent Document 1] Synthetic Communications,39,3804,(2009) Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide 2,7-dibromo-9-fluorenone having improved reactivity and color, and a method for producing the same. [Means for solving the problem]

[0010] The present invention has been achieved as a result of studies conducted to solve the problems of the above-mentioned conventional techniques, and aims to provide 2,7-dibromo-9-fluorenone, which is excellent in hue and reactivity and has high quality and is an excellent raw material for aromatic dialcohol compounds, and a method for producing the same. Specifically, the present invention relates to 2,7-dibromo-9-fluorenone and a method for producing the same, which are shown in the following items [1] to [5].

[0011] [1] 2,7-dibromo-9-fluorenone, characterized in that when made into a 5% tetrahydrofuran solution, the transmittance at 500 nm is 85% or more, and the electrical conductivity of treated water obtained by the method described below is 1.0 mS / m or less. Conductivity of treated water: 5 g of 2,7-dibromo-9-fluorenone was added to 50 g of distilled water, ultrasonicated for 30 minutes, and the conductivity (mS / m) of the distilled water after filtering out the 2,7-dibromo-9-fluorenone - conductivity (mS / m) of the distilled water itself [2] 2,7-dibromo-9-fluorenone according to [1], having an HPLC purity of 98 area % or more. [3] The method for producing 2,7-dibromo-9-fluorenone according to the item [1], comprising at least the following steps 1 and 2: Step 1: Reacting 9-fluorenone with bromine in water to produce crude 2,7-dibromo-9-fluorenone Step 2: The crude 2,7-dibromo-9-fluorenone produced in step 1 is purified by heating and stirring in an aqueous alcohol solution under reflux for a certain period of time. [4] The method for producing 2,7-dibromo-9-fluorenone according to item [3], wherein the alcohol used in step 2 is ethanol or 2-propanol. [5] 2,7-dibromo-9-fluorenone as described in [1], which is used as a raw material for aromatic dialcohol compounds. Effect of the Invention

[0012] According to the present invention, 2,7-dibromo-9-fluorenone with high purity and excellent hue and reactivity can be synthesized in high yield, and the use of this compound can improve the reactivity when synthesizing aromatic dialcohol compounds, and can also improve the hue of the target compound after reaction and the hue of the thermoplastic resin using it. Such thermoplastic resin is useful as optical components such as optical molded products, optical sheets, and optical films, and can be specifically used suitably for lenses, prisms, optical disks, transparent conductive substrates, optical cards, optical fibers, optical films, optical filters, hard coat films, etc., and the industrial effects it provides are exceptional. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail below. However, the description of the components described below is a representative example of an embodiment of the present invention, and the contents thereof are not limited to these.

[0014] [2,7-Dibromo-9-fluorenone] The transmittance at 500 nm when the 2,7-dibromo-9-fluorenone obtained by the present invention is prepared as a 5% tetrahydrofuran solution (hereinafter sometimes abbreviated as "solution transmittance") is 85% or more, preferably 87% or more, more preferably 88% or more, even more preferably 89% or more, and particularly preferably 90% or more. If this solution transmittance is lower than the above lower limit, when an aromatic dialcohol compound is synthesized from 2,7-dibromo-9-fluorenone, the hue becomes poor and it is not suitable for optical applications. The upper limit is not particularly limited, but may be 99% or less.

[0015] The conductivity of the distilled water (treated water) obtained by irradiating the 2,7-dibromo-9-fluorenone obtained by the present invention in distilled water for 30 minutes with ultrasonic waves, and filtering out the 2,7-dibromo-9-fluorenone, is less than 1.0 mS / m, preferably less than 0.9 mS / m, and more preferably less than 0.8 mS / m. If the conductivity is higher than the upper limit, not only will the reaction time be longer when synthesizing an aromatic dialcohol compound from 2,7-dibromo-9-fluorenone, and the productivity will decrease, but the heat history during the reaction will cause a decrease in hue, making it unsuitable for optical applications. The lower limit is not particularly limited, but may be 0.1 mS / m or more.

[0016] The liquid chromatography (HPLC) purity of 2,7-dibromo-9-fluorenone obtained by the present invention is preferably 80 area% or more, more preferably 90 area% or more, even more preferably 95 area% or more, particularly preferably 98 area% or more, and most preferably 99 area% or more. If the liquid chromatography purity is lower than the lower limit, the color may be poor when an aromatic dialcohol compound is synthesized from 2,7-dibromo-9-fluorenone, and it may not be suitable for optical applications. The upper limit is not particularly limited, but may be 99.9 area% or less.

[0017] [Method of manufacturing 2,7-dibromo-9-fluorenone] As a method for producing 2,7-dibromo-9-fluorenone of the present invention, a production method comprising at least the following steps 1 and 2 is preferable. Step 1: Reacting 9-fluorenone with bromine in water to produce crude 2,7-dibromo-9-fluorenone Step 2: The crude 2,7-dibromo-9-fluorenone produced in step 1 is purified by heating and stirring in an aqueous alcohol solution under reflux for a certain period of time.

[0018] The method for producing 2,7-dibromo-9-fluorenone of the present invention has a high reaction selectivity even without a catalyst, and includes only a step of heating and refluxing the obtained crude 2,7-dibromo-9-fluorenone in an aqueous alcohol solution for a certain period of time. Therefore, the target 2,7-dibromo-9-fluorenone can be obtained very simply and efficiently in high yield and high purity.

[0019] In addition, as described above, the 2,7-dibromo-9-fluorenone produced by the production method of the present invention has a solution transmittance of 85% or more and a treated water conductivity of 1.0 mS / m or less, and therefore can be suitably used as a raw material for aromatic dialcohol compounds.

[0020] In step 1, the amount of bromine used is preferably in the range of 2.0 mol to 10.0 mol, more preferably in the range of 3.0 mol to 5.0 mol, relative to 1 mol of 9-fluorenone. The reaction temperature is preferably 50° C. to 100° C., more preferably 60° C. to 80° C. The reaction time is preferably 30 minutes to 10 hours, more preferably 2 hours to 9 hours, and further preferably 5 hours to 8 hours.

[0021] Examples of the alcohol that can be used in step 2 include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and 1-hexanol. Of these, methanol, ethanol, 1-propanol, and 2-propanol are preferred, and ethanol or 2-propanol is particularly preferred.

[0022] The amount of the alcohol used in step 2 is not particularly limited, but is preferably 3 times by weight or more, more preferably 4 to 15 times by weight, and even more preferably 5 to 10 times by weight, based on the theoretical yield of 2,7-dibromo-9-fluorenone. If the amount of the alcohol used is less than the lower limit, a decrease in solution transmittance, an increase in the electrical conductivity of the treated water, and a decrease in liquid chromatography purity may be observed, whereas if the amount of the alcohol used exceeds the upper limit, there is no effect commensurate with the amount used, volume efficiency is deteriorated, and the production cost and productivity of 2,7-dibromo-9-fluorenone may be poor.

[0023] The alcohol aqueous solution in step 2 has a weight ratio of alcohol to water preferably in the range of 10:1 to 1:1, more preferably in the range of 5:1 to 2:1. By setting the weight ratio in the above range, 2,7-dibromo-9-fluorenone can be obtained with good purification efficiency, high solution transmittance, low treated water conductivity, high liquid chromatography purity, and excellent hue.

[0024] In step 2, the temperature during heating and refluxing with stirring varies depending on the type of alcohol used, but is preferably 50 to 100°C, more preferably 60 to 100°C, and even more preferably 80 to 100°C. If the reaction temperature is lower than the lower limit, the purification efficiency is poor, and an increase in the electrical conductivity of the treated water and a decrease in the liquid chromatography purity may be observed. If the reaction temperature exceeds the upper limit, the purification efficiency is high, but the hue may deteriorate and the solution transmittance may decrease due to the thermal history, and when an aromatic dialcohol compound is synthesized using such 2,7-dibromo-9-fluorenone, the hue of the resulting aromatic dialcohol compound may also decrease.

[0025] In step 2, the treatment time for heating under reflux and stirring is not particularly limited, but is preferably in the range of 30 minutes to 10 hours, more preferably in the range of 1 hour to 8 hours, and even more preferably in the range of 1 hour and 30 minutes to 4 hours. If the treatment time is shorter than the above lower limit, the purification efficiency will be poor, and the electrical conductivity of the treated water may increase and the liquid chromatography purity may decrease. The reaction time when synthesizing an aromatic dialcohol compound using such 2,7-dibromo-9-fluorenone will be long, and the liquid chromatography purity and hue of the obtained aromatic dialcohol compound may decrease. In addition, if the treatment time exceeds the above upper limit, the purification efficiency will be high, but the hue will be deteriorated due to the thermal history, and the solution transmittance may be reduced. When an aromatic dialcohol compound is synthesized using such 2,7-dibromo-9-fluorenone, the hue of the obtained aromatic dialcohol compound may also be deteriorated.

[0026] In addition, the reaction mixture after the reaction in step 1 usually contains unreacted 9-fluorenone, 2-bromo-9-fluorenone, hydrogen bromide, etc. in addition to the produced 2,7-dibromo-9-fluorenone. Therefore, it can be separated and purified by a conventional method, such as neutralization, filtration, concentration, crystallization, recrystallization, reprecipitation, column chromatography, or a combination of these. For example, bromine can be quenched by a conventional method (a method of adding water to quench bromine and adding a reducing agent such as sodium hydrogen sulfite), recovered by filtration, and then purified by the operation of step 2 to obtain high-quality 2,7-dibromo-9-fluorenone.

[0027] [Characteristics and uses of 2,7-dibromo-9-fluorenone] The 2,7-dibromo-9-fluorenone of the present invention can be used as a raw material for monomers of various high-performance resins. For example, it can be used as a raw material for monomers of thermoplastic resins (e.g., polyester resins, polycarbonate resins, polyester carbonate resins, polyurethane resins, etc.) and as a raw material for polyol components of thermosetting resins (e.g., epoxy resins, phenolic resins, thermosetting polyurethane resins, (meth)acrylates ((meth)acrylic acid esters), etc.). In particular, it is typically used as a raw material for aromatic dialcohol compounds for polyester resins, polycarbonate resins, and polyester carbonate resins.

[0028] When the 2,7-dibromo-9-fluorenone of the present invention is used as a raw material for an aromatic dialcohol compound, the solution transmittance and liquid chromatography purity of the 2,7-dibromo-9-fluorenone are high, and the resulting aromatic dialcohol compound has excellent hue. Furthermore, since the electrical conductivity of the treated water of 2,7-dibromo-9-fluorenone is low, the reaction time when synthesizing an aromatic dialcohol compound from the 2,7-dibromo-9-fluorenone is shortened, and not only can the compound be synthesized in high yield, but the purity and hue are also excellent. The APHA of the resulting aromatic dialcohol compound solution is preferably 80 or less, more preferably 70 or less, and even more preferably 60 or less. In particular, the 2,7-dibromo-9-fluorenone of the present invention is preferably used as a raw material for an aromatic dialcohol compound used as a raw material for a thermoplastic resin for optical members. EXAMPLES

[0029] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention. In the examples, various measurements were carried out as follows.

[0030] (1) Liquid chromatography measurement (HPLC) Each compound obtained in the examples was measured using a Hitachi high performance liquid chromatograph L-2450 under the measurement conditions in Table 1. In the examples, unless otherwise specified, % is an area percentage value corrected excluding the solvent in HPLC.

[0031] [Table 1]

[0032] (2) Solution transmittance measurement The 2,7-dibromo-9-fluorenone obtained in Example <Step 2> was measured using the following device and method. Equipment: Shimadzu UV-1800 Measurement wavelength: 500nm Cell length: 1cm Method: A 5% solution of 2,7-dibromo-9-fluorenone in tetrahydrofuran was prepared, and the transmittance of the solution was measured.

[0033] (3) Conductivity measurement The 2,7-dibromo-9-fluorenone obtained in Example <Step 2> was measured using the following device and method. Equipment: HORIBA ES-71 Electrode:HORIBA 9392-10D Distilled water: Fujifilm Wako Pure Chemical for high performance liquid chromatography (HPLC) Method: 5g of 2,7-dibromo-9-fluorenone was added to 50g of distilled water and ultrasonicated for 30 minutes, and the conductivity (mS / m) of the distilled water from which the 2,7-dibromo-9-fluorenone was filtered was measured. The conductivity (mS / m) of the distilled water itself was also measured as a blank, and the value subtracted from this was used as the conductivity (mS / m) of the treated water.

[0034] (4)APHA measurement A solution of 0.5 g of 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]-2,7-dibromofluorene obtained in Example <Step 3> dissolved in 10 mL of N,N-dimethylformamide was placed in a φ25 mm test tube and measured using a TZ6000 manufactured by Nippon Denshoku Industries Co., Ltd. In addition, 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]-2,7-diphenylfluorene obtained in Example <Step 4> was also measured in the same manner.

[0035] [Example 1] <Process 1> 62.97g (0.35 mol) of 9-fluorenone and 874g of water were added to a flask equipped with a stirrer, a condenser, and a thermometer, and then cooled to 0°C. After confirming that the temperature had reached 0°C, 90.00g (1.75 mol) of bromine was added and the mixture was stirred at 80°C for 10 hours to terminate the reaction. The reaction solution was cooled to room temperature, and water was added, followed by the addition of an aqueous solution of sodium hydrogen sulfite. The yellow solid was then filtered to obtain 106g of the desired crude 2,7-dibromo-9-fluorenone in a crude yield of 90%.

[0036] <Process 2> In a flask equipped with a stirrer, a condenser, and a thermometer, 106 g (0.31 mol) of the crude 2,7-dibromo-9-dibromofluorenone obtained in step 1, 410 g of ethanol, and 140 g of water were added, and the mixture was refluxed and stirred at 80°C for 2 hours. The reaction solution was then gradually cooled to room temperature, and the yellow solid was filtered out to obtain 103.5 g of the desired 2,7-dibromo-9-fluorenone (sometimes abbreviated as DBFN) in a yield of 88%. The HPLC purity, solution transmittance, and electrical conductivity of the obtained DBFN were measured and are shown in Table 2.

[0037] <Process 3> In a flask equipped with a stirrer, a water separator with a condenser, and a thermometer, 56.2 g (0.17 mol) of DBFN obtained in step 2, 52.7 g (0.37 mol) of 2-naphthol, 0.12 g (0.83 mmol) of 1-octanethiol, 12-tungsto(VI)phosphate n-hydrate (H3[PW 12 O 40 ]·nH2O), 51.9g of toluene, and 15.4g of ethylene carbonate were added, and the mixture was then depressurized to 27.5kPa, heated to 80°C, and stirred at the same temperature for 5 hours while discharging the by-product water from the system. After the reaction was completed, a 24% by weight aqueous solution of sodium hydroxide was added to obtain 12-tungsto(VI)phosphate n-hydrate (H3[PW 12 O 40]·nH2O) was neutralized, and the water in the system was distilled off at 120°C. Then, 2.3g (0.017 mol) of potassium carbonate, 22.7g (0.26 mol) of ethylene carbonate, and 197mL of N,N-dimethylformamide were added and the reaction was carried out by stirring at 110°C for 4.5 hours. The progress of the reaction was confirmed by HPLC, and the reaction was terminated when it was confirmed that the remaining amount of 9,9'-bis(6-hydroxy-2-naphthyl)-2,7-dibromofluorene was 0.0%. After the reaction was completed, the reaction solution obtained was concentrated, toluene and ethyl acetate were added, and the mixture was washed with hot water five times. Then, it was recrystallized from methanol to obtain 106g of the desired white crystals of 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]-2,7-dibromofluorene (hereinafter sometimes abbreviated as BNDB) in a yield of 91%. The HPLC purity and APHA of the obtained BNDB were measured, and the results are shown in Table 2.

[0038] <Step 4> (Production of aromatic dialcohol compound) In a flask equipped with a stirrer, a condenser, and a thermometer, 106 g (0.15 mol) of BNDB obtained in step 3, 41 g (0.33 mol) of phenylboronic acid, 0.2 g (0.18 mmol) of tetrakis(triphenylphosphine)palladium, 169 mL of 2M potassium carbonate aqueous solution, 362 mL of toluene, and 183 mL of N,N-dimethylformamide were added, and the mixture was stirred at 100 ° C for 3 hours. The progress of the reaction was confirmed by HPLC, and the reaction was terminated when it was confirmed that the remaining amount of BNDB was 0.0%. After the reaction was completed, toluene was added to dilute the reaction solution, the stirrer was stopped, the toluene layer and the water layer were separated, and the collected toluene layer was washed five times with warm water. Tetrahydrofuran was added to the toluene layer after washing and treated with activated carbon, after which the tetrahydrofuran was distilled off and recrystallization was carried out with toluene. The crystals obtained were dried overnight under reduced pressure and heated to obtain 84 g of white crystals of 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]-2,7-diphenylfluorene (hereinafter sometimes abbreviated as BNDP) in a yield of 80%. The HPLC purity of the obtained BNDP was 98.5%, and APHA was 50.

[0039] [Example 2] Except for changing the ethanol in <Step 2> to 2-propanol, DBFN, BNDB and BNDP were synthesized in the same manner as in Example 1. The results of various analyses of the obtained DBFN, BNDB and BNDP are shown in Table 2.

[0040] [Comparative Example 1] Except for not carrying out <Step 2> and carrying out toluene recrystallization instead, DBFN, BNDB and BNDP were synthesized under the same conditions as in Example 1. The results of various analyses of the obtained DBFN, BNDB and BNDP are shown in Table 2.

[0041] [Comparative Example 2] DBFN, BNDB and BNDP were synthesized under the same conditions as in Example 1, except that <Step 2> was not carried out and cyclohexanone recrystallization was carried out instead. The results of various analyses of the obtained DBFN, BNDB and BNDP are shown in Table 2.

[0042] [Table 2] [Industrial Applicability]

[0043] The 2,7-dibromo-9-fluorenone of the present invention is useful as a raw material for an aromatic dialcohol compound for a thermoplastic resin, and a thermoplastic resin obtained using such an aromatic dialcohol compound as a raw material is useful as an optical member such as an optical molded product, an optical sheet, or an optical film. Specifically, it can be suitably used for lenses, prisms, optical disks, transparent conductive substrates, optical cards, optical fibers, optical films, optical filters, hard coat films, etc.

Claims

1. 2,7-dibromo-9-fluorenone, characterized in that when made into a 5% tetrahydrofuran solution, the transmittance at 500 nm is 85% or more, and the electrical conductivity of treated water obtained by the method described below is 1.0 mS / m or less. Conductivity of treated water: Conductivity (mS / m) of distilled water obtained by adding 5 g of 2,7-dibromo-9-fluorenone to 50 g of distilled water, irradiating the water with ultrasonic waves for 30 minutes, and filtering out the 2,7-dibromo-9-fluorenone - Conductivity (mS / m) of distilled water itself

2. 2,7-dibromo-9-fluorenone according to claim 1, having an HPLC purity of 98 area % or more.

3. The method for producing 2,7-dibromo-9-fluorenone according to claim 1, comprising at least the following steps 1 and 2: Step 1: Reacting 9-fluorenone with bromine in water to produce crude 2,7-dibromo-9-fluorenone Step 2: Purifying the crude 2,7-dibromo-9-fluorenone produced in step 1 by heating and refluxing in an aqueous alcohol solution for a certain period of time.

4. The method for producing 2,7-dibromo-9-fluorenone according to claim 3, wherein the alcohol used in step 2 is ethanol or 2-propanol.

5. The 2,7-dibromo-9-fluorenone according to claim 1, which is used as a raw material for aromatic dialcohol compounds.

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