Method for manufacturing fluorenone

Abstract

A method for producing fluorenone successively includes a pretreatment step of heating fluorene in the presence of a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst; and an oxidation step of continuously supplying fluorene and oxygen to carry out an oxidation reaction.

Description

Technical Field

[0001] The present invention relates to a method for producing fluorenone. Background Art

[0002] Fluorenone is used as a raw material or intermediate for pharmaceuticals, resins, etc. Specifically, it is a very useful compound as a raw material for electrophotographic photoreceptors, a raw material for pigments, and a raw material for optical resins.

[0003] As a method for producing fluorenone, a method of oxidizing fluorene has been continuously carried out. Among them, a production method based on liquid-phase oxidation using an oxygen-containing gas such as air has been developed.

[0004] For example, in Patent Document 1, for the purpose of obtaining fluorenones in high yield, a method for producing fluorenones is disclosed, which is characterized in that fluorenes are oxidized with molecular oxygen in an organic solvent in the presence of a phase transfer catalyst and a solid alkali metal hydroxide.

[0005] In addition, in Patent Document 2, for the purpose of obtaining fluorenone in high yield, a method of reacting a dimethyl sulfoxide solution of fluorene with oxygen molecules in the presence of a small amount of alkali metal hydroxide is disclosed.

[0006] In Patent Document 3, for the purpose of simply, economically, and obtaining diallyl ketone in high yield, the following method is disclosed: using a lower saturated aliphatic monocarboxylic acid as a solvent and a heavy metal as an oxidation catalyst, reacting an aromatic compound with oxygen molecules to obtain diallyl ketone, and as an example thereof, a method for obtaining fluorenone is disclosed.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-182399

[0010] Patent Document 2: U.S. Patent No. 3,875,237 Specification

[0011] Patent Document 3: U.S. Patent No. 3,038,940 Specification Summary of the Invention

[0012] According to Patent Document 3, an example of synthesizing fluorenone using the so-called Amoco method is disclosed. In particular, using ammonium bromide as part of a cocatalyst, the target product is obtained in a yield of 76%. However, according to this reaction, oxygen is supplied in the presence of acetic acid as a solvent, and it is necessary to heat at 205°C, which has a risk of ignition and explosion. In particular, an increase in the oxygen concentration in the exhaust gas (exhaust) becomes a safety problem during industrial production.

[0013] On the other hand, if the oxygen supply is reduced to avoid such a danger, the reaction temperature is lowered, or the oxidation reaction conditions are changed such as changing the catalyst, the conversion rate and the selectivity are correspondingly reduced, and the yield of the target fluorenone is reduced.

[0014] Therefore, industrially, a method for safely obtaining fluorenone with a high yield is required.

[0015] Therefore, the subject of the present invention is to provide a method for producing fluorenone with a high yield, excellent conversion rate and selectivity, and high industrial safety.

[0016] As a result of intensive studies by the present inventors, it was found that by heating fluorene as a raw material under specific conditions and continuously supplying fluorene and oxygen to carry out the oxidation reaction, the above-mentioned subject can be solved.

[0017] That is, the present invention relates to the following [1] to [9].

[0018] [1] A method for producing fluorenone, which sequentially includes: a pretreatment step of heating fluorene in the presence of a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst; and an oxidation step of continuously supplying fluorene and oxygen to carry out an oxidation reaction.

[0019] [2] The method for producing fluorenone according to the above [1], wherein in the above oxidation reaction, the molar ratio of continuously supplied oxygen to fluorene [oxygen / fluorene] is 0.5 to 4.0.

[0020] [3] The method for producing fluorenone according to the above [1] or [2], wherein the heating temperature of the above pretreatment step is 160 to 250 °C.

[0021] [4] The method for producing fluorenone according to any one of the above [1] to [3], wherein the heating time of the above pretreatment step is 3 to 30 minutes.

[0022] [5] The method for producing fluorenone according to any one of the above [1] to [4], wherein the reaction temperature of the above oxidation reaction is 120 to 250 °C.

[0023] [6] The method for producing fluorenone according to any one of the above [1] to [5], wherein the reaction pressure of the above oxidation reaction is 0.1 to 3.0 MPa.

[0024] [7] The method for producing fluorenone according to any one of the above [1] to [6], wherein the above metal catalyst is at least one selected from a cobalt catalyst, a manganese catalyst, a zirconium catalyst, a nickel catalyst, and a cerium catalyst.

[0025] [8] The method for producing fluorenone according to any one of [1] to [7] above, wherein the lower aliphatic carboxylic acid is acetic acid.

[0026] [9] The method for producing fluorenone according to any one of [1] to [8] above, wherein in the oxidation step, oxygen is supplied by introducing air.

[0027] According to the production method of the present invention, a method for producing fluorenone can be provided, which can obtain fluorenone in a high yield, has excellent conversion rate and selectivity, and is highly safe industrially. Detailed Description of the Invention

[0028] The method for producing fluorenone of the present invention successively includes: a pretreatment step of heating fluorene in the presence of a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst; and an oxidation step of continuously supplying fluorene and oxygen to carry out an oxidation reaction.

[0029] Hereinafter, the production method of the present invention will be described in detail.

[0030] [Pretreatment Step]

[0031] In the method for producing fluorenone of the present invention, first, a pretreatment step of heating fluorene in the presence of a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst is carried out.

[0032] <Lower Aliphatic Carboxylic Acid>

[0033] The lower aliphatic carboxylic acid used in this step is preferably an aliphatic carboxylic acid having 1 to 4 carbon atoms, more preferably an aliphatic carboxylic acid having 2 to 3 carbon atoms, and still more preferably an aliphatic carboxylic acid having 2 carbon atoms.

[0034] As specific lower aliphatic carboxylic acids, at least one selected from formic acid, acetic acid, propionic acid, and butyric acid is preferred, at least one selected from acetic acid and propionic acid is more preferred, and acetic acid is still more preferred. When using acetic acid, a mixed solution prepared by mixing water and acetic acid described below in advance can be used, or only acetic acid can be used. From the viewpoint of easily dissolving the bromine compound and the metal catalyst, it is preferred to use acetic acid containing water as a mixed solution of water and acetic acid.

[0035] By using the above-mentioned lower aliphatic carboxylic acid, the activity of the catalyst can be improved, so it is preferred.

[0036] With respect to 100 parts by mass of all fluorene, the amount of the lower aliphatic carboxylic acid used in the pretreatment step is preferably 10 to 1000 parts by mass, more preferably 50 to 400 parts by mass, still more preferably 70 to 200 parts by mass, and even more preferably 80 to 100 parts by mass.

[0037] By making the amount of the lower aliphatic carboxylic acid within the above range, it is possible to adjust the viscosity appropriately in this pretreatment step and the subsequent oxidation step, so the operation becomes easier. In addition, the reaction heat can be controlled.

[0038] It should be noted that "total fluorene" means "all the fluorene introduced into the reaction vessel from this pretreatment step to the end of the oxidation step and used in the oxidation reaction". The same applies hereinafter.

[0039] The lower aliphatic carboxylic acid can be one kind, or two or more kinds can be used.

[0040] <Bromine compound>

[0041] As the bromine compound used in this step, hydrogen bromide, bromide salts, and organic bromine compounds are preferably selected, more preferably at least one selected from hydrogen bromide and bromide salts, and further preferably hydrogen bromide.

[0042] Hydrogen bromide is preferably used in the form of an aqueous solution.

[0043] As specific bromide salts, sodium bromide, potassium bromide, ammonium bromide, etc. can be cited.

[0044] The amount of the bromine compound used in the pretreatment step, in terms of bromine conversion, is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, further preferably 0.05 to 1 part by mass, and even more preferably 0.05 to 0.5 part by mass, relative to 100 parts by mass of all the fluorene.

[0045] By making the amount of the bromine compound within the above range, corrosion of the reaction vessel, etc. can be inhibited, and the reaction rate in this pretreatment step and the subsequent oxidation step is increased, and the yield is increased, so it is preferred.

[0046] The bromine compound can be one kind, or two or more kinds can be used.

[0047] <Metal catalyst>

[0048] The metal catalyst used in this step is preferably at least one selected from transition metal catalysts and rare earth metal catalysts, and more preferably a transition metal catalyst.

[0049] As specific transition metal catalysts, preferably at least one selected from cobalt catalysts, manganese catalysts, zirconium catalysts, nickel catalysts, and cerium catalysts, and more preferably at least one selected from cobalt catalysts and manganese catalysts. Further, both cobalt catalyst and manganese catalyst are used.

[0050] As described above, as the metal catalyst used in this step, it is preferably at least one selected from a cobalt catalyst, a manganese catalyst, a zirconium catalyst, a nickel catalyst, and a cerium catalyst, and more preferably at least one selected from a cobalt catalyst and a manganese catalyst. It is further preferred to use both a cobalt catalyst and a manganese catalyst.

[0051] The metal catalyst can be used in the form of a salt, a metal monomer, an oxide, a hydroxide, etc., but the metal catalyst used in this step is preferably a salt, more preferably an aliphatic carboxylate, further preferably a lower aliphatic carboxylate, and still more preferably an acetate. Among them, it is still more preferably at least one selected from cobalt acetate and manganese acetate.

[0052] By using the above-mentioned metal catalyst, fluorenone can be obtained in a high yield, so it is preferred.

[0053] The amount of the metal catalyst used in the pretreatment step, in terms of the metal element, is preferably 0.02 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, further preferably 0.1 to 3 parts by mass, and still more preferably 0.1 to 1 part by mass, relative to 100 parts by mass of all fluorene used as a raw material in the oxidation reaction.

[0054] By making the amount of the metal catalyst within the above range, side reactions can be suppressed, and the reaction rates in this pretreatment step and the subsequent oxidation step are increased, and the yield is increased, so it is preferred.

[0055] If the catalyst concentration is above the above lower limit value, the reaction rate is increased and the yield is also increased. If the catalyst concentration is below the above upper limit value, the catalyst cost becomes low, and no adverse effect on the reaction occurs.

[0056] The metal catalyst can be one kind, or two or more kinds can be used.

[0057] According to the manufacturing method including this pretreatment step, using fluorene as a raw material, the conversion rate and selectivity are excellent, fluorenone can be obtained in a high yield, and the reason for being able to carry out production with high industrial safety is uncertain, but it is considered as follows.

[0058] It is considered that in the pretreatment step, by heating fluorene in the presence of the above catalyst, a part of fluorene becomes an active species, and the oxidation reaction can proceed smoothly from the initial stage of oxygen introduction. Therefore, it is considered that oxygen retention does not occur, and production with high safety can be carried out. In addition, it is considered that since the raw material is consumed uniformly in the reaction, side reactions can also be suppressed, the conversion rate and selectivity are excellent, and the yield is also increased.

[0059] <Water>

[0060] Water can be used in this step. Since the bromine compound is easily dissolved, it is preferred to use water.

[0061] With respect to 100 parts by mass of all fluorene used as a raw material in the oxidation reaction, the amount of water used in the pretreatment step is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, still more preferably 2 to 50 parts by mass, and even more preferably 3 to 10 parts by mass.

[0062] If the moisture concentration is within the above range, a decrease in the catalyst activity can be prevented and the bromine compound can be dissolved, and thus the yield can be increased in the subsequent oxidation step.

[0063] <Conditions of the pretreatment step, etc.>

[0064] With respect to all fluorene used as a raw material in the oxidation reaction, the amount of fluorene used in this step is preferably 1 to 50% by mass, more preferably 2 to 40% by mass, still more preferably 3 to 30% by mass, and even more preferably 5 to 20% by mass.

[0065] By setting the amount of fluorene used in this step within the above range, the high molecular weight of fluorene caused by side reactions and the resulting decrease in yield can be suppressed, and thus it is preferred.

[0066] In addition, the fluorene used in this step may be introduced all at once and then heated, or may be continuously introduced slowly. From the viewpoint of suppressing side reactions, continuous introduction is preferred.

[0067] When all the fluorene is set to 100 parts by mass, the supply rate in the case of continuous introduction is preferably 0.1 to 10 parts by mass per minute, more preferably 0.2 to 5 parts by mass per minute, still more preferably 0.3 to 3 parts by mass per minute.

[0068] In addition, when the metal catalyst is set to 100 parts by mass, the supply rate of fluorene in the pretreatment step is preferably 4 to 1700 parts by mass per minute, more preferably 8 to 850 parts by mass per minute, still more preferably 13 to 400 parts by mass per minute, and even more preferably 130 to 300 parts by mass per minute.

[0069] The heating temperature of the pretreatment step is preferably 160 to 250 °C, more preferably 180 to 250 °C, still more preferably 200 to 250 °C, even more preferably 220 to 250 °C, and even more preferably 220 to 240 °C.

[0070] By setting the heating temperature within the above range, the reaction rate can be easily controlled, and thus it is preferred.

[0071] The heating time of the pretreatment step can be appropriately changed according to the heating temperature, the amounts of the catalyst or raw materials, the size of the reaction vessel, the raw material introduction method, etc., but it is preferably 3 to 30 minutes, more preferably 3 to 20 minutes, still more preferably 3 to 15 minutes, and even more preferably 5 to 15 minutes.

[0072] By making the heating time within the above range, the high molecular weight of fluorene caused by side reactions and the resulting reduction in yield can be suppressed, so it is preferred.

[0073] In this step, from the viewpoint of safety, it is preferred to introduce an inert gas such as nitrogen before introducing oxygen into the reaction vessel containing the raw materials. The inert gas may contain a trace amount of oxygen that exists as an impurity and does not substantially assist in the oxidation reaction.

[0074] This pretreatment step is a step carried out before introducing oxygen. The starting point of this pretreatment step is the moment when the heating temperature first exceeds the lowest temperature of the set heating temperature (160 °C in the case of heating at 160 to 250 °C) in the presence of fluorene, a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst. It should be noted that when any one of fluorene, a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst is supplied after heating, the starting point of this pretreatment step is the moment when the heating temperature is the set heating temperature and fluorene, a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst are all present in the reaction vessel. For example, in the presence of a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst, when the heating temperature is the set heating temperature and then fluorene is supplied into the reaction vessel, the moment when fluorene is first supplied into the reaction vessel is taken as the starting point of the pretreatment step.

[0075] The end point of this pretreatment step is the moment when the heating temperature finally drops below the lowest temperature of the set heating temperature or the moment when the supply of oxygen starts. It should be noted that in this pretreatment step, when the heating temperature is lower than the lowest temperature of the set heating temperature, the time when the heating temperature is lower than the lowest temperature of the set heating temperature is not included in the above heating time.

[0076] [Oxidation step]

[0077] In the method for producing fluorenone of the present invention, after the above pretreatment step, an oxidation step of continuously supplying fluorene and oxygen to carry out an oxidation reaction is included next.

[0078] This oxidation step is to oxidize fluorene to obtain fluorenone by continuously supplying the remaining fluorene other than the fluorene added in the above pretreatment step and oxygen in the presence of a lower aliphatic carboxylic acid, a metal catalyst, and a bromine compound.

[0079] Herein, "continuously supplying fluorene and oxygen" means that the oxidation reaction of fluorene in the reaction vessel proceeds in parallel with the supply of fluorene and oxygen, and during the reaction time from the start to the end of the oxidation reaction, fluorene and oxygen are supplied for more than 50% of the reaction time.

[0080] In the method for producing fluorenone of the present invention, after the above-mentioned pretreatment step, by continuously supplying fluorene as a raw material, fluorenone can be obtained with high conversion and high selectivity under industrially safe conditions. The reason is not yet certain, but it is considered as follows.

[0081] Fluorene radicals are generated through the pretreatment step. Thereafter, if fluorene and oxygen as raw materials are continuously supplied, the supplied oxygen is immediately consumed successively for the oxidation reaction from the introduction, so that the oxygen concentration in the exhaust gas (exhaust) during the reaction can be reduced, and it will not reach the explosion limit of lower aliphatic carboxylic acids relative to the vapor, and the reaction can be safely terminated industrially. In addition, it is considered that the supplied oxygen and raw materials are successively used for the oxidation reaction as described above, so that the oxidation reaction can be carried out without the raw materials remaining in the reaction system and causing side reactions, and thus fluorenone can be obtained with high conversion and high selectivity.

[0082] <Reaction conditions for oxidation reaction, etc.>

[0083] In this step, fluorene and oxygen are continuously supplied.

[0084] The supply rate of fluorene can be constant, or the supply rate can be appropriately changed during the supply. However, from the viewpoint of simplicity of supply, it is preferably substantially constant.

[0085] The supply rate of fluorene in this oxidation step can be appropriately changed according to the size of the reaction vessel. When all the fluorene is set to 100 parts by mass, it is preferably 0.1 to 10 parts by mass / minute, more preferably 0.2 to 5 parts by mass / minute, and further preferably 0.3 to 3 parts by mass / minute.

[0086] From the viewpoint of appropriately controlling the reaction and improving safety, when the metal catalyst is set to 100 parts by mass, the supply rate of fluorene is preferably 4 to 1700 parts by mass / minute, more preferably 8 to 850 parts by mass / minute, further preferably 13 to 400 parts by mass / minute, and even more preferably 130 to 300 parts by mass / minute.

[0087] The oxygen used in this step can be oxygen gas, or a mixed gas with an inert gas or the like. Among them, in this step, from the viewpoints of safety and economy, it is preferred to supply oxygen by introducing air.

[0088] The supply rate of oxygen can be constant, or the supply rate can be appropriately changed during the supply. However, from the viewpoint of simplicity of supply, it is preferably constant.

[0089] The supply rate of oxygen can be appropriately changed according to the size of the reaction vessel and the supply rate of fluorene. In this step, the molar ratio of continuously supplied oxygen to fluorene [oxygen / fluorene] is preferably 0.5 to 4.0, more preferably 0.6 to 3.0, further preferably 0.7 to 2.5, still further preferably 0.8 to 2.0, and still further preferably 0.9 to 1.5.

[0090] By setting the supply ratio within the above range, the selectivity and yield of fluorenone are improved, which is thus preferred.

[0091] As described above for the supply rates of the above-mentioned fluorene and oxygen and their molar ratio, considering the aspects of safety, yield improvement, and simplicity as the effects of the present invention, it is preferably substantially constant. However, as the oxidation reaction proceeds, the ratio of the remaining raw material fluorene to oxygen and the amount of fluorene radicals in the reaction system change, so the oxygen concentration in the waste gas sometimes changes. Especially when the oxygen concentration in the waste gas rises, it is preferred to reduce the oxygen supply amount and the molar ratio of the supplied oxygen to fluorene for supply.

[0092] It should be noted that in order to end the oxidation reaction after the supply of fluorene is completed, it is preferred to continuously supply oxygen. If the oxidation reaction ends, oxygen will not be absorbed and the oxygen concentration in the waste gas will rise, so the supply of oxygen is ended. From the viewpoint of safety, it is preferred to end the supply of oxygen when the oxygen concentration in the waste gas is lower than the explosion limit of the lower aliphatic carboxylic acid.

[0093] The reaction temperature of the oxidation reaction is preferably 120 to 250 °C, more preferably 140 to 250 °C, further preferably 200 to 250 °C, still further preferably 220 to 250 °C, and still further preferably 220 to 240 °C.

[0094] By setting the reaction temperature within the above range, the conversion rate is increased, which is thus preferred.

[0095] The reaction pressure of the oxidation reaction is preferably 0.1 to 3.0 MPa, more preferably 0.3 to 3.0 MPa, further preferably 0.5 to 3.0 MPa, still further preferably 1.0 to 3.0 MPa, still further preferably 1.5 to 3.0 MPa, and still further preferably 1.5 to 2.5 MPa.

[0096] The reaction time of the oxidation reaction can be appropriately changed according to the reaction temperature, the amount of catalyst or raw materials, the size of the reaction vessel, the supply rate of raw materials, etc., but it is preferably 30 to 300 minutes, more preferably 60 to 200 minutes, and further preferably 80 to 120 minutes.

[0097] In this step, fluorene and oxygen are continuously supplied as described above to the reaction mixture that has undergone the pretreatment step and contains a lower aliphatic carboxylic acid, a metal catalyst, a bromine compound used in the above pretreatment step, and a part of the fluorene added in the pretreatment step.

[0098] Since the above-mentioned respective components used in this step are directly the respective components used in the above pretreatment step, it is simple and thus preferred.

[0099] In addition, a lower aliphatic carboxylic acid, a metal catalyst, and a bromine compound can be further added in this step. By adding a metal catalyst and a bromine compound, the continuous reaction can be sustained for a long time. When these substances are added in this step, it is preferably supplied continuously in the same manner as fluorene, and more preferably supplied in such a way that the supply amounts of the metal catalyst and fluorene fall within the above-mentioned ranges.

[0100] [Other steps]

[0101] In the method for producing fluorenone of the present invention, any steps other than the above pretreatment step and the above oxidation step can be included.

[0102] Examples of any steps included in the method for producing fluorenone of the present invention include a solvent removal step and a distillation step.

[0103] The solvent removal step is a step of removing a solvent having a boiling point lower than that of fluorenone, which is the target substance of this production method, i.e., a lower aliphatic carboxylic acid and water. By the distillation step, these solvents are removed in advance before removing by-products generated in the oxidation reaction and fluorene as a raw material, whereby the distillation step can be continuously and efficiently carried out.

[0104] In the solvent removal step, in order to efficiently remove the solvent, the solvent can be removed by heating and distilling under reduced pressure, or the solvent can be heated and distilled under normal pressure.

[0105] The distillation step can be any method as long as it can separate and recover fluorenone as the target substance with high purity.

[0106] The distillation temperature can be appropriately adjusted so as to be around the boiling point of fluorenone under the distillation pressure (the boiling point at 1 atm is 342 °C). For example, when the distillation pressure is adjusted to 3 kPa, it is preferably 150 - 300 °C, more preferably 160 - 250 °C, further preferably 180 - 240 °C, and even more preferably 180 - 220 °C.

[0107] When a distillation column is used in the distillation step, low-boiling components are appropriately removed from the top of the column, and high-boiling components are appropriately removed from the bottom of the column, thereby recovering fluorenone with high purity.

[0108] Examples

[0109] The present invention will be specifically described based on the following embodiments, but the present invention is not limited by these embodiments.

[0110] [Evaluation]

[0111] <Oxygen concentration in the waste gas>

[0112] The oxygen concentration in the waste gas is determined as follows.

[0113] Apparatus: Portable oxygen analyzer POT-101 manufactured by Shimadzu Corporation

[0114] Measurement method: Connect the gas discharge pipe of the autoclave to the above oxygen analyzer, and measure the oxygen concentration in the waste gas in real time, and evaluate according to the following criteria.

[0115] It should be noted that, considering the safety during industrial manufacturing, it is preferably that the oxygen concentration in the waste gas is 8% by volume or less, which is the explosion limit of acetic acid as a solvent. From the aspect of safety, the lower the oxygen concentration in the waste gas, the higher the degree of freedom of the reaction conditions, so it is preferred.

[0116] (Evaluation criteria)

[0117] 〇: During the oxidation reaction time, the oxygen concentration in the waste gas is always 8% by volume or less.

[0118] △: During the oxidation reaction time, the time when the oxygen concentration in the waste gas exceeds 8% by volume is less than 10% of the oxidation reaction time.

[0119] ×: During the oxidation reaction time, the time when the oxygen concentration in the waste gas exceeds 8% by volume is 10% or more of the oxidation reaction time.

[0120] <Conversion rate>

[0121] The amount (moles) of fluorene contained in the oxidation reaction product after the oxidation step is calculated by the internal standard method using gas chromatography (internal standard: triphenylmethane), and the amount (moles) of consumed fluorene is obtained by subtracting it from the amount (moles) of fluorene in the raw material.

[0122] The conversion rate is calculated by the following formula from the amount of consumed fluorene and the amount of fluorene in the raw material. It should be noted that the conversion rate refers to the raw material conversion rate.

[0123] Conversion rate (%) = (Amount of consumed fluorene (moles)) / (Amount of fluorene in the raw material (moles)) × 100

[0124] The higher the conversion rate, the more efficiently the raw material can be converted into fluorenone as the product, so it is preferred.

[0125] <Fluorenone selectivity · Fluorenone yield>

[0126] The amount (moles) of fluorenone contained in the oxidation reaction product after the oxidation step (the amount of fluorenone produced) was calculated by using the internal standard method of gas chromatography (internal standard: triphenylmethane).

[0127] The fluorenone selectivity was determined by the following formula from the amount of fluorenone produced as described above and the amount of fluorene in the raw material (the amount of fluorene consumed).

[0128] Selectivity (%) = (amount of fluorenone produced (moles)) / (amount of fluorene consumed (moles)) × 100

[0129] It should be noted that the fluorenone yield is a value calculated by multiplying the above conversion rate by the fluorenone selectivity. The higher the fluorenone selectivity and the fluorenone yield, the more efficiently high-purity fluorenone can be obtained, so it is preferred.

[0130] Example 1 (Manufacture of Fluorenone)

[0131] (1. Pretreatment Step)

[0132] Cobalt acetate tetrahydrate, manganese acetate tetrahydrate, 48% hydrobromic acid aqueous solution, glacial acetic acid, and water were mixed to obtain a catalyst solution such that the cobalt metal atom concentration was 0.75% by mass, the manganese metal atom concentration was 0.75% by mass, the bromide ion concentration was 0.075% by mass, the acetic acid concentration was 88.425% by mass, and the water concentration was 10% by mass.

[0133] 150 g of the above catalyst solution was charged into a 500 mL titanium autoclave equipped with a gas discharge pipe with a reflux condenser, a gas injection pipe, a raw material continuous liquid feed pump, and a stirrer. Under a nitrogen atmosphere, the temperature was raised to 200 °C (set temperature: 190 - 210 °C), and the pressure was increased to 1.0 MPa. 14 g of fluorene was supplied over 10 minutes. The production rate was 1.4 g / min.

[0134] (2. Oxidation Step)

[0135] After the pretreatment step was completed, the introduction of air was started simultaneously with the start of the supply of the additional raw material, and the raw material and air were continuously supplied. 136 g of the raw material fluorene was supplied over 97.1 minutes. The production rate was 1.4 g / min. Air was supplied at 1.90 L / min (0.40 L / min in terms of oxygen). After 1.8 hours from the start of the air supply, the oxygen concentration in the exhaust gas became 8% by volume, so the supply was terminated. The oxidation reaction product was obtained as described above. The obtained oxidation reaction product was analyzed, and as a result, the conversion rate was 100%, the fluorenone selectivity was 84.1 mol%, and the fluorenone yield was 84.1 mol%. The results are shown in Table 1.

[0136] Example 2 (Manufacture of Fluorenone)

[0137] In the 2. oxidation process, as shown in Table 1, the supply rate and supply time of air were changed, and otherwise, the process was carried out in the same manner as in Example 1 to obtain an oxidation reaction product. The oxygen concentration in the exhaust gas and the evaluation results of the obtained product are shown in Table 1.

[0138] Example 3 (Manufacture of Fluorenone)

[0139] In the 1. pretreatment process, instead of the catalyst solution of Example 1, a catalyst solution obtained by mixing cobalt acetate tetrahydrate, manganese acetate tetrahydrate, 48% hydrobromic acid aqueous solution, glacial acetic acid, and water in such a manner that the cobalt metal atom concentration is 0.24% by mass, the manganese metal atom concentration is 0.15% by mass, the bromide ion concentration is 0.18% by mass, the acetic acid concentration is 89.61% by mass, and the water concentration is 10% by mass was used. As shown in Table 1, the supply amount, supply rate, supply time, and temperature of fluorene were changed. It should be noted that the set temperature was 220 - 240 °C.

[0140] In addition, in the 2. oxidation process, as shown in Table 1, the supply amount, supply rate, supply time, supply rate of air, supply time, and conditions (temperature, pressure) of fluorene were changed, and otherwise, the process was carried out in the same manner as in Example 1 to obtain an oxidation reaction product. The oxygen concentration in the exhaust gas and the evaluation results of the obtained product are shown in Table 1.

[0141] Example 4 (Manufacture of Fluorenone)

[0142] In the 2. oxidation process, as shown in Table 1, the supply time and supply rate of fluorene and the supply rate of air were changed, and otherwise, the process was carried out in the same manner as in Example 3 to obtain an oxidation reaction product. The oxygen concentration in the exhaust gas and the evaluation results of the obtained product are shown in Table 1.

[0143] Example 5 (Manufacture of Fluorenone)

[0144] In the 1. pretreatment process, as shown in Table 1, the temperature was changed (the set temperature was 160 - 180 °C), and in the 2. oxidation process, as shown in Table 1, the temperature was changed (the set temperature was 160 - 180 °C), and otherwise, the process was carried out in the same manner as in Example 3 to obtain an oxidation reaction product. The oxygen concentration in the exhaust gas and the evaluation results of the obtained product are shown in Table 1.

[0145] Example 6 (Manufacture of Fluorenone)

[0146] In the 1. pretreatment process, as shown in Table 1, the temperature was changed (the set temperature was 160 - 180 °C), and otherwise, the process was carried out in the same manner as in Example 3 to obtain an oxidation reaction product. The oxygen concentration in the exhaust gas and the evaluation results of the obtained product are shown in Table 1.

[0147] Comparative Example 1 (Manufacture of Fluorenone)

[0148] Prepare the catalyst solution described in the 1. Pretreatment Step of Preparation Example 1, and put 150 g of the above catalyst solution into a 500 mL titanium autoclave equipped with a gas discharge pipe with a reflux condenser, a gas injection pipe, a raw material continuous liquid feed pump, and a stirrer. The 1. Pretreatment Step was not carried out.

[0149] (2. Oxidation Step)

[0150] Start the introduction of air simultaneously with the start of the supply of the raw material fluorene, and continuously supply the raw material and air. Supply 150 g of raw material fluorene in 48.4 minutes. The production rate is 3.1 g / minute. Air is supplied at 2.50 L / minute (oxygen converted to 0.52 L / minute). Immediately after the start of the air supply, the oxygen concentration in the waste gas exceeds 8% by volume, and the oxygen concentration in the waste gas exceeds 8% by volume until the end of the air supply (the lowest concentration is 11% by volume, and the highest concentration is 20% by volume). Carry out as above to obtain an oxidation reaction product. The oxygen concentration in the waste gas and the evaluation results of the obtained product are shown in Table 1.

[0151] Comparative Example 2 (Manufacture of Fluorenone)

[0152] (1. Pretreatment Step)

[0153] Prepare the catalyst solution described in the 1. Pretreatment Step of Preparation Example 1, and put 150 g of the above catalyst solution into a 500 mL titanium autoclave equipped with a gas discharge pipe with a reflux condenser, a gas injection pipe, a raw material continuous liquid feed pump, and a stirrer. Under a nitrogen atmosphere, raise the temperature to 200 °C (set temperature: 190 - 210 °C) and raise the pressure to 1.0 MPa. Heat 150 g of fluorene for 10 minutes.

[0154] (2. Oxidation Step)

[0155] After the Pretreatment Step is completed, start the introduction of air and supply only air. Air is supplied at 1.90 L / minute (oxygen converted to 0.40 L / minute). Stop the supply 2 hours after the start of the air supply. Carry out as above to obtain an oxidation reaction product. The oxygen concentration in the waste gas and the evaluation results of the obtained product are shown in Table 1.

[0156] [Table 1]

[0157] Table 1

[0158]

[0159] From the results of the examples shown in Table 1, it can be seen that by the manufacturing method of the present invention, fluorenone can be obtained in a high yield, the conversion rate and selectivity are also excellent, and high-purity fluorenone can be obtained. In addition, it can be seen that the oxidation reaction can be carried out while suppressing the oxygen concentration in the waste gas, so the industrial safety is also high.

Claims

1. A method for manufacturing fluorenone, successively including: A pretreatment step of heating fluorene in the presence of a lower aliphatic carboxylic acid, a bromine compound, and a metal catalyst; And an oxidation step of continuously supplying fluorene and oxygen to carry out an oxidation reaction, The lower aliphatic carboxylic acid is an aliphatic carboxylic acid having 1 to 4 carbon atoms, The bromine compound is at least one selected from hydrogen bromide, sodium bromide, potassium bromide, and ammonium bromide, The metal catalyst is at least one selected from a cobalt catalyst, a manganese catalyst, a zirconium catalyst, a nickel catalyst, and a cerium catalyst, The heating temperature in the pretreatment step is 160 to 250 °C, Relative to all the fluorene used as a raw material in the oxidation reaction, the usage amount of fluorene in the pretreatment step is 1 to 50% by mass, wherein the total fluorene refers to all the fluorene introduced into the reaction vessel from the pretreatment step to the end of the oxidation step and used in the oxidation reaction, The reaction temperature of the oxidation reaction is 120 to 250 °C, In the oxidation reaction, the molar ratio of continuously supplied oxygen to fluorene, i.e., oxygen / fluorene, is 0.5 to 4.

0.

2. The method for producing fluorenone according to claim 1, wherein, The heating time in the pretreatment step is 3 to 30 minutes.

3. The method for manufacturing fluorenone according to claim 1 or 2, wherein, The reaction pressure of the oxidation reaction is 0.1 to 3.0 MPa.

4. The method for manufacturing fluorenone according to claim 1 or 2, wherein, The lower aliphatic carboxylic acid is acetic acid.

5. The method for manufacturing fluorenone according to claim 1 or 2, wherein, In the oxidation step, oxygen is supplied by introducing air.

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