Method for producing aminomethyl aromatics

Abstract

A method for producing an aminomethyl aromatic, comprising hydrogenating an aromatic nitrile in an organic solvent containing a polar organic solvent having a solubility parameter (SP value) of 9 or more in the presence of a quaternary ammonium compound, at least one metal hydroxide selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and a hydrogenation catalyst.

Description

Technical Field

[0001] The invention relates to a process for producing aminomethyl aromatics by hydrogenating aromatic nitriles. Background Art

[0002] Aminomethyl aromatics are useful as raw materials or intermediates for pharmaceuticals, pesticides, resins, curing agents, etc. In particular, xylylenediamine having two aminomethyl groups is a very useful compound as a raw material for polyamide resins, curing agents, etc., and as an intermediate for isocyanates.

[0003] As a method for producing aminomethyl aromatics, a method of hydrogenating aromatic nitrile is carried out.

[0004] In the hydrogenation of aromatic nitriles, a method using liquid ammonia as a solvent is known. However, due to environmental considerations, the liquid ammonia needs to be recovered after the hydrogenation reaction and not released to the outside, which places a heavy burden on production. Various studies have been conducted on production methods that do not use liquid ammonia.

[0005] For example, Patent Document 1 discloses a method for producing cyanamidomethyl aromatics by hydrogenating aromatic nitrile in the presence of alcohol and tetraalkylammonium hydroxide using a palladium catalyst for the purpose of obtaining cyanamidomethyl aromatics, one of the aminomethyl aromatics, in high yield without using liquid ammonia and under mild reaction conditions and by a simple reaction operation to suppress the by-production of diaminomethyl aromatics.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2002-205980 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] In order to use aminomethyl aromatics as raw materials for polyamide resins, curing agents, and isocyanate intermediates, very high-purity aminomethyl aromatics are required, and a method for obtaining aminomethyl aromatics in high yield in a production method that does not use liquid ammonia is desired.

[0011] In addition, according to the method of Patent Document 1, hydrogenation can be performed under mild reaction conditions without using liquid ammonia, but the resulting aminomethyl aromatic contains impurities, which is a problem. If impurities are contained, when the aminomethyl aromatic is used as a raw material for polyamide resins, etc., as described above, polymerization is inhibited.

[0012] Therefore, a synthesis method that can achieve high yield and suppress the generation of impurities is required.

[0013] Therefore, an object of the present invention is to provide a production method which can obtain aminomethyl aromatics at a high yield without substantially using liquid ammonia and can also suppress the generation of impurities.

[0014] Solutions for solving problems

[0015] The present inventors have conducted intensive studies and have found that the above-mentioned problems can be solved by hydrogenating an aromatic nitrile in a specific solvent in the presence of a quaternary ammonium compound and a specific metal hydroxide.

[0016] That is, the present invention is a method for producing aminomethyl aromatics as follows: an aromatic nitrile is hydrogenated in an organic solvent containing a polar organic solvent having a solubility parameter (SP value) of 9 or more in the presence of a quaternary ammonium compound, at least one metal hydroxide selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and a hydrogenation catalyst.

[0017] Effects of the Invention

[0018] According to the production method of the present invention, aminomethyl aromatics can be obtained at a high yield without substantially using liquid ammonia, and the generation of impurities can also be suppressed. DETAILED DESCRIPTION

[0019] In the method for producing aminomethyl aromatics of the present invention, an aromatic nitrile is hydrogenated in an organic solvent containing a polar organic solvent having a solubility parameter (SP value) of 9 or more in the presence of a quaternary ammonium compound, at least one metal hydroxide selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and a hydrogenation catalyst.

[0020] The production method of the present invention is described in detail below.

[0021] [Organic solvents]

[0022] The organic solvent used in the present invention contains a polar organic solvent having a solubility parameter (SP value) of 9 or more.

[0023] In the production method of the present invention, it is considered that by using a polar organic solvent having an SP value of 9 or more, the aminomethyl aromatic compound as a product is distributed therein, and the hydrogenation reaction can be efficiently performed.

[0024] The organic solvent used in the present invention may consist only of the aforementioned polar organic solvent, but by further using a nonpolar organic solvent having an SP value of less than 9, the aromatic nitrile and hydrogen as raw materials are well dissolved, and the hydrogenation reaction can be efficiently performed.

[0025] The nonpolar organic solvent having an SP value of less than 9 is not particularly limited, but a hydrocarbon solvent is preferred.

[0026] Each solvent is described below.

[0027] (Polar organic solvent with solubility parameter (SP value) of 9 or more)

[0028] The solubility parameter (SP value) of the polar organic solvent used in the present invention is 9 or more, preferably 10 or more, more preferably 11 or more, further preferably 12 or more, and further preferably 13 or more. The upper limit is preferably 20 or less, more preferably 17 or less, and further preferably 15 or less.

[0029] In addition, the SP value in the present invention is a value calculated|required by the following Hildebrand's solubility parameter formula.

[0030] Solubility parameter (SP value) = (ΔH A V -RT) 0.5 / V A 0.5

[0031] ΔH A V : Enthalpy of evaporation of liquid A (polar organic solvent)

[0032] R: Gas constant

[0033] T: Temperature

[0034] V A : Molar volume of liquid A

[0035] The polar organic solvent used in the present invention is at least one selected from alcohols, esters, amides, sulfoxides, ketones and amines, and alcohols are preferred.

[0036] Examples of the alcohol include monohydric alcohols and polyhydric alcohols, and monohydric alcohols are preferred. Examples of the monohydric alcohol include aliphatic alcohols and aromatic alcohols, and aliphatic alcohols are preferred.

[0037] The number of carbon atoms in the aliphatic alcohol is preferably 1 to 8, more preferably 1 to 4, and even more preferably 1 and 2, from the viewpoint of industrial availability.

[0038] Specific examples of aliphatic alcohols include methanol (SP value 14.5), ethanol (SP value 12.7), n-propanol (SP value 11.9), isopropanol (SP value 11.5), n-butanol (SP value 11.4), sec-butanol (SP value 10.8), tert-butanol (SP value 10.6), pentanol, hexanol (SP value 10.7), heptanol (SP value 10.6), n-octanol (SP value 10.3), etc. Preferably, at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol and n-butanol, more preferably at least one selected from the group consisting of methanol and ethanol, and still more preferably methanol.

[0039] (Hydrocarbon Solvents)

[0040] The organic solvent used in the present invention preferably further contains a hydrocarbon solvent.

[0041] The hydrocarbon solvent is one or more selected from aromatic hydrocarbon solvents and aliphatic hydrocarbon solvents, and an aromatic hydrocarbon solvent is preferred.

[0042] The solubility parameter (hereinafter also referred to as SP value) of the hydrocarbon solvent is preferably less than 9. The lower limit is preferably more than 7.0, more preferably more than 8.0. It is believed that if the hydrocarbon solvent is an aromatic hydrocarbon solvent, aromatic nitrile and hydrogen as raw materials will dissolve well, and hydrogenation can be carried out efficiently. In addition, it is believed that by making the SP value less than 9, aromatic nitrile and hydrogen as raw materials will also dissolve well, and hydrogenation can be carried out efficiently.

[0043] When the hydrocarbon solvent is an aromatic hydrocarbon solvent, the number of carbon atoms in the aromatic hydrocarbon solvent is preferably 7-12, more preferably 7-9, and even more preferably 8-9.

[0044] Specific examples of aromatic hydrocarbon solvents include toluene, ethylbenzene, three isomers of xylene (o-xylene, m-xylene, p-xylene), mesitylene, trimethylbenzene (pseudocumene) and other monocyclic aromatic hydrocarbon compounds, and naphthalene, methylnaphthalene and other polycyclic aromatic hydrocarbon compounds, preferably monocyclic aromatic hydrocarbon compounds. Among them, from the perspective of good solubility of aromatic nitriles and hydrogen as raw materials and easy industrial availability, xylene and mesitylene are more preferred, xylene (SP value 8.8) is further preferred, m-xylene and p-xylene are further preferred, and m-xylene is further preferred.

[0045] (Composition of organic solvent)

[0046] The organic solvent in the present invention refers to all liquid compounds (all liquid organic compounds) contained in the solution during the hydrogenation reaction, excluding the aromatic nitrile as a raw material and the aminomethyl aromatic as a product.

[0047] As described above, the organic solvent used in the present invention may consist of only a polar organic solvent, but preferably also contains a nonpolar organic solvent having an SP value of less than 9. The nonpolar organic solvent having an SP value of less than 9 is not particularly limited, but is preferably a hydrocarbon solvent.

[0048] When the organic solvent contains a hydrocarbon solvent and a polar organic solvent, the mass ratio of the hydrocarbon solvent to the polar organic solvent in the organic solvent (hydrocarbon solvent / polar organic solvent) is preferably 60 / 40 to 99 / 1, more preferably 70 / 30 to 99 / 1, more preferably 80 / 20 to 99 / 1, and still more preferably 82 / 18 to 99 / 1. By using a larger amount of hydrocarbon solvent than polar organic solvent, the concentration of nitrile dissolved in the hydrocarbon solvent is reduced, and high boiling point substances are less likely to be generated on the catalyst.

[0049] The total content of the hydrocarbon solvent and the polar organic solvent in the organic solvent is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and further preferably 99 to 100% by mass.

[0050] The content of the water in the organic solvent is preferably below 5 mass %, more preferably below 2 mass %, further preferably below 1 mass %. It is believed that by making the content of water be below 5 mass %, the side reaction with the raw material can be suppressed, and the yield of the product can be improved. For water, it is preferably not substantially included, and the lower limit can be 0 mass %.

[0051] In addition, the organic solvent of the present invention preferably contains substantially no liquid ammonia, and more preferably contains no liquid ammonia. By containing no liquid ammonia, the load during production due to recovery of ammonia can be reduced.

[0052] The difference in SP value between the hydrocarbon solvent and the polar organic solvent in the organic solvent is preferably 0.5 or more, more preferably 1.0 or more, further preferably 2.0 or more, and further preferably 4.0 or more. In addition, it is preferably 12 or less, more preferably 10 or less, further preferably 8 or less, and further preferably 6 or less.

[0053] As a combination of the hydrocarbon solvent and the polar organic solvent in the organic solvent, a monocyclic aromatic hydrocarbon compound and an alcohol are preferred, xylene and an aliphatic alcohol having 1 or 2 carbon atoms are more preferred, and m-xylene and methanol are further preferred.

[0054] (Quaternary Ammonium Compounds)

[0055] In the method for producing an aminomethyl aromatic compound of the present invention, a quaternary ammonium compound and at least one metal hydroxide selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides are used as the basic compound.

[0056] By using a quaternary ammonium compound and a metal hydroxide simultaneously, aminomethyl aromatics can be obtained at a high yield and the generation of impurities can be suppressed. The reason why aminomethyl aromatics can be obtained at a high yield and the generation of impurities can be suppressed is not clear, but it is considered as follows.

[0057] Quaternary ammonium compound is to obtain aminomethyl aromatics in high yield stably without corrosion, catalytic degradation etc. of reaction vessel etc., but can generate impurities with aminomethyl aromatics reaction in distillation.Think that alkali metal hydroxide or alkaline earth metal hydroxide can hinder the reaction that these impurities generate, so the combination use of alkali metal etc. helps the minimizing of impurities.And then think that quaternary ammonium salt preferably acts on catalyst in reaction, therefore reduce the catalytic degradation property that alkali metal, alkaline earth metal have, and yield also becomes good.

[0058] Examples of the quaternary ammonium compound used in the present invention include tetraalkylammonium hydroxides and organic acid tetraalkylammonium. It is preferred to use one or more selected from these. Among these, tetraalkylammonium hydroxide is more preferred.

[0059] Examples of the tetraalkylammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide. Tetramethylammonium hydroxide and tetraethylammonium hydroxide are preferred. From the viewpoint of suppressing impurities, tetraethylammonium hydroxide is more preferred.

[0060] Examples of the organic acid tetraalkylammonium include tetraalkylammonium phenoxides, fatty acid tetraalkylammoniums, and tetraalkylammonium tetraphenylborates.

[0061] Examples of the fatty acid tetraalkylammonium include tetramethylammonium acetate.

[0062] The amount of the quaternary ammonium compound is preferably 0.1 to 10 mmol, more preferably 0.2 to 5 mmol, and further preferably 0.5 to 1 mmol relative to 1 g of the hydrogenation catalyst. In addition, it is preferably 1 to 20 mass %, more preferably 3 to 10 mass %, and further preferably 5 to 10 mass % relative to the hydrogenation catalyst. By using the quaternary ammonium compound of the above amount, the catalyst does not deteriorate, the reaction rate can be maintained, and the target aminomethyl aromatics can be obtained in high yield. In addition, when it is less than 20 mass % relative to the hydrogenation catalyst, when the quaternary ammonium compound is used in an aqueous solution, the amount of water brought in can also be suppressed.

[0063] (Metal Hydroxide)

[0064] The metal hydroxide used in the present invention is at least one selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and among them, alkali metal hydroxides are preferred.

[0065] As the alkali metal hydroxide, at least one selected from the group consisting of sodium hydroxide and potassium hydroxide is preferred, and among these, sodium hydroxide is more preferred.

[0066] As the alkaline earth metal hydroxide, at least one selected from the group consisting of calcium hydroxide and magnesium hydroxide is preferred, and among these, calcium hydroxide is more preferred.

[0067] That is, as the metal hydroxide, preferably at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide and magnesium hydroxide, among which at least one selected from the group consisting of sodium hydroxide, potassium hydroxide and calcium hydroxide is more preferably selected, further preferably at least one selected from the group consisting of sodium hydroxide and potassium hydroxide, and further preferably sodium hydroxide.

[0068] The amount of the metal hydroxide is preferably 0.1 to 10 mmol, more preferably 0.2 to 5 mmol, and further preferably 0.5 to 1 mmol relative to 1 g of the hydrogenation catalyst. In addition, it is preferably 1 to 20% by mass, more preferably 3 to 10% by mass, and further preferably 5 to 10% by mass relative to the hydrogenation catalyst. It is believed that by using the above amount of metal hydroxide, impurities are also suppressed, the reaction rate can be maintained, and the target aminomethyl aromatics can be obtained in high yield. In addition, when it is less than 20% by mass relative to the hydrogenation catalyst, when the metal hydroxide is used in an aqueous solution, the amount of water brought in can also be suppressed.

[0069] The molar ratio of the quaternary ammonium compound to the metal hydroxide (quaternary ammonium compound / metal hydroxide) is preferably 70 / 30 to 20 / 80, more preferably 60 / 40 to 30 / 70, more preferably 50 / 50 to 35 / 65, and further preferably 45 / 55 to 40 / 60. When it is within this range, not only can aminomethyl aromatics be obtained in high yield, but also the catalytic degradation rate is small, the catalyst can be reused, and impurities can be fully reduced, so it is preferred.

[0070] (Hydrogenation Catalyst)

[0071] As the hydrogenation catalyst used in the manufacturing method of the present invention, as long as it is a catalyst used in the hydrogenation of an organic compound, there is no restriction, preferably a metal catalyst. As the metal contained in the metal catalyst, cobalt, nickel, palladium, platinum can be cited, preferably one or more selected from cobalt and nickel, more preferably cobalt. That is, preferably containing one or more metal catalysts selected from cobalt, nickel, palladium, platinum, more preferably containing one or more metal catalysts selected from nickel and cobalt, further preferably containing cobalt. By using a cobalt catalyst, the generation of high boiling point substances on the catalyst can be suppressed, the yield can be improved, and the degradation of the catalyst can also be reduced.

[0072] Examples of the metal catalyst containing one or more metals selected from nickel and cobalt include metal-supported catalysts and sponge metal catalysts, and sponge metal catalysts are preferred.

[0073] Examples of metal-supported catalysts include catalysts in which one or more selected from nickel and cobalt are supported on Al2O3, SiO2, diatomaceous earth, SiO2-Al2O3, or ZrO2 by a precipitation method.

[0074] As the sponge metal catalyst, there can be mentioned catalysts prepared by dissolving a part of the components from an alloy of two or more components (nickel, cobalt, aluminum, iron, copper, etc.) using an acid or an alkali, preferably a sponge cobalt catalyst and a sponge nickel catalyst, more preferably a sponge cobalt catalyst. The above catalysts can be used alone or in combination of two or more.

[0075] The amount of the catalyst is preferably 0.1 to 100 parts by mass, more preferably 1 to 50 parts by mass, and even more preferably 10 to 20 parts by mass based on 100 parts by mass of the aromatic nitrile. By using the above amount of the catalyst, the yield of the obtained aminomethyl aromatic can be increased.

[0076] (Aromatic Nitrile)

[0077] The aromatic nitrile used as a raw material in the production method of the present invention has a nitrile group bonded to an aromatic ring (benzene ring), and the number of the nitrile groups is preferably 1 or 2, and more preferably 2.

[0078] In addition, other substituents may be bonded to the aromatic ring.

[0079] Specific examples of the aromatic nitrile include benzonitrile and dicyanobenzene, and dicyanobenzene is preferably used.

[0080] As dicyanobenzene, there are three isomers of o-phthalonitrile (1,2-dicyanobenzene), isophthalonitrile (1,3-dicyanobenzene), and terephthalonitrile (1,4-dicyanobenzene), among which isophthalonitrile and terephthalonitrile are preferred, and terephthalonitrile is more preferred.

[0081] The concentration of the aromatic nitrile during the hydrogenation reaction is preferably 2 to 30% by mass, more preferably 5 to 25% by mass, and further preferably 7 to 20% by mass in the reaction solution. It should be noted that the reaction solution does not contain a catalyst. The reaction solution contains liquid components other than raw materials, organic solvents, organic solvents such as water, quaternary ammonium compounds, and metal hydroxides. The concentration of the aromatic nitrile during the hydrogenation reaction can be calculated in the form of a total concentration of the mass of the components constituting a uniform solution when blended in the manufacturing method of aminomethyl aromatics described later. That is, the concentration of the aromatic nitrile during the hydrogenation reaction can be calculated in the form of a total concentration of the mass of the aromatic nitrile as a raw material, the organic solvent used in the hydrogenation reaction, the liquid components other than organic solvents such as water, the quaternary ammonium compound, and the metal hydroxide when blended.

[0082] (Aminomethyl aromatic)

[0083] The aminomethyl aromatic obtained by the production method of the present invention has an aminomethyl group bonded to an aromatic ring (benzene ring), and the amount of the aminomethyl group is preferably 1 or 2, and more preferably 2.

[0084] In addition, other substituents may be bonded to the aromatic ring.

[0085] Specific examples of the aminomethyl aromatic group include benzylamine and xylylenediamine, and xylylenediamine is preferred.

[0086] Xylylenediamine exists in three isomers, namely, o-xylylenediamine, m-xylylenediamine, and p-xylylenediamine. Among them, m-xylylenediamine and p-xylylenediamine are preferred, and p-xylylenediamine is more preferred.

[0087] These isomers of xylylenediamine can be obtained by the production method of the present invention using the corresponding dicyanobenzene as a raw material.

[0088] (Method for producing aminomethyl aromatic compounds)

[0089] In the method for producing aminomethyl aromatics of the present invention, an aromatic nitrile is hydrogenated in an organic solvent containing a polar organic solvent having a solubility parameter (SP value) of 9 or more in the presence of a quaternary ammonium compound, at least one metal hydroxide selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and a hydrogenation catalyst.

[0090] In the present production method, the order of mixing the raw materials and the like is not particularly limited, but it is preferred that the organic solvent, the quaternary ammonium compound, the metal hydroxide, and the hydrogenation catalyst are placed in a pressure vessel and hydrogen is introduced.

[0091] In order to prevent the hydrogenation catalyst from containing gases other than hydrogen such as air and water, it is preferred that the catalyst be immersed in water and then replaced with the above-mentioned organic solvent to be added as a catalyst slurry.

[0092] The reaction in the present production method may be carried out by either a batch method or a flow method, but a batch method is preferred.

[0093] In the present invention, the hydrogen used as the raw material for hydrogenation does not need to be specially purified, and industrial grade hydrogen may be used. The hydrogen pressure during the reaction is preferably 2.0 to 20.0 MPa, more preferably 3.0 to 15.0 MPa, and further preferably 5.0 to 10.0 MPa. When the hydrogen pressure is within the above range, the yield of the product is sufficient, a high-pressure pressure-resistant reactor is not required, and the cost can be reduced, so it is preferred.

[0094] The reaction temperature is preferably 20 to 150° C., more preferably 50 to 130° C., and further preferably 60 to 120° C. Within this range, the conversion rate of the aromatic dinitrile as a raw material is good, and the formation of by-products can be suppressed, so that the yield is improved.

[0095] The reaction time varies depending on the reaction temperature, hydrogen pressure, etc., and is generally 0.1 to 100 hours, preferably 0.5 to 10 hours, under the above conditions.

[0096] The obtained aminomethyl aromatics can be recovered by a known method. For example, it is preferred to separate the gaseous component and the liquid component from the reaction mixture at the end of the reaction, filter out the solid components such as the catalyst, and then distill and recover the liquid component. In addition, it is also preferred to further distill the obtained aminomethyl aromatics to improve the purity.

[0097] Example

[0098] The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples. It should be noted that in the following examples, gas chromatography was used for composition analysis.

[0099] <Gas chromatography (GC) analysis conditions>

[0100] Gas chromatography analysis was performed under the following conditions.

[0101] Instrument used: Gas chromatograph Nexis GC-2030 (manufactured by Shimadzu Corporation)

[0102] Column: DB-1 (length 30m, inner diameter 0.53mm, membrane thickness 1.5μm)

[0103] Detector: FID (H2 30mL / min, Air 300mL / min)

[0104] Carrier gas: He (constant flow: average linear velocity 38 cm / s)

[0105] Split ratio: 28.1

[0106] Inlet temperature: 300℃

[0107] Detector temperature: 300°C

[0108] Injection volume: 1.0 μL

[0109] Oven temperature: Raise the temperature from 50°C to 150°C at 5°C / min, then raise the temperature to 280°C at 10°C / min after reaching 150°C, and then keep it for 7 minutes. Then raise the temperature to 300°C at 10°C / min and keep it for 5 minutes.

[0110] <Conversion rate and yield>

[0111] The conversion rate of the raw material (terephthalonitrile) and the yield of the product (paraphenylenediamine) were measured by the internal standard method using the aforementioned gas chromatography, and calculated from the amounts of the raw material and the product in the reaction mixture after the hydrogenation reaction obtained in the Examples and Comparative Examples. Since diphenylmethane was used as the internal standard, a calibration curve was prepared in advance using terephthalonitrile and paraphenylenediamine solutions of known concentrations.

[0112] To 5.0 g of the reaction mixture, 0.5 g of diphenylmethane was added to prepare a sample, and the gas chromatography was measured under the above-mentioned conditions to determine the conversion rate and yield according to the following formula.

[0113] Conversion rate (mol%) = [1-(amount of terephthalonitrile (mol) in the reaction mixture) / (amount of terephthalonitrile (mol) at the time of introduction)] × 100

[0114] Yield (mol%) = (amount of p-xylylenediamine in the reaction mixture [mol]) / (amount of terephthalonitrile at the time of introduction [mol]) × 100

[0115] <Impurity Concentration>

[0116] The impurity concentration was calculated from the amount of impurities relative to the amount of the product after distillation obtained in Examples and Comparative Examples. The impurity concentration was determined by the simple area method using the above-mentioned gas chromatography.

[0117] The area of ​​the impurity is set as the total area of ​​the peaks having the same retention time as the main components of the impurities, 1-(4-(aminomethyl)phenyl)-N-methylmethanamine and 1-(4-(aminomethyl)phenyl)-N-ethylmethanamine (the total area of ​​the N-alkyl form), and the area of ​​the product is set as the area of ​​all peaks excluding the dilution solvent (the area of ​​the product), and the impurity concentration is calculated by the following formula.

[0118] Impurity concentration (%) = (total area of ​​N-alkyl forms) / (area of ​​product) × 100

[0119] <Example 1>

[0120] (Preparation of Catalyst Slurry)

[0121] The following operation uses a 50 mL beaker.

[0122] 5.90 g of (RANEY2724, manufactured by W.R. Grace) was placed in 30 mL of water and allowed to stand to allow the catalyst to settle. The supernatant was then removed by decantation. Then 30 mL of methanol was added and stirred for 1 minute. The supernatant was removed in the same manner. The above replacement in methanol was repeated 5 times to prepare a methanol slurry of the catalyst.

[0123] (Hydrogenation reaction)

[0124] In a 500 mL autoclave container, the methanol slurry of the above catalyst (catalyst amount 5.90 g) was added to adjust the total mass of methanol to 39.5 g. Then, 51.8 g of terephthalonitrile, 197.3 g of m-xylene, 0.76 g of a 25% tetramethylammonium hydroxide aqueous solution (2.1 mmol, 0.19 g as tetramethylammonium hydroxide), and 0.084 g (2.1 mmol) of sodium hydroxide were added.

[0125] The reactor was pressurized to 0.5 MPa with nitrogen and then returned to atmospheric pressure for nitrogen replacement. This nitrogen replacement was performed three times in total, and then hydrogen replacement was performed three times in the same manner using hydrogen.

[0126] The hydrogen pressure was set to 8.0 MPa, and the temperature was raised to 100°C while stirring at 1200 rpm. The temperature was maintained at 8.0 MPa while hydrogen was supplied, and the reaction was carried out at 100°C. The reaction was terminated when the hydrogen was consumed. After the reaction was completed, the reaction mixture was cooled to 50°C and filtered under a pressure of 0.4 MPa to filter out the catalyst and obtain a reaction mixture containing p-phenylenediamine as a reaction product. The same hydrogenation reaction was then carried out twice, and the reaction mixtures obtained from the three reactions were mixed and collected into one to obtain a reaction mixture used for distillation and measurement / calculation of conversion and yield. The above-mentioned conversion and yield were calculated using this reaction mixture.

[0127] (Distillation)

[0128] The p-xylylenediamine was distilled using a glass jacketed distillation column (distillation stage number: 10 stages). The reaction mixture was placed in a three-necked flask. The distillation was performed in four stages as shown below (1) to (4). The product obtained after the distillation was used to determine the impurity concentration.

[0129] (1) Pressure: 760 torr, reflux ratio: 5, bottom temperature: 74°C → 149°C, top temperature: start temperature 64°C. End when the top temperature reaches 139°C.

[0130] (2) Pressure: 300 torr, reflux ratio: 1, bottom temperature: start temperature 115°C, top temperature: 108°C. End when the bottom temperature reaches 170°C.

[0131] (3) Pressure: 10 torr, reflux ratio: 15, bottom temperature: 123° C. → 142° C., top temperature: 139° C. The reaction was terminated after 10% by mass of the initial reaction mixture was distilled off.

[0132] (4) Pressure: 10 torr, reflux ratio: 1, bottom temperature: start temperature 142°C, top temperature: 139°C. The process ends when the bottom temperature reaches 155°C.

[0133] <Example 2>

[0134] The same operation as in Example 1 was performed except that 0.67 g of 35% tetraethylammonium hydroxide aqueous solution (1.6 mmol, 0.19 g in terms of tetraethylammonium hydroxide) was used instead of 25% tetramethylammonium hydroxide aqueous solution and the amount of sodium hydroxide was changed to 0.096 g (2.4 mmol). The hydrogenation reaction was performed three times to obtain a reaction mixture. The reaction mixture was used to determine the aforementioned conversion rate and yield. In addition, the aforementioned reaction mixture was used to perform distillation by the same operation as in Example 1 to obtain a product. The aforementioned impurity concentration was determined using the product obtained after distillation.

[0135] <Comparative Example 1>

[0136] The same operation as in Example 1 was performed except that sodium hydroxide was not used, and hydrogenation reaction was performed three times to obtain a reaction mixture. The reaction mixture was used to determine the aforementioned conversion rate and yield. In addition, the aforementioned reaction mixture was used to perform distillation by the same operation as in Example 1 to obtain a product. The product obtained after distillation was used to determine the aforementioned impurity concentration.

[0137] [Table 1]

[0138] Table 1

[0139]

[0140] The results in Table 1 show that, when the production method of the example is used, p-xylylenediamine can be obtained at a high yield, and further, the impurity concentration in the product is low, and the generation of impurities can be suppressed.

Claims

1. A method for producing an aminomethyl aromatic, wherein: Aromatic nitrile is hydrogenated in an organic solvent containing a polar organic solvent having a solubility parameter (SP value) of 9 or more in the presence of a quaternary ammonium compound, at least one metal hydroxide selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and a hydrogenation catalyst, wherein the organic solvent further contains a hydrocarbon solvent, the quaternary ammonium compound is tetraalkylammonium hydroxide, and the hydrogenation catalyst is a metal catalyst containing cobalt. The aromatic nitrile is dicyanobenzene, the aminomethyl aromatic is xylylenediamine, The polar organic solvent is alcohol, and the hydrocarbon solvent is toluene, ethylbenzene, xylene or trimethylbenzene.

2. The method for producing aminomethyl aromatics according to claim 1, wherein The metal hydroxide is one or more selected from the group consisting of sodium hydroxide and potassium hydroxide.

3. The method for producing aminomethyl aromatics according to claim 1 or 2, wherein: The mass ratio of the hydrocarbon solvent to the polar organic solvent in the organic solvent, ie, hydrocarbon solvent / polar organic solvent, is 60 / 40 to 99 / 1.

4. The method for producing aminomethyl aromatics according to claim 1 or 2, wherein The total amount of the hydrocarbon solvent and the polar organic solvent in the organic solvent is 90 to 100% by mass.

5. The method for producing aminomethyl aromatics according to claim 1 or 2, wherein: The amount of the quaternary ammonium compound is 1 to 20% by mass relative to the hydrogenation catalyst.

6. The method for producing an aminomethyl aromatic according to claim 1 or 2, wherein: The amount of the metal hydroxide is 1 to 20% by mass relative to the hydrogenation catalyst.

7. The method for producing an aminomethyl aromatic according to claim 1 or 2, wherein: The molar ratio of the quaternary ammonium compound to the metal hydroxide, i.e., quaternary ammonium compound / metal hydroxide, is 70 / 30 to 20 / 80.

8. The method for producing an aminomethyl aromatic according to claim 1 or 2, wherein: The organic solvent does not contain liquid ammonia.

9. The method for producing aminomethyl aromatics according to claim 1 or 2, wherein The water content in the organic solvent is 5 mass % or less.

10. The method for producing an aminomethyl aromatic compound according to claim 1 or 2, wherein: The aromatic nitrile is terephthalonitrile.

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