JP2010059092A - Process for producing 1,3-diamino-4,6-dibenzyloxybenzene and salt thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce 4,6-diaminoresorcinol and its salt by safely producing 1,3-diamino-4,6-dibenzyloxybenzene and its salt and debenzylating them. <P>SOLUTION: The 4,6-diaminoresorcinol and its salt are produced by subjecting m-phenylenedihydroxylamine to Bamberger rearrangement in the presence of benzyl alcohol and an acid to obtain 1,3-diamino-4,6-dibenzyloxybenzene and its salt and debenzylating them. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing 1,3-diamino-4,6-dibenzyloxybenzene and a salt thereof. 4,6-Diaminoresorcinol obtained by debenzylation of 1,3-diamino-4,6-dibenzyloxybenzene is a polybenzobisoxazole (PBO) monomer having many excellent properties, , One of the important raw materials. PBO provides super fibers far superior to existing aromatic polyamide fibers in strength, elastic modulus, and heat resistance.

  Conventionally, as a method for producing 4,6-diaminoresorcinol, there is a method using halobenzene as a raw material, a method of nitration of trichlorobenzene (for example, see Patent Document 1), a method of nitration of dihalobenzene and hydrolysis with an alkali. (For example, refer to Patent Documents 2 to 4). However, in these methods, trichlorobenzene and its nitrate are highly toxic and have problems such as causing skin irritation, which is not preferable for the safety of workers. Moreover, in the method using dihalobenzene as a starting material, undesired by-products such as isomers and 1,3-dihalo-2,4,6-trinitrobenzene are generated, and yield reduction, safety management, etc. There was a problem. In addition, there are industrial problems such as a large number of steps, complicated operations and high costs.

  A method for directly producing 4,6-diaminoresorcinol from inexpensive m-dinitrobenzene is also known. For example, m-phenylenedihydroxylamine is obtained by a reduction reaction with a metal powder reducing agent in a heterogeneous two-layer reaction medium composed of an inorganic electrolyte aqueous solution and an organic solvent using m-dinitrobenzene as a starting material, and an acid catalyst is used. The example which is performing rearrangement reaction is mentioned (for example, refer patent document 5). However, in the reaction system, 4,6-diaminoresorcinol is very sensitive and unstable to oxidants such as oxygen, so that there is a problem of significant yield reduction.

  On the other hand, 1,3-diamino-4,6-dibenzyloxybenzene, which is an intermediate of 4,6-diaminoresorcinol, is produced by dinitrating 1,3-dichlorobenzene and then acting on sodium benzylate. The method of making it etherify is known (for example, refer patent document 6, 7). However, in the nitration reaction, impact-sensitive polynitrates are easily produced as by-products, which presents industrial risks and requires careful attention from a safety standpoint. In addition, there is a problem of yield reduction due to isomer formation. Furthermore, since m-dichlorobenzene is relatively expensive, it is difficult to say that it is an economical production method.

JP-A-2-500743 JP-A-1-238561 JP 7-233127 A JP-A-8-73417 JP 11-49732 A JP-A-3-24038 JP-A-8-208567

  Thus, there is no problem in safety and a method for producing 1,3-diamino-4,6-dialkoxybenzene having a stable molecular structure, and production of 4,6-diaminoresorcinol using this as a synthetic intermediate A method was sought.

  The present inventors have solved the above-mentioned problems, obtained 1,3-diamino-4,6-dialkoxybenzene from an inexpensive raw material, and synthesized 4,6-diaminoresorcinol using this as an intermediate. We studied diligently. That is, m-phenylenedihydroxylamine (PDHA) undergoes rearrangement [Bamberger rearrangement] reaction in the presence of benzyl alcohol and acid to produce 1,3-diamino-4,6-dibenzyloxybenzene (DAR-OBn). It was found that can be obtained. Furthermore, the obtained 1,3-diamino-4,6-dibenzyloxybenzene was debenzylated to find that 4,6-diaminoresorcinol (DAR) or a salt thereof could be synthesized, and the present invention was completed.

  An object of the present invention is to provide a process for producing 1,3-diamino-4,6-dibenzyloxybenzene and a salt thereof which are important intermediates.

  The step of synthesizing 1,3-diamino-4,6-dibenzyloxybenzene from m-phenylenedihydroxylamine is a rearrangement step, and 1,6-diamino-4,6-dibenzyloxybenzene is converted to 4,6-diaminoresorcinol. The step of synthesizing is a debenzylation step.

  Hereinafter, the present invention will be described in detail.

  First, the dislocation process will be described.

  The addition amount of benzyl alcohol used for the rearrangement reaction of m-phenylene dihydroxylamine is at least twice the equivalent to the starting material m-phenylene dihydroxylamine, and is usually based on 1 part by weight of m-phenylene dihydroxylamine. 10 to 60 parts by weight. It can also be used as a solvent. Benzyl alcohol is preferably degassed to remove oxides such as dissolved oxygen.

  The acid used for the rearrangement reaction acts as a catalyst. As the acid catalyst used in the present invention, at least one acid selected from the group consisting of hydrochloric acid, phosphoric acid, sulfonic acid, and carboxylic acid can be used.

  The sulfonic acid referred to in the present invention is a compound containing a sulfonic acid group in the structure, and is not particularly limited. For example, inorganic sulfonic acids such as sulfuric acid, fluorosulfonic acid, and chlorosulfonic acid, methanesulfonic acid Ethanesulfonic acid, propanesulfonic acid, allylsulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, heptanesulfonic acid, octanesulfonic acid, nonanesulfonic acid, decanesulfonic acid, dodecanesulfonic acid, tetradecanesulfonic acid, DL -Aliphatic sulfonic acids such as camphor-10-sulfonic acid, trifluoromethanesulfonic acid, aminomethanesulfonic acid, 2-bromoethanesulfonic acid, 2- (N-morpholino) ethanesulfonic acid, N, N'-bis (2 -Hydroxyethyl) -2-aminoethane Phosphonic acid, N- (2-acetamido) -2-aminoethanesulfonic acid, N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid, N-cyclohexyl-2-aminoethanesulfonic acid, 3-aminopropane Sulfonic acid, N-cyclohexyl-2-hydroxy-3-aminopropanesulfonic acid, 3-chloro-2-hydroxypropanesulfonic acid, 3- (N-morpholino) propanesulfonic acid, 2-hydroxy-3-morpholinopropanesulfonic acid Substituted aliphatic sulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid, 2-amino-5-methylbenzene-1-sulfonic acid, taurine, benzenesulfonic acid, p-chlorobenzenesulfonic acid, p-phenolsulfonic acid Guaiacol-4-sulfonic acid, p-styrene Acid, phenylhydrazine-p-sulfonic acid, 1,2-benzenedisulfonic acid, 1,3-benzenedisulfonic acid, 1,4-benzenedisulfonic acid, m-toluenesulfonic acid, p-toluenesulfonic acid, 2,4 -Dimethylbenzenesulfonic acid, 2,5-dimethylbenzenesulfonic acid, 2-mesitylenesulfonic acid, p-ethylbenzenesulfonic acid, o-aminobenzenesulfonic acid, m-xylidine-6-sulfonic acid, 4-amino-2-methyl Benzenesulfonic acid, 4-amino-chlorotoluene-5-sulfonic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, 1-naphthol-2- Sulfonic acid, 1-naphthol-4-sulfonic acid, 1-naphthol-8-sulfonic acid 2-naphthol-6-sulfonic acid, 2,3-dihydroxynaphthalene-6-sulfonic acid, 2-amino-5-naphthol-7-sulfonic acid, 8-amino-1-naphthol-3,6-disulfonic acid, 8-aminonaphthalene-1,3,6-trisulfonic acid, 8-anilino-1-naphthalenesulfonic acid, 4,4′-diaminostilbene-2,2′-disulfonic acid, 7-iodo-8-hydroxyquinoline- Aromatic sulfonic acids such as 5-sulfonic acid, diphenylamine-4-sulfonic acid, 1-pyrenesulfonic acid, sulfanilic acid, methallylic acid, Nafion (manufactured by DuPont), sulfonic acid type amberlist, sulfonic acid type amberlite (above) , Rohm and Haas), sulfonic acid type Diaion (Mitsubishi Chemical), sulfonic acid type duolite ( Sulfonic acid type cation exchange resins such as sulfonic acid type dowex (manufactured by Dow Chemical Co., Ltd.), sulfonic acid type purolite (manufactured by Purolite), sulfonic acid type levacit (manufactured by Bayer), etc. It is done.

  The carboxylic acid referred to in the present invention is a compound containing a carboxyl group in the structure and is not particularly limited. For example, formic acid, acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monofluoroacetic acid, difluoroacetic acid , Trifluoroacetic acid, bromoacetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, 2-methylpropanoic acid, 2-fluoropropanoic acid, 2-bromopropanoic acid, 2,2-dimethylpropanoic acid, 2-methylbutanoic acid, 2,2-dimethylbutanoic acid, 3-methylbutanoic acid, 2,3-dimethylbutanoic acid, 3-methylbutanoic acid, 2,3-dimethylbutanoic acid, 3,3 -Dimethylbutanoic acid, succinic acid, acetic anhydride, 1,3-propanedioic acid, 1,4-butanedioic acid, 1,5-pentanedioic acid Aliphatic carboxylic acids such as 1,6-hexanedioic acid, fumaric acid, maleic acid, maleic anhydride, 2-methyl-1,3-propanedioic acid, 2,2-dimethyl-1,3-propanedioic acid, Benzoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 4-acetylbenzoic acid, o-fluorobenzoic acid, phthalic acid, 1,2,4,5-benzenetetracarboxylic acid, 1 -Aromatic carboxylic acids such as naphthoic acid, 3-hydroxy-2-naphthoic acid, 4-biphenylcarboxylic acid, 4,4'-biphenyldicarboxylic acid, 9-anthracenecarboxylic acid, 2-quinolinecarboxylic acid, 4-pyridinecarboxylic acid Examples include acids.

  Of these, sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, propionic acid, trifluoroacetic acid, methanesulfonic acid, and p-toluenesulfonic acid are particularly effective in the present invention. In view of safety and economy, the use of sulfuric acid is particularly effective.

  The amount of the acid used is required to be 2 times or more equivalent to m-phenylenedihydroxylamine which is a starting material, and 4 to 20 times equivalent is preferable.

  In the rearrangement step, tin (II) chloride can be added as an antioxidant for 1,3-diamino-4,6-dibenzyloxybenzene. Tin (II) chloride includes an anhydride and a dihydrate, and both can be used. The amount used is 0.01 to 20 parts by weight, preferably 0.1 to 5 parts by weight, based on 1 part by weight of m-phenylenedihydroxylamine.

  An organic solvent can be used in the rearrangement step. Usually, the organic solvent inert to the reaction is not particularly limited, and examples thereof include ether organic solvents and aromatic organic solvents. Specifically, ether-based organic solvents such as diethyl ether, isopropyl ether, t-butyl methyl ether, dibenzyl ether, cyclopentyl methyl ether, 1,2-dimethoxyethane, tetrahydrofuran and dioxane, and aromatics such as benzene, toluene and xylene Group organic solvents.

  The reaction temperature can be in the range of 0 to 150 ° C, but is preferably in the range of 20 to 120 ° C.

  The reaction can be performed under normal pressure or under pressure, but may be performed under an inert gas atmosphere such as nitrogen or argon, a hydrogen atmosphere, or both.

  The post-treatment after the rearrangement reaction is not particularly limited, but after completion of the rearrangement reaction, water is added to the reaction solution, and extraction is performed by adding ether or the like as necessary, and neutralized to pH 7-8. Further, ethyl acetate is added to the neutralized solution for extraction, and the oil layer is concentrated. The obtained residue is dissolved in a tetrahydrofuran-hexane solution and purified by reprecipitation to obtain 1,3-diamino-4,6-dibenzyloxybenzene.

  In addition, although m-phenylene dihydroxylamine which is a raw material of a rearrangement process is not specifically limited, For example, it is compoundable by the method of reduce | restoring m-dinitrobenzene.

  In order to reduce m-dinitrobenzene to produce m-phenylenedihydroxylamine, for example, a reducing agent or a reduction catalyst can be used.

  When using a reducing agent, although not particularly limited, for example, metal powder such as zinc, iron, tin, etc. can be used. Zinc powder is preferred. As an addition amount, in order to make m-dinitrobenzene which is a raw material lose | disappear, 4 times equivalent or more is required with respect to m-dinitrobenzene, and 6.0-8.0 times equivalent is preferable. The metal powder reducing agent reduces the nitro group to a hydroxylamino group, and the reducing agent itself becomes a metal oxide and remains in the reaction system.

  When a large excess of the metal powder reducing agent is added, the overreduction is promoted and the yield of m-phenylene dihydroxylamine is lowered. In this case, overreduction means that m-phenylenedihydroxylamine, which is a reaction intermediate produced in the reduction reaction, is further reduced to produce m-phenylenediamine.

  The method of charging the metal powder reducing agent is not particularly limited, but it is preferable to add gradually. If the addition rate is too high, overreduction occurs and the yield of m-phenylene dihydroxylamine is reduced. In addition, with the addition of the metal powder reducing agent, it is preferable to increase the stirring speed to promote the reduction reaction.

  When using metal powder as a reducing agent, it is necessary to carry out in the presence of water. The amount of water added is at least twice the equivalent of m-dinitrobenzene, and when used as a solvent. Is 5 to 20 parts by weight per 1 part by weight of m-dinitrobenzene.

  On the other hand, when a reduction catalyst is used to reduce m-dinitrobenzene, the reduction catalyst may be a single group VIII metal such as nickel, cobalt, iron, palladium, rhodium, ruthenium, platinum, or carbon, alumina, silica. Catalysts supported on zeolite, magnesia and other supports can be used. Among these catalysts, platinum-carbon in which platinum is supported on carbon and palladium-carbon supported catalyst in which palladium is supported on carbon are particularly preferable. The amount of the catalyst used is preferably 0.1 to 30% by weight as a 1 to 5% metal-supported catalyst with respect to m-dinitrobenzene.

  The reaction is carried out under a hydrogen pressure atmosphere, and preferably 0.1 to 0.3 MPa.

  An organic solvent can be used in the reduction step. Usually, the organic solvent inert to the reaction is not particularly limited, and examples thereof include alcohol-based organic solvents, ether-based organic solvents, and aromatic-based organic solvents. Specifically, methanol, ethanol, isopropyl alcohol, diethyl ether, isopropyl ether, t-butyl methyl ether, dibenzyl ether, cyclopentyl methyl ether, 1,2-dimethoxyethane, tetrahydrofuran, dioxane, benzene, toluene, xylene, etc. Can be mentioned. Of these organic solvents, tetrahydrofuran is particularly preferred. The usage-amount of an organic solvent is 5-50 weight part with respect to 1 weight part of m-dinitrobenzene which is a raw material, Preferably it is 10-20 weight part.

  The reaction can be performed under normal pressure or under pressure, but may be performed under an inert gas atmosphere such as nitrogen or argon, a hydrogen atmosphere, or both.

  When a metal powder reducing agent is used, the reaction temperature can be in the range of -10 to 80 ° C, preferably in the range of 0 to 20 ° C. On the other hand, when using a metal catalyst, the reaction temperature can use the range of 0-150 degreeC.

  The post-treatment after the reduction step is not particularly limited, but after completion of the reduction reaction, the reaction solution is filtered to remove solids and used as it is in the next step, or the solvent is immediately removed under reduced pressure. It can also be used immediately in the next step after being distilled off.

  Next, the debenzylation process will be described.

  The debenzylation reaction of 1,3-diamino-4,6-dibenzyloxybenzene is not particularly limited, but 4,6-diaminoresorcinol is synthesized by catalytic hydrogenation in a solvent using a noble metal catalyst. Is possible.

  Examples of the noble metal catalyst used include palladium, platinum, rhodium, ruthenium and the like, and these single group VIII metals or catalysts supported on carbon, alumina, silica, zeolite, magnesia and other supports can be used. Among these catalysts, platinum-carbon in which platinum is supported on carbon and palladium-carbon supported catalyst in which palladium is supported on carbon are particularly preferable. The amount of the catalyst used varies depending on the reaction conditions, but is 0.1 to 30% by weight, preferably 0.1 to 5% as a metal-supported catalyst with respect to 1,3-diamino-4,6-dibenzyloxybenzene. 2 to 10% by weight.

  The reaction is carried out under a hydrogen pressure of 0.1 to 3.0 MPa in a temperature range of 20 to 100 ° C., preferably in a temperature range of 20 to 80 ° C.

  As the solvent, an organic solvent inert to the reaction can be usually used, and is not particularly limited, and examples thereof include alcohol-based organic solvents, ether-based organic solvents, and aromatic-based organic solvents. Specifically, methanol, ethanol, isopropyl alcohol, butanol, isobutanol, diethyl ether, isopropyl ether, t-butyl methyl ether, dibenzyl ether, cyclopentyl methyl ether, 1,2-dimethoxyethane, tetrahydrofuran, dioxane, benzene, Toluene, xylene and the like, or a mixture thereof can be mentioned. Of these organic solvents, tetrahydrofuran is particularly preferred.

  The amount of the organic solvent used is 1 to 100 parts by weight, preferably 2 to 20 parts by weight with respect to 1 part by weight of 1,3-diamino-4,6-dibenzyloxybenzene. The organic solvent is preferably used after being deaerated.

  1,3-diamino-4,6-dibenzyloxybenzene and a salt thereof can be safely produced by subjecting m-phenylenedihydroxylamine to a Bamburger rearrangement reaction in the presence of benzyl alcohol and an acid. Furthermore, 4,6-diaminoresorcinol and its salt can be manufactured by these debenzylation.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these.

Example 1
In a 50 mL three-necked flask, 0.80 g (4.8 mmol) of m-dinitrobenzene and 2.50 g (47 mmol) of ammonium chloride were added and dissolved in a mixed solvent of 15 g of water and 13 g of tetrahydrofuran. Under ice-cooling, 2.3 g (35 mmol) of zinc powder was added little by little over 15 minutes with vigorous stirring. After the addition was completed, stirring was continued for another 30 minutes at the same temperature. After completion of the reaction, the reaction solution was filtered to remove solids, and the solvent was distilled off under vacuum to obtain a residue. To this black residue, 40 g of benzyl alcohol and 1.0 g of tin (II) chloride were added, and the atmosphere in the flask was replaced with nitrogen under reduced pressure. While vigorously stirring, 7.8 g (80 mmol) of concentrated sulfuric acid was added dropwise, and the mixture was heated and stirred at 50 ° C. for 2 hours under a nitrogen atmosphere. After cooling to room temperature, 1.0 g of tin (II) chloride was further added and stirred for 10 minutes, and the reaction solution was added to 100 mL of water. Next, the aqueous layer was washed with 150 mL of diethyl ether and separated. The mixture was neutralized with 28% aqueous ammonia and extracted with ethyl acetate. After drying over magnesium sulfate, the solvent was distilled off under reduced pressure, the residue was dissolved in a tetrahydrofuran-hexane solution, and reprecipitation resulted in 1,3-diamino-4,6-dibenzyloxybenzene (0.78 g, 51 %). The compound was identified by mass spectrometry and nuclear magnetic resonance analysis.

Mass spectrometer: MICRO-TOF manufactured by Bruker Daltonics
Nuclear magnetic resonance analyzer: Gemini200 manufactured by Varian
Comparative Examples 1-2
The same procedure as in Example 1 was carried out except that water was used in Comparative Example 1 and methanol was used as a reaction solvent instead of benzyl alcohol in Comparative Example 2. In Comparative Examples 1 and 2, benzoquinones were obtained, but 1,3-diamino-4,6-dialkoxybenzenes were not obtained.

Reference example 1
0.50 g (2.50 mmol) of 1,3-diamino-4,6-dibenzyloxybenzene was added to 20 mL of tetrahydrofuran. A palladium catalyst supporting 5% by weight of palladium on activated carbon was added to 0.25 g of the mixture. The mixture was hydrogenated at 75 ° C. under a hydrogen pressure of 0.35 MPa until no hydrogen was absorbed. Cool to room temperature, add 5 mL hydrochloric acid (37%) and filter the mixture with suction. Further, 5 mL of hydrochloric acid (37%) in which 125 mg of tin (II) chloride was dissolved was added, and the mixture was stirred for 1 hour and then ice-cooled. The precipitated crystals were separated by filtration and dried to obtain 4,6-diaminoresorcin dihydrochloride (0.38 g, 71%).

Claims (6)

A method for producing 1,3-diamino-4,6-dibenzyloxybenzene and a salt thereof, wherein a rearrangement reaction of m-phenylenedihydroxylamine with Bamberger is carried out in the presence of benzyl alcohol and an acid. The 1,3-diamino-4,6-dibenzyloxybenzene according to claim 1, wherein the acid is at least one acid selected from the group consisting of hydrochloric acid, phosphoric acid, sulfonic acid, and carboxylic acid. And a method for producing the salt thereof. The 1,3-diamino- of claim 2, wherein the sulfonic acid is sulfuric acid, methanesulfonic acid or p-toluenesulfonic acid and the carboxylic acid is formic acid, acetic acid, propionic acid or trifluoroacetic acid. A process for producing 4,6-dibenzyloxybenzene and its salts. The method for producing 1,3-diamino-4,6-dibenzyloxybenzene and a salt thereof according to claim 1, wherein the acid is sulfuric acid. The method for producing 1,3-diamino-4,6-dibenzyloxybenzene and a salt thereof according to claim 1, wherein the rearrangement reaction is carried out at a reaction temperature of 0 to 150 ° C. 6. The method for producing 1,3-diamino-4,6-dibenzyloxybenzene and a salt thereof according to claim 1, wherein the rearrangement reaction is carried out in an inert gas atmosphere and / or a hydrogen atmosphere.