JP2904038B2 - Process for producing 4,6-diaminoresorcinol and its precursor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing 4,6-diaminoresorcinol or a salt thereof. The present invention also relates to a method for producing a compound which can be a precursor of 4,6-diaminoresorcinol or a salt thereof. 4,6-diaminoresorcinol or a salt thereof can be a monomer of polybenzobisoxazole, and this polybenzobisoxazole has high strength and high elastic modulus, and is excellent in heat resistance and chemical resistance. It is known as a polymer having properties (for example, Japanese Patent Publication No. 61-501452 (= WO 85/04178)).
And JP-A-2-229143).

[0002]

2. Description of the Related Art Conventionally, the following method has been known as a method for producing 4,6-diaminoresorcinol.

1) Ber. Dtsch. Chem. Ges., 16 , 551 (1
883), a method of reducing 4,6-dinitroresorcinol obtained by dinitrating resorcinol acetate, 2) a method described in JP-A-2-500743 (= EP-A-266,222). Thus, 1,2,3-trichlorobenzene is nitrated to obtain 2,3,4-trichloro-1,5-dinitrobenzene, and the trichlorodinitrobenzene is hydrolyzed to give 2-chloro-4, Method for obtaining 6-dinitroresorcinol and reducing it; and 3) converting 4,6-bis (phenylazo) resorcinol to chloride as described in Ber. Dtsch. Chem. Ges., 17 , 876 (1884). A method of decomposing with tin and hydrochloric acid into 4,6-diaminoresorcinol.

In the method 1), there is a risk that the intermediate 4,6-dinitroresorcinol explodes due to strong impact or rapid heating,
Since the yield of 6-dinitroresorcinol was as low as about 30%, it was not sufficient for an industrial production method.
In addition, 2,3,4-trichloro-1,5-dinitrobenzene and 2-chloro-4,6-dinitroresorcinol, which are intermediates in the method of 2), may also explode due to strong impact or rapid heating. Therefore, this method was not necessarily sufficient as an industrial production method. Furthermore, both methods 1) and 2) produce a large amount of waste acid as a by-product during nitration, and require an enormous amount of a neutralizing base to treat waste acid. It was not satisfactory. On the other hand, the method 3) of decomposing 4,6-bis (phenylazo) resorcinol with tin chloride and hydrochloric acid requires the use of a large amount of expensive tin chloride as a reducing agent.
After all, it was not satisfactory as an industrial manufacturing method.

Further, 4,6-bis (phenylazo) resorcinol used as a raw material in the method of 3) is disclosed in Helv. Chim.
As described in Cta., 41 , 1816 (1958), it is known that the compound can be selectively synthesized by coupling resorcinol and a benzenediazonium salt in a buffer solution having a pH of 9 or more. However, the method described here has a problem that the production efficiency is extremely poor because a buffer solution of 1000 ml is used for 0.01 mol (1.1 g) of resorcinol. According to the supplementary tests of the present inventors, when the amount of the buffer solution used was reduced, impurities such as 2,4-bis (phenylazo) resorcinol and 2,4,6-tris (phenylazo) resorcinol were produced as by-products. It was confirmed that the property was reduced. Furthermore, the use of a buffer solution is not industrially advantageous because it leads to an increase in the types of production materials.

[0006]

Accordingly, an object of the present invention is to provide an industrially advantageous method for producing 4,6-diaminoresorcinol or a salt thereof without passing through a nitro compound which may explode by impact or heating. To manufacture.

Another object of the present invention is to recover the 4,6-diaminoresorcinol thus produced with high purity in the form of a mineral acid salt.

Another object of the present invention is to provide a precursor of 4,6-diaminoresorcinol or a salt thereof produced by such a method, 4,6-bis (arylazo).
It is to produce resorcinol with good selectivity and efficiently.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that 4,6-bis (arylazo) resorcinol is used as a raw material to undergo hydrogenolysis under specific conditions. Have found that 4,6-diaminoresorcinol or a salt thereof can be synthesized. That is, the present invention provides a method for producing 4,6-diaminoresorcinol or a salt thereof by subjecting 4,6-bis (arylazo) resorcinol to a hydrogenolysis reaction in a solvent in the presence of a metal catalyst. It is.

[0010] The 4,6-bis (arylazo) resorcinol, which is a raw material for this reaction, is usually obtained by diazotizing an arylamine to form an aryldiazonium salt, and coupling this with resorcinol.
Accordingly, the present invention also provides an aryldiazonium salt obtained by diazotizing an arylamine, which is subjected to a coupling reaction with resorcinol to obtain 4,6-bis (arylazo) resorcinol, which is obtained in a solvent in the presence of a metal catalyst. A method for producing 4,6-diaminoresorcinol or a salt thereof by hydrogenolysis is also provided.

In addition, it has been found that, in particular, 4,6-diaminoresorcinol obtained by any of the above methods can be recovered in the form of a high-purity mineral acid salt by performing a specific treatment. Therefore, the present invention further comprises crystallizing the 4,6-diaminoresorcinol obtained by the above method, separating it from the arylamine formed by the hydrogenolysis reaction, and then dissolving and crystallizing by adding a mineral acid. The present invention also provides a method for producing 4,6-diaminoresorcinol mineral acid salt.

Further, 4,6-bis (arylazo) resorcinol, which is a raw material in the above-mentioned method, is obtained by diazotizing an arylamine to form an aryldiazonium salt with a resorcinol in a specific solvent under controlled pH. It has been found that the ring can be efficiently manufactured with high positional selectivity. Therefore, from another aspect, the present invention provides a method for reacting an aryldiazonium salt obtained by diazotizing an arylamine with resorcinol at pH 9 or higher in a solvent containing an organic solvent miscible with water to obtain 4,6.
Also provided is a method for producing bis (arylazo) resorcinol.

The reaction according to the invention when starting from arylamines can be represented by the following reaction scheme:

[0014]

(Wherein, X represents an aryl group)

Hereinafter, the reaction of each step will be described sequentially starting from an arylamine. However, the method of the present invention is not necessarily limited to a method starting from an arylamine, and is described in the claims. It will be understood by those skilled in the art that, within the stated range, it is possible to start at and end at any stage.

The arylamine includes, for example, aniline, aniline in which hydrogen of an aromatic ring is substituted, naphthylamine, naphthylamine in which hydrogen of an aromatic ring is substituted, and the like. Examples of the group which may be substituted on the aromatic ring of aniline and naphthylamine include, for example, a lower alkyl group, a lower alkoxy group, an unsubstituted or substituted phenyl group, an unsubstituted or substituted phenoxy group, a hydroxyl group, Examples include a substituted or substituted amino group, carboxyl group, sulfonic acid group, halogen atom and the like. Specific examples of the lower alkyl group include methyl, ethyl,
n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl and the like, and specific examples of the lower alkoxy group are methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy,
Isobutoxy, tert-butoxy and the like. Examples of the group which may be further substituted with a phenyl group and a phenoxy group which are substituents of aniline or naphthylamine include, for example, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxy group having 1 to 4 carbon atoms, a halogen atom and the like. No. The amino group which is a substituent of aniline or naphthylamine is
Unsubstituted or mono- or di-substituted groups which may be substituted with an amino group include, for example, lower alkyl groups such as methyl, ethyl, n-propyl and isopropyl. No. The aromatic ring of aniline or naphthylamine may be substituted by one of the substituents described above or by the same or different substituent 2
It may be replaced by more than one.

Among the arylamines exemplified above,
Unsubstituted aniline or naphthylamine or lower alkyl group, lower alkoxy group, phenoxy group, hydroxyl group, amino group, N-substituted amino group, N, N-di-
Aniline or naphthylamine substituted with an electron donating group such as a substituted amino group is preferred. More preferred arylamines include aniline and p-anisidine. In particular, by using p-anisidine, regioselectivity and production efficiency in the subsequent coupling reaction can be further improved.

In obtaining the aryldiazonium salt by diazotizing the arylamine, generally, for example, the following method can be employed.

(A) dissolving the arylamine in a thin inorganic acid or suspending it in a solvent in the form of an inorganic acid salt and reacting with an alkali metal nitrite; (b) reacting the arylamine with nitrosylsulfuric acid (C) dissolving or suspending an arylamine in dilute sulfuric acid and reacting it with a mixed gas containing nitric oxide and oxygen, or (d) reacting an arylamine with nitrites in an organic solvent. How to let.

The inorganic acid used in the method (a) is preferably hydrochloric acid or sulfuric acid, and the alkali metal nitrite is preferably sodium nitrite or potassium nitrite. Each of the reactions (a) to (c) is carried out in a solvent, and usually, only water or a mixed solvent composed of water and an organic solvent miscible with water is used, but only water or water and methanol are used. Is preferably used. Each of the above-mentioned reactions (a) to (d) may be performed in either a batch system or a continuous system.

The aryldiazonium salt thus obtained is obtained by a coupling reaction with resorcinol.
It leads to 4,6-bis (arylazo) resorcinol. The aryldiazonium salt obtained by diazotization is usually 1.8 to 1.8% based on the amount of resorcinol.
It is preferably used in the range of 2.5 mole times, more preferably 1.9 to 2.2 times. When the amount of the aryldiazonium salt exceeds 2.5 mol times with respect to resorcinol,
When 2,4,6-tris (arylazo) resorcinol is produced as a by-product and when the amount is less than 1.8 mol times, a large amount of 4-mono (arylazo) resorcinol which is an intermediate of the coupling reaction remains unreacted. Therefore, the above range is preferable.

The coupling reaction is usually performed in a solvent. Examples of the solvent used herein include those containing not only water but also an organic solvent miscible with water. In particular, using a mixed solvent composed of water and an organic solvent miscible with water can improve the volumetric efficiency of the coupling reaction, which is industrially advantageous. Examples of water-miscible organic solvents include lower alcohols such as methanol, ethanol and 2-propanol, lower ketones such as acetone, cyclic ethers such as dioxane and tetrahydrofuran, N, N-dimethylformamide,
An aprotic polar solvent such as N-methylpyrrolidone is exemplified, and any of these can be used alone or in combination of two or more. In particular, a mixed solvent of water and methanol is preferably used in the coupling reaction. When using a mixed solvent composed of water and an organic solvent miscible with water, the mixing ratio of both is
Although it depends on the type of the organic solvent, it is usually preferable that the amount of the organic solvent miscible with water is in the range of 5 to 90% by weight, particularly 20 to 90% by weight based on the total amount of the solvent. .

The amount of the solvent used varies depending on the type of the solvent and the mixing ratio with the organic solvent, and is not particularly limited. Any amount may be used as long as resorcinol can be dissolved during the reaction. Usually, 4-1000 to resorcinol
It is preferred that the solvent be present in a weight-fold range. In consideration of regioselectivity and volume efficiency at the time of coupling, it is more preferable that a mixed solvent composed of water and an organic solvent miscible with water be present in a range of 20 to 500 times by weight relative to resorcinol. .

The coupling reaction can be carried out, for example, by dropping an aryldiazonium salt into a solution of resorcinol dissolved in a solvent. In the case of such a method, it is preferable to add an alkali in accordance with the dropwise addition of the aryldiazonium salt and keep the pH of the reaction solution at 9 or more, particularly in the range of 9 to 14. Above all, it is more preferable to maintain the pH at 10 or higher, which is also within the range of 10 to 12. When the pH of the reaction solution is too low, the regioselectivity in the coupling reaction decreases, and the amount of 2,4-bis (arylazo) resorcinol that is a by-product increases. When the pH of the reaction solution becomes too high, by-products 2,
The production amount of 4,6-tris (arylazo) resorcinol is increased, and further, a tar component is easily generated by its decomposition.

Further, in order to suppress the by-product of 2,4,6-tris (arylazo) resorcinol and the by-product of tar component due to decomposition of the aryldiazonium salt, there is a method in which the coupling reaction is performed in two stages. . That is, to a solution in which resorcinol is dissolved in a solvent, the aryldiazonium salt is added dropwise in an amount of 0.8 to 1.1 mole times, preferably 0.9 to 1.0 mole times, based on the amount of resorcinol, After 4-mono (arylazo) resorcinol is formed, and if necessary, the 4-mono (arylazo) resorcinol is separated by an operation such as filtration, the aryldiazonium is again added to a liquid in which the 4-mono (arylazo) resorcinol is suspended. The salt was added dropwise, and the total amount with the aryldiazonium salt used in the first-stage coupling reaction was 1.8 to 1.8% based on the initial amount of resorcinol.
In this method, 4,6-bis (arylazo) resorcinol is produced at a molar ratio of 2.5, preferably 1.9 to 2.2. In this case, in the first-stage coupling reaction, the pH is in the range of 4 to 13, and furthermore, 5 to 13.
, Preferably in the range of 9 to 14, and more preferably in the range of 10 to 13 in the second-stage coupling reaction.
More preferably, it is kept in the range of 0 to 12.

The coupling reaction can be carried out by either a batch system or a continuous system.

The alkali used for pH adjustment is not particularly limited as long as it can change the pH in a solvent, and examples thereof include lithium hydroxide, sodium hydroxide, potassium hydroxide, and hydroxide. Alkali metal hydroxides such as cesium and their aqueous solutions, alkaline earth metals such as calcium hydroxide and magnesium hydroxide and their solutions or suspensions, ammonia, aqueous ammonia, and organic bases such as triethylamine. Is exemplified.

After completion of the reaction, solid-liquid separation may be carried out by filtration or the like as it is. However, in order to reduce loss to the liquid side, an acid such as hydrochloric acid or sulfuric acid is used, and the pH of the reaction solution is usually adjusted. After the precipitation of 4,6-bis (arylazo) resorcinol as 10 or less, preferably 9 or less, the crystal can be separated from the reaction solution. Alternatively, an organic solvent immiscible with water may be added to perform solvent extraction. Further, if necessary, the obtained crystals can be purified by recrystallization.

Specific examples of the 4,6-bis (arylazo) resorcinol thus obtained include the following.

4,6-bis (phenylazo) resorcinol, 4,6-bis (α-naphthylazo) resorcinol, 4,6-bis (β-naphthylazo) resorcinol, 4,6-bis (2-, 3- or 4 -Methylphenylazo) resorcinol, 4,6-bis (2-, 3- or 4-methoxyphenylazo) resorcinol, 4,
6-bis (2-, 3- or 4-biphenylylazo)
Resorcinol, 4,6-bis (2-, 3- or 4-
Phenoxyphenylazo) resorcinol, 4,6-bis (2-, 3- or 4-hydroxyphenylazo) resorcinol, 4,6-bis (2-, 3- or 4-aminophenylazo) resorcinol, 4,6- Screw [2
-, 3- or 4- (N, N-dimethylamino) phenylazo] resorcinol, 4,6-bis (2-, 3- or 4-carboxyphenylazo) resorcinol,
4,6-bis (2-, 3- or 4-sulfophenylazo) resorcinol, 4,6-bis (2-, 3-, 4
-, 5-, 6-, 7- or 8-sulfo-1-naphthylazo) resorcinol, 4,6-bis (1-, 3-, 4
-, 5-, 6-, 7- or 8-sulfo-2-naphthylazo) resorcinol and the like.

4,6-Bis (arylazo) resorcinol is subjected to a hydrogenolysis reaction in a solvent in the presence of a metal catalyst to be converted to 4,6-diaminoresorcinol or a salt thereof.

The hydrocracking reaction is performed in a solvent. As the solvent used here, for example, water, lower alcohols, aromatic hydrocarbons, halo-substituted benzenes, halogenated aliphatic hydrocarbons, cyclic or acyclic ethers,
Examples include lower ketones and aprotic polar solvents. Specific examples of lower alcohols are methanol, ethanol, 2-propanol and the like, specific examples of aromatic hydrocarbons are benzene, toluene, xylene and the like, specific examples of halo-substituted benzenes are monochlorobenzene, o-dichlorobenzene and the like; specific examples of halogenated aliphatic hydrocarbons include dichloromethane and dichloroethane; specific examples of ethers include dioxane;
Specific examples of lower ketones include acetone and methyl ethyl ketone, and specific examples of the aprotic polar solvent include N, N-dimethylformamide and N-methylpyrrolidone.
These solvents can be used alone or in combination of two or more. The solvent is usually 1 based on the amount of 4,6-bis (arylazo) resorcinol.
It is preferably used in a range of from 50 to 50 times by weight, more preferably in a range of from 2 to 50 times by weight, and particularly preferably in a range of from 2 to 20 times by weight.

This hydrocracking reaction is carried out in the presence of a metal catalyst. The metals that make up the metal catalyst are listed in the Periodic Table VI.
Group II elements are preferred, and such metal catalysts are particularly
Examples thereof include palladium, nickel, platinum, rhodium, ruthenium, cobalt, and iridium. A simple substance of these metals, an alloy containing any of these metals, or a compound of any of these metals can be used as a catalyst. Examples of the alloy include Raney nickel and the like, and examples of the metal compound include palladium oxide, palladium acetate and platinum oxide. Among them, palladium-based or platinum-based catalysts are preferred. Further, these metal catalysts can be used by being supported on a carrier, for example, an oxide such as alumina, zirconia, or titania, or carbon. Among them, palladium or platinum supported on carbon is preferable, and palladium carbon on which palladium is supported on carbon is particularly preferable. The metal catalyst is generally used in the range of 0.05 to 10% by weight, preferably in the range of 0.01 to 10% by weight, as a metal component, based on the amount of 4,6-bis (arylazo) resorcinol. , More preferably in the range of 0.01 to 5% by weight.

The hydrogenolysis reaction is carried out by blowing hydrogen gas into a solvent containing 4,6-bis (arylazo) resorcinol in the presence of the above-described metal catalyst. At this time, the general range of normal pressure ~100kgf / cm ^2, preferably at a hydrogen pressure ranging from atmospheric pressure ~20kgf / cm ^2, the reaction is carried out. The temperature of the hydrocracking reaction is generally in the range of −30 to + 100 ° C., preferably 10 to 70 ° C.
It is in the range of ° C.

Thus, 4,6-diaminoresorcinol is formed in the form of a free amine or a salt thereof. That is, if no acid is present in the system, it is produced in the form of a free amine, and if an acid is present in the system, it is produced in the form of a salt. Usually, it is often formed in the form of a free amine, but after the reaction is completed, an acid may be added to form a salt. Therefore, after completion of the reaction, after separating the metal catalyst, the arylamine generated by the hydrogenolysis reaction, and 4,6-diaminoresorcinol or a salt thereof, the metal catalyst, the arylamine, Mineralization of 6-diaminoresorcinol, crystallization of 4,6-diaminoresorcinol salt, and the like can be performed. Depending on the type of metal catalyst used, the type of arylamine, and the type of solvent used in the hydrogenolysis reaction, several steps may be taken to separate the metal catalyst, the arylamine and 4,6-diaminoresorcinol or a salt thereof. Is applicable. For example, the following can be mentioned.

(1) When the metal catalyst is insoluble in the solvent, the reaction solution is concentrated and cooled if necessary.
By adding a solvent different from the solvent used for the hydrogenolysis reaction,
After crystallizing 4,6-diaminoresorcinol,
By solid-liquid separation, an arylamine was obtained on the liquid side, and a mixture of 4,6-diaminoresorcinol and a metal catalyst were obtained on the solid side. A mineral acid aqueous solution was added to the solid side mixture, and the mixture was heated, if necessary, to obtain 4,6-diaminoresorcinol. A method of dissolving diaminoresorcinol as a mineral acid salt to obtain 4,6-diaminoresorcinol mineral acid salt on the liquid side by solid-liquid separation;

(2) When the metal catalyst is soluble in the solvent, the reaction solution is concentrated and cooled if necessary, and 4,6-diaminoresorcinol is crystallized. And obtaining a metal catalyst and 4,6-diaminoresorcinol on the solid side;

(3) If necessary, the reaction solution is mixed with a high-boiling solvent, and then the solvent and arylamine are distilled off. A dilute mineral acid solution is added to the distillation residue, and if necessary, heated, A method of dissolving diaminoresorcinol in the form of a mineral acid salt and obtaining a metal catalyst on the solid side and 4,6-diaminoresorcinol mineral acid salt on the liquid side by solid-liquid separation;

(4) After adding a solvent to the reaction solution, if necessary, removing the metal catalyst if necessary, adding a mineral acid to the remaining liquid to make it acidic with a mineral acid, and concentrating if necessary, and depositing the solution. A method for separating 6-diaminoresorcinol mineral acid salt;

(5) If necessary, after removing the metal catalyst from the reaction solution and, if necessary, concentrating the reaction solution, a hydrophobic organic solvent and water are added to the reaction solution to adjust the pH to 6 or more, and the aryl A method of extracting an amine into a hydrophobic organic solvent layer and extracting 4,6-diaminoresorcinol or a salt thereof into an aqueous layer to separate the amine;

(6) A method in which the metal catalyst is removed from the reaction solution, if necessary, followed by concentration to obtain 4,6-diaminoresorcinol or a salt thereof in the concentrated residue.

These operations are desirably performed in an oxygen-free atmosphere because 4,6-diaminoresorcinol is easily oxidized, or by performing these operations in the presence of a reducing agent such as tin chloride. Is also good. Mineral acids used in these operations include, for example, hydrochloric acid, hydrogen chloride gas,
Sulfuric acid, phosphoric acid and the like can be mentioned, and preferred are hydrochloric acid and hydrogen chloride gas. Note that the arylamine generated by hydrogenolysis can be recovered and reused. Also, of course, the metal catalyst can be recovered and reused.

The thus obtained 4,6-diaminoresorcinol or a salt thereof can be further purified by recrystallization after adding a mineral acid to a mineral acid salt if necessary. As the recrystallization solvent, water; hydrochloric acid, sulfuric acid aqueous solution,
Mineral acid aqueous solutions such as phosphoric acid aqueous solutions; alcoholic solvents such as methanol and ethanol; ketone solvents such as acetone; aprotic polar solvents such as N, N-dimethylformamide; Or a combination of two or more. Preferably, water or hydrochloric acid is used. Recrystallization can be carried out by either crystallization by temperature drop or acid precipitation by addition of a mineral acid, or a combination thereof.

For example, in the case of purification using hydrochloric acid, the concentration of hydrochloric acid is generally 5 to 35% by weight.
, Preferably in the range of 10 to 25% by weight, and hydrochloric acid at such a concentration is generally in the range of 5 to 40 times by weight based on the amount of 4,6-diaminoresorcinol or a salt thereof, and furthermore, It is preferable to use it in the range of 10 to 20 times by weight. In recrystallization, usually, 4,6-diaminoresorcinol or a salt thereof is mixed with hydrochloric acid, and is mixed for about 10 to 10 minutes.
Heat to a temperature of 100 ° C. to dissolve, and perform a decoloring operation using activated carbon or the like as needed in a completely dissolved state,
Upon cooling, the dihydrochloride of 4,6-diaminoresorcinol precipitates. The cooling temperature is usually in the range of -10 to + 30C, preferably in the range of 0 to 10C. The precipitated crystals are collected by filtration and dried to obtain 4,6-diaminoresorcinol dihydrochloride with high purity.

In another embodiment, during recrystallization, acid precipitation by addition of hydrochloric acid and crystallization by temperature drop can be combined. This case will be described. 4,6
To diaminoresorcinol dihydrochloride, under oxygen-free condition, for example, under a nitrogen atmosphere, generally add 1 to 20 times by weight, preferably 3 to 10 times by weight of water, and add 20 to 100 ° C, preferably 40 to 90 ° C. The temperature was raised to ° C. to dissolve the hydrochloride, and if necessary, a decoloring operation using activated carbon or the like was performed. Then, insoluble materials were removed by filtration while hot. The filtrate was removed under oxygen-free condition at -5.
To + 30 ° C, preferably 0 to 20 ° C, and the concentration of hydrogen chloride in the solution is 5 to 35% by weight, preferably 10 to 35%.
Hydrochloric acid is dripped or hydrogen chloride gas is blown in so as to obtain the weight%. The cooling operation and the adding operation of hydrochloric acid or hydrogen chloride gas may be performed in reverse order, or may be performed simultaneously. The crystals thus precipitated are separated by filtration and dried to obtain 4,6-diaminoresorcinol dihydrochloride with high purity.

Among the methods for extracting and purifying 4,6-diaminoresorcinol or a salt thereof as described above, it is preferable to combine the method (1) with crystallization with a mineral acid. That is, 4,6-diaminoresorcinol produced by the hydrogenolysis reaction is crystallized,
After separation from the arylamine, a mineral acid is added to dissolve and crystallize, whereby a highly pure 4,6-diaminoresorcinol mineral acid salt can be efficiently obtained. In this case, the arylamine generated by the hydrogenolysis reaction can be efficiently recovered.

[0048]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Parts and percentages in the examples are by weight unless otherwise specified. First, an example until an aryldiazonium salt is obtained will be described.

Example 1: Reference A reactor equipped with a stirrer and a thermometer was charged with 96 parts of water and 88 parts of 35% hydrochloric acid and cooled to 5 ° C. or lower.
While stirring this solution, 36.1 parts of aniline and 96 parts of cold water were added thereto.
72.9 parts of a 0% aqueous sodium nitrite solution were slowly added. After the addition, about 91 parts of cold water was added to weigh the solution to 48.
0 parts, and an aqueous solution of benzenediazonium chloride having a concentration of 11.2% was obtained.

Example 2: Reference A reaction vessel equipped with a stirrer and a thermometer was charged with 53 parts of water and 48 parts of 35% hydrochloric acid, and cooled to 5 ° C. or lower.
While stirring this solution, p-anisidine 2 was introduced into the solution.
After adding 6 parts and 53 parts of cold water, 40 parts of a 40% sodium nitrite aqueous solution was slowly added while keeping the temperature at 5 ° C. or lower. After the addition, about 99 parts of cold water was added to adjust the weight of the solution to 319 parts to obtain an aqueous solution of p-methoxybenzenediazonium chloride having a concentration of 11.2%.

Next, an example in which a coupling reaction with resorcinol was carried out using the aqueous solution of benzenediazonium chloride obtained in Example 1 and the coupling product was subjected to a hydrogenolysis reaction will be described.

Example 3 A reaction vessel equipped with a stirrer, a pH meter and a thermometer was charged with 800 g of water and 800 g of methanol, and 8.9 g of resorcinol was added and dissolved therein. To this solution was added a 10% aqueous sodium hydroxide solution to adjust the pH to 1
Adjusted to 1.5. The solution was cooled to 0 to 5 ° C., and 220 g of the benzenediazonium chloride aqueous solution prepared by the method of Example 1 was added dropwise thereto while stirring. 10% during this time
An aqueous solution of sodium hydroxide is also dropped into the reaction solution, and p
H was kept at 11.5-12. After completion of the reaction, hydrochloric acid was added to make the reaction solution acidic, and 4,6-bis (phenylazo) resorcinol was precipitated and collected by filtration. The crystals collected by filtration were dissolved in dichloromethane, washed with water, and then the dichloromethane layer was concentrated to obtain 27.6 g (content: 70%) of 4,6-bis (phenylazo) resorcinol. The yield based on resorcinol was 75%.

11.2 g of the obtained 70% 4,6-bis (phenylazo) resorcinol was added to methanol 12%.
7 g and 5% palladium carbon (52% water-containing product) 1
Together with 5.1 g, they were charged in an autoclave equipped with a stirrer and a thermometer. After replacing the atmosphere in the vessel with hydrogen, the hydrogen pressure was adjusted to 3 kgf / cm ² · G, and the pressure was increased to 20 to ² with stirring.
The reaction was performed at 5 ° C. When the absorption of hydrogen was stopped and the reaction was completed, the reaction atmosphere was returned to normal pressure, and the atmosphere was replaced with nitrogen. Then, 127 g of 35% hydrochloric acid was added, and the catalyst was separated by filtration. The methanol and hydrochloric acid were distilled off from the filtrate under reduced pressure to give 4,6.
Crude crystals containing diaminoresorcinol dihydrochloride 10.4
g was obtained. The content of 4,6-diaminoresorcinol dihydrochloride in the crude crystals was 48%, and the yield from 4,6-bis (phenylazo) resorcinol was 95%.
The crude crystals were added to 103 g of 35% hydrochloric acid, heated to 80 ° C. and dissolved. Thereafter, the mixture was cooled to 0 ° C., and the precipitated crystals were filtered and dried to obtain 3.15 g of 4,6-diaminoresorcinol dihydrochloride. When analyzed by high performance liquid chromatography, the content of 4,6-diaminoresorcinol dihydrochloride was 99%, and the purification yield was 62.6%.
Met.

Example 4 A 70% content of 4,6- obtained as in the first half of Example 3.
9.6 g of bis (phenylazo) resorcinol were added to 150 g of methanol and 5% palladium carbon (52%
(Hydrated product) together with 2 g in an autoclave equipped with a stirrer and a thermometer. After the atmosphere in the container was replaced with hydrogen, the hydrogen pressure was adjusted to 3 kgf / cm ² · G, and
The reaction was performed at 0 to 25 ° C. When the absorption of hydrogen was stopped and the reaction was completed, the reaction atmosphere was returned to normal pressure, and the atmosphere was replaced with nitrogen. Then, 50 g of 35% hydrochloric acid was added, and the catalyst was separated by filtration.
Methanol and hydrochloric acid were distilled off under reduced pressure from the filtrate,
9.93 g of crude crystals containing 4,6-diaminoresorcinol dihydrochloride were obtained. The content of 4,6-diaminoresorcinol dihydrochloride in the crude crystals was 43%, and the yield from 4,6-bis (phenylazo) resorcinol was 95%. This was recrystallized from hydrochloric acid to obtain 2.7 g of 4,6-diaminoresorcinol dihydrochloride.

In the following examples, a coupling reaction with resorcinol was carried out using the aryldiazonium salt obtained in Example 1 or 2.

Example 5 A reaction vessel equipped with a stirrer and a thermometer was charged with 250 ml of a 50% aqueous methanol solution, and 1.10 g of resorcinol was added and dissolved therein. To this solution was added a 10% aqueous sodium hydroxide solution to adjust the pH to 11.5, and then cooled to 0 to 5 ° C, and while stirring,
25.0 g of the aqueous solution of benzenediazonium chloride prepared by the method of Example 1 was added dropwise. During this time, a 10% aqueous sodium hydroxide solution was also dropped into the reaction solution to adjust the pH of the reaction solution to 11.5 to 1
It was kept at 2.0. After completion of the reaction, the reaction solution was analyzed by high performance liquid chromatography to determine the composition of the reaction product. The results are shown in Table 1.

Example 6: In place of the 50% aqueous methanol solution in Comparative Example 5,
The experiment was performed in the same manner as in Example 5, except that 50 ml was used. Table 1 shows the results.

Example 7: An experiment was conducted in the same manner as in Example 6 except that the amount of water in Example 6 was changed to 1000 ml. Table 1 shows the results.

Example 8: Comparison A reaction vessel equipped with a stirrer, a pH meter and a thermometer was charged with 0.1 g.
A buffer solution (1000 ml) consisting of 10 M-Na ₂ HPO ₄ , 0.05 M-NaOH and 0.05 M-KCl was charged, and 1.10 g of resorcinol was added and dissolved therein. This solution is
25.0 g of the aqueous solution of benzenediazonium chloride prepared by the method of Example 1 was added dropwise thereto while cooling to 0 ° C and stirring. During this time, a 10% aqueous solution of sodium hydroxide was also added dropwise to the reaction solution to maintain the pH of the solution at 11.5 to 12.0. After completion of the reaction, the reaction solution was acidified by adding hydrochloric acid, and crude 4,6-
Bis (phenylazo) resorcinol was collected by filtration. This was analyzed by high performance liquid chromatography, and the results are shown in Table 1.

[0060]

[Table 1]

Examples 9 to 13 The procedure of Example 5 was repeated except that the pH of the reaction solution before the addition of the aqueous benzenediazonium chloride solution and the pH of the reaction solution during the addition of the aqueous benzenediazonium chloride solution were changed as shown in Table 2. An experiment was performed by the same operation as described above. Table 2 shows the results of each example together with the results of Example 5.

[0062]

[Table 2]

Example 14 A reaction vessel equipped with a stirrer, a pH meter and a thermometer was charged with 800 g of water, 800 g of methanol and 8.85 g of resorcinol, and the solution was cooled to 0 ° C.
The pH was adjusted to 11.5 with a 0% aqueous sodium hydroxide solution. While stirring this solution, the 11.2% aqueous benzenediazonium chloride solution 2 prepared by the method of Example 1 was added thereto.
10 g was added dropwise over 3 hours. During this period, a 10% aqueous solution of sodium hydroxide was also dropped into the reaction solution to maintain the pH of the reaction solution at 11.5 to 12.0. As the dripping proceeded, the reaction liquid became a slurry. After the completion of the dropping of the benzenediazonium chloride aqueous solution, the dropping of the sodium hydroxide aqueous solution is also stopped,
Stirred at 0 ° C. for 1 hour. To this reaction solution, 10% hydrochloric acid was added dropwise, the pH of the reaction solution was adjusted to 3 over 1 hour, and the solution was allowed to stand at 5 ° C. for 12 hours. After filtering the reaction solution, the solid on the filter paper was washed with 400 g of methanol, and the obtained wet cake was dried at 50 ° C. and 1 mmHg for 6 hours to obtain crude 4,6-bis (phenylazo) resorcinol. 0g
I got Analysis by an absolute calibration curve method by high performance liquid chromatography revealed that the purity of 4,6-bis (phenylazo) resorcinol was 85.6%, 5.9% of 2,4-bisazo form and 2,4,6- It contained 5.8% of the trisazo compound, but no 4-monoazo compound was detected. The yield of 4,6-bis (phenylazo) resorcinol based on resorcinol was 80.3%.

Example 15 In place of the 11.2% aqueous solution of benzenediazonium chloride in Example 14, 255 g of an aqueous solution of 11.2% p-methoxybenzenediazonium chloride prepared by the method of Example 2
An experiment was performed by the same operation as in Example 14 except for using
6-Bis (p-methoxyphenylazo) resorcinol was obtained. Table 3 shows the results.

Example 16 An experiment was carried out in the same manner as in Example 15, except that 180 g of water and 180 g of methanol were used instead of 800 g of water and 800 g of methanol used as the reaction solvent. Table 3 shows the results.

Example 17 An experiment was conducted in the same manner as in Example 15, except that 36 g of water and 36 g of methanol were used instead of 800 g of water and 800 g of methanol used as the reaction solvent. Table 3 shows the results.

[0067]

[Table 3]

Example 18 An experiment was conducted in the same manner as in Example 16, except that 180 g of water and 180 g of N, N-dimethylformamide were used instead of 180 g of water and 180 g of methanol used as the reaction solvent. . The results are shown in Example 1.
The results are shown in Table 4 together with the results of Table 6. Note that “DM” in Table 4
"F" represents N, N-dimethylformamide.

Example 19 An experiment was conducted in the same manner as in Example 16, except that 180 g of water and 180 g of acetone were used instead of 180 g of water and 180 g of methanol used as the reaction solvent. Table 4 shows the results.

[0070]

[Table 4]

Example 20: Reference A reaction vessel equipped with a stirrer, pH meter and thermometer was charged with 800 g of water, 800 g of methanol and 8.85 g of resorcinol, and the solution was cooled to 0 ° C. The pH of the solution was 5.5. To this solution was added 95 g of an aqueous solution of 11.2% benzenediazonium chloride prepared by the method of Example 1.
Was added dropwise over 80 minutes. During this time, a 10% aqueous sodium hydroxide solution was also dropped into the reaction solution to adjust the pH of the reaction solution to 5-6.
Kept. After the completion of the dropwise addition of the aqueous benzenediazonium chloride solution, the pH of the reaction solution was adjusted to 11.5 using a 10% aqueous sodium hydroxide solution. Then, 115 g of a 11.2% aqueous benzenediazonium chloride solution was added dropwise over 90 minutes.
During this time, the pH of the reaction solution was maintained at 11.5 to 12.0 using a 10% aqueous sodium hydroxide solution. After the completion of the dropping of the benzenediazonium chloride aqueous solution, the dropping of the aqueous sodium hydroxide solution was stopped, and the mixture was stirred at 0 ° C. for 1 hour. Thereafter, the same operation as in Example 14 was carried out to obtain 24.2 g of 4,6-bis (phenylazo) resorcinol having a content of 85.0%. It contained 7.3% of the 2,4-bisazo compound and 3.8% of the 2,4,6-trisazo compound, but no 4-monoazo compound was detected.
The yield of 4,6-bis (phenylazo) resorcinol based on resorcinol was 80.4%.

4,6 obtained by the above Examples 5 to 20
-Bis (arylazo) resorcinols, especially Example 1
The product obtained as a solid from 4 to 20 can be advantageously used for producing 4,6-diaminoresorcinol or a salt thereof by a hydrogenolysis reaction. Here, an example in which a hydrogenolysis reaction was performed using 4,6-bis (p-methoxyphenylazo) resorcinol obtained in Example 16 is shown.

Example 21 20 g of 93.4% pure 4,6-bis (p-methoxyphenylazo) resorcinol obtained in Example 16 were mixed with 114 g of methanol and 5% palladium carbon (52%
Together with 0.44 g of water-containing product in an autoclave equipped with a stirrer and a thermometer. After replacing the atmosphere in the container with hydrogen, while maintaining the hydrogen pressure at 5 kgf / cm ² · G,
The reaction was carried out at 40 ° C. with stirring. When the absorption of hydrogen was stopped and the reaction was completed, the reaction atmosphere was returned to normal pressure, and the atmosphere was replaced with nitrogen. After that, 35% hydrochloric acid was added to dissolve 4,6-diaminoresorcinol into hydrochloride, and then the catalyst was separated by filtration. did. When the filtrate was analyzed by high performance liquid chromatography, the yield of 4,6-diaminoresorcinol dihydrochloride was 91%.

In the following example, 4,6-diaminoresorcinol obtained by the reaction was recovered as a hydrochloride by another method.

Example 22 In an autoclave equipped with stirrer and thermometer, Example 1
20 g of 4,6-bis (p-methoxyphenylazo) resorcinol having a purity of 93.4% obtained in the same manner as in Example 6,
114 g of methanol and 0.44 g of 5% palladium carbon (52% water-containing product) were charged. The reaction was carried out in the same manner as in Example 21. When the reaction was completed, the reaction atmosphere was returned to normal pressure, and the atmosphere was replaced with nitrogen.
The catalyst and 4,6-diaminoresorcinol were filtered from the reaction solution through a glass filter covered with Celite. Analysis of the filtrate by high performance liquid chromatography revealed that 91% of p-anisidine was recovered in the filtrate.

The solid on the glass filter was transferred to a container under a nitrogen atmosphere, and subsequently 110 g of degassed pure water was added and stirred under a nitrogen atmosphere, and 12 g of 35% hydrochloric acid was added dropwise at 50 ° C. 6-Diaminoresorcinol was dissolved in the hydrochloride. The catalyst was filtered, 65 g of 35% hydrochloric acid was added dropwise to the filtrate, and the mixture was cooled to 0 ° C. to crystallize 4,6-diaminoresorcinol dihydrochloride. These operations are
All were performed under a nitrogen atmosphere. The crystallized crystals are filtered,
Drying yielded 4.4 g of 100% 4,6-diaminoresorcinol dihydrochloride. The yield based on 4,6-bis (p-methoxyphenylazo) resorcinol is 41.
%Met.

Example 23 Except that the amount of methanol in Example 22 was changed to 40 g,
The same operation as in Example 22 was performed. 87% p-anisidine
The recovered, 100% content of 4,6-diaminoresorcinol dihydrochloride was obtained in 66% yield based on 4,6-bis (p-methoxyphenylazo) resorcinol.

Example 24 The same operation as in Example 22 was carried out except that 114 g of 2-propanol was used instead of methanol in Example 22. 93% recovered p-anisidine, 100% content
Of 4,6-diaminoresorcinol dihydrochloride is 4,6
68% yield based on -bis (p-methoxyphenylazo) resorcinol.

Example 25 Instead of methanol in Example 22, methanol 38
g and toluene, and the same operation as in Example 22 was performed, except that a mixed solvent of 76 g was used. 98% of p-anisidine was recovered and 100% of 4,6-diaminoresorcinol dihydrochloride was obtained in a 63% yield based on 4,6-bis (p-methoxyphenylazo) resorcinol. .

[0080]

According to the present invention, without passing through a nitro compound which may explode due to impact or heating,
4,6-Diaminoresorcinol or a salt thereof can be produced from 6-bis (arylazo) resorcinol or from an arylamine and resorcinol. By subjecting the thus obtained 4,6-diaminoresorcinol to a specific treatment, a mineral salt of 4,6-diaminoresorcinol can be taken out with high purity. Further, in this method, 4,6-bis (arylazo) resorcinol, which is a precursor of 4,6-diaminoresorcinol, can be efficiently produced from arylamine and resorcinol with good regioselectivity.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Murata 3-1-198 Kasuganaka, Konohana-ku, Osaka City Inside Sumitomo Chemical Co., Ltd. (72) Inventor Tetsuhiko Takahata 2- 10-1 Tsukahara, Takatsuki-shi, Osaka No. Sumitomo Chemical Co., Ltd. (72) Inventor Isao Yoshida 3-1-198, Kasuganaka, Konohana-ku, Osaka Sumitomo Chemical Co., Ltd. (56) References Special Table 9-509425 (JP, A) J . Chem. Soc. , Perkin Trans. {II} [8] (1985) 1247 Helv. Chim. Acta. , [41] (1958) 1816 (58) Fields investigated (Int. Cl. ⁶ , DB name) C07C 213/02 C07C 215/80 C07C 245/08 CA (STN) CAOLD (STN) REGIATRY (STN)

Claims (14)

(57) [Claims] An aryldiazonium salt obtained by diazotizing an arylamine is subjected to a coupling reaction with resorcinol to obtain 4,6-bis (arylazo) resorcinol. A method for producing 4,6-diaminoresorcinol or a salt thereof, wherein the hydrogenolysis reaction is carried out in a solvent in the presence of a metal catalyst. 2. The method according to claim 1, wherein the coupling reaction is carried out in a mixed solvent comprising water and an organic solvent miscible with water. 3. The method according to claim 2, wherein the water-miscible organic solvent is methanol. 4. The method according to claim 1, wherein the coupling reaction is carried out at pH 9 or higher. 5. In a state where resorcinol is present in a solvent, an aryldiazonium salt is added in an amount of 0.8 to 1.1 mol times based on the amount of resorcinol, and a first-stage coupling reaction is performed at pH 4 to 13. In a state where the coupling product is suspended in the solvent, the total amount with the aryldiazonium salt used in the first-stage coupling reaction is 1.8 to 2.5 based on the initial amount of resorcinol. An aryldiazonium salt was further added so that the molar
The second-stage coupling reaction is carried out in 9 to 14.
3. The method according to any one of 3. 6. The method according to claim 1, wherein the arylamine is aniline or p-anisidine. 7. The method according to claim 1, wherein the metal catalyst is a palladium-based or platinum-based metal catalyst. 8. The method according to claim 7, wherein the metal catalyst is palladium carbon. 9. A process for producing 4,6-diaminoresorcinol or a salt thereof, comprising subjecting 4,6-bis (arylazo) resorcinol to a hydrogenolysis reaction in a solvent in the presence of a metal catalyst. 10. Crystallizing 4,6-diaminoresorcinol obtained by the method according to any one of claims 1 to 9 and separating from the arylamine, dissolving by adding a mineral acid, and crystallizing. A method for producing 4,6-diaminoresorcinol mineral acid salt, characterized by comprising: 11. A coupling reaction of an aryldiazonium salt obtained by diazotizing an arylamine with resorcinol at a pH of 9 or more in a solvent containing an organic solvent miscible with water, characterized in that it is 4,6-bis ( A process for producing an arylazo) resorcinol. 12. The method according to claim 11, wherein the solvent is a mixed solvent consisting of an organic solvent miscible with water and water. 13. The method according to claim 12, wherein the solvent is present in an amount of 20 to 500 times the weight of resorcinol. 14. The method according to claim 11, wherein the coupling reaction is carried out at a pH in the range of 10 to 12.