JP2003206267A - Method for producing 4,6-diaminoresorcin dihydrochloride - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing 4,6-diaminoresorcin dihydrochloride, capable of effectively producing the 4,6-diaminoresorcin dihydrochloride from a solution containing the 4,6-diaminoresorcin dihydrochlorde by reducing the amount of a discharged waste fluid to the least possible extent. <P>SOLUTION: This method for producing the 4,6-diaminoresorcin dihydrochloride includes (1) a first process for mixing the aqueous solution containing the 4,6-diaminoresorcin dihydrochloride with hydrochloric acid to form a hydrochloric acid aqueous solution containing the 4,6-diaminoresorcin dihydrochloride, (2) a second process for concentrating the hydrochloric acid aqueous solution containing the 4,6-diaminoresorcin dihydrochloride to form a concentrate in which the 4,6-diaminoresorcin dihydrochloride is deposited, subjecting the concentrate to solid-liquid separation, and recovering the deposited 4,6-diaminoresorcin dihydrochloride from the concentrate together with a filtrate, and (3) a third process for reusing the filtrate which is recovered in the second process, or the hydrochloric acid which is recovered from the filtrate, as the hydrochloric acid which is mixed with a new aqueous solution containing the 4,6-diaminoresorcin dihydrochloride in the first process. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for producing 4,6-diaminoresorcin dihydrochloride. 4,6-Diaminoresorcinol is used as a raw material monomer of polybenzobisoxazole (PBO) resin, which is excellent in properties such as heat resistance, strength, and elastic modulus, and is an industrially very important compound.

[0002]

[Prior art]

As a conventional method for producing 4,6-diaminoresorcin, a method of hydrolyzing 4,6-bis (arylazo) resorcin (JP-A-7-242604) and a method of nitrating trichlorobenzene (JP-A-2)
No. 5,00743) is known. Since 4,6-diaminoresorcin is easily oxidized, it is usually treated as a mineral acid salt in any of the production methods, and the dihydrochloride is generally used. Hydrochloric acid may be added to the obtained crude 4,6-diaminoresorcinol to form a hydrochloride, or the reaction in the final step of obtaining the compound may be carried out in hydrochloric acid to form a hydrochloride simultaneously with the formation of the compound. In any case, a step of isolating the hydrochloride salt of the compound from the solution is required. To isolate 4,6-diaminoresorcinol dihydrochloride from the solution, it is described in JP-A-7-242604 that a method of adding hydrogen chloride gas or concentrated hydrochloric acid to precipitate crystals can be adopted.

However, when these conventional techniques are applied to an industrial scale, a waste liquid containing a large amount of hydrogen chloride is generated. Is not described at all. Treatment of waste liquid containing a large amount of hydrogen chloride inevitably requires treatment costs, resulting in high manufacturing costs. At the same time, the treated product generated by the waste liquid treatment gives a load to the environment. Therefore, when manufacturing on an industrial scale, reducing the amount of waste liquid containing a large amount of hydrochloric acid and reducing the load on the environment are important issues.

[0004]

[Problems to be Solved by the Invention]

The purpose of the present invention is to minimize the generation of waste liquid to be discarded.
An object of the present invention is to provide a method for efficiently producing 4,6-diaminoresorcinol dihydrochloride from a solution containing 6-diaminoresorcinol dihydrochloride. As a result of intensive studies to solve the above problems, the present inventors have found a production method that can effectively utilize a filtrate containing hydrogen chloride that is separated when 4,6-diaminoresorcinol dihydrochloride is recovered, The present invention has been completed.

[0005]

[Means for Solving the Problems]

That is, the present invention relates to a method for producing 4,6-diaminoresorcinol dihydrochloride, a method for producing 4,6-diaminoresorcinol dihydrochloride, wherein (1) an aqueous solution containing 4,6-diaminoresorcinol dihydrochloride. The first step of mixing hydrochloric acid with hydrochloric acid to obtain an aqueous hydrochloric acid solution of 4,6-diaminoresorcin dihydrochloride, (2)
Then, from the concentrated solution obtained by concentrating the aqueous hydrochloric acid solution containing 4,6-diaminoresorcinol dihydrochloride, the precipitated 4,6-diaminoresorcinol dihydrochloride is subjected to solid-liquid separation and is collected together with the filtrate. Second step, (3) Reuse of the filtrate recovered in the second step or the hydrochloric acid recovered from the filtrate as hydrochloric acid which is mixed with the fresh aqueous solution containing 4,6-diaminoresorcinol dihydrochloride in the first step The method for producing 4,6-diaminoresorcin dihydrochloride is characterized by including the step of:

[0006]

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the present invention will be described in detail. The method of obtaining the aqueous solution containing 4,6-diaminoresorcin dihydrochloride used in the first step of the present invention is not particularly limited, but a conventionally known method can be adopted. For example, in JP-A-7-242604, 4,6-diamino obtained by reacting resorcin with an aqueous benzenediazonium chloride solution to obtain 4,6-bis (phenylazo) resorcin, and then hydrogenolyzing the compound. A method of mineralizing resorcin to isolate 4,6-diaminoresorcinol mineral acid salt, and then dissolving the 4,6-diaminoresorcinol mineral acid salt in hydrochloric acid. Alternatively, as described in JP-A-10-168040, a method of hydrolyzing 4,6-bis (phenylazo) resorcinol in hydrochloric acid to obtain an aqueous solution of 4,6-diaminoresorcinol dihydrochloride can be mentioned. Further, as described in JP-A-2001-039935, resorcin is sulfonated to give 2,4,6-trisulfonic acid resorcin, followed by nitration to obtain 2-sulfonic acid-4,6-dinitroresorcin. There is also a method in which 4,6-dinitroresorcinol is hydrolyzed to give 4,6-dinitroresorcinol, and then the resulting 4,6-diaminoresorcinol is salified with hydrochloric acid and dissolved in water. Further, in this method, reduction of 4,6-dinitroresorcinol in hydrochloric acid water to obtain an aqueous solution of 4,6-diaminoresorcinol dihydrochloride is also mentioned. In addition, 4,6-diaminoresorcin dihydrochloride is
When contacting with oxygen in the solid state or in the state of being dissolved in a solvent such as water, it tends to be colored. Therefore, in carrying out the present invention, the atmosphere in which 4,6-diaminoresorcin dihydrochloride is present is changed to nitrogen or the like. It is preferable that the atmosphere is free of oxygen such as filling with an inert gas.

The concentration of 4,6-diaminoresorcinol dihydrochloride in the aqueous solution containing 4,6-diaminoresorcinol dihydrochloride is usually 1 to 20 wt% in consideration of mixing the aqueous solution and hydrochloric acid. You can select from%. Since the solubility of 4,6-diaminoresorcin dihydrochloride in hydrochloric acid is lower than that in water,
The concentration of 4,6-diaminoresorcinol dihydrochloride in the aqueous solution is preferably 5 to 18% by weight, more preferably 8 to 15% by weight. When the concentration of 4,6-diaminoresorcinol dihydrochloride is extremely low, the volumetric efficiency is lowered, and extra energy is required for concentrating the aqueous hydrochloric acid solution containing 4,6-diaminoresorcinol dihydrochloride in the second step described later. Therefore, it is uneconomical.

The above-mentioned JP-A-7-242604 and JP-A-10-242604
As described in JP-A-168040, in carrying out hydrocracking,
In addition to water, various solvents such as lower alcohol and acetone can be used. When various solvents described in these publications are used for hydrogenolysis, an aqueous solution containing 4,6-diaminoresorcin dihydrochloride is The above-mentioned various solvents other than water may be mixed. The aqueous solution containing 4,6-diaminoresorcinol dihydrochloride that can be used in the present invention contains the above-mentioned lower alcohol or acetone unless it affects separation of 4,6-diaminoresorcinol dihydrochloride. Good. In addition, in the aqueous solution containing 4,6-diaminoresorcinol dihydrochloride of the present invention, a reducing agent such as stannous chloride or an inorganic salt may be used as long as it does not affect the separation of 4,6-diaminoresorcinol dihydrochloride. , And other compounds may be dissolved.

The hydrochloric acid to be mixed with the above-mentioned aqueous solution containing 4,6-diaminoresorcinol dihydrochloride is usually hydrogen chloride gas which is industrially easily available or has various concentrations prepared from 35% by weight hydrochloric acid and water. Hydrochloric acid can be used. The lower limit of the concentration of hydrochloric acid is not particularly limited, but if the concentration is too low, the volumetric efficiency will decrease, which is uneconomical. Preferably 10 to 20.2% by weight, more preferably 15 to
20.2% by weight hydrochloric acid is used. It is most preferable to use a filtrate obtained by separating and recovering 4,6-diaminoresorcinol dihydrochloride in the second step described below or the concentration of hydrochloric acid recovered from the filtrate, that is, 20.2% by weight of hydrochloric acid. Hydrogen chloride concentration 20.2
Weight% hydrochloric acid corresponds to the hydrogen chloride concentration of the azeotrope of water and hydrogen chloride.

The amount of hydrochloric acid to be mixed with the above-mentioned aqueous solution containing 4,6-diaminoresorcin dihydrochloride is dependent on the substrate concentration of the initial aqueous solution containing 4,6-diaminoresorcin dihydrochloride. However, it can be controlled by the concentration of hydrogen chloride in the aqueous solution obtained by mixing hydrochloric acid. When the concentration of hydrogen chloride in the aqueous solution is low at the time of carrying out the concentration in the second step described later, 4,6-diaminoresorcinol dihydrochloride is likely to be oxidized, and if the concentration of hydrogen chloride is increased more than necessary, the volume is increased. Efficiency is reduced. The preferred hydrogen chloride concentration of the aqueous solution obtained by adding hydrochloric acid is 3 to 15% by weight, and more preferably 5 to 12% by weight. The mixing of the aqueous solution containing 4,6-diaminoresorcinol dihydrochloride with hydrochloric acid can usually be performed at 0 to 110 ° C. under atmospheric pressure. When hydrochloric acid is added to an aqueous solution containing 4,6-diaminoresorcinol dihydrochloride, the operating conditions such as the addition rate of hydrochloric acid and stirring conditions can be appropriately selected. When an aqueous solution containing 4,6-diaminoresorcinol dihydrochloride is mixed with hydrochloric acid, 4,6-diaminoresorcinol dihydrochloride is precipitated in an aqueous hydrochloric acid solution containing 4,6-diaminoresorcinol dihydrochloride. You can proceed to the process.

In the second step of the present invention, first, the aqueous hydrochloric acid solution containing 4,6-diaminoresorcinol dihydrochloride obtained in the first step is concentrated. The concentration method is not particularly limited, but a distillation method is usually used. The distillation pressure is atmospheric pressure to 100 Pa, and the distillation temperature is 30 ° C to 110 ° C. Concentration is 4,6-
The process is terminated when the hydrogen chloride concentration of the concentrated solution containing diaminoresorcin dihydrochloride (excluding hydrogen chloride of 4,6-diaminoresorcin dihydrochloride) is 15% to 20.2% by weight. The lower limit of the hydrogen chloride concentration is preferably 18% by weight or more,
The recovery rate of 4,6-diaminoresorcin dihydrochloride is slightly improved as compared with the case where the hydrogen chloride concentration is 15% by weight. If the hydrogen chloride concentration is less than 15% by weight, the recovery rate of 4,6-diaminoresorcinol dihydrochloride recovered from the concentrated solution is lowered. Adjust the hydrogen chloride concentration to 20.
Most preferably, it is 2% by weight. As the concentration proceeds, the amount of 4,6-diaminoresorcinol dihydrochloride precipitated in the concentrated liquid containing 4,6-diaminoresorcinol dihydrochloride increases. After the concentration is completed, a concentrated liquid containing the precipitated 4,6-diaminoresorcinol dihydrochloride is obtained.

After the concentration is completed, the concentrated liquid containing the precipitated 4,6-diaminoresorcin dihydrochloride is cooled. Usually, after cooling to room temperature (25 ° C), the concentrated liquid is subjected to solid-liquid separation, and precipitated 4,6-diaminoresorcin dihydrochloride (solid)
And collect the filtrate (liquid) respectively. Known methods such as filtration and decanting can be used for solid-liquid separation, but filtration is preferred. The filtration method is not particularly limited, and a commonly known method such as a Centle filtration or a press filter can be used.
It is preferable that the solid-liquid separator has a structure that prevents air from entering in order to prevent contact of 4,6-diaminoresorcin dihydrochloride with oxygen during solid-liquid separation.

In the third step of the present invention, the filtrate recovered in the second step is reused as hydrochloric acid in the first step for treating a new aqueous solution of 4,6-diaminoresorcin dihydrochloride. You can The filtrate can be concentrated or diluted with water and reused so as to obtain a desired hydrogen chloride concentration. Alternatively, hydrochloric acid can be separated and recovered from the filtrate, and the recovered hydrochloric acid can be reused as hydrochloric acid to be added to a new aqueous solution of 4,6-diaminoresorcin dihydrochloride. As a method for recovering hydrochloric acid from the filtrate, a distillation method is usually used.

As a preferred embodiment of the present invention, for example, 4,6-
The first step of mixing an aqueous solution containing diaminoresorcinol dihydrochloride with hydrochloric acid having a hydrogen chloride concentration of 20.2% by weight to obtain an aqueous hydrochloric acid solution containing 4,6-diaminoresorcinol dihydrochloride, and then the aqueous hydrochloric acid solution The second step in which the concentration of hydrogen chloride in the concentrated liquid obtained by concentrating is adjusted to 20.2% by weight, and the concentrated and precipitated 4,6-diaminoresorcin dihydrochloride is subjected to solid-liquid separation and is collected together with the filtrate. , Hydrochloric acid having a hydrogen chloride concentration of 20.2% by weight was recovered from the filtrate by distillation, and the recovered hydrochloric acid was replaced with fresh 4,6-
It includes a third step of reuse as hydrochloric acid mixed with an aqueous solution containing diaminoresorcin dihydrochloride. By repeating this method, hydrochloric acid can be effectively used and the generation of waste liquid containing hydrochloric acid can be suppressed as much as possible.

The 4,6-diaminoresorcinol dihydrochloride obtained by the method of the present invention is dried under an atmosphere of an inert gas such as nitrogen to obtain a product in order to prevent coloration. In order to prevent the product from being colored during storage such as when the product is stored for a long period of time, an antioxidant such as stannous chloride can be added before or after drying, if necessary.

[0016]

【Example】

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 4,6-Diaminoresorcinol dihydrochloride 10.0 g and stannous chloride dihydrate 1. After dissolving 0 g in 74.5 g of water, 74.5 g of 20 wt% hydrochloric acid was added dropwise at room temperature with stirring, and crystals were precipitated to give a white suspension. When this suspension was heated and concentrated, it was uniformly dissolved, but crystals were precipitated as water was distilled. When 76 g of water had distilled off, the mixture was cooled and filtered to obtain 9.7 g of 4,6-diaminoresorcinol dihydrochloride. When the filtrate was titrated with sodium hydroxide, the hydrochloric acid concentration was 18. It was 7% by weight.

Example 2 An aqueous solution of 4,6-diaminoresorcinol dihydrochloride was prepared in the same manner as in Example 1, and then the filtrate obtained in Example 1 was added dropwise to precipitate crystals to give white suspension. It became a suspension. When this suspension was heated and concentrated, it was uniformly dissolved, but crystals were precipitated as water was distilled. When 76 g of water had distilled off, it was cooled and filtered to obtain 9.6 g of 4,6-diaminoresorcinol dihydrochloride. When the filtrate was titrated with sodium hydroxide, the hydrochloric acid concentration was 18.7% by weight.

Example 3 10.0 g of 4,6-diaminoresorcin dihydrochloride and stannous chloride dihydrate 1. After dissolving 0 g in 74.5 g of water, 74.5 g of 20 wt% hydrochloric acid was added dropwise at room temperature with stirring, and crystals were precipitated to give a white suspension. Add this suspension to 6. When the pressure was reduced to 5 kPa and the mixture was heated and concentrated, water was distilled out without being uniformly dissolved. When 76 g of water had distilled off, it was cooled, filtered and 4,6-
9.7 g of diaminoresorcin dihydrochloride were obtained. When the filtrate was titrated with sodium hydroxide, the hydrochloric acid concentration was 20. It was 2% by weight.

Example 4 An aqueous solution of 4,6-diaminoresorcinol dihydrochloride was prepared in the same manner as in Example 3, and the filtrate obtained in Example 3 was added dropwise to precipitate crystals, which resulted in a white slurry. Became. When this crystallization mass was depressurized to 6.5 kPa and then concentrated by heating, water was distilled out without being uniformly dissolved. When 76 g of water had distilled off, the mixture was cooled and filtered to obtain 9.7 g of 4,6-diaminoresorcinol dihydrochloride. When the filtrate was titrated with sodium hydroxide, the hydrochloric acid concentration was 20.2% by weight.

Example 5 The filtrate obtained by crystallization in the same manner as in Example 3 was heated and distilled under normal pressure to collect hydrochloric acid. When titrated with sodium hydroxide, the concentration of hydrochloric acid is 2
It was 0.2% by weight, and 4,6-diaminoresorcinol dihydrochloride was not detected by HP LC measurement. Crystallization was carried out in the same manner as in Example 3 using this recovered hydrochloric acid.
9.7 g of 6-diaminoresorcin dihydrochloride was obtained.

[0022]

【The invention's effect】

According to the present invention, 4,6-diaminoresorcinol dihydrochloride can be efficiently isolated from an aqueous solution without generating a waste liquid containing a large amount of hydrochloric acid. The hydrochloride salt can be produced.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideki Mizuta             30 Asamu-cho, Omuta City, Fukuoka Prefecture             In the company (72) Inventor Matsuzaki Yoriaki             30 Asamu-cho, Omuta City, Fukuoka Prefecture             In the company F term (reference) 4H006 AA02 AC90 AD15 AD17 BC31                       BC35 BE01 BJ50 BN30 BU46

Claims (3)

[Claims] 1. A method for producing 4,6-diaminoresorcin dihydrochloride, which comprises mixing (1) an aqueous solution containing 4,6-diaminoresorcin dihydrochloride with hydrochloric acid to prepare 4,6-diaminoresorcin dihydrochloride. The first step of obtaining an aqueous hydrochloric acid solution containing (2) and then concentrating the aqueous hydrochloric acid solution containing 4,6-diaminoresorcinol dihydrochloride to obtain 4,6-diaminoresorcinol which is precipitated. The second step in which the dihydrochloride is subjected to solid-liquid separation and recovered together with the filtrate, (3) the filtrate recovered in the second step or the hydrochloric acid recovered from the filtrate is used as a new 4,6-diaminoresorcinol in the first step. A method for producing 4,6-diaminoresorcin dihydrochloride, which comprises the step of reuse as hydrochloric acid mixed with an aqueous solution containing dihydrochloride. 2. The 4,6-diamino according to claim 1, wherein the hydrochloric acid concentration of hydrochloric acid mixed with the aqueous solution containing 4,6-diaminoresorcinol dihydrochloride in the first step is 20.2% by weight or less. Method for producing resorcin dihydrochloride. 3. The concentration of hydrogen chloride in the concentrate of the second step is 15 to.
The method for producing 4,6-diaminoresorcinol dihydrochloride according to claim 1 or 2, wherein the content is 20.2% by weight.