JPH07100681B2 - Method for purifying m-aminophenol aqueous solution - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for purifying an aqueous solution of m-aminophenol, and more specifically, separating m-phenylenediamine, which is difficult to separate from m-aminophenol, from m-aminophenol. The present invention relates to a method for purifying m-aminophenol, which enables high-purity m-aminophenol to be obtained.

Technical background of the invention and its problems As a method for producing m-aminophenol, for example, Japanese Patent Publication
As disclosed in JP-B No. 60-13026, JP-B No. 60-16929, JP-A No. 62-215358, etc., one of the hydroxyl groups of resorcin is converted into an amino group by reacting resorcin with ammonia. It is known how to do this. However, when trying to obtain m-aminophenol by reacting resorcin with ammonia, m-phenylenediamine is always produced as a by-product in the reaction process.

Therefore, in order to obtain highly pure m-aminophenol, m-phenylenediamine and the like as impurities must be removed from the reaction product obtained by the reaction with ammonia. However, since the boiling points of m-aminophenol and m-phenylenediamine are close to each other, and the mixture of m-aminophenol and m-phenylenediamine forms the highest azeotrope, it can be combined with m-aminophenol. It cannot be separated from m-phenylenediamine by conventional distillation methods.

Moreover, since m-aminophenol and m-phenylenediamine are both aromatic primary amines and have similar chemical properties, m-aminophenol and m-phenylenediamine are extracted or oxidatively decomposed. It is difficult to separate by chemical methods such as.

Therefore, as a method for separating m-aminophenol and m-phenylenediamine, for example, JP-A-61-27239 discloses that m-aminophenol containing m-phenylenediamine as an impurity is dissolved in water to give a difference in solubility. There is disclosed a crystallization method in which only m-aminophenol is recrystallized and separated by utilizing. Further, in Japanese Patent Laid-Open No. 61-5059, m-aminophenol containing m-phenylenediamine as an impurity is dissolved in an ether solvent and similarly, only the m-aminophenol is recrystallized by utilizing the difference in solubility. A crystallization method of separating by separation is disclosed.

However, when trying to separate m-aminophenol and m-phenylenediamine by the crystallization method as described above, a part of m-aminophenol is dissolved in the mother liquor, resulting in a large loss of m-aminophenol. There was a problem.

OBJECT OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and efficiently removes m-phenylenediamine from an aqueous m-aminophenol solution containing m-phenylenediamine as an impurity. Therefore, it is an object of the present invention to provide a method for purifying m-aminophenol, which is capable of recovering high-purity m-aminophenol.

SUMMARY OF THE INVENTION A method for purifying an aqueous m-aminophenol solution according to the present invention,
An extraction operation is performed using a saturated aliphatic hydrocarbon halide or an aromatic hydrocarbon halide in an aqueous m-aminophenol solution containing m-phenylenediamine.
It is characterized in that phenylenediamine is extracted into the organic layer.

In the method for purifying an aqueous m-aminophenol solution according to the present invention, an aqueous m-aminophenol solution containing m-phenylenediamine is subjected to an extraction operation using a saturated aliphatic hydrocarbon or an aromatic hydrocarbon halide, and m- Since it is characterized by extracting phenylenediamine into the organic layer,
It is possible to efficiently remove m-phenylenediamine from an aqueous m-aminophenol solution containing m-phenylenediamine as an impurity, and thus to obtain highly pure m-aminophenol.

DETAILED DESCRIPTION OF THE INVENTION The method for purifying an aqueous m-aminophenol solution according to the present invention will be specifically described below.

Generally, when an attempt is made to react m-aminophenol by reacting resorcin with ammonia, m-phenylenediamine is by-produced in addition to m-aminophenol, and in some cases, a high content of 3,3′-dihydroxydiphenylamine or the like is generated. Boiling point impurities are also by-produced.

In the present invention, an extraction operation is carried out using a saturated aliphatic hydrocarbon halide or an aromatic hydrocarbon halide in an aqueous m-aminophenol solution containing m-phenylenediamine as such an impurity, m-phenylenediamine. Is selectively extracted into the organic layer.

The m-aminophenol aqueous solution to be purified according to the present invention usually contains 5 to 70% by weight, preferably 10 to 70% by weight of m-aminophenol.
It is contained in a concentration of 50% by weight, and m-phenylenediamine is contained in an amount of 0.5 to 20% by weight, preferably 1 to 10% by weight, based on m-aminophenol. Further, the above m-aminophenol aqueous solution contains m-aminophenol as described above.
In addition to phenylenediamine, high boiling impurities such as 3,3′-dihydroxydiphenylamine as described above, a small amount of unreacted resorcin, and a catalyst used for the amination reaction may be contained.

In the present invention, an extraction operation is added to such an aqueous m-aminophenol solution, and its flowchart is shown in FIG.

In the present invention, when applying an extraction operation to such an m-aminophenol aqueous solution, a halide of a saturated aliphatic hydrocarbon or a halide of an aromatic hydrocarbon, preferably a chloride, is used, but specifically, As the saturated aliphatic hydrocarbon halide, methylene chloride, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-
Trichloroethane, 1,1,2-trichloroethane, pentachloroethane, dichloropropane and the like are used. Of these, methylene chloride, chloroform, 1,2-dichloroethane and the like are preferable.

As the aromatic hydrocarbon halide, chlorobenzene, o-dichlorobenzene, or the like is used.

These saturated aliphatic hydrocarbon halides or aromatic hydrocarbon halides may be used alone or in combination of two or more. In addition, a small amount of another organic compound may be mixed with the above-mentioned halide.

In the present invention, when performing the extraction operation to the m-aminophenol aqueous solution, the halide of the saturated aliphatic hydrocarbon or the halide of the aromatic hydrocarbon as described above,
The amount varies depending on the amount of m-phenylenediamine contained in the m-aminophenol aqueous solution, but is 0.1 to 20 parts by weight, preferably 0.2 to 1 part by weight of the m-aminophenol aqueous solution.
Used in an amount of 10 parts by weight. The amount of the above-mentioned halide is 0.1 with respect to 1 part by weight of the m-aminophenol aqueous solution.
If it is less than 10 parts by weight, the separation of m-phenylenediamine contained in the m-aminophenol aqueous solution will be insufficient, which is not preferable. On the other hand, if it exceeds 20 parts by weight per 1 part by weight of the m-aminophenol aqueous solution, It is not preferable because the loss of m-aminophenol increases and the energy required for solvent recovery increases.

The extraction operation of the m-aminophenol aqueous solution as described above,
It is preferable to employ a countercurrent extraction method, and the extraction temperature is 10 to 100 ° C, preferably 20 to 90 ° C, more preferably 25.
It is desirable that the temperature is -80 ° C. The method for contacting the m-aminophenol aqueous solution with the saturated aliphatic hydrocarbon halide or the aromatic hydrocarbon halide may be a batch system or a continuous system, of which continuous countercurrent contact is used. It is preferable to adopt the method.

Such an extraction operation is preferably carried out specifically using an extraction tower, the aqueous solution of m-aminophenol is supplied from the lower part of the extraction tower, and the above halide is the upper part of the extraction tower. It is preferable to supply by the counter flow contact method. The theoretical plate number of this extraction column is preferably about 2 to 10. The supply amount of the m-aminophenol aqueous solution and the above-mentioned halide per unit time to the extraction column is determined according to the volume of the extraction column, the extraction capacity and the like.

When the aqueous m-aminophenol aqueous solution is extracted in this manner, m-phenylenediamine is selectively extracted into the organic layer, and m-aminophenol remains in the aqueous layer. Therefore, if the organic layer and the aqueous layer are separated after the extraction operation, an organic layer mainly containing m-phenylenediamine and an aqueous layer mainly containing m-aminophenol can be obtained.

From the aqueous layer containing m-aminophenol thus obtained, water is removed by, for example, a concentration operation, and then vacuum distillation is performed to easily separate m-aminophenol and high-boiling impurities, and Pure m-aminophenol is obtained.

Distillation for separating m-aminophenol and high-boiling impurities is desirably performed at a distillation temperature of 120 to 300 ° C, preferably 140 to 250 ° C, and a distillation pressure of 0.1 to 600 mmHg, preferably 1 to 400 mmHg. , Continuous distillation or batch distillation.

Further, the organic layer mainly containing m-phenylenediamine obtained as described above, contains a small amount of m-aminophenol transferred to the organic layer during the extraction operation,
It is preferable to recover a small amount of m-aminophenol contained in this organic layer in order to improve the recovery rate of m-aminophenol. To recover a small amount of m-aminophenol contained in the organic layer, for example, the following may be performed.

(A) Water may be added to the organic layer, m-aminophenol may be extracted from the aqueous layer, and the aqueous layer containing m-aminophenol may be separated.

At this time, water is preferably added in an amount of 0.1 to 10 parts by weight with respect to 1 part by weight of the organic layer, and the extraction temperature is 10 to 100 ° C.
It is preferably 30 to 80 ° C.

The extraction operation is preferably performed by countercurrent extraction.

The aqueous layer containing m-aminophenol thus separated is combined with the aqueous m-aminophenol solution and again subjected to extraction operation with a saturated aliphatic hydrocarbon halide or an aromatic hydrocarbon halide. Be done.

It is preferable that the saturated aliphatic hydrocarbon or aromatic hydrocarbon halide in the organic layer is recovered and used again as an extraction solvent.

(B) Formalin is added to the organic layer containing m-phenylenediamine and m-aminophenol to selectively react with m-phenylenediamine and formalin to remove as a precipitate, and then the precipitate and organic Removal of the solvent gives high-purity m-aminophenol.

(C) When the organic layer is cooled and the precipitated crystals are separated, high-purity m-aminophenol is obtained.

EFFECT OF THE INVENTION In the method for purifying an aqueous m-aminophenol solution according to the present invention, an aqueous m-aminophenol solution containing m-phenylenediamine is extracted by using a saturated aliphatic hydrocarbon halide or an aromatic hydrocarbon halide. Operation,
Since it is characterized by extracting m-phenylenediamine into the organic layer, it is possible to efficiently remove m-phenylenediamine from an aqueous m-aminophenol solution containing m-phenylenediamine as an impurity, and thus to obtain a highly purified product.
m-Aminophenol can be obtained.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 4.35% by weight of m-aminophenol, m-phenylenediamine
An aqueous solution of crude m-aminophenol containing 0.13% by weight and 0.27% by weight of high-boiling impurities such as 3,3′-dihydroxydiphenylamine was added from the bottom of the countercurrent extraction column with 8 theoretical plates to obtain 10
The m-phenylenediamine was subjected to countercurrent extraction at a temperature of 35 ° C. by supplying methylene chloride at a rate of 180 g / hour from the upper part of the countercurrent extraction column at a rate of 0 g / hour.

A methylene chloride solution containing 0.25% by weight of m-aminophenol and 0.066% by weight of m-phenylenediamine was obtained from the lower part of the countercurrent extraction column at a rate of 181 g / hour. An aqueous solution containing 3.94% by weight of m-aminophenol and 0.011% by weight of m-phenylenediamine was obtained from the upper part of the countercurrent extraction column at a rate of 99 g / hour.

From these results, it was found that 91.9% of m-phenylenediamine contained in the crude aqueous m-aminophenol solution before extraction was extracted with methylene chloride, and 89.7% of m-aminophenol remained in the aqueous solution. Do you get it.

Then, the aqueous solution obtained from the upper part of the countercurrent extraction column as described above is concentrated to remove water, and then distilled under reduced pressure.
99.7% pure m-aminophenol was obtained.

Example 2 In Example 1, chloroform was used instead of methylene chloride as the extraction solvent, and the solvent supply rate was 180 g /
Example 1 was repeated except that the time was changed to 350 g / hour.

It was found that before extraction, 85.3% of m-phenylenediamine contained in the crude aqueous m-aminophenol solution was extracted with chloroform, and 87.1% of m-aminophenol remained in the aqueous solution.

Example 3 (1) A crude m-aminophenol (13.1 g / hour) containing 88.7% by weight of m-aminophenol, 3.67% by weight of m-phenylenediamine, and 7.3% by weight of high-boiling impurities such as 3,3′-dihydrodiphenylamine was added. , M- obtained from the second extraction tower described later
Aminophenol 9.6% by weight, m-phenylenediamine 0.4
An aqueous solution containing 8% by weight was dissolved in 86.9 g / hour at 60 ° C., and 100 g from the bottom into a countercurrent extraction column (first extraction column) with 7 theoretical plates.
Supplied at a rate of / hour. On the other hand, from the top, 1,2-dichloroethane preheated to 60 ° C was supplied at a rate of 200 g / hour,
Countercurrent extraction was performed at ° C. An aqueous solution containing 12.3% by weight of m-aminophenol and 0.046% by weight of m-phenylenediamine was obtained from the upper part of the first extraction column at a rate of 89.4 g / hour, and 4.27% by weight of m-aminophenol from the lower part of the first extraction column. A 1,2-dichloroethane solution containing 0.408% by weight of m-phenylenediamine was obtained at a rate of 210 g / hour.

(2) The 1,2-dichloroethane solution obtained from the lower part of the first extraction column was fed at a rate of 210 g / hour from the upper part of the countercurrent extraction column (second extraction column) with 5 theoretical plates, while from the lower part. Water preheated to 60 ° C was supplied at a rate of 77.8 g / hour, and countercurrent extraction was performed at 60 ° C. M-aminophenol from the upper part of the second extraction tower
An aqueous solution containing 9.6% by weight and 0.48% by weight of m-phenylenediamine was obtained at a rate of 86.9 g / hour, and 0.31% by weight of m-aminophenol and 0.22% by weight of m-phenylenediamine were obtained from the lower part of the second extraction column. 20,2-g, 2-dichloroethane solution
Obtained at the speed of time. The aqueous solution obtained from the upper part of the second extraction column was used for dissolving the crude m-aminophenol in (1) above.

(3) When water was distilled off from the aqueous solution obtained from the upper part of the first extraction column of (1) above, distillation was performed under reduced pressure,
99.6% pure m-aminophenol was obtained at a rate of 10.83 g / hr.

This means that 93.5% of the m-aminophenol in the crude m-aminophenol used as the raw material was recovered as high-purity m-aminophenol.

Example 4 Example 1 was repeated except that 1,2-dichloropropane was used as the extraction solvent instead of methylene chloride and the solvent supply rate was 450 g / hour instead of 180 g / hour. The same was done.

Before extraction, 93.6% of m-phenylenediamine contained in the crude aqueous m-aminophenol solution was extracted with 1,2-dichloropropane, and 82.3% of m-aminophenol remained in the aqueous solution. Do you get it.

Example 5 In Example 1, chlorobenzene was used instead of methylene chloride as the extraction solvent, and the solvent supply rate was 180 g.
The same procedure as in Example 1 was performed except that 1500 g / hour was used instead of / hour.

It was found that 92.1% of m-phenylenediamine contained in the crude aqueous m-aminophenol solution before extraction was extracted with chlorobenzene, and 80.7% of m-aminophenol remained in the aqueous solution.

[Brief description of drawings]

FIG. 1 is a flowchart showing a method for purifying an aqueous m-aminophenol solution according to the present invention.

Claims (1)

[Claims] 1. A m-aminophenol aqueous solution containing m-phenylenediamine is extracted with a saturated aliphatic hydrocarbon halide or an aromatic hydrocarbon halide to extract m-phenylenediamine in an organic layer. A method for purifying an aqueous m-aminophenol solution, which comprises extracting.