JP4508548B2 - Process for producing aromatic hydroxycarboxylic acid - Google Patents

Description

Ａ：２−ヒドロキシ−３−ナフトエ酸
Ｂ：２−ヒドロキシ−６−ナフトエ酸
Ｃ：２−ヒドロキシナフタレン−３，６−ジカルボン酸
Ｄ：β−ナフトール、およびβ−ナフトールナトリウム
Ｅ：不明生成物（仕込みβ―ナフトールナトリウムおよび、添加β−ナフトールからＡ、Ｂ、ＣおよびＤの総量を差し引いたもの）
【００３６】
このように、本発明の方法により、反応液を十分に攪拌することによって、反応収率が向上し、副反応による原料の損失が抑えられる。
【図面の簡単な説明】
【図１】実施例１において使用した、本発明に使用する攪拌機構を備える反応槽の模式図である。
【図２】比較例１において使用した、パドル翼による攪拌機構を備える反応槽の模式図である。
【符号の説明】
１ 反応槽
２ 攪拌軸
３ 攪拌翼
４ 反応槽側壁
５ 反応槽底部
６ 邪魔板
７ 後退翼付パドル翼[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an aromatic hydroxycarboxylic acid by reacting an alkali metal salt of an aromatic hydroxy compound with carbon dioxide.
[0002]
[Prior art]
Aromatic hydroxycarboxylic acids are obtained by the reaction of an alkali metal salt of an aromatic hydroxy compound and carbon dioxide, which has long been known as the Kolbe-Schmidt reaction, and are important chemical products used in a wide range of applications.
[0003]
For example, 2-hydroxy-3-naphthoic acid is an important compound used as a raw material for pigment and dye intermediates and charge control agents for toners. In addition, p-hydroxybenzoic acid is a raw material for preservatives such as polymer raw materials, cosmetics and pharmaceuticals, and 2-hydroxy-6-naphthoic acid is a useful compound widely used as a polymer raw material and liquid crystal compound intermediates. It is.
[0004]
As the Kolbe-Schmidt reaction, which is a process for producing an aromatic hydroxycarboxylic acid, a reaction in a solid gas phase between a sufficiently dehydrated alkali metal salt of an aromatic hydroxy compound and carbon dioxide has been known for a long time. However, the reaction in the solid gas phase requires a long reaction time, the loss of the alkali metal salt of the aromatic hydroxy compound as a raw material is large due to the thermal heterogeneity of the reaction at high temperature, However, it is difficult to control the reaction due to the phase change, and it is difficult to obtain a stable yield. Various proposals have been made to improve this problem.
[0005]
One of the inventors of the present invention has already studied the liquid reaction using various media for the Kolbe-Schmidt reaction that has been carried out in the solid phase, and proposed an improved technique that is currently being implemented industrially. Yes.
[0006]
For example, regarding a method for producing 2-hydroxy-3-naphthoic acid, a method of reacting a liquid mixture comprising light oil or kerosene, β-naphthol sodium and β-naphthol with carbon dioxide has been invented (Patent Document 1). This method can provide 2-hydroxy-3-naphthoic acid that can be continuous, has a small impurity content, and has very little quality variation. Furthermore, the improvement technique regarding the manufacturing method (patent document 2) of 2-hydroxy-6-naphthoic acid and the manufacturing method (patent document 3) of p-hydroxybenzoic acid is proposed, respectively.
[0007]
However, the Kolbeschmitt reaction to which various improvements are added as described above also has a problem that the reaction efficiency is still poor and a raw material loss due to a side reaction occurs.
[0008]
[Patent Document 1]
Japanese Patent Publication No. 56-53296 [Patent Document 2]
Japanese Patent Publication No. 7-45431 [Patent Document 3]
Japanese Patent Publication No. 45-9529 [0009]
[Problems to be solved by the invention]
In view of the above problems, an object of the present invention is to react aromatic hydroxy compound alkali metal salt with carbon dioxide in the presence of a medium that does not substantially dissolve the alkali metal salt of aromatic hydroxy compound. In the method for producing carboxylic acid, the reaction is to proceed efficiently.
[0010]
[Means for Solving the Problems]
As a result of intensive studies on the improvement of the industrial production process of aromatic hydroxycarboxylic acids by the present inventors, it has been found that the problems in the prior art are caused by changes in the viscosity of the reaction solution. That is, in the Kolbeschmitt reaction, a slurry or molten liquid of an alkali metal salt of an aromatic hydroxy compound, which has high fluidity at the start of the reaction, is an alkali metal of an aromatic hydroxycarboxylic acid in the reaction system as the reaction proceeds. Since salt fine crystals increase, a high-viscosity paste is formed in the late reaction stage. It is considered that due to such a change in viscosity, the reaction efficiency is lowered, and thermal non-uniformity occurs, resulting in a loss of raw materials due to side reactions.
Therefore, by using a specific stirring device that can efficiently stir regardless of the viscosity of the reaction liquid throughout the reaction step, it was found that the reaction efficiency was improved and side reactions were suppressed, and the present invention was It came to be completed.
[0011]
That is, the present invention uses an aromatic hydroxy compound using a reaction vessel having an agitation blade disposed so as to be rotatable along the side wall and the bottom of the reaction vessel on an agitation shaft disposed perpendicularly to the center of the reaction vessel. The present invention relates to a method for producing an aromatic hydroxycarboxylic acid, characterized by reacting an alkali metal salt of an aromatic hydroxy compound with carbon dioxide in the presence of a medium that does not substantially dissolve the alkali metal salt.
[0012]
The reaction tank used in the present invention includes a stirring shaft and a stirring blade, and has the following characteristics as shown in FIG.
(1) The cross section of the reaction vessel 1 is circular, and the stirring shaft 2 is disposed perpendicular to the center thereof.
(2) The stirring blade 3 is rotatably installed on the stirring shaft along the side wall 4 and the bottom 5 of the reaction tank 1.
An anchor blade is preferably employed as the stirring blade.
[0013]
The lower part of the stirring blade 3 may have a paddle blade 7 with a receding blade having a shape along the bottom 5 of the reaction vessel 1, and the upper portion of the stirring blade 3 has a paddle blade, a helical ribbon blade, or the like. It may be.
The reaction vessel used in the present invention may further have a baffle plate 6. In this case, it is preferable that the baffle plate 6 is installed on the center side of the reaction tank from the rotation trajectory of the stirring blade 3.
The baffle plate may be attached to the side wall of the reaction tank or may be attached from the upper part of the reaction tank.
[0014]
The material of the reaction vessel, the stirring shaft, the stirring blade and the baffle used in the present invention is not particularly limited as long as it has corrosion resistance to the alkali metal salt of the aromatic hydroxy compound in the reaction conditions. For example, SUS316L or the like Are preferably used.
As such a stirring device equipped with a stirring blade and a baffle plate, an NX mixer manufactured by Nippon Chemical Machinery Co., Ltd. is preferably used.
[0015]
In addition to the above, the reaction tank used in the present invention may have a carbon dioxide introduction pipe, a thermometer support pipe, a pressure gauge, an exhaust pipe, and the like.
[0016]
Using a reaction vessel equipped with such a stirring mechanism, the alkali metal salt of the aromatic hydroxy compound and carbon dioxide are reacted in the presence of a medium that does not substantially dissolve the alkali metal salt of the aromatic hydroxy compound. By this, it becomes possible to efficiently stir from the low viscosity state at the initial stage of the reaction to the high viscosity state at the late stage of the reaction, and it becomes possible to reduce the raw material loss due to the side reaction and improve the reaction yield. .
[0017]
The aromatic hydroxy compound in the method of the present invention is preferably phenol or β-naphthol, and the alkali metal is preferably sodium or potassium. Moreover, as a suitable example of the alkali metal salt of an aromatic hydroxy compound, β-naphthol sodium can be mentioned.
[0018]
The reaction medium that does not substantially dissolve the alkali metal salt of the aromatic hydroxy compound used in the present invention includes light oil, kerosene, white oil, alkylbenzene, alkylnaphthalene, diphenyl, diphenylalkane, alkyldiphenyl, triphenyl, hydrogenated trihydride. Examples thereof include phenyl, diphenyl ether, alkylphenyl ether, alkyldiphenyl ether, high-boiling higher alcohols such as iso-octyl alcohol, and mixtures thereof. Particularly preferably, light oil or hydrogenated triphenyl is used.
[0019]
In the method for producing an aromatic hydroxycarboxylic acid of the present invention, a method in which an alkali metal salt of an aromatic hydroxy compound and carbon dioxide are reacted in the presence of a medium that does not substantially dissolve the alkali metal salt of the aromatic hydroxy compound. If it is, it will not specifically limit, What is necessary is just to use the method regarding the Kolbeschmitt reaction known conventionally. As a method suitably used, for example, a method of performing a dehydration step of an alkali metal salt of an aromatic hydroxy compound or a reaction step with carbon dioxide in the presence of an aromatic hydroxy compound, an aromatic hydroxy compound added by this method And a method of removing the aromatic hydroxy compound and water by-produced by the reaction in a gaseous state during the reaction together with carbon dioxide.
[0020]
In the production method of the present invention, the method for preparing an alkali metal salt of a dehydrated aromatic hydroxy compound used as a reaction raw material is not particularly limited. For example, an alkali metal salt of an aromatic hydroxy compound prepared from an alkali metal compound such as an alkali metal hydroxide and an aromatic hydroxy compound is heated in a medium used for the reaction in a dehydration tank provided separately from the reaction tank. The dehydration may be performed. Moreover, you may prepare the alkali metal salt of the aromatic hydroxy compound similarly dehydrated with the reaction tank used by this invention.
[0021]
The alkali metal salt of the dehydrated aromatic hydroxy compound thus obtained is then subjected to a reaction with carbon dioxide.
[0022]
The temperature during the reaction between the alkali metal salt of the aromatic hydroxy compound and carbon dioxide is preferably 200 to 350 ° C, particularly preferably 250 to 300 ° C. If the reaction temperature is lower than 200 ° C., there is a problem that the reaction yield is low or a long time is required to obtain a good yield. If the reaction temperature is higher than 350 ° C., the yield decreases due to thermal decomposition of the alkali metal salt of the aromatic hydroxycarboxylic acid product, the increase in resinous matter (tar) generated due to the loss of raw materials due to side reactions, This causes problems in the quality of the product, such as color tone and purity.
The carbon dioxide pressure during the reaction is preferably 0.05 to 2 MPa (G), particularly preferably 0.2 to 1 MPa (G).
[0023]
As for the stirring conditions, the stirring blade diameter (m) × circularity × stirring rotational speed (rpm) ÷ the stirring rotational speed at which the tip peripheral speed of the stirring blade is 2 to 8 m / sec is calculated. Is preferred. When the tip peripheral speed is slower than 2 m / sec, sufficient agitation is not achieved and a good yield cannot be obtained. If the tip peripheral speed is higher than 8 m / sec, a problem of jumping up the reaction solution to the upper part of the reaction layer and a waste of stirring power are caused.
[0024]
The reaction time varies depending on the reaction conditions and the type of the alkali metal salt of the aromatic hydroxy compound to be used, but is usually 0.5 to 10 hours, preferably 1 to 7 hours.
[0025]
The reaction tank contents after completion of the reaction are dissolved by adding water after cooling and stirring. Or you may melt | dissolve by stirring, using a pump etc., after transferring to the separately provided hydrolysis dissolution tank.
[0026]
The obtained solution is mainly a reaction medium in a state of being kept at a temperature of 80 to 100 ° C. so that an alkali metal salt of an aromatic hydroxycarboxylic acid and an aromatic hydroxy compound produced as a by-product or addition are not precipitated. And an aqueous layer containing an alkali metal salt of an aromatic hydroxycarboxylic acid.
[0027]
The obtained aqueous layer is adjusted to pH 6.5-8 with mineral acid or the like, and then the aromatic hydroxy compound released by neutralization of the alkali metal salt of the unreacted aromatic hydroxy compound is used with a hydrophobic organic solvent. Extracted. Examples of the hydrophobic organic solvent used for extraction include aromatic hydrocarbons such as toluene, xylene and nitrobenzene, alcohols such as n-butanol, n-octyl alcohol and 2-ethylhexyl alcohol, ethers such as dibutyl ether and diphenyl ether, A ketone solvent such as cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone is preferably used.
[0028]
The aromatic hydroxy compound extracted in the reaction medium layer and in the hydrophobic organic solvent is extracted as an alkali metal salt of the aromatic hydroxy compound by an aqueous solution of an alkali metal hydroxide, etc., and returned to the dehydration step to react again. Can be served.
[0029]
If desired, the aqueous layer from which the free aromatic hydroxy compound has been extracted is subjected to acid precipitation after removing colored tar-like substances and the like with an adsorbent such as activated carbon. The acid used for acid precipitation is not particularly limited, but is adjusted to pH 1 to 3 with a mineral acid, for example, a binary acid such as hydrochloric acid or hydrofluoric acid, or an oxo acid such as sulfuric acid, nitric acid, phosphoric acid or perchloric acid. Is done.
[0030]
The suspension of aromatic hydroxycarboxylic acid obtained by acid precipitation is separated from the mother liquor by a conventional method such as centrifugation or filter press, and after being subjected to a purification process such as washing or recrystallization, if desired, dried. It is said.
The aromatic hydroxycarboxylic acid thus obtained is suitably used for various applications such as pigments, dye intermediates and polymer raw materials.
[0031]
【Example】
Example 1
48% sodium hydroxide and β-naphthol were placed in a reaction vessel having a capacity of 50 L shown in FIG. 1, and 24.9 kg (75 mol) of a 50% β-naphthol sodium aqueous solution was prepared in a nitrogen atmosphere.
Light oil was added to this aqueous solution, and the temperature was raised to 260 ° C. under a nitrogen stream to perform dehydration. During this time, since the low boiling fraction of light oil distills out of the system together with water, the amount of distillate light oil is measured and adjusted by adding light oil so that the final light oil amount in the reaction tank is 17.4 kg. did.
After heating the obtained light oil suspension of anhydrous β-naphthol sodium to 280 ° C., 5.4 kg (37.5 mol) of β-naphthol was added.
[0032]
Subsequently, the carbon dioxide pressure was increased to 6.0 kg / cm ² (G) and the blade tip peripheral speed was maintained at 290 ° C. for 1.8 hours under conditions of a blade tip peripheral speed of 2.7 m / second (stirring rotation speed 140 rpm, stirring blade diameter 370 mm). The reaction was carried out.
After completion of the reaction, the contents were transferred to a dissolution tank filled with 200 L of water, and dissolved at 90 ° C. in a nitrogen atmosphere. Subsequently, 50 L of water was put into the reaction tank, and it wash | cleaned by hold | maintaining at 90 degreeC, and the washing | cleaning liquid was transferred to the dissolution tank.
The solution obtained by combining the reaction solution and the washing solution for the reaction tank was kept at 90 ° C. and allowed to stand, and then separated into an aqueous layer and a light oil layer.
[0033]
The composition of each layer obtained was analyzed by high performance liquid chromatography, and the recovered amounts of raw materials and products were measured. The results are shown in Table 1. From the analysis results, the yield of 2-hydroxy-3-naphthoic acid based on β-naphthol sodium was 41.2%, and the conversion rate to an unknown product was 8.3%.
[0034]
Comparative Example 1
The same operation as in Example 1 was performed except that the reaction was performed at a blade tip peripheral speed of 4.7 m / sec (stirring rotation speed 500 rpm, stirring blade diameter 180 mm) using a reaction tank having a capacity of 50 L shown in FIG. It was.
The composition of the water layer and the light oil layer was analyzed by high performance liquid chromatography, and the recovered amounts of raw materials and products were measured. The results are shown in Table 1. From the analysis results, the yield of 2-hydroxy-3-naphthoic acid based on β-naphthol sodium was 37.7%, and the conversion rate of β-naphthol sodium to an unknown product was 28.1%. .
[0035]
[Table 1]

A: 2-hydroxy-3-naphthoic acid B: 2-hydroxy-6-naphthoic acid C: 2-hydroxynaphthalene-3,6-dicarboxylic acid D: β-naphthol and β-naphthol sodium E: unknown product ( The total amount of A, B, C and D subtracted from the charged β-naphthol sodium and added β-naphthol)
[0036]
Thus, by sufficiently stirring the reaction solution according to the method of the present invention, the reaction yield is improved and the loss of raw materials due to side reactions is suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic view of a reaction tank equipped with a stirring mechanism used in the present invention used in Example 1. FIG.
FIG. 2 is a schematic view of a reaction tank equipped with a stirring mechanism using paddle blades used in Comparative Example 1.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Stirring shaft 3 Stirring blade 4 Reaction tank side wall 5 Reaction tank bottom part 6 Baffle plate 7 Paddle blade with receding blade

Claims (5)

The stirring shaft disposed vertically in the center of the reaction vessel, along the sidewalls and bottom of the reaction vessel have a rotatably installed anchor blade, and the center side of the reaction vessel from the rotation locus of anchor blade In the presence of a medium that does not substantially dissolve the alkali metal salt of the aromatic hydroxy compound, the alkali metal salt of the aromatic hydroxy compound and carbon dioxide are reacted using a reaction vessel having a baffle plate installed in A process for producing an aromatic hydroxycarboxylic acid, characterized in that   The method for producing an aromatic hydroxycarboxylic acid according to claim 1, wherein the aromatic hydroxy compound is phenol or β-naphthol, and the alkali metal is sodium or potassium.   The method for producing an aromatic hydroxycarboxylic acid according to claim 1, wherein the alkali metal salt of the aromatic hydroxy compound is β-naphthol sodium.   Medium that does not substantially dissolve the alkali metal salt of the aromatic hydroxy compound is light oil, kerosene, white oil, alkylbenzene, alkylnaphthalene, diphenyl, diphenylalkane, alkyldiphenyl, triphenyl, hydrogenated triphenyl, diphenyl ether, alkylphenyl ether The method for producing an aromatic hydroxycarboxylic acid according to claim 1, wherein the aromatic hydroxycarboxylic acid is one or a mixture of two or more selected from the group consisting of alkyldiphenyl ether and iso-octyl alcohol.   2. The aromatic hydroxycarboxylic acid according to claim 1, wherein the alkali metal salt of the aromatic hydroxy compound and carbon dioxide are reacted under a stirring condition in which the tip peripheral speed of the stirring blade is 2 to 8 m / sec. Manufacturing method.

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