JPH0211530A - Preparation of aromatic hydroxy compound by continuous alkali fusion method - Google Patents

Abstract

PURPOSE:To economically provide the subject compound in a high conversion rate by continuously supplying an aromatic sulfonic acid alkali metal salt and a caustic alkali to a thin film type evaporator and subsequently carrying out the evaporation of water, a kneading process and a reaction with the evaporator and a biaxial kneader. CONSTITUTION:An aromatic sulfonic acid alkali metal salt and a caustic alkali are mixed in a mixing tank 1 and supplied to a thin film type evaporator 3. The water in the mixture is evaporated in the evaporator 3 and the dried mixture is heated and supplied to a biaxial kneader 4 comprising a combination of a screw and a paddle, followed by kneading at 250-400 deg.C for 5min-5hr. The reaction product is mixed with water in a water-mixing tank 5 and further with an acid in a neutralization tank 6 to deposit the product, followed by subjecting to a step such as the separation of the product with a centrifugal separator 7 to provide the objective compound. The above-mentioned method reduces the loss of energy because of the continuous method and can prevent the heating of a local position. Further, since the control of the reaction is easy, the quality of the product is constant and the quality is highly readily controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing an aromatic hydroxy compound by continuously alkali-melting an alkali metal salt of an aromatic sulfonic acid.

<Prior Art> Sulfonation-alkali fusion is still an effective method for producing aromatic hydroxy compounds today, although it has many problems.

The alkali melting reaction mixture is in the form of a powder or a highly viscous slurry, and it has been thought that the alkali melting reaction is not suitable for a normal flow-type continuous reactor in terms of mixing and heat transfer. The industrial implementation of alkaline melting reactions has only been carried out batchwise. However, batch reactors have many problems as follows.

■Since temperature raising, reaction, and cooling are repeated in the same reactor, energy loss is large and productivity is poor.

■It becomes a highly viscous slurry with extremely poor fluidity, making stirring difficult. Moreover, as a result, heat transfer deteriorates, local heating is unavoidable, and product decomposition due to local heating occurs. For this reason, it is not possible to increase the size of the system, and small devices must be installed in parallel, which increases equipment investment and requires a large amount of labor.

■It takes a lot of time and energy to preheat the reactor and evaporate water.

■The state of the reactants changes moment by moment, and sometimes abnormal foaming occurs, making it impossible to control the reaction and becoming extremely dangerous.

In order to overcome these problems, several continuous alkali melting reaction systems have been proposed so far. These are, for example, Japanese Patent Publication No. 35-13213, Japanese Patent Application Publication No. 10/1986.
No. 0329, U.S. Pat. No. 2,378,314, U.S. Pat. No. 2,353
No. 237, No. 3285706, or Industrial Chemistry Magazine, Vol. 60, No. 2, pp. 287-289 (1966).

<Problems to be solved by the invention> Therefore, the present inventors investigated these problems in detail and found that all reaction methods are unsatisfactory or lack versatility for continuous alkali melting. I've come to a conclusion. That is, in continuous alkali melting, it is important to consider three processes: feeding of raw materials, evaporation of water, and reaction. It is necessary to continuously and stably supply the raw material to the reactor, and for this purpose, it is desirable to feed the raw material as a solution or a low-viscosity slurry. Tokuko Sho 35-13
In the method seen in No. 213, the raw material is a mixture of aromatic sulfonic acid powder and caustic alkali that has been melted in advance, or an aqueous solution that has been heated to 290°C to evaporate water, but as mentioned above, The mixture after water evaporation often becomes an extremely viscous slurry, and it is extremely difficult to feed the liquid in this state. In addition, the water evaporation process is essential to raise the temperature of the reaction mixture to the reaction temperature and obtain a high conversion rate, but it usually takes a lot of time and has a large impact on the subsequent reaction, so this is not an important step. It is a very important element in the alkaline melting process. In the next reaction process, it is essential to effectively knead and stir the reaction mixture and to suppress mixing of reactants and products in the flow direction (plug flow) in order to increase the conversion rate. However, the reaction mixture is usually an extremely viscous slurry, which not only makes it difficult to obtain a satisfactory stirring state but also tends to stick to walls.
The methods described in the specifications of No. 353237 and No. 3285706 do not provide sufficient stirring, and tend to remain attached to important points.

To improve the mixing condition
A reaction in a No. 70 kneader type reactor is known, but this is a batch type reaction and does not solve all of the above-mentioned problems specific to the batch type reactor.

Furthermore, the overflow in method using a stirred seed reactor disclosed in JP-A-54-100329 is applicable only to reaction mixtures exhibiting good fluidity, and is therefore not universally applicable.

The present invention aims to overcome the drawbacks of the conventional batch and continuous alkali melting methods and provide a method for producing aromatic hydroxy compounds by a continuous alkali melting method with high conversion rate, easy control, and high productivity. It is something to do. In other words, there is no residual adhesion of the reaction mixture, there is no risk of foaming, and there is also a thin film evaporator that can evaporate water in a short time of about 2 minutes, and a two-shaft blade that combines a screw and paddle with good crosstalk. Kneaders are connected vertically in series, and an alkaline aqueous solution or slurry of an alkali metal salt of aromatic sulfonic acid is continuously fed thereto to continuously evaporate water, knead and react. It is an object of the present invention to provide a method for producing an aromatic hydroxy compound by a continuous alkali melting method that enables continuous alkali melting with a high conversion rate and high productivity that is easy to control.

<Means for Solving the Problems> In order to achieve the above object, according to the present invention, when producing an aromatic hydroxy compound by continuously melting an aromatic sulfonic acid metal salt with an alkali, The alkali metal salt and caustic alkali are continuously supplied to a thin film evaporator, and water is evaporated by the evaporator and a twin-shaft kneader having blades that are a combination of screws and paddles connected in series to the evaporator. Provided is a method for producing an aromatic hydroxy compound by a continuous alkali melting method, which comprises performing kneading and reaction.

Among these, the temperature of kneading and reaction in the twin-screw kneader is 2.
It is preferable that it is 50-400 degreeC.

The present invention will be explained in more detail below.

Alkali metal salts of aromatic sulfonic acids that can be used in the present invention include compounds having an aromatic ring, such as fused with a heterocyclic ring such as benzene, naphthalene, anthracene, phenanthrene, diphenyl, triphenyl, diphenylalkane, triphenylalkane or quinoline. Sodium of a compound having one or more sulfonic acid groups on the aromatic ring of an aromatic compound or a partially hydrogenated product thereof,
Examples include alkali metal salts such as potassium. These compounds may have other substituents on the ring or in the connecting chain that do not affect the reaction. These compounds can be prepared by sulfonating the aromatic ring-containing compound with sulfuric acid or fuming sulfuric acid using a conventional method. After that, it is obtained by converting it into an alkali metal salt.

The caustic alkali that can be used in the present invention may be in the form of caustic soda, caustic potash, or a mixture of both. The amount of caustic alkali to be used is 1 to 5 times the theoretical amount, more preferably 1 to 3.5 times the theoretical amount based on the sulfonic acid group.
Use within the range of double.

The reaction temperature varies somewhat depending on the type of raw materials, but it is 250
The temperature is preferably in the range of ~400°C.

The average residence time in the 2-hour kneader varies depending on the raw materials, but is preferably in the range of 5 minutes to 5 hours.

Although the reaction pressure can be normal pressure, reduced pressure, or increased pressure, the effects of the present invention are best expressed under normal pressure.

The present invention will be explained below with reference to FIGS. 1 to 5, but these are only specific examples of the present invention, and changes can be made without departing from the spirit of the present invention.

FIG. 1 shows the overall configuration of the present invention.

A mixture of caustic alkali and an alkali metal salt of aromatic sulfonic acid is stirred and mixed in a mixing tank 1 and is continuously supplied to a thin film evaporator 3 by a liquid feed pump 2.

Water is evaporated in a thin film evaporator 3, and the heated mixture is supplied to a twin-screw kneader 4 that combines a screw and a paddle, where it is kneaded and reacted at the above reaction temperature and residence time. . The reactant discharged from the twin-screw kneader 4 is mixed with water in a water mixing tank 5,
Next, an acid is added in the neutralization tank 6 to precipitate the product, and the target product is obtained by performing operations such as separation using a centrifugal separator 7, for example.

Next, an example of the structure of the thin film evaporator 3 will be explained.

Figure 2 is a sectional view along the long sleeve of the evaporator;
The figure is a sectional view perpendicular to the long axis.

The distance between the stirring blade 8 and the inner wall surface of the main body must be within a range that allows a thin film to be formed. The structure of the stirring blade may be any structure as long as it can effectively form a thin film, and the material may be alkali-resistant and abrasion-resistant. Note that 9 is a long sleeve, 10 is a raw material supply nozzle, and 11 is a mixture. discharge nozzle,
12 is a steam discharge nozzle, 13 is a liquid feeding screw, and 14 is a heat medium jacket.

Next, FIGS. 4 and 5 show an example of the structure of a two-shaft kneader 4 having blades that combine screws and paddles.
FIG. 4 is a sectional view along the long sleeve of the biaxial kneader, and FIG. 5 is a sectional view perpendicular to the long sleeve.

Screw 15 and paddle 16.17.18 and 1
The distance between 9 and the wall is 1 to prevent the reaction mixture from adhering.
It is preferable to make it less than mm. Also, one paddle 16 and 17 of the two axes is always connected to the other paddle 18 and 19.
It is preferable that the material has a self-cleaning structure that renews the surface of the material. Note that 20 is a raw material supply nozzle, 21 is a reaction mixture discharge nozzle, 22 is a steam discharge nozzle, and 23 is a heat medium jacket.

In the present invention, the object of the present invention can be sufficiently achieved with one thin film evaporator and one twin-shaft kneader, but it is of course possible to arrange two or more in series.

<Examples> The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples.

(Example) Benzene sulfonic acid sodium salt was mixed with a caustic soda aqueous solution, and the concentration of benzene sulfonic acid in the mixture was 30%.
, caustic soda and benzenesulfonic acid sodium salt 2.
The molar ratio was adjusted to 5:1.0. This liquid was reacted using an evaporator and a twin-screw kneader as shown in FIGS. 3 and 4. The material of the evaporator and twin-shaft kneader is made of 5US316, and the heating is done by circulating a heat medium.
The temperature of the supplied heating medium was 350°C. In addition, temperature control was performed by adjusting the amount of heat medium supplied. The temperature of the mixture discharged from the thin film evaporator was adjusted to 290°C, and the temperature of the reactant discharged from the twin-screw kneader was adjusted to 300°C. Approximately 5 hours had passed since the start of supply of raw materials, and after a reactant with a sufficiently steady composition was obtained, a portion of it was collected, dissolved in water, neutralized with sulfuric acid, and further methanol was added and dissolved. The sample was analyzed by liquid chromatography to determine the conversion rate. As a result, the conversion rate of benzenesulfonic acid was 95% and the phenol selectivity was 92%.

(Example 2) The reaction was carried out under the same conditions as in Example 1 except that the raw material was β-naphthalenesulfonic acid sodium salt and the temperature of the discharge from the thin film evaporator and twin-screw kneader was 310°C and 325°C, respectively. As a result, the conversion rate of β-naphthalenesulfonic acid was 95%, and the selectivity of β-naphthol was 90%.

(Example 3) The reaction was carried out under the same conditions as in Example 1 except that the raw material was 2,7-naphthalenedisulfonic acid sodium salt and the molar ratio of caustic soda and 2,7-naphthalenedisulfonic acid sodium salt was 5:1. As a result, the conversion rate of 2.7-naphthalenedisulfonic acid was 95%, and the selectivity of 2.7-naphthalenediol was 92%.

<Effects of the Invention> According to the present invention, as explained above, it is composed of a thin-film evaporator that can efficiently evaporate water and a twin-shaft kneader that has good crosstalk and good heat transfer characteristics. It has become possible to produce aromatic hydroxy compounds by a continuous alkaline melting method with high productivity and easy control of conversion. Furthermore, since it is a continuous method, energy loss is reduced and local heating can be prevented. Furthermore, since it is easy to control, the properties of the product are constant and quality control is extremely easy.

In addition, the thin film evaporator effectively evaporates water in a short time, eliminating the need for long concentration operations and eliminating the risk of foaming.

Furthermore, since the present invention can use a general-purpose thin film evaporator and a twin-shaft kneader, the present invention has the effect of facilitating design and reducing manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram showing the configuration of the present invention. Figure 2 shows It is a diagram. Figure 3 shows Side cross section showing an example of a thin film evaporator FIG. 2 is a cross-sectional view of a thin film evaporator. FIG. 4 is a side sectional view showing an example of a two-axis kneader. FIG. 5 is a cross-sectional view of the two-shaft kneader. 6.17.18.19...paddle, 0...raw material supply nozzle, 1... Reaction mixture discharge nozzle, 2...Steam exhaust nozzle, 3...heat medium jacket, Explanation of symbols 1...mixing tank, 3...thin film evaporator, 5...Water mixing tank, 7... Centrifugal separator, 9...long axis, 10... Raw material supply nozzle, 11...Mixture discharge nozzle, 12... Steam exhaust nozzle, 13...Liquid feeding screw 14...heat medium jacket, 1 2...liquid pump, 4...2-axis kneader 6...neutralization tank, 8... Stirring blade, 5...Screw FIG.1

Claims (2)

[Claims] (1) When producing an aromatic hydroxy compound by continuously melting an aromatic sulfonic acid metal salt with an alkali, an alkali metal salt of an aromatic sulfonic acid and a caustic alkali are continuously supplied to a thin film evaporator. 2, which has an evaporator and blades that are a combination of screws and paddles connected in series to the evaporator.
A method for producing an aromatic hydroxy compound by a continuous alkali melting method, which comprises evaporating water, kneading, and reacting with a shaft kneader. (2) The kneading and reaction temperature in the twin-screw kneader is 250°C.
The method for producing an aromatic hydroxy compound according to claim 1, wherein the temperature is 400°C.