JP5380683B2 - Process for producing aromatic hydroxycarboxylic acid - Google Patents

Description

  The present invention relates to a method for producing an aromatic hydroxycarboxylic acid without subjecting an aromatic hydroxy compound as a raw material to alkali metal chloride.

  Aromatic hydroxycarboxylic acids are important compounds as preservatives and preservatives for foods and cosmetics, and as raw materials or intermediates for pigments and dyes, liquid crystal polymers and engineering plastics.

  Conventionally, when producing an aromatic hydroxycarboxylic acid such as salicylic acid (o-hydroxybenzoic acid) or p-hydroxybenzoic acid, the raw material aromatic hydroxy compound such as phenol or naphthol is an alkali metal salt such as sodium, It was common to carry out the reaction. For example, as a well-known reaction, Kolbe-Schmitt reaction (Kolbe-Schmitt reaction) which obtains aromatic hydroxycarboxylic acid by carrying out solid-phase reaction with carbon dioxide using an aromatic compound having a phenolic hydroxyl group as an alkali metal salt. reaction) etc. is common.

In addition, as described in Patent Document 1, as a method of not using an aromatic hydroxy compound as a raw material as an alkali metal salt, melting an aromatic hydroxy compound, an inorganic carbonate, and carbon dioxide with triphenyl hydride or the like. A method for producing an aromatic hydroxycarboxylic acid by reacting at a temperature of 473 K or higher under a pressure of 0.05 to 2.5 MPa in the presence of an agent is shown.
JP 2002-302465 A

  However, since the raw material is an alkali metal salt in the Kolbe-Schmidt reaction, it is necessary to separate the alkali metal and the aromatic hydroxycarboxylic acid after the completion of the reaction. Moreover, as shown in Patent Document 1, in the method for producing an aromatic hydroxycarboxylic acid, a separation operation from a solvent is required after completion of the reaction.

  Such a purification operation after completion of the reaction increases the cost for producing the aromatic hydroxycarboxylic acid.

  In view of the above problems, the present invention provides the following method for producing an aromatic hydroxycarboxylic acid. That is, as a first invention, there is provided a method for producing an aromatic hydroxycarboxylic acid, characterized by reacting an aromatic hydroxy compound, a basic catalyst, and carbon dioxide in a supercritical fluid state.

  As a second invention, there is provided the method for producing an aromatic hydroxycarboxylic acid according to the first invention, wherein the basic catalyst is potassium carbonate.

  As a third invention, there is provided the method for producing an aromatic hydroxycarboxylic acid according to the first invention, wherein the aromatic hydroxy compound is phenol.

  As a fourth invention, there is provided the process for producing an aromatic hydroxycarboxylic acid according to the first invention, wherein the aromatic hydroxy compound is 1-naphthol or 2-naphthol.

  As a fifth invention, a reaction furnace for filling an aromatic hydroxy compound, a basic catalyst, and carbon dioxide and maintaining the carbon dioxide in a supercritical fluid state, and a first filling for filling the reaction furnace with the aromatic hydroxy compound A second filling part for filling the reaction furnace with a basic catalyst, a third filling part for filling the reaction furnace with carbon dioxide, and a reaction furnace filled with the respective members with carbon dioxide. Aromatic hydroxycarboxyl having a critical control unit that pressurizes and adjusts the temperature so as to be in a supercritical fluid state, and a takeout unit for taking out the aromatic hydroxycarboxylic acid that is a product in the reaction furnace from the reaction furnace An acid production apparatus is provided.

  According to the present invention, it is possible to produce an aromatic hydroxycarboxylic acid without alkali metal chlorinating an aromatic hydroxy compound as a raw material and without using a melting agent or the like. As a result, the basic catalyst and the reaction product can be easily separated after completion of the reaction due to the difference in solubility in organic solvents such as methanol, and there is no need for complicated separation operations such as desalting and solvent separation. An aromatic hydroxycarboxylic acid can be produced. This also allows the reactor to be run in a flow-through manner.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, this invention should not be limited to these embodiments at all, and can be implemented in various modes without departing from the gist thereof.

  The first embodiment mainly relates to claim 1 and the like.

  The second embodiment mainly relates to claim 2 and the like.

  The third embodiment mainly relates to claim 3 and the like.

  The fourth embodiment mainly relates to claim 4 and the like.

The fifth embodiment mainly relates to claim 5 and the like.
<Embodiment 1>
<Summary of Embodiment 1>

This embodiment is a method for producing an aromatic hydroxycarboxylic acid by reacting an aromatic hydroxy compound as a raw material with a basic catalyst under carbon dioxide in a supercritical fluid state. The aromatic hydroxy compound and carbon dioxide did not react with carbon dioxide under normal temperature and pressure conditions, and the aromatic hydroxy compound had to be chlorinated with an alkali metal or reacted in an organic solvent. Therefore, in the present invention, an aromatic hydroxycarboxylic acid is produced without reacting in the presence of an alkali metal chloride or in an organic solvent by reacting carbon dioxide in a supercritical fluid state via a basic catalyst. Provide a method.
<Configuration of Embodiment 1>

  In the method for producing an aromatic hydroxycarboxylic acid of this embodiment, an aromatic hydroxy compound, a basic catalyst, and carbon dioxide in a supercritical fluid state are reacted.

  Conventionally, the reaction in a gas phase-solid phase system in which an aromatic hydroxy compound such as phenol and carbon dioxide are reacted does not react with an acidic substance such as phenol because carbon dioxide is electrophilic. It was necessary to react carbon dioxide with an aromatic hydroxy compound as an alkali metal salt. Further, in the case of the production method in which the aromatic hydroxy compound is not an alkali metal salt as in Patent Document 1, it is necessary to use an organic solvent as a melting agent and perform the reaction in a liquid phase system.

  In the present invention, the inventors have found a method for producing an aromatic hydroxycarboxylic acid from an aromatic hydroxy compound without subjecting the aromatic hydroxy compound to alkali metal chloride or using an organic solvent. That is, this is a method for producing an aromatic hydroxycarboxylic acid from an aromatic hydroxy compound via a basic catalyst using carbon dioxide in a supercritical fluid state as an acidic solvent.

  In the reaction of the method for producing an aromatic hydroxycarboxylic acid of the present embodiment, first, the proton of the hydroxyl group of the aromatic hydroxy compound was extracted by the Lewis base (electron pair donor) point on the basic catalyst, and at the same time, the proton was extracted. The phenoxy oxygen of the aromatic hydroxy compound binds to a Lewis acid (electron pair acceptor) point on the basic catalyst. Next, carbon dioxide undergoes an electrophilic reaction with the aromatic nucleus of the phenoxy anion bonded to the Lewis acid point, and generation of an aromatic hydroxycarboxylic acid proceeds.

  <Aromatic hydroxy compound>

  The aromatic hydroxy compound used in the present invention is a compound having one or more hydroxyl groups in an aromatic ring (monocyclic aromatic ring, polycyclic aromatic ring, condensed aromatic ring, aromatic heterocyclic ring). That's fine. As the aromatic hydroxy compound used as a raw material, commercially available products (for example, products having a purity of 98%, etc.) can be used, but it is preferable that the types and contents of impurities are small.

  <CO2>

  Carbon dioxide used in the present invention is not particularly limited as long as it is commercially available (for example, a product having a purity of 99%). However, it is desirable to have a low impurity type and content. Carbon dioxide may be diluted with an inert gas such as a rare gas or nitrogen. In the method for producing an aromatic hydroxycarboxylic acid of this embodiment, carbon dioxide is reacted in a supercritical fluid state. The conditions for carbon dioxide to be in a supercritical fluid state are a pressure of 7.38 MPa or more and a temperature of 304.1 K or more. In the production of the aromatic hydroxycarboxylic acid of this embodiment, the reaction is performed at these pressures and temperatures or more. .

  <Basic catalyst>

  The basic catalyst used in the present embodiment is a catalyst having a Lewis basic point. A Lewis base point is an electron pair donating to a Lewis acid. That is, the basic catalyst of this embodiment is a basic catalyst having an electron pair donating to a Lewis acid.

  Here, in order to select a catalyst for producing an aromatic hydroxycarboxylic acid from an aromatic hydroxy compound, the following experiment was conducted.

  The reaction conditions for carrying out this experiment are a reaction temperature of 473 K, a reaction time of 5 hours, a carbon dioxide pressure of 8 MPa, and an inorganic solid catalyst of 1 g. The aromatic hydroxy compound used as a raw material was phenol.

Fig. 1 shows the amount of aromatic hydroxycarboxylic acid (salicylic acid (o-hydroxybenzoic acid), p-hydroxybenzoic acid) produced (mol%) produced when aromatic hydroxycarboxylic acid is produced using various inorganic solid catalysts. )showed that. The inorganic solid catalysts studied were silica (SiO ₂ ) and sulfated zirconia (ZrO ₂ —SO ₄ ²⁻ ), Lewis acid catalysts, and γ-alumina (ALO-2, ALO-3), acid-base amphoteric catalysts. , ALO-4) and hydroxyapatite (HAP-1, HAP-2, HAP-3), basic catalysts such as zirconium oxide (ZRO-2, ZRO-3), cerium oxide (CEO-1, CEO-2, CEO-3), calcium oxide (CaO), magnesium oxide (MgO), and potassium carbonate (K ₂ CO ₃ ) were used. As a result, it was clarified that the reaction does not occur in the Lewis acid catalyst silica and sulfated zirconia. Even when γ-alumina and hydroxyapatite, which are acid-base amphoteric catalysts, were used, hydroxybenzoic acid was not produced. On the other hand, in the reaction on the basic catalyst, production of hydroxybenzoic acid was confirmed. Of these, potassium carbonate, which is a carbonate, produced a large amount of hydroxybenzoic acid. From the above results, it was shown that a catalyst necessary for producing an aromatic hydroxycarboxylic acid by reacting an aromatic hydroxy compound with carbon dioxide in a supercritical fluid state is a basic catalyst. More specifically, in the method for producing an aromatic hydroxycarboxylic acid of the present embodiment, potassium carbonate (K ₂ CO ₃ ), sodium carbonate (Na ₂ ) are used as the basic catalyst for producing the aromatic hydroxycarboxylic acid. CO ₃ ), lithium carbonate (LiCO ₃ ), rubidium carbonate (RbCO ₃ ), calcium carbonate (CaCO ₃ ), barium carbonate (BaCO ₃ ), potassium hydrogen carbonate (KHCO ₃ ), potassium acetate (CH ₃ COOK) It is done.

Of the various catalysts shown in Fig. 1, ALO-2, ALO-3, ALO-4, ZRO-2, ZRO-3, CEO-1, CEO-2, and CEO-3 are provided by the Catalysis Society of Japan. The reference catalyst.
<Embodiment 1 effect>

As in this embodiment, it is possible to efficiently produce an aromatic hydroxycarboxylic acid by reacting an aromatic hydroxy compound with carbon dioxide in a supercritical fluid state via a basic catalyst. In addition, it is possible to produce an aromatic hydroxycarboxylic acid without using a solvent such as an organic solvent in the reaction and without using an alkali metal or the like.
<Embodiment 2>
<Overview of Embodiment 2>

This embodiment is a method for producing an aromatic hydroxycarboxylic acid, which is based on Embodiment 1 and further uses potassium carbonate as a basic catalyst. By using potassium carbonate as the basic catalyst, it becomes possible to produce an aromatic hydroxycarboxylic acid at a higher conversion rate than other basic catalysts.
<Embodiment 2 configuration>

  In the method for producing an aromatic hydroxycarboxylic acid of this embodiment, potassium carbonate was used as the basic catalyst.

  Potassium carbonate is not particularly limited, and commercially available potassium carbonate can be used. However, it is desirable that the type and content of impurities be small.

As described in Embodiment 1, in the method for producing an aromatic hydroxycarboxylic acid of the present invention, it is preferable to use a basic catalyst as the catalyst. At this time, potassium carbonate (K ₂ CO ₃ ) was a basic catalyst that produced a large amount of aromatic hydroxycarboxylic acid. Therefore, in this embodiment, the influence on the amount of aromatic hydroxycarboxylic acid produced by the type of carbonate shown in FIG. 2 was examined. In the reaction, phenol is used as the starting aromatic hydroxy compound, and the aromatic hydroxycarboxylic acids produced are salicylic acid (o-hydroxybenzoic acid) and p-hydroxybenzoic acid. The reaction conditions were a reaction temperature of 473 K, a reaction time of 5 hours, a carbon dioxide pressure of 8 MPa, and a carbonate catalyst of 10 mmol. The carbonate catalysts we examined include lithium carbonate (Li ₂ CO ₃ ), sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ ), rubidium carbonate (Rb ₂ CO ₃ ), calcium carbonate (CaCO ₃ ), barium carbonate (BaCO ₃ ), potassium hydrogen carbonate (KHCO ₃ ). As a result of the reaction, as shown in FIG. 2, the formation of hydroxybenzoic acid was confirmed in all carbonates, but it was potassium carbonate that produced the largest amount of hydroxybenzoic acid.

  Next, in order to investigate the effect of potassium on potassium carbonate, which produced the largest amount of hydroxybenzoic acid, the influence on the reaction due to the difference in anion species was examined. In the reaction, phenol is used as the starting aromatic hydroxy compound, and the aromatic hydroxycarboxylic acids produced are salicylic acid (o-hydroxybenzoic acid) and p-hydroxybenzoic acid. The reaction conditions were a reaction temperature of 473 K, a reaction time of 5 hours, a carbon dioxide pressure of 8 MPa, and a carbonate catalyst of 10 mmol. The potassium salt catalysts that have been studied are potassium sulfate, potassium nitrate, potassium acetate, potassium chloride, and potassium carbonate. The results of the reaction are shown in FIG. As a result of the reaction, it was revealed that potassium sulfate and potassium acetate showed almost no activity. Moreover, it was suggested that the activity of potassium nitrate and potassium chloride is lower than that of potassium carbonate. From these, it was shown that the point of direct carboxylation of phenol in supercritical carbon dioxide is to select a catalyst having basicity suitable for the reaction, and in particular, potassium carbonate is excellent. .

From the above results, it was shown that it is desirable to use potassium carbonate as the basic catalyst in order to produce the aromatic hydroxycarboxylic acid of the present embodiment.
<Embodiment 2 effect>

As in the method for producing an aromatic hydroxycarboxylic acid of this embodiment, by using potassium carbonate as a basic catalyst, it becomes possible to efficiently produce an aromatic hydroxycarboxylic acid from an aromatic hydroxy compound.
<Embodiment 3>
<Overview of Embodiment 3>

The present embodiment is a method for producing an aromatic hydroxycarboxylic acid, which is based on Embodiments 1 and 2, wherein the aromatic hydroxy compound as a raw material is phenol. By using phenol as the raw material, salicylic acid (o-hydroxybenzoic acid) and p-hydroxybenzoic acid can be obtained by the method for producing an aromatic hydroxycarboxylic acid of this embodiment.
<Embodiment 3 configuration>

  In the method for producing an aromatic hydroxycarboxylic acid of this embodiment, the aromatic hydroxy compound is phenol. By using phenol as the aromatic hydroxy compound that is the raw material of aromatic hydroxycarboxylic acid, the aromatic hydroxycarboxylic acid produced after the reaction is salicylic acid (o-hydroxybenzoic acid) and p-hydroxybenzoic acid. The

  The phenol is not particularly limited, and a commercially available phenol can be used. However, it is preferable to use those having a low impurity type and content.

  Hereinafter, specific examples when aromatic hydroxycarboxylic acid is produced under various reaction conditions when an aromatic hydroxy compound as a raw material of aromatic hydroxycarboxylic acid is phenol are shown.

  <Effect of reaction temperature on reactivity>

  Next, the influence of reaction temperature in the production of aromatic hydroxycarboxylic acid was examined. FIG. 4 shows the production rate of aromatic hydroxycarboxylic acid when the reaction temperature is changed. The reaction shown in FIG. 4 uses phenol as an aromatic hydroxy compound as a raw material, and the produced aromatic hydroxycarboxylic acids are salicylic acid (o-hydroxybenzoic acid) and p-hydroxybenzoic acid. In the reaction, 10.0 mmol of potassium carbonate was used as a basic catalyst, the reaction temperature was changed from 313 K to 473 K, and the reaction was performed at a reaction time of 5 hours and a carbon dioxide pressure of 8 MPa.

  As a result of the reaction, it was revealed that hydroxybenzoic acid was not produced up to a reaction temperature of 413 K regardless of the temperature. The yield of hydroxybenzoic acid was 36.6 mol% at a reaction temperature of 473 K, and the salicylic acid selectivity at this time was 98.5%. In other words, the production of hydroxybenzoic acid requires a temperature of 413K or higher.

  <Effect of carbon dioxide pressure on reactivity>

  Next, the influence of the pressure of carbon dioxide during the reaction in the production of aromatic hydroxycarboxylic acid was examined. FIG. 5 shows the production rate of aromatic hydroxycarboxylic acid when the carbon dioxide pressure during the reaction was changed. The reaction shown in FIG. 5 uses phenol as an aromatic hydroxy compound as a raw material, and the aromatic hydroxycarboxylic acids produced are salicylic acid (o-hydroxybenzoic acid) and p-hydroxybenzoic acid. In the reaction, 10.0 mmol of potassium carbonate was used as a basic catalyst, the reaction temperature was 473 K, the reaction time was 5 hours, and the carbon dioxide pressure was changed from 1 MPa to 17 MPa.

  As a result of the reaction, the amount of salicylic acid produced increased with increasing carbon dioxide pressure up to a carbon dioxide pressure of 7 MPa. In the vicinity of the critical pressure, the amount of salicylic acid produced reached a maximum.

  From the above results, in order to produce an aromatic hydroxycarboxylic acid from an aromatic hydroxy compound via a basic catalyst, it is desirable that the reaction temperature is 300 K or higher and the carbon dioxide pressure during the reaction is 8 MPa. In other words, it is desirable to react the carbon dioxide at a temperature above 304.1K at which it becomes a supercritical state under the condition of 7.3 MPa or more.

  <Influence of reaction time>

  Next, the influence of reaction time in the production of aromatic hydroxycarboxylic acid was examined. FIG. 6 shows the production rate of the aromatic hydroxycarboxylic acid when the reaction time is changed. The reaction shown in FIG. 6 uses phenol as an aromatic hydroxy compound as a raw material, and the aromatic hydroxycarboxylic acids produced are salicylic acid (o-hydroxybenzoic acid) and p-hydroxybenzoic acid. In the reaction, 10.0 mmol of potassium carbonate was used as a basic catalyst, the reaction temperature was 473 K, the reaction time was changed from 1 hour to 10 hours, and the carbon dioxide pressure was 8 MPa. It was revealed that the salicylic acid yield depends on the increase in reaction time and shows an increasing tendency. In addition, after the reaction time of 5 hours, the production rate of salicylic acid is almost flat.

  <Influence of added amount of catalyst>

  Next, the influence of the addition amount of the basic catalyst in the production of aromatic hydroxycarboxylic acid was examined. FIG. 7 shows the production rate of aromatic hydroxycarboxylic acid when the addition amount of the basic catalyst is changed. The reaction shown in FIG. 7 uses phenol as an aromatic hydroxy compound as a raw material, and the aromatic hydroxycarboxylic acids produced are salicylic acid (o-hydroxybenzoic acid) and p-hydroxybenzoic acid. In the reaction, potassium carbonate was changed from 1 mmol to 20 mmol as a basic catalyst, the reaction temperature was 473 K, the reaction time was 5 hours, and the carbon dioxide pressure was 8 MPa. The salicylic acid production rate showed an increasing tendency with the increase of the amount of potassium carbonate as the basic catalyst. Above 10 mmol, the salicylic acid production rate remained flat. It was revealed that the salicylic acid yield reached 68.3% when potassium carbonate was added at 20 mmol. Regardless of the amount added, the salicylic acid selectivity was 98% or more.

  In this embodiment, by using phenol as the aromatic hydroxy compound that is the raw material of the aromatic hydroxycarboxylic acid, the aromatic hydroxycarboxylic acid produced after the reaction is salicylic acid (o-hydroxybenzoic acid), m- Although three types of hydroxybenzoic acid and p-hydroxybenzoic acid are assumed, m-hydroxybenzoic acid was not produced.

Further, in Embodiments 1 to 3, qualitative and quantitative determination of the produced aromatic hydroxycarboxylic acid was calculated by an internal standard method using HPLC (High Performance Liquid Chromatography). As control substances, phenol (C ₆ H ₅ OH, Wako Pure Chemical Co., 99.5 wt% purity), salicylic acid (C ₇ H ₇ O ₃ , Wako Pure Chemical Co., 99.5 wt% purity), p-hydroxybenzoic acid ( _{C 7 H 7 O 3, Wako} Pure Chemical Co., was used 99.5 wt% purity). The HPLC system was Shimadzu LC-10AD chromatograph, the column used was TSK-gel ODS-100V, length: 250 mm, diameter 4.6 mm, the mobile phase was CH ₃ CN / H ₂ O = 1.5, and the mobile phase The moving speed was 0.5 ml / min. The column temperature was 313 K, and detection was performed with an ultraviolet absorbance detector (190-600 nm).
<Embodiment 3 effects>

The method for producing an aromatic hydroxycarboxylic acid according to this embodiment uses phenol as an aromatic hydroxy compound as a raw material, and efficiently uses salicylic acid (o-hydroxybenzoic acid) without using a solvent or an alkali metal. It can be manufactured. Moreover, p-hydroxybenzoic acid is produced as a by-product. Salicylic acid can be used as a synthetic intermediate for various substances in addition to food preservatives and dermatological treatments. By-product p-hydroxybenzoic acid can also be used as a synthetic intermediate for liquid crystal polymers. It is.
<Embodiment 4>
<Outline of Embodiment 4>

The present embodiment is a method for producing an aromatic hydroxycarboxylic acid, which is based on Embodiments 1 and 2, wherein the aromatic hydroxy compound as a raw material is 1-naphthol or 2-naphthol. By using 1-naphthol or 2-naphthol as a raw material, hydroxynaphthoic acid can be obtained by the method for producing an aromatic hydroxycarboxylic acid of this embodiment.
<Embodiment 4 configuration>

  In the method for producing an aromatic hydroxycarboxylic acid of this embodiment, the aromatic hydroxy compound is 1-naphthol or 2-naphthol. By using 1-naphthol or 2-naphthol as an aromatic hydroxy compound as a raw material for the aromatic hydroxycarboxylic acid, hydroxynaphthoic acid is produced as the aromatic hydroxycarboxylic acid produced after the reaction.

  1-naphthol and 2-naphthol are not particularly limited, and commercially available 1-naphthol and 2-naphthol can be used. However, it is preferable to use those having a low impurity type and content.

  An example of producing hydroxynaphthoic acid from 2-naphthol is shown below. As production conditions, 5.0 mmol of 2-naphthol and 10.0 mmol of potassium carbonate as a catalyst are sealed in a reaction vessel, and the inside of the reaction vessel is set to a carbon dioxide atmosphere. The temperature in the reaction vessel was raised to 473 K, carbon dioxide was injected so that the partial pressure of carbon dioxide in the reaction vessel was 8 MPa, and the reaction was carried out for 10 hours. After completion of the reaction, the reaction vessel was quenched and the product in the reaction vessel was recovered as an aqueous solution. The recovered product was subjected to TMS (trimethylsilylation) and separated, qualitatively and quantitatively analyzed by GC / FID (Gas Chromatography / Flame Photometric Detector).

  FIG. 8 shows the results obtained by GC-FID. From this result, when an aromatic hydroxy compound (hydroxynaphthoic acid) was produced under the above conditions, 2-hydroxy-1-naphthoic acid shown in FIG. 9 (a) was obtained at a conversion rate of 18.9%. It was. In addition, various hydroxynaphthoic acids (a) to (c) shown in FIG. 9 can be obtained by changing reaction conditions such as reaction temperature, reaction pressure, reaction time, and catalyst. When the raw material is 1-naphthol, it is possible to obtain hydroxynaphthoic acid shown in FIGS. 10 (a) to 10 (d).

In Embodiments 1 to 4, an aromatic hydroxycarboxylic acid was produced using a stainless steel (SUS-316) electromagnetic induction rotor blade type autoclave (manufactured by Nitto Reactor) with an internal volume of 50 ml. To maintain the reaction, the inside was stirred with a rotary blade.
<Embodiment 4 Effect>

The method for producing an aromatic hydroxycarboxylic acid of the present embodiment uses 1-naphthol or 2-naphthol as an aromatic hydroxy compound as a raw material, and without using a solvent or an alkali metal, 2-hydroxy-1- It becomes possible to produce hydroxynaphthoic acid such as naphthoic acid at an efficient time.
<Embodiment 5>
<Overview of Embodiment 5>

This embodiment is a production apparatus for producing an aromatic hydroxycarboxylic acid from an aromatic hydroxy compound, and is characterized in that the reaction furnace can be controlled so that carbon dioxide is in a supercritical fluid state. It is a manufacturing device.
<Embodiment 5 configuration>

  The conceptual diagram of the manufacturing apparatus of the aromatic hydroxycarboxylic acid of this embodiment was shown in FIG. The apparatus for producing an aromatic hydroxycarboxylic acid according to this embodiment includes a reaction furnace (1101) that is charged with an aromatic hydroxy compound, a basic catalyst, and carbon dioxide, and that maintains the carbon dioxide in a supercritical fluid state. A first filling part (1102) for filling the reaction furnace, a second filling part (1103) for filling the reaction furnace with a basic catalyst, and a third filling part for filling the reaction furnace with carbon dioxide. (1104), a critical control section (1105) for pressurizing and adjusting the temperature of the reactor filled with the above-mentioned members so that carbon dioxide is in a supercritical fluid state, and a product in the reactor A take-out portion (1106) for taking out the aromatic hydroxycarboxylic acid from the reaction furnace.

  The apparatus for producing an aromatic hydroxycarboxylic acid according to the present embodiment includes a batch production method in which carbon dioxide, an aromatic hydroxy compound, and a basic catalyst are sequentially charged into a reaction furnace to carry out a reaction, or a basic catalyst is previously placed in the reaction furnace. It is possible to correspond to a flow-type production method in which carbon dioxide and an aromatic hydroxy compound are reacted while flowing in a reaction furnace.

  <Batch production method>

  The apparatus for producing an aromatic hydroxycarboxylic acid according to this embodiment in the batch production method will be described with reference to FIG.

  The “reactor” is a furnace in which an aromatic hydroxy compound as a raw material for an aromatic hydroxycarboxylic acid, carbon dioxide, and a basic catalyst are charged and carbon dioxide can be maintained in a supercritical fluid state. The reaction from the aromatic hydroxy compound to the aromatic hydroxycarboxylic acid described in Embodiments 1 to 4 is performed in a reaction furnace. The reaction furnace is equipped with a heating device for maintaining the temperature in the reaction furnace. This heating device is controlled by a critical control unit described later. Particularly when the reaction is carried out batchwise, it is preferable that a stirring blade for stirring the aromatic hydroxy compound, carbon dioxide, and basic catalyst is provided. The reaction furnace is provided with a pressure gauge and a thermocouple for measuring the temperature and pressure in the reaction furnace, and the obtained data is transmitted to a critical control unit described later.

  The “first filling portion” fills the aromatic hydroxy compound in the aforementioned reaction furnace. In the production apparatus of FIG. 11, when the reaction is performed in a batch system, the reaction furnace in a normal pressure state before pressurization is filled with a solid or liquid / gas aromatic hydroxy compound. Here, when the aromatic hydroxy compound is phenol, since phenol has a melting point of 313.9K, it is solid at room temperature. The solid state phenol may be filled in the reaction furnace, or a heating device may be provided in the first filling unit to heat the phenol and fill the reaction furnace in a liquid state. In this case, the amount of phenol charged into the reaction furnace can be controlled by controlling the flow rate with a pump that transports liquid phenol to the reaction furnace. The first filling unit is provided with a check valve so as to keep the pressure in the reaction furnace after the aromatic hydroxy compound is filled in the reaction furnace and prevent the contents in the reaction furnace from flowing back.

  The “second filling unit” fills the above-described reaction furnace with a basic catalyst. Basic catalysts are generally in a solid state at normal temperature and pressure. The second filling unit fills the reaction furnace with the solid basic catalyst. At this time, the basic catalyst is transported by a conveyor such as a belt conveyor or a screw conveyor and filled in the reaction furnace. In addition, as shown in FIGS. 12 and 13, a basic catalyst may be mixed in a fluid such as carbon dioxide in a gaseous state or an aromatic hydroxy compound heated to a liquid state, and filled in a reaction furnace. The second filling unit is provided with a check valve so as to keep the pressure in the reaction furnace after the basic catalyst is filled in the reaction furnace and prevent the contents in the reaction furnace from flowing back.

  Moreover, the manufacturing apparatus of aromatic hydroxycarboxylic acid of this embodiment may fix a basic catalyst in a reaction furnace. For example, in the batch production method, carbon dioxide and the aromatic hydroxy compound may be charged and taken out every time the reaction is performed, and the basic catalyst may be fixed in the reaction furnace. Basically, since the basic catalyst is a catalyst, the amount that increases or decreases depending on the reaction is extremely small. do it. As a method for immobilizing the basic catalyst in the reaction furnace, it may be supported on a support such as a metal plate or alumina, or just a powdery basic catalyst may be filled in the reaction furnace. In the latter case, the aromatic hydroxy compound or aromatic hydroxycarboxylic acid dissolves in carbon dioxide in the supercritical fluid state, but the basic catalyst does not dissolve, and the basic catalyst is trapped in the take-out part described later. For example, a filter may be provided.

  The “third filling section” fills the above-described reaction furnace with carbon dioxide. The pressure in the reaction furnace is adjusted by the amount of carbon dioxide filled in the third filling section. For this reason, the 3rd filling part is equipped with the pump etc. which pump carbon dioxide in order to make the inside of a reactor high. Moreover, the 3rd filling part may be provided with the preliminary heating apparatus which heats the carbon dioxide with which it fills separately from the heating apparatus with which the reaction furnace was equipped. Similar to the first filling portion and the second filling portion, the third filling portion is also provided with a check valve so as to maintain the pressure in the reaction furnace and prevent the contents in the reaction furnace from flowing back.

  Here, in the batch production method, it is desirable that the aromatic hydroxy compound and the basic catalyst filled in the reaction furnace by the first filling part and the second filling part are filled in the reaction furnace at normal pressure. Since the inside of the reaction furnace in which the carbon dioxide is in a supercritical state is at a high pressure, it is necessary to fill the reaction furnace with a higher pressure in order to fill the reaction furnace with the aromatic hydroxy compound or the basic catalyst. Such a state not only increases the energy required for filling, but also reduces the service life of the apparatus. For this reason, in the batch production method, the reactor is filled with the aromatic hydroxy compound and the basic catalyst by the first filling portion and the second filling portion, and then the carbon dioxide is filled by the third filling portion to be in a supercritical state. Is desirable. Note that this is not the case when the aromatic hydroxy compound and the basic catalyst are gas-transported by carbon dioxide and charged into the reaction furnace.

  The “criticality control unit” pressurizes and adjusts the temperature of the reactor filled with the first filling unit, the second filling unit, and the third filling unit so that carbon dioxide is in a supercritical fluid state. In the batch production method, in order to adjust the inside of the reaction furnace so that carbon dioxide is in a supercritical fluid state, the critical control unit controls the third filling unit, the reaction furnace, and the take-out unit. For the third filling portion, the amount of carbon dioxide charged in the reaction furnace is controlled, and the carbon dioxide pressure in the reaction furnace is controlled. Further, when a preheating device is provided in the third filling portion, temperature control of the preheating device is also performed. For the reaction furnace, the temperature in the reaction furnace is controlled by controlling a heating device provided in the reaction furnace. Regarding the take-out section, the opening and closing status of a take-out valve that becomes an outlet from the reaction furnace, which will be described later, is monitored, and with the take-off valve closed, the third filling section is filled with carbon dioxide and Controls such as increasing the pressure. The above is the minimum control necessary for the critical control unit to adjust the inside of the reactor so that carbon dioxide is in a supercritical fluid state.

  Although not shown, the critical control unit may control the first filling unit and the second filling unit to control the timing of filling the aromatic hydroxy compound or the basic catalyst. The process flow in the batch manufacturing method will be described later.

  The “removal unit” retrieves carbon dioxide, a basic catalyst, and an unreacted aromatic hydroxy compound in addition to the aromatic hydroxycarboxylic acid produced from the reaction furnace after completion of the reaction. The take-out portion is provided with a take-off valve for taking the reaction furnace into a closed system and taking out the aromatic hydroxycarboxylic acid in the reaction furnace. Since the inside of the reaction furnace is in a high pressure state even after the completion of the reaction, when the take-off valve is opened, carbon dioxide, aromatic hydroxycarboxylic acid, basic catalyst, etc. in the reaction furnace are ejected. Aromatic hydroxycarboxylic acids and aromatic hydroxy compounds are dissolved in carbon dioxide in the supercritical fluid state. It is separated into hydroxycarboxylic acid, aromatic hydroxy compound and basic catalyst. The carbon dioxide in the gaseous state may be opened to the atmosphere as it is, but may be sent again to the third filling section and used again for the reaction. In addition, when fixing the basic catalyst in the reaction furnace, install a filter to trap the basic catalyst on the reaction furnace side from the take-off valve so that the solid basic catalyst does not flow out of the reaction furnace. Also good.

  <Processing flow in batch manufacturing method>

  The flowchart for demonstrating an example of the flow of the process in the batch type manufacturing method of the manufacturing apparatus of the aromatic hydroxycarboxylic acid of this embodiment in FIG. 14 was shown.

  First, the criticality control unit confirms that the takeout valve of the takeout unit is closed (S1401), and opens the check valve (S1402) with respect to the first filling unit and the second filling unit (S1402). Control is performed so that a predetermined amount of the catalyst is charged into the reaction furnace at room temperature and normal pressure (S1403). After the reactor is filled with a predetermined amount of the aromatic hydroxy compound and the basic catalyst, the critical control unit controls the check valves of the first filling unit and the second filling unit to be closed (S1404). Next, the criticality control unit controls the heating device of the reaction furnace so that the temperature inside the reaction furnace becomes a predetermined temperature, and raises the temperature (S1405). The temperature rise in the reaction furnace may be before filling with the aromatic hydroxy compound and the basic catalyst. The criticality control unit controls the third filling unit to fill with carbon dioxide until the pressure in the reactor reaches a predetermined pressure (S1406), and closes the check valve after the filling is completed.

  At this stage, the carbon dioxide in the reactor becomes a supercritical fluid state, and the reaction is started (S1407). When the reaction is completed after a predetermined time has elapsed, the criticality control unit controls the opening of the takeout valve of the takeout unit, and collects the contents in the reaction furnace (S1408). In addition, when fixing a basic catalyst, the filling of the basic catalyst by a 2nd filling part becomes unnecessary.

  <Distributed manufacturing method>

  The manufacturing method by the flow-type manufacturing method in the aromatic hydroxycarboxylic acid manufacturing apparatus of this embodiment will be described. The conceptual diagram for demonstrating the manufacturing apparatus of the aromatic hydroxycarboxylic acid by the flow type manufacturing method of this embodiment to FIG. 15 was shown.

  In the flow-type production method, carbon dioxide and an aromatic hydroxy compound are reacted through the reaction furnace (1501). At this time, the basic catalyst may be circulated in the same manner as carbon dioxide and aromatic hydroxy compound. However, as described in the batch production method, it is more efficient to fix the basic catalyst in the reaction furnace. It is. Therefore, the following description is a flow-type manufacturing method in which a basic catalyst is fixed in a reaction furnace. In addition, since the 2nd filling part (1503) which fills a basic catalyst in a reaction furnace is as substantially the same as a batch type manufacturing method, detailed description is abbreviate | omitted.

  The first filling part (1502) in the flow type production method is substantially the same as the batch production method, but the reaction furnace is continuously filled with a predetermined amount of the aromatic hydroxy compound during the reaction. Moreover, since the carbon dioxide is in a supercritical fluid state, the inside of the reactor is at a high pressure. For this reason, the first filling unit includes a pump for filling the aromatic hydroxy compound at a high pressure.

  The third filling part (1504) in the flow type production method is substantially the same as the batch production method, but the reaction furnace is continuously filled with carbon dioxide during the reaction. The third filling unit adjusts the pressure in the reaction furnace by controlling the amount of contents taken out from the take-out valve of the take-out unit and the amount of carbon dioxide filled from the third filling unit.

  Since the critical control unit (1505) in the flow-type manufacturing method is almost the same as that in the batch manufacturing method, detailed description thereof is omitted. The criticality control unit controls the amount of carbon dioxide charged in the third filling unit and the amount of extraction from the extraction unit while monitoring the pressure in the reaction furnace.

  The take-out part (1506) in the flow-type production method is almost the same as the batch production method, but the contents in the reaction furnace are continuously taken out from the reaction furnace during the reaction.

  <Processing flow in distribution manufacturing method>

  The flowchart for demonstrating an example of the flow of the process of the manufacturing method of aromatic hydroxycarboxylic acid by the flow type manufacturing method in this embodiment in FIG. 16 was shown. The flow chart of FIG. 16 explains the flow until the reaction is continuously performed in the flow-type manufacturing method.

First, it is confirmed whether or not the basic catalyst fixed in the reaction furnace needs to be charged (S1601). When the basic catalyst is not fixed at all in the reaction furnace or when the basic catalyst is deteriorated, the basic catalyst is filled into the reaction furnace and fixed (S1602). Next, the criticality control unit confirms that the takeout valve of the takeout unit is closed (S1603), and fills the reaction furnace with carbon dioxide (S1604). After the start of filling with carbon dioxide, the temperature is increased and the pressure is increased until the temperature in the reaction furnace reaches a predetermined temperature and a predetermined pressure (S1605). Next, in a state where carbon dioxide is continuously filled in the reaction furnace, the take-off valve is set so that the temperature and pressure in the reaction furnace maintain predetermined values and are held in the reaction furnace for a certain time. A part is opened (S1606). In this state, carbon dioxide is continuously charged into the reaction furnace from the third filling part, and the carbon dioxide in the reaction furnace is in a supercritical fluid state and flows out from the take-out part by a certain amount. Next, the aromatic hydroxy compound is continuously charged into the reaction furnace from the first filling portion. The aromatic hydroxy compound filled in the reaction furnace is held in the reaction furnace for a certain time together with carbon dioxide, the reaction is performed, and the outside is taken out from the take-out portion. By continuously charging the aromatic hydroxy compound into the reaction furnace, the aromatic hydroxycarboxylic acid is obtained from the take-out portion by a certain amount. In this state, an aromatic hydroxycarboxylic acid is continuously produced from the aromatic hydroxy compound.
<Embodiment 5 effects>

  The apparatus for producing an aromatic hydroxycarboxylic acid according to the present embodiment efficiently produces aromatic hydroxycarboxylic acid from an aromatic hydroxy compound by making the carbon dioxide in a supercritical fluid state in the reaction furnace. Is possible. In the aromatic hydroxycarboxylic acid production apparatus of the present embodiment, it is possible to produce the aromatic hydroxycarboxylic acid by a batch-type or flow-type production method.

Change in production amount of aromatic hydroxycarboxylic acid due to difference in catalyst type of embodiment 1 Change in production amount of aromatic hydroxycarboxylic acid due to difference in carbonate of catalyst species of embodiment 2 Change in production amount of aromatic hydroxycarboxylic acid due to difference in anion of catalyst species of embodiment 2 Change in production amount of aromatic hydroxycarboxylic acid due to difference in reaction temperature in embodiment 3 Change in production amount of aromatic hydroxycarboxylic acid due to difference in reaction pressure in embodiment 3 Change in production amount of aromatic hydroxycarboxylic acid due to difference in reaction time in embodiment 3 Change in production amount of aromatic hydroxycarboxylic acid due to difference in catalyst addition amount in embodiment 3 Conversion rate of hydroxynaphthoic acid obtained when 2-naphthol is used as a raw material in Embodiment 4 Example of hydroxynaphthoic acid obtained by using 2-naphthol as a raw material in Embodiment 4 Example of hydroxynaphthoic acid obtained when 1-naphthol is used as a raw material in Embodiment 4 An example of the manufacturing method of aromatic hydroxycarboxylic acid by the batch type manufacturing method of Embodiment 5 An example of the manufacturing method of aromatic hydroxycarboxylic acid by the batch type manufacturing method of Embodiment 5 An example of the manufacturing method of aromatic hydroxycarboxylic acid by the batch type manufacturing method of Embodiment 5 Flowchart for explaining a method for producing an aromatic hydroxycarboxylic acid by a batch production method according to Embodiment 5 Example of production method of aromatic hydroxycarboxylic acid by flow-type production method of embodiment 5 Flowchart for explaining a method for producing an aromatic hydroxycarboxylic acid by a flow-type production method according to Embodiment 5

Explanation of symbols

△ Salicylic acid (o-hydroxybenzoic acid)
○ p-Hydroxybenzoic acid 1101 Reaction furnace 1102 First filling part 1103 Second filling part 1104 Third filling part 1105 Critical control part 1106 Extraction part 1201 Reactor 1202 First filling part 1203 Second filling part 1204 Third filling part 1205 Critical control unit 1206 Extraction unit 1301 Reactor 1302 First charging unit 1303 Second charging unit 1304 Third charging unit 1305 Critical control unit 1306 Extraction unit 1501 Reactor 1502 First charging unit 1503 Second charging unit 1504 Third charging unit 1505 Critical control unit 1506 Extraction unit

Claims (4)

A method for producing an aromatic hydroxycarboxylic acid, comprising reacting an aromatic hydroxy compound with carbon dioxide in a supercritical fluid state using potassium carbonate as a basic catalyst without subjecting the aromatic hydroxy compound to alkali metal chloride. The method for producing an aromatic hydroxycarboxylic acid according to claim 1, wherein the aromatic hydroxy compound is phenol. The method for producing an aromatic hydroxycarboxylic acid according to claim 1, wherein the aromatic hydroxy compound is 1-naphthol or 2-naphthol. A reactor for filling an aromatic hydroxy compound, potassium carbonate, and carbon dioxide, and maintaining the carbon dioxide in a supercritical fluid state, a first filling section for filling the reactor with the aromatic hydroxy compound, and potassium carbonate for the reactor A second filling part for filling the reactor, a third filling part for filling the reaction furnace with carbon dioxide, and a reaction furnace filled with the respective members so that the carbon dioxide is in a supercritical fluid state. Production of an aromatic hydroxycarboxylic acid having a critical control unit for adjusting pressure and temperature, and a take-out unit for taking out the non-alkali metal aromatic hydroxycarboxylic acid which is a product in the reaction furnace from the reaction furnace apparatus.

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