JPH059155A - Control of isomer formation ratio of aromatic hydroxycarboxylic acids - Google Patents

Abstract

PURPOSE:To control the subject ratio in a method for carrying out carboxylation in an organic phosphine oxide solvent by changing a ratio of an organic phosphine oxide and an alkali metal salt of a phenol in a specific range. CONSTITUTION:In a method of reacting an alkali metal salt of a phenol with carbon dioxide in an organic phosphine oxide solvent such as trimethylphosphine oxide, the molar ratio of the organic phosphine oxide solvent to the alkali metal salt of a phenol is changed from 1 to 4, formation ratio of isomers of aromatic hydroxycarboxylic acids is optionally changed and can be controlled in a wide range. This method is industrially advantageous without increasing the amount of by-products.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Aromatic hydroxycarboxylic acids are industrially useful as fine chemical intermediates and resin raw materials.

The present invention relates to a method for controlling the isomer formation ratio of these aromatic hydroxycarboxylic acids.
More specifically, when an aromatic hydroxy compound is reacted with carbon dioxide to produce aromatic hydroxycarboxylic acids, the present invention relates to a method for controlling the isomer formation ratio of the aromatic hydroxycarboxylic acids obtained, wherein the aromatic hydroxy compound is a monocyclic phenol. In the case of, ortho-position and para-position substitution product, 1-
In the case of naphthols, 1,2-position and 1,4-position substitution products, 2-
In the case of naphthols, it relates to a method for controlling the substitution products at the 2,3 and 2,6 positions.

Hereinafter, parahydroxybenzoic acid is referred to as PHB,
Salicylic acid is SA, 4-hydroxyisophthalic acid is OI
P, 1-hydroxynaphthalene-2-carboxylic acid 1-
HNC-2,1-hydroxynaphthalene-4-carboxylic acid was converted to 1-HNC-4,1-hydroxynaphthalene-5-
Carboxylic acid is 1-HNC-5, 2-hydroxynaphthalene-1-carboxylic acid is 2-HNC-1, 2-hydroxynaphthalene-3-carboxylic acid is 2-HNC-3, 2-hydroxynaphthalene-6-carboxylic acid 2-HNC-6
Is abbreviated.

[0004]

2. Description of the Related Art Conventionally, the reaction between an alkali metal salt of a phenol and carbon dioxide has been known as a Kolbe Schmidt reaction which is carried out by a solventless method under high temperature and pressure. In this reaction, carbon dioxide was absorbed in the anhydrous sodium salt of phenol to 120-140.
By raising the temperature to ° C, monosodium and disodium salts of SA are produced. Further, when a potassium salt of phenol is used and heated to a high temperature, PHB becomes a main product and SA is a by-product (Organic Chemistry Handbook).
P.454 (Tokyo, Gihodo)).

In the solvent method, a variety of solvents such as protic solvents such as tert-butanol, aprotic solvents such as toluene, diphenyl ether and dimethylformamide and dimethyl sulfoxide, or high boiling point solvents such as kerosene and light oil are used. The reaction has been studied by Hirao et al. (Journal of the Organic Synthesis Society, 24, P. 1051 (1966), 25, P. 412, 417, 57).
7, 1031, 1202 (1967), Volume 26 P. 439, 992 (1968
Volume 27, P. 648 (1969), Volume 28 P. 426 (1970)
Year)). Further, various hydroxynaphthalenecarboxylic acids can be obtained from alkali metal salts of naphthols and carbon dioxide in a polar solvent.
(7) 1164.

[0006]

Some aromatic hydroxycarboxylic acids have different substitution positions of the hydroxy group and the carboxy group, and these are useful compounds. Therefore, in the production of aromatic hydroxycarboxylic acids, for example, if the isomer production ratio of various hydroxybenzoic acids and various hydroxynaphthalenecarboxylic acids can be changed as necessary, industrial production has great merit, but the above-mentioned synthetic method , There is no known method for changing the production ratio without increasing the amount of by-products.

[0007]

[Means for Solving the Problems] The present inventors have found that a carboxyl group is selectively introduced at a position para to a hydroxy group of phenol by carrying out a carboxylation reaction in an organic phosphine oxide solvent. And found a patent application first (Japanese Patent Laid-Open No. 02-22354).

Further, as a result of intensive studies, the present inventors have found that in the method of carrying out a carboxylation reaction in an organic phosphine oxide solvent, the ratio of the organic phosphine oxide to the alkali metal salt of phenol is within a specific range. It was found that the ratio of isomer formation of aromatic hydroxycarboxylic acids can be controlled by changing the ratio by the method described above, and the present invention has been completed.

That is, according to the present invention, when an alkali metal salt of a phenol is reacted with carbon dioxide in an organic phosphine oxide solvent, the molar ratio of the organic phosphine oxide to the alkali metal salt of the phenol is changed. In 1
The method for controlling the isomer production ratio is characterized in that the isomer production ratio of the aromatic hydroxycarboxylic acid is changed by changing the isomer production ratio by 4 to 4.

According to the method of the present invention, when the ratio of the organic phosphine oxide to the alkali metal salt of phenols is small, the production of SAs is large, and as the ratio becomes large, the production of PHBs increases. However, the ratio is 4
With the above, the isomer production ratio becomes almost constant, and even if the ratio is 8, the selectivity only slightly improves. When the ratio is 10 or more, the merit in production efficiency decreases. Further, when the ratio is less than 1, the reaction is difficult to proceed because the solubility of the alkali metal salt of phenol as a raw material in organic phosphine oxide is insufficient.

Such a phenomenon is commonly observed in various organic phosphine oxides. Therefore, from this fact, the alkali metal salt of phenols and the organic phosphine oxide form a complex in a solution, It is considered that the formation ratio of various isomers, which are products, is determined by the formation method.

The organic phosphine oxide used in the present invention has the general formula (Formula 2) shown below.

[0013]

[Chemical 2] Represented by, for example, trimethylphosphine oxide, triethylphosphine oxide, tri-n-propylphosphine oxide, triisopropylphosphine oxide, tri-n-butylphosphine oxide, tri-secondary butylphosphine oxide, tri -n-hexylphosphine oxide, tri-n-octylphosphine oxide, dimethylethylphosphine oxide, methyldiethylphosphine oxide,
Examples thereof include diethylpropylphosphine oxide, ethyldipropylphosphine oxide, ethylpropylbutylphosphine oxide and triphenylphosphine oxide.

Preferably, it is a linear or branched trialkylphosphine oxide having 1 to 8 carbon atoms or triphenylphosphine oxide in which R ¹ , R ² and R ³ are the same, and more preferably trimethyl. Phosphine oxide, triethylphosphine oxide, tri-n-propylphosphine oxide, triisopropylphosphine oxide, tri-secondary butylphosphine oxide, tri-n-butylphosphine oxide, tri-n-hexylphosphine oxide and tri -n-octylphosphine oxide is selected from the group consisting of.

In the reaction, these organic phosphine oxides can be used alone or as a mixture of two or more kinds. Examples of the mixture of two or more kinds include triethylphosphine oxide (melting point: 50 ° C.) and tri-n-butylphosphine oxide (melting point: 67 to 69) which are solid at room temperature.
C.) is a liquid at room temperature and is therefore easy to handle, and can be used in the same manner as when used alone without deteriorating the characteristics of the original organic phosphine oxide. .

Phenols used for producing alkali metal salts of phenols include phenol, cresols, monoalkyl-substituted monohydric phenols substituted with an alkyl group having 2 to 12 carbon atoms and 2 carbon atoms. To monocyclic phenols such as monoaryl-substituted monohydric phenols substituted with aryl groups of 1 to 12 or naphthols. Specifically, phenol, cresol, ethylphenol, n-propylphenol, iso-
Propylphenol, n-butylphenol, sec-butylphenol, tert-butylphenol, amylphenol, hexylphenol, octylphenol, nonylphenol, decylphenol, dodecylphenol, cyclohexylphenol, phenylphenol,
Or these ortho or meta substitution products, or 1
-Naphthol, 2-naphthol and the like can be mentioned.

As the alkali metal used in the production of the raw material alkali metal phenolate (alkali metal salt of phenols), light atoms such as lithium to heavy atoms such as sodium, potassium and rubidium are used. To be In particular, it is economically advantageous to control the isomer production ratio of aromatic hydroxycarboxylic acids in a wide range by using an inexpensive raw material such as sodium hydroxide.

Alkali metal salts of phenols can be obtained by various methods. For example, a method of adding an equivalent amount of an aqueous sodium hydroxide solution to phenol and evaporating to dryness to obtain a substantially anhydrous product under a vacuum, more preferably, dissolving phenol in an organic solvent to obtain an aqueous sodium hydroxide solution. A method of drying after neutralizing with.

The alkali metal salt of phenols, which is a raw material, is well dissolved in the above organic phosphine oxide in a heated state. Therefore, it is considered that the reaction efficiency with carbon dioxide is high and the carboxylation proceeds rapidly.

The ratio of the organic phosphine oxide to the alkali metal salt of phenols is appropriately determined according to a preset production ratio of isomers of aromatic hydroxycarboxylic acids. For example, the ratio of triethylphosphine oxide to alkali metal salt of phenol, P
The relationship between the production ratio of HB and SA is calculated in advance, and the ratio of triethylphosphine oxide to the alkali metal salt of phenol is calculated from this relationship with respect to the production ratio of PHB and SA, which changes depending on the need. The reaction may be performed under the conditions.

The preferred reaction temperature is 50 to 300 ° C. although it varies depending on the type of raw material and reaction pressure. Reaction temperature is 50 ℃
When it is lower than the above range, the conversion rate of the alkali metal salt of phenols is lowered, and the reaction proceeds slowly, which is not preferable. Increasing the reaction temperature improves the conversion rate of alkali metal salts of phenols. However, if the temperature exceeds 300 ° C., the by-product of the dicarboxylic acid body as a byproduct becomes remarkable, which is not preferable.

The pressure of carbon dioxide is not particularly limited, but is preferably 1 atm or higher, and the higher the pressure, the higher the reaction rate, so that good results can be obtained. To achieve the same reaction rate, the reaction temperature may be decreased and the reaction pressure increased. Of course, the reaction may be carried out above the critical point of carbon dioxide.

The reaction time is not particularly limited, but generally the reaction rate can be increased by extending the reaction time. The appropriate reaction time depends on the reaction temperature, the type of solvent and other conditions, but the reaction is usually completed within 12 hours.

As the reaction method, the following two methods are frequently used. For example, the first method is a method in which an alkali metal salt of phenols is dissolved in a solvent, carbon dioxide is absorbed, and then the temperature is raised to carry out a carboxylation reaction.

The second method is a method of carrying out the carboxylation reaction while blowing carbon dioxide while heating the alkali metal salt of phenol and the solvent to a predetermined temperature.
Any method may be used, and the method is not limited to these methods.

In this reaction, a substance having a weak coordinating ability with the alkali metal salt of phenols, for example, a hydrocarbon does not affect the selectivity and may be present as necessary.

However, those that strongly coordinate with or dissociate from the phenolate like water are not preferred. Therefore, in carrying out the reaction, the water content in the reaction solution must be 1% or less, and preferably 0.1% or less.

The reaction of the present invention can be carried out in either a batch system or a continuous system.

Water is added to the reaction mixture obtained by the above reaction, and the aromatic hydroxycarboxylic acid salt is transferred to the aqueous layer by stirring, countercurrent extraction or other known method, and then the organic phosphine oxide solvent layer is added. And the aqueous layer can be separated to separate the aromatic hydroxycarboxylic acid salt from the reaction mixture. By adding an acid to the obtained aqueous solution of the aromatic hydroxycarboxylic acid salt to adjust the pH, the isomers of the aromatic hydroxycarboxylic acid can be precipitated and separated according to the acid strength thereof.

In the above method, a second solvent which is a good solvent for organic phosphine oxide and a poor solvent for water is used in order to increase the distribution of the reaction mixture into the aqueous layer. There is no problem even if added.

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

In the examples, the raw materials and products are liquid chromatographs (filler; silica gel-C18, eluent;
Acetonitrile-water).

Example 1 11.6 g (100 mmol) of anhydrous sodium phenolate,
Equipped with stirrer, carbon dioxide blowing tube and reflux condenser
53.7 g of anhydrous triethylphosphine oxide (hereinafter abbreviated as TEPO) placed in a 200 ml glass four-necked flask and previously dried with a molecular sieve as a solvent
(400 mmol) was added, and the mixture was heated to about 50 ° C. and dissolved.
Next, blow carbon dioxide with stirring at 50 ° C under normal pressure to sufficiently absorb the carbon dioxide, and then continue blowing carbon dioxide to raise the internal temperature of the reactor to 140 ° C in 10 minutes. Is blown at atmospheric pressure,
The reaction was continued for 1 hour.

As a result of analyzing the reaction mass by liquid chromatography, sodium phenolate conversion was 30%, PHB
Selectivities of SA and SA were 90% and 9%, respectively, and other trace amounts of OIP were detected.

The results are shown in Table 1.

60 g of water and 30 g of toluene were added to the reaction mass, and the mixture was shaken and allowed to stand still to separate the aqueous layer from the organic layer, and the produced organic acid salt was transferred to the aqueous layer.

Parahydroxybenzoic acid was deposited by adding sulfuric acid to the aqueous layer to adjust the pH of the aqueous layer to 4.0. Sulfuric acid was precipitated by adding sulfuric acid to the filtrate obtained by filtering and separating the mixture to adjust the pH of the aqueous layer to 1.5.

The obtained para-hydroxybenzoic acid and salicylic acid each had a purity of 99%, which was sufficiently high as an industrial grade.

Example 2 The molar ratio of TEPO to sodium phenolate was 2
The reaction was performed in the same manner as in Example 1 except that The results are shown in Table 1.

Example 3 The molar ratio of TEPO to sodium phenolate was 1
The reaction was performed in the same manner as in Example 1 except that The results are shown in Table 1.

Examples 4 and 5 The reaction was carried out as in Example 1 except that the solvent was changed to tributylphosphine oxide and the molar ratios of tributylphosphine oxide to sodium phenolate were 4 and 1, respectively. . The results are shown in Table 1.

Examples 6 to 9 In the same manner as in Example 1 except that a stainless steel autoclave made of SUS316 was used as a reactor, the solvent was triphenylphosphine oxide or tributylphosphine oxide, and the reaction was carried out under pressure. I did. The results are shown in Table 1.
Shown in.

Examples 10 to 12 The reaction was carried out in the same manner as in Examples 1, 2 and 3 except that potassium phenolate was used as the alkali metal salt of phenol. The results are shown in Table 2.

Examples 13 and 14 An SUS autoclave was used as the reactor, the solvent was triethylphosphine oxide, the sodium salt of phenol was used as the raw material, and the carbon dioxide pressure was 90 kg / cm ^2.
G, the reaction was carried out at a reaction temperature of 60 ° C. for 1 hour. Table 2 shows the results when the molar ratio of triethylphosphine oxide to sodium salt of phenol was 4 or 1.

Comparative Example 1 Table 2 shows the results of Example 13 in which the molar ratio of triethylphosphine oxide to sodium salt of phenol was 8.

The production ratio of PHB and SA was about the same as when the molar ratio was 4, and the isomer production ratio hardly changed even if the molar ratio of triethylphosphine oxide to sodium salt of phenol was changed.

Examples 15 and 16 Using tributylphosphine oxide as a solvent, a sodium salt of orthocresol was used as a raw material, and a reaction was carried out at a carbon dioxide pressure of 10 kg / cm ² G and a reaction temperature of 140 ° C. for 1 hour. Table 3 shows the results when the molar ratio of tributylphosphine oxide to the sodium salt of orthocresol was set to 4 or 1.

Examples 17 and 18 Anhydrous sodium salt of meta-cresol was added to an equimolar mixed solvent of tributylphosphine oxide and trioctylphosphine oxide, and carbon dioxide was blown into the mixture at atmospheric pressure for reaction at 120 ° C for 3 hours. Table 3 shows the results when the molar ratio of the mixed solvent to the sodium salt of metacresol was 4 or 2.

Comparative Example 2 Example 17 was repeated except that the molar ratio of the equimolar mixed solvent to the sodium salt of metacresol was 8 in Example 17.
I went the same way. The results are shown in Table 3.

The production ratio of PHBs and SAs was about the same as when the molar ratio was 4, and the isomer production ratio hardly changed even if the molar ratio of the mixed solvent to the sodium salt of metacresol was changed.

Examples 19 and 20 Anhydrous potassium salt of orthophenylphenol was dissolved in tributylphosphine oxide, and carbon dioxide was reacted at 100 ° C. under normal pressure for 1 hour. The results are shown in Table 3.

Examples 21 and 22 Using tributylphosphine oxide as a solvent and using anhydrous sodium salt of 1-naphthol as a raw material, the reaction was carried out at a carbon dioxide pressure of 10 kg / cm ² G and a reaction temperature of 200 ° C. for 2 hours. It was Table 4 shows the results when the molar ratio of tributylphosphine oxide to sodium salt of 1-naphthol was set to 4 or 2.

As a result of analyzing the reaction mass by liquid chromatography, 1-HNC-2 and 1-HNC-4 were the main components, and a small amount of 1-HNC-5 was also detected.

The same weight of water was added to tributylphosphine oxide to extract the carboxylate formed in the aqueous layer. Sulfuric acid is added little by little to the aqueous layer, and first, 1-H
NC-4 is precipitated and sulfuric acid is further added to add 1-HNC-
2 was precipitated and separated and obtained.

Examples 23 and 24 Using triethylphosphine oxide as a solvent and using anhydrous potassium salt of 2-naphthol as a raw material, reaction was carried out at a carbon dioxide pressure of 30 kg / cm ² G and a reaction temperature of 260 ° C. for 1 hour. It was Table 5 shows the results when the molar ratio of triethylphosphine oxide to the potassium salt of 2-naphthol was set to 4 or 2.

As a result of analyzing the reaction mass by liquid chromatography, 2-HNC-3 and 2-HNC-6 were the main components, and a small amount of 2-HNC-1 was also detected.

Comparative Example 3 The procedure of Example 23 was repeated, except that the molar ratio of triethylphosphine oxide to potassium salt of 2-naphthol was changed to 5. The results are shown in Table 5.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

[Table 3]

[0061]

[Table 4]

[0062]

[Table 5]

[0063]

By the method of the present invention, the production ratio of isomers of aromatic hydroxycarboxylic acids can be controlled in a wide range, which is very advantageous to the industry.

Claims (7)

[Claims] 1. When reacting an alkali metal salt of a phenol with carbon dioxide in an organic phosphine oxide solvent, the molar ratio of the organic phosphine oxide to the alkali metal salt of a phenol is 1 to 1. 4. A method for controlling the isomer production ratio, which is characterized by varying the isomer production ratio of aromatic hydroxycarboxylic acids. 2. An organic phosphine oxide is represented by the general formula (Formula 1): The method according to claim 1, which is one kind or a mixture of two or more kinds of the organic phosphine oxide represented by. 3. The phenol according to claim 1, wherein the phenols are monocyclic phenols, and the aromatic hydroxycarboxylic acids are 2-hydroxyphenyl-1-carboxylic acids and 4-hydroxyphenyl-1-carboxylic acids. Method. 4. The monocyclic phenol is a phenol, a cresol, a monoalkyl-substituted monohydric phenol substituted with an alkyl group having 2 to 12 carbons, and a monosubstituted phenol with an aryl group having 2 to 12 carbons. The method according to claim 3, which is a phenol compound selected from the group consisting of aryl-substituted monohydric phenols. 5. The method according to claim 3, wherein the monocyclic phenol is phenol. 6. The method according to claim 1, wherein the phenols are 1-naphthols and the aromatic hydroxycarboxylic acids are 1-hydroxynaphthalene-2-carboxylic acids and 1-hydroxynaphthalene-4-carboxylic acids. Method. 7. The phenol according to claim 1, wherein the phenols are 2-naphthols, and the aromatic hydroxycarboxylic acids are 2-hydroxynaphthalene-3-carboxylic acids and 2-hydroxynaphthalene-6-carboxylic acids. Method.