JPH0791220B2 - Method for producing para-hydroxybenzoic acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for producing para-hydroxybenzoic acid using the Kolbe-Schmidt method.

<Prior Art> Para-hydroxybenzoic acid has a wide range of uses as a raw material for polymer materials, and recently, it has been attracting attention as a raw material for liquid crystal polyesters having high strength and high heat resistance. Most of the alkyl esters are also useful substances as fungicides for cosmetics and industry.

Traditionally, the industrial production method of para-hydroxybenzoic acid is a solid-gas phase reaction according to the so-called Kolbe-Schmidt method in which powdered phenol potassium and carbon dioxide are reacted under high temperature and pressure, and usually potassium para-hydroxybenzoate is used. It is obtained by acid precipitation from an aqueous salt solution.

It has long been known that this Kolbe-Schmidt reaction produces salicylic acid when sodium phenol is used as a raw material and para-hydroxybenzoic acid becomes a main product when phenol potassium is used. Many patents have been issued for the method for producing hydroxybenzoic acid to which such a solid-gas phase reaction is applied.

<Problems to be Solved by the Invention> In the above-mentioned production method, while salicylic acid is often obtained in a high yield of about 90%, in the case of parahydroxybenzoic acid, the yield is about 50% at most, I can only find an example of what I obtained. Then, in recent years, in solid-gas phase reaction, the stirring efficiency is poor, the contact of carbon dioxide gas is hindered, and defects such as easy formation of groups in heat transfer have been pointed out.
A method using various inert reaction media has been proposed as an improved method.

For example, a method using an aprotic polar solvent (Japanese Patent Publication No.
-29942), a method using an aromatic hydrocarbon or an aromatic ether (Japanese Patent Publication No. 41617, Japanese Patent Publication No. 50-30063) or a method using a diaryl, diarylalkane, triarylalkane or a hydride thereof (special Kaisho 59
-164751), and a method using kerosene or light oil (Japanese Patent Publication No. 52-12185), etc., but the yields of parahydroxybenzoic acid are 44%, 47%, 54%, 78% and 53%, respectively. %.

On the other hand, in the case of salicylic acid, there are many cases where the reaction using the reaction medium can be obtained in a high yield of about 90% as in the solid-gas phase reaction.

Further, as an improved method for these, a method in which phenol is allowed to coexist in the reaction system (Japanese Patent Publication No. 37658/1975, No. 11658/1986)
3 and Japanese Patent Publication No. 45-9529), the yields of parahydroxybenzoic acid are reported to be 64%, 78% and 75%, respectively.

However, each of the methods is basically only to the extent that the type of reaction medium is changed or the reaction conditions are limited, and the production of parahydroxybenzoic acid should be first discussed in the synthetic chemical industry. Regarding the yield, it cannot be said that the yield is high.

Therefore, it is an object of the present invention to provide a method for producing parahydroxybenzoic acid, which can be widely used as a raw material for various polymer materials and can yield parahydroxybenzoic acid in high yield.

<Means for Solving the Problems> The above object is produced by the present invention described below.

That is, in the present invention, an alkali metal salt of phenol other than lithium salt and sodium salt and carbon dioxide are reacted in the presence of at least one compound of the compounds represented by the following formula (I) or (II). The present invention provides a method for producing para-hydroxybenzoic acid, characterized in that para-hydroxybenzoic acid is obtained.

{In the above formulas (I) and (II), M represents an alkali metal excluding lithium and sodium.

In the formula (I), R is an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a hydroxyaliphatic group having 5 or more carbon atoms, an acyl group, an amino group, an imino group, a halogen group, a nitro group, a phenyl group, a hydroxyaromatic group. Group, aminoalkyl, alkylaminoalkyl, dialkylaminoalkyl, acylamino, halogenated alkyl, nitroalkyl, phenylalkyl, alkylamino, dialkylamino, styryl, alkylphenyl, alkoxyphenyl Group, aminophenyl group, halogenated phenyl group, nitrophenyl group.

In the formula (II), R'is a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a hydroxyaliphatic group having 5 or more carbon atoms, an acyl group, an amino group, an imino group, a halogen group, a nitro group, phenyl. Group, hydroxyaromatic group, aminoalkyl group, alkylaminoalkyl group, dialkylaminoalkyl group, acylamino group, halogenated alkyl group, nitroalkyl group, phenylalkyl group, alkylamino group, dialkylamino group, styryl group, alkylphenyl Group, alkoxyphenyl group,
It represents an aminophenyl group, a halogenated phenyl group and a nitrophenyl group.

In the formula (I), n represents an integer of 1 to 5, and n is 2
In the above cases, R may be the same or different. In formula (II), m represents an integer of 1 to 5 and l represents an integer of 0 to 4. When m is 1 or more, M may be the same or different, and when l is 2 or more, R ' May be the same or different. } Further, it is preferable to use a potassium salt of phenol as the alkali metal salt of phenol, and the formula (I) and /
Alternatively, the compound represented by (II) is preferably a potassium salt.

The compound of formula (I) is preferably mono-, di- and / or tri-substituted potassium phenol.

The tar in which the alkali metal salt of phenol is phenol potassium, and the mixture of the potassium potassium and the potassium salt of the compound represented by the formula (I) and / or (II) is a mixture of phenol and a substituted phenol. It is preferably obtained from an acid or cresylic acid.

In addition, the reaction may use a medium inert to the reaction, or may perform the reaction without using a medium.

Hereinafter, the present invention will be described in detail.

In the present invention, when the alkali metal salt of phenol other than lithium salt and sodium salt is reacted with carbon dioxide, the compound represented by the formula (I) and / or (II) is present.

Formula (I) used in the present invention is represented as follows.

In the formula (I), R is an aliphatic hydroxy group having 4 or less carbon atoms, an aliphatic mercapto group having 4 or less carbon atoms, a substituent containing at least one of these groups in a structural unit, a hydrogen atom, and And all other substituents except, for example, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, an imino group, a halogen atom, a hydroxy group (aromatic), a nitro group or a phenyl group. However, these groups, excluding the halogen atom, may further have a substituent, or may be a combination of a plurality of groups, as long as they satisfy the conditions of R above. For example, isopropyl group,
Aminoalkyl group, alkylaminoalkyl group, dialkylaminoalkyl group, acylamino group, halogenated alkyl group, nitroalkyl group, phenylalkyl group, methoxy group, alkylamino group, dialkylamino group, acyl group, styryl group, alkylphenyl group , An alkoxyphenyl group, an aminophenyl group, a halogenated phenyl group, a hydroxyphenyl group and a nitrophenyl group.

Among the substituents used in the formula (I), preferable ones are those having an electron donating property such as an alkyl group of a methyl group and alkoxy such as a methoxy group, but a phenyl group is also preferable.

Further, the formula (II) is represented by the following formula.

R'in the formula (II) includes a hydrogen atom in addition to the above R.

Among the substituents used in the formula (II), preferable ones include
An electron-donating substance such as an alkyl group such as a methyl group or an alkoxy group such as a methoxy group, but a hydrogen atom or a phenyl group is also preferable.

In the present invention, the alkali metal of phenol and M of the compound represented by the formula (I) and / or (II) are
Examples thereof include K, Rb, Cs and Fr, which may be the same or different, but the same is preferable, and among them, K is economically preferable.

The method of the present invention may be applied to the reaction using no reaction medium, or may be applied to the method using an inert reaction medium,
Parahydroxybenzoic acid can also be obtained in high yields without the use of a reaction medium. In particular, when the reaction temperature is equal to or higher than the melting point of the reaction mixture, the mixture which is the starting material of the present invention becomes liquid due to the melting point lowering phenomenon. However, the conventional solid-gas phase reaction is advantageous in terms of stirring, and the compound represented by the formula (I) and / or (II) is liquid or has a low melting point as the reaction progresses. Since it is converted into a substituted phenol, para-hydroxybenzoic acid can be obtained in a high yield, which is applicable as a convenient method.

Therefore, whether the method using the reaction medium or the method not using the reaction medium can be used as a standard based on the mixed melting point of the mixture used in the reaction.

The coexisting amount of the compound represented by the formula (I) and / or (II) is 0.2 times as much as the equivalent number of these alkalioxy groups with respect to the raw material phenol potassium, phenol bidium, phenol cesium or phenol francium. ~ 30 times equivalent, preferably 0.5 times to 10 times equivalent,
More preferably, it is 0.8 times to 3 equivalents.

For example, when phenol potassium is a raw material and a dipotassium salt of dihydroxybenzene is used as the compound represented by the above formula (II), the coexisting amount thereof is 0.
It should be 1 to 15 times mol, preferably 0.25 to 5 times mol, and more preferably 0.4 to 1.5 times mol, and it should be determined in consideration of the mixed melting point of the mixture system. It suffices to consider both, especially when no reaction medium is used.

In addition, the compound represented by the above formula (I) and / or (II), after the reaction, is wholly or mostly recovered as it is and / or as a free substituted phenol.
It has the advantage that it can be reused.

In the present invention, the reaction temperature is 100 ° C or higher, preferably 2
00 ~ 500 ℃, carbon dioxide pressure is normal pressure ~ 50kg / cm ² (G),
The pressure is preferably normal pressure to 15 kg / cm ² (G).

The carbon dioxide used in the present invention may be diluted or mixed with a gas or the like which is inert to the raw materials and products under the present reaction conditions, for example, nitrogen, hydrogen, helium, argon, carbon monoxide, It may be mixed with hydrocarbon and the like.

Further, blast furnace gas and the like produced as a byproduct in an iron mill also contain carbon dioxide, and can be used as an economically convenient one. When using such a carbon dioxide mixed gas,
The partial pressure of carbon dioxide may be atmospheric pressure to -50 kg / cm ² (G), preferably atmospheric pressure to 15 kg / cm ² (G).

Preferred examples of the compound represented by the above formula (I) are shown below.

Among the compounds represented by the formula (I), preferred examples include mono-substituted phenol potassium, and the substitution position may be any of the ortho, meta and para positions, and cresol potassium and phenylphenol potassium (potassium salt of hydroxydiphenyl). ) Etc. are specifically mentioned.

Further, mono-substituted phenol cesium or mono-substituted phenol bidium corresponding to the above can be exemplified as effective ones.

Among the compounds represented by the formula (I), disubstituted phenol potassium is preferred, and the two substitution positions may be any combination, and 2,3-, 2,4-, 2,5-,
Specific examples include 2,6-, 3,4- or 3,5-xylenol potassium.

Among the compounds represented by the above formula (I), preferred is tri-substituted phenol potassium, and the three substitution positions may be any combination, but the 2,4,6-tri-substituted phenol potassium is suitable for carbonation. It is preferable because it is inactive, and 2,4,6-trimethylphenol potassium and the like are specifically mentioned.

In these cases, the amount of the substituted phenol potassium used may be determined based on the equivalent number of the potassium oxy group to phenol potassium and the mixed melting point within the above range.

Other reaction conditions such as reaction temperature and carbon dioxide pressure may be appropriately selected within the above range.

Examples of the compound represented by the formula (II) include the dipotassium salt of hydroxybenzene described above.
In addition, various kinds can be used.

The compounds represented by the above formulas (I) and / or (II) may be used alone or in combination of two or more kinds.

In the present invention, the alkali metal salt of phenol and the formula (I) and / or (I
The compound represented by I) can be obtained from tar acid and / or cresylic acid, which is a mixture of phenol obtained from coal tar and substituted phenols, and / or cresylic acid. Since the intended mixed system is formed, it can be applied as a particularly preferable method. In this case, it is preferable to use these tar acids and / or cresylic acids to form potassium salts, and they may also be used as rubidium salts or cesium salts.

In the present invention, either a batch system, a continuous system, or a combination of both systems may be used, but the continuous system is preferred from the viewpoint of industrial significance.

When the method of the present invention is carried out in an inert reaction medium, examples of the medium include aromatic hydrocarbons, aromatic ethers,
Examples thereof include aromatic alkanes, aromatic alkenes, aromatic ketones, or hydrides thereof, petroleum hydrocarbons of aspiring groups, aprotic polar solvents, and higher alcohols. These reaction media may be used alone or in combination of two or more as a mixed medium. For example, biphenyl, terphenyl, naphthalene, anthracene, ditolylethane, dibenzyltoluene, methylnaphthalene, isopropylnaphthalene, GS250 (mixture of aromatic compounds whose main component is methylnaphthalene), NeoSK-oi1 (Soken Chemical Co., Ltd. medium), Dowtherm (mixture of diphenyl and diphenyl ether), ethylbiphenyl, diphenyl ether, hydrogenated terphenyl, benzophenone, boiling point 15
Kerosene and / or light oil at 0 ° C or higher, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, carbon number 5 to 15
Higher alcohols, or mixtures thereof.
Preferably, potassium phenol and the compounds represented by the formulas (I) and / or (II) are insoluble, insoluble in water, and liquid at a temperature of 100 ° C. or higher, but a liquid at room temperature or higher. Is more convenient, and more preferably has a boiling point of 200 ° C. or higher.

Specifically, it is preferable to use light oil having a boiling point of 250 ° C. or higher, NeoSK-oi1, Dowtherm, isopropylnaphthalene, or the like. The use of these media has an advantage that the reaction pressure can be easily controlled.

Further, in order to carry out the reaction system continuously using the reaction medium, the reaction medium may be selected in consideration of the melting point, the fluidity and the solubility of the free phenols.

In addition, the reaction system is preferably stirred in any method using no reaction medium, any method using a reaction medium,
High-speed rotation and / or vigorous shaking are preferable for better contact between the contents, and more preferable are conditions under which turbulent flow is generated.

Phenol potassium and the compounds represented by the above formulas (I) and / or (II) are powders, and it is preferable that all the compounds have a small particle size (about 300 μm or less). The particle size is an important factor especially in the reaction without using the reaction medium.

The yield of parahydroxybenzoic acid in the present invention is higher than that in the conventional method.

<Example> The present invention will be specifically described below with reference to Examples and Comparative Examples. In addition, the quantification in the following Examples and Comparative Examples was performed by chromatography.

(Example 1) Phenol potassium (5.99 g) in dry powder form, paracresol potassium (7.30 g), and NeoSK-1400 (Soken Chemical Co., Ltd. raw medium, dibenzyltoluene mixture) (25 g) were charged into a pressure resistant reactor, and carbon dioxide (7 kg / cm ^2). (G) at 300 ° C for 1 hour,
The reaction was carried out under stirring at 1000 rpm.

After the reaction, the reaction product was acidified and analyzed. As a result, the yield of parahydroxybenzoic acid was 88.4% (6.09 g) based on potassium phenol.

Example 2 15.28 g equimolar mixture of potassium potassium powder and 2,4,6-trimethylphenol potassium powder and NeoSK-14002
Put 4.7g in pressure resistant reactor, carbon dioxide pressure 7kg / cm
² (G) at 230 ° C. for 1 hour under stirring at 1000 rpm.

After the reaction, the reaction mixture was acidified and analyzed, and the yield of parahydroxybenzoic acid was found to be based on potassium phenol.
It was 82.3%.

(Example 3) 6.69 g of dried powder potassium phenol and 8.95 g of 2,4,6-trimethylphenol potassium and a boiling point range of 250 to 34
25.0g of light oil at 0 ℃ was put into a pressure resistant reactor and carbon dioxide pressure was set to 11
The reaction was carried out under stirring at 1000 rpm for 1 hour at 230 ° C. under kg / cm ² (G).

After the reaction, when the reaction mixture was acidified and analyzed, the yield of parahydroxybenzoic acid was 84.6% based on potassium phenol.

(Example 4) Cresolic acid, which is a mixture of phenol and substituted phenols obtained from coal tar, was used. Dry cresylate potassium was obtained from cresylic acid and potassium hydroxide, and this component was analyzed. , Phenol potassium: 44.68%, orthocresol potassium: 12.
99%, metacresol potassium: 25.44%, para-cresol potassium: 13.47%, and the remaining 3.42% is a mixture of those mainly containing xylenol potassium.

Neosk-1400 with 10.24 g of this powdered cresol potassium
Put it in a pressure resistant reactor together with 25 ml, carbon dioxide 7 kg / cm ²
Under (G), the mixture was reacted at 250 ° C. for 3 hours with stirring at 1000 rpm.

After the reaction, the reaction mixture was acidified and analyzed, and the yield of parahydroxybenzoic acid was found to be based on potassium phenol.
It was 89.9%.

(Example 5) Tar acid, which is a mixture of phenol obtained from coal tar and substituted phenols, was used.

From this tar acid and potassium hydroxide, dry potassium tarate was obtained, and when this component was analyzed, in weight percentage,
Phenol potassium: 41.15%, orthocresol potassium: 9.55%, metacresol potassium: 17.61%, paracresol potassium: 9.13%, xylenol potassium: 8.
It was 95%, and the residue of 13.61% was thought to be an impurity peculiar to tar acid, but details were unknown.

13.60 g of this powdery potassium tarrate was added to 25 g of NeoSK-1400.
Put it in a pressure resistant reactor together with carbon dioxide pressure 7 kg / cm
² (G) at 270 ° C. for 1 hour with stirring at 1000 rpm.

After the reaction, when the reaction mixture was acidified and analyzed, the yield of para-hydroxybenzoic acid was 81.5% based on potassium phenol.

(Example 6) Phenol potassium 6.76 g and orthocresol potassium
Put 7.54g and NeoSK-1400 25g in a pressure resistant reactor, and under carbon dioxide pressure of 7kg / cm ² (G), 300 ℃ for 1 hour, 10
The reaction was carried out under stirring at 00 rpm.

After the reaction, the reaction mixture was acidified and analyzed, and the yield of parahydroxybenzoic acid was 83.6% based on potassium phenol.

(Example 7) Phenol potassium 6.98 g and metacresol potassium 7.5
4 g and NeoSK-1400 25 g were placed in a pressure resistant reactor and reacted in the same manner as in Example 6.

After the reaction, when the reaction mixture was acidified and analyzed, the yield of para-hydroxybenzoic acid was 80.0% based on potassium phenol.

(Examples 8 to 13) 6.6 g of phenol potassium, 8.0 g of xylenol potassium, and 250 g of NeoSK-1400 were charged in a pressure resistant reaction vessel and reacted. After the reaction, the reaction mixture was acidified and analyzed. The results are shown in the table below.

(Example 14) 6.63 g of phenol potassium, 10.98 g of orthophenylphenol potassium, and 25 g of NeoSK-1400 were placed in a pressure-resistant reaction vessel and stirred at 300 rpm for 1 hour at 1000 rpm under a carbon dioxide pressure of 7 kg / cm ² (G). Reacted below.

After the reaction, the reaction mixture was acidified and analyzed. As a result, the yield of parahydroxybenzoic acid was 77.8% based on potassium phenol.

(Example 15) 6.60 g of potassium phenol, 10.96 g of metaphenylphenol potassium and 25 g of NeoSK-1400 were placed in a pressure resistant reactor and reacted in the same manner as in Example 14.

After the reaction, when the reaction mixture was acidified and analyzed, the yield of parahydroxybenzoic acid was 78.5% based on potassium phenol.

(Example 16) 17.79 g of an equimolar mixture of phenol dibium and paracresol rudibium and 25 g of NeoSK-1400 were placed in a pressure resistant reaction vessel, and carbon dioxide pressure was 3 kg / cm ² (G) at 300 ° C. for 1 hour. The reaction was carried out under stirring at 1000 rpm.

After the reaction, when the reaction mixture was acidified and analyzed, the yield of parahydroxybenzoic acid was 81.3% based on phenoldibium.

(Example 17) 27.60 g of an equimolar mixture of phenol cesium and para-cresol cesium and 25 g of NeoSK-1400 were placed in a pressure resistant reaction vessel and reacted in the same manner as in Example 16.

After the reaction, when the reaction mixture was acidified and analyzed, the yield of parahydroxybenzoic acid was 62.2% based on phenol cesium.

(Example 18) 6.65 g of dry powdery phenol potassium and 7.40 g of orthocresol potassium were placed in a pressure resistant reactor and reacted for 10 minutes while stirring at 220 to 240 ° C. under a carbon dioxide pressure of 7 kg / cm ² (G). It was The melting point of the equimolar mixture of potassium potassium and potassium orthocresol was 209 g as a peak value by differential thermal analysis (the same applies hereinafter). After the reaction
When the reaction mixture was acidified and analyzed, the yield of para-hydroxybenzoic acid was 79.6% based on potassium phenol.
Met.

(Example 19) Tar acid, which is a mixture of phenol obtained from coal tar and substituted phenols, was used.

From this tar acid and potassium hydroxide, dry potassium tarate was obtained, and when this component was analyzed, in weight percentage,
Phenol potassium: 40.96%, orthocresol potassium: 9.66%, metacresol potassium: 17.82%, para-cresol potassium: 9.23%, xylenol potassium: 9.
It was 19%, and the remaining 13.14% was an impurity peculiar to tar acid that contained thiophenols and other traces, but the details were unknown. The mixed melting point of this potassium tarrate is about 230 ° C.
Met.

15.03 g of this powdery potassium tarrate was placed in a pressure resistant reactor and reacted under a carbon dioxide pressure of 8 kg / cm ² (G) at 250 to 260 ° C. for 1 hour while stirring. After the reaction, the reaction mixture was acidified and analyzed. As a result, the yield of parahydroxybenzoic acid was 71.1% on the basis of phenol potassium.

(Comparative Example 1) 6.60 g of phenol potassium and 26.4 g of NeoSK-1400 were put into a pressure resistant reactor, and carbon dioxide was kept at 7 kg / cm ² (G) at 230 ° C.
Was reacted for 20 minutes at 1000 rpm under stirring.

After the reaction, when the reaction mixture was acidified and analyzed, the yield of parahydroxybenzoic acid was 45.1% based on potassium phenol.

(Comparative Example 2) 6.59 g of phenol potassium, 2.36 g of phenol and NeoS
K-1400 (26.5 g) was placed in a pressure resistant reactor, the reaction was carried out under the same conditions as in Comparative Example 1, and then the reaction mixture was acidified and analyzed. The yield of parahydroxybenzoic acid was found to be based on potassium phenol. It was 47.3%.

(Comparative Example 3) 6.83 g of phenol potassium, 7.30 g of 2,4,6-trimethylphenol and 25.5 g of NeoSK-1400 were put in a pressure resistant reactor and reacted under the same conditions as in Example 1.

After the reaction, the reaction mixture was acidified and analyzed, and the yield of parahydroxybenzoic acid was 46.8% based on potassium phenol.

<Effects of the Invention> According to the present invention, parahydroxybenzoic acid is produced in good yield,
Obtained in high purity.

Therefore, it can be used in a very wide range as a raw material for polymer materials and medicines and agricultural chemicals.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tokio Iizuka 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Headquarters (72) Inventor Masahiro Wakui 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Technical Research Division

Claims (7)

[Claims] 1. An alkali metal salt of phenol other than lithium salt and sodium salt is reacted with carbon dioxide in the presence of at least one compound represented by the following formula (I) or (II). A method for producing para-hydroxybenzoic acid, which comprises obtaining para-hydroxybenzoic acid. {In the above formulas (I) and (II), M represents an alkali metal excluding lithium and sodium. In the formula (I), R is an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a hydroxyaliphatic group having 5 or more carbon atoms, an acyl group, an amino group, an imino group, a halogen group, a nitro group, a phenyl group, a hydroxyaromatic group. Group, aminoalkyl, alkylaminoalkyl, dialkylaminoalkyl, acylamino, halogenated alkyl, nitroalkyl, phenylalkyl, alkylamino, dialkylamino, styryl, alkylphenyl, alkoxyphenyl Group, aminophenyl group, halogenated phenyl group, nitrophenyl group. In the formula (II), R'is a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a hydroxyaliphatic group having 5 or more carbon atoms, an acyl group, an amino group, an imino group, a halogen group, a nitro group, phenyl. Group, hydroxyaromatic group, aminoalkyl group, alkylaminoalkyl group, dialkylaminoalkyl group, acylamino group, halogenated alkyl group, nitroalkyl group, phenylalkyl group, alkylamino group, dialkylamino group, styryl group, alkylphenyl Group, alkoxyphenyl group,
It represents an aminophenyl group, a halogenated phenyl group and a nitrophenyl group. In the formula (I), n represents an integer of 1 to 5, and n is 2
In the above cases, R may be the same or different. In the formula (II), m represents an integer of 1 to 5 and l represents an integer of 0 to 4. When m is 1 or more, Ms may be the same or different, and when l is 2 or more, R ' May be the same or different. } 2. The method for producing parahydroxybenzoic acid according to claim 1, wherein the alkali metal salt of phenol is a potassium salt of phenol. 3. The method for producing parahydroxybenzoic acid according to claim 1, wherein the compound represented by the formula (I) and / or (II) is a potassium salt. 4. The method for producing parahydroxybenzoic acid according to claim 1, wherein the compound represented by the formula (I) is potassium mono-, di- and / or tri-substituted phenol. 5. The alkali metal salt of phenol is phenol potassium, and the potassium potassium and the formula (I) are used.
And / or the method for producing parahydroxybenzoic acid according to claim 1, wherein the mixture of the compound represented by (II) with a potassium salt is obtained from tar acid or cresylic acid, which is a mixture of phenol and a substituted phenol. 6. The method for producing parahydroxybenzoic acid according to claim 1, wherein the reaction is carried out in a medium inert to the reaction. 7. The method for producing parahydroxybenzoic acid according to claim 1, wherein the reaction is performed without using it as a reaction medium.