JP3106476B2 - Method for producing phenolic compounds - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an industrially useful phenol compound. More specifically, a substantially anhydrous 2,4-dialkylphenol alkali metal salt, and 3,5-
Regarding the method for producing dialkylsalicylic acid, 3,5-dialkylsalicylic acid is useful as a raw material for synthesizing chemicals such as a color developer for pressure-sensitive recording paper, agricultural chemicals, and antioxidants.

[Problems to be solved by conventional technology and invention]

As a method for producing 3,5-dialkylsalicylic acid, which is useful as a raw material for the synthesis of chemicals such as developers for pressure-sensitive recording paper, agricultural chemicals, and antioxidants, an alkali metal salt of 2,4-dialkylphenol and carbon dioxide have been used since ancient times. The Kolbe-Schmidt reaction to be reacted is known.

For example, J. Chem. Eng. Data, Vol. 14, pp. 388-391 (19
In 1969), a 2,4-dialkylphenol alkali metal salt (hereinafter, referred to as an alkali metal salt) was prepared from an alkali metal alcoholate and a 2,4-dialkylphenol, and then reacted with carbon dioxide to produce 3,5-dialkylphenol. Methods for obtaining dialkylsalicylic acids have been described. According to this method,
Although dehydration is essentially unnecessary, it is difficult to say that it is an industrial production method because dangerous and expensive metallic sodium and metallic potassium are used when producing an alkali metal alcoholate.

JP-A-62-61949 discloses that 2,4-di-t-butylphenol and an aqueous solution of an alkali metal hydroxide are mixed and heated.
After removing water under reduced pressure, pulverize, and reacting the obtained alkali metal salt with carbon dioxide without solvent
A method for producing 3,5-di-t-butylsalicylic acid is disclosed. However, the 2,4-di-t-
Since a mixture of butylphenol and an alkali metal hydroxide does not form a homogeneous solution, formation of the alkali metal salt does not proceed smoothly, and it is also difficult to completely dehydrate the obtained alkali metal salt. Therefore, in the carboxylation reaction in the next step, the alkali metal salt with the remaining water causes a reduction in the conversion to the target product.

Therefore, as a method of obtaining an anhydrous alkali metal salt,
A method of adding an organic solvent immiscible with water to a mixture of a 4-dialkylphenol and an aqueous solution of an alkali metal hydroxide and removing water by azeotropic dehydration is considered. But,
For example, in a method of removing water by azeotropic dehydration while adding an aqueous solution of an alkali metal hydroxide to a solution containing a hydrocarbon solvent as a water-immiscible organic solvent and a dialkylphenol, an insoluble material swollen into a paste is used. Are generated, stirring becomes impossible, the formation of the alkali metal salt does not proceed smoothly, and it is obviously difficult to completely dehydrate the obtained alkali metal salt. Therefore, even in this method, it is impossible to obtain an anhydrous alkali metal salt having a high conversion rate to a target salicylic acid compound in the carboxylation reaction in the next step.

Further, JP-A-63-165341 discloses that a 2,4-dialkylphenol to an alkali metal hydroxide is added to a hydrocarbon-based solvent in an amount maintained at a molar ratio of 1.25 or more, and water is removed by azeotropic dehydration. Then, a method has been proposed in which an anhydrous 2,4-dialkylphenol alkali metal salt solution is prepared and then reacted with carbon dioxide to produce 3,5-dialkylsalicylic acid. However, in this method in which it is essential to use an excess amount of the 2,4-dialkylphenol, the 2,4-dialkylphenol must be recovered after all, and the operation is complicated.

JP-A-64-34944 discloses that 2,4-di-t-butylphenol and 2,4-di-t-butylphenol are dehydrated from an alkali metal hydroxide by a dehydration reaction.
Disclosed is a method for forming an alkali metal salt of 4-di-t-butylphenol and carrying out the reaction in a homogeneous liquid in the presence of sulfolane through a reaction of carboxylation with carbon dioxide. However, also in this reaction, sulfolane is essential as a solvent, and operations such as recovery of the solvent are required.

When industrial production is carried out by the Kolbe-Schmidt reaction, it is more advantageous to use a substantially anhydrous solid compound rather than the coexistence of a solvent.

Further, conventionally, the Kolbe-Schmidt reaction is performed under a high pressure of 5 to 10 kg / cm ² G of carbon dioxide.

J. Chem. Eng. Data. Vol. 14 shows an example of reaction under normal pressure, which requires the use of sodium metal and the use of dimethylamides, a special solvent.

[Means for solving the problem]

The present inventors produced 2,4-dialkylphenol and alkali metal hydroxide for the purpose of obtaining an anhydrous 2,4-dialkylphenol alkali metal salt having a sufficiently high conversion rate to 3,5-dialkylsalicylic acid. The present invention has been achieved by intensive studies on the steps.

That is, the present invention reacts a 2,4-dialkylphenol with an alkali metal hydroxide to form a substantially anhydrous 2,4
A method for producing a dialkylphenol alkali metal salt, comprising the steps of dissolving a 2,4-dialkylphenol and an alkali metal hydroxide in a lower alcohol and reacting the same, and then distilling off the lower alcohol and produced water. A method for producing an anhydrous 2,4-dialkylphenol alkali metal salt, and further reacting the obtained substantially anhydrous 2,4-dialkylphenol alkali metal salt with carbon dioxide to produce a 3,5-dialkylsalicylic acid. On how to do it.

The alkyl group of the 2,4-dialkylphenol used in the present invention is a linear or branched alkyl group having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. , Isobutyl, s-butyl, t-butyl, pentyl, hexyl, 2-
Examples include an ethylhexyl group and an octyl group. The two alkyl groups can be the same or different.

The lower alcohol used in the present invention includes methanol, ethanol, propanol, isopropyl alcohol, butanol and the like.

The alkali metal hydroxide includes sodium hydroxide, potassium hydroxide and the like, and these are used in the form of a solid or an aqueous solution.

To explain the production method of the present invention in more detail, 0.8 to 1.2 mol, preferably 1.
0 mol of liquid or solid alkali metal hydroxide is 2,4-
After reacting by dissolving in a lower alcohol of 0.2 to 3 times the weight of the dialkylphenol, the mixture is heated and a mixture of the lower alcohol and water distilled off is removed to thereby obtain a substantially anhydrous 2,4-dialkylphenol. An alkali metal salt is obtained.

In particular, when distilling the mixture of lower alcohol and water, the lower alcohol and water are gradually dissolved at normal pressure for 2 to 5 hours after uniform dissolution in a reaction vessel at 50 to 60 ° C. and salt formation reaction. The mixture of is distilled off. Further, by distilling the mixture under reduced pressure at an internal temperature of 100 to 130 ° C., substantially anhydrous 2,4
A dialkylphenol alkali metal salt.

The reaction temperature of the thus obtained substantially anhydrous 2,4-dialkylphenol alkali metal salt is increased to 130 to 150 ° C.
While maintaining the pressure, gradually blow carbon dioxide from under reduced pressure. The carboxylation reaction proceeds at a pressure close to atmospheric pressure under reduced pressure (preferably in the range of −1 kg / cm ² G to 50 mmHg / cm ² G). From 2,4-dialkylphenol
The conversion to 3,5-dialkylsalicylic acid reaches 90-95%.

After the reaction, dissolve the reactants in water and remove from the container,
Add hydrocarbon solvents (such as aliphatic hydrocarbons such as hexane, heptane, octane, ligroin, and kerosene; and aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene) to remove unreacted 2,4-dialkylphenol. Remove from aqueous layer by extracting into layers. An acid (mineral acid such as hydrochloric acid, sulfuric acid or nitric acid) is added to the aqueous layer according to a conventional method, and the precipitated crystals are collected by filtration, washed with water and dried to obtain 3,5-dialkylsalicylic acid.

[Action]

In the present invention, by adding a lower alcohol, the mixture of the 2,4-dialkylphenol and the alkali metal hydroxide becomes a homogeneous solution, and the formation of the alkali metal salt proceeds smoothly. Also, by gradually distilling the mixture of the lower alcohol and the produced water under normal pressure and then under reduced pressure, the dehydration of the alkali metal salt is completely and easily performed, and the adhesion of the target substance to the inner wall of the container is suppressed. This is operationally advantageous.

Since the alkali metal salt thus obtained is in a powder form and substantially anhydrous, the conversion rate to 3,5-dialkylsalicylic acid is high, which is very advantageous for industrial production. .

The present invention, since by producing reactive good phenolate are possible reactions at close to atmospheric pressure from the reduced pressure to the pressure ^{-1kg / cm 2 G~50mmHg / cm 2} G, industrially produced In this case, there is an advantage that a special high-pressure autoclave is not required.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. Incidentally, the obtained compound was IR spectrum, NMR spectrum, H
It was confirmed that it was the target compound by means such as PLC and elemental analysis.

Example 1 (1) A 200-ml autoclave equipped with a magnetic stirrer and a thermometer was charged with 51.6 g of 2,4-di-t-butylphenol, 10 g of flaky sodium hydroxide, and 36.1 g of methanol.
The contents were dissolved by heating to 60 ° C. to form a uniform solution. Then, after the air in the autoclave is replaced with nitrogen gas, methanol and water are gradually distilled off under normal pressure for 2 hours. The mixture of methanol and water distilled out during that time was led to a condenser and liquefied. Then, internal temperature 110-160 ℃,
The dehydration operation was continued for a further 2 hours under a reduced pressure of an absolute pressure of 5 to 50 mmHg. The obtained 2,4-di-t-butylphenol sodium salt was in the form of powder, and it was confirmed by analysis that it was the target compound. The state of adhesion to the inner wall of the container is
It was less than 10%.

(2) Make the absolute pressure 5mmHg again and stop the vacuum. While maintaining the reaction temperature at 130 to 150 ° C., carbon dioxide was gradually blown from the reduced pressure of 5 mmHg, and the pressure became atmospheric in 2 hours. At this time, the gas absorption was 85% of theory. Continue gauge pressure 50mmHg
The reaction was continued for 3 hours below. After cooling the reaction, water 10
After adding 0 g, the slurry was taken out of the autoclave, and 200 g of water was further added to obtain a uniform aqueous solution. 100 g of hexane was added to the aqueous solution, and unreacted 2,4-di-t-butylphenol was transferred to the hexane layer, followed by liquid separation, and 24.5 g of 50% sulfuric acid was added dropwise to the obtained aqueous layer. The precipitated crystals were collected by filtration, washed with water, and dried to obtain 54.6 g of white 3,5-di-t-butylsalicylic acid. 87.3% yield, melting point 16
1.5-163.5 ° C. HPLC purity 98.5 area%.

Example 2 (1) 2,4-di-t- was added to a kneader with a heating jacket.
Butylphenol 103.2g, Flaky sodium hydroxide
After charging 20 g of methanol and 70 g of methanol and replacing the air in the container with nitrogen gas, the jacket is heated and uniformly dissolved. The methanol and water are distilled off under normal pressure for 3 hours. The distillate was led to a condenser and liquefied. Subsequently, the dehydration operation was continued for 3 hours at an internal temperature of 110 to 130 ° C. and a reduced pressure of 5 to 50 mmHg in absolute pressure. The obtained 2,4-di-t-butylphenol sodium salt was in the form of a powder, and it was confirmed by analysis that it was the target compound. The state of adhesion to the inner wall of the container was 10% or less of the vessel wall area.

(2) After the dehydration is completed, the same operation as in (2) of Example 1 is performed. Carbon dioxide was gradually blown in from a reduced pressure of 5 mmHg to reach atmospheric pressure in 30 minutes. At this time, gas absorption is
93%. Subsequently, the reaction was continued at a gauge pressure of 50 mmHg or less for 3 hours. From 3,4-di-t-butylphenol to 3,5-
The conversion to di-t-butylsalicylic acid was 94%.
Hereinafter, processing is performed in substantially the same manner as in Example 1 to obtain 3,5
111 g of di-t-butylsalicylic acid were obtained.

Comparative Example 2,4-di-t-butylphenol 51.6 g, flaky sodium hydroxide 10 g and water 30 g in a 200 ml autoclave
After stirring at 80 ° C. for 1 hour, water was distilled off while gradually increasing the degree of vacuum and the temperature. After the distillation of water almost stopped, dehydration was further continued at 150 ° C. and an absolute pressure of 3 mmHg for 5 hours. Then, the same operation as in the embodiment is performed. Carbon dioxide
The pressure was reduced to 3 mmHg, and the pressure was gradually increased to atmospheric pressure in 3 hours. At this time, the gas absorption was 35% of theory. Subsequently, the reaction was continued at a gauge pressure of 50 mmHg or less for 10 hours. 2,4-di-
The conversion of t-butylphenol to 3,5-di-t-butylsalicylic acid was 39.1%.

〔The invention's effect〕

As is clear from the above examples, the method of the present invention
Since the 2,4-dialkylphenol alkali metal salt can be obtained in powder form and substantially anhydrous,
The conversion to dialkylsalicylic acid is high, and the reaction is carried out under reduced pressure to almost atmospheric pressure, which is industrially advantageous.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-61949 (JP, A) JP-A-64-34944 (JP, A) JP-A-59-155334 (JP, A) JP-A 61-61334 282336 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 37/66 C07C 39/235 C07C 51/15 C07C 65/05

Claims (3)

(57) [Claims] 1. A method for producing a substantially anhydrous 2,4-dialkylphenol alkali metal salt by reacting a 2,4-dialkylphenol with an alkali metal hydroxide.
After dissolving the 4-dialkylphenol and the alkali metal hydroxide in a lower alcohol and reacting, a substantially anhydrous 2,2 is characterized by distilling off the lower alcohol and produced water.
A method for producing an alkali metal salt of a 4-dialkylphenol. 2. Production of a 3,5-dialkylsalicylic acid by reacting an alkali metal salt of a 2,4-dialkylphenol with carbon dioxide, dissolving a 2,4-dialkylphenol and an alkali metal hydroxide in a lower alcohol. After the reaction, the lower alcohol and the produced water are distilled off, and the obtained substantially anhydrous 2,4-dialkylphenol alkali metal salt is reacted with carbon dioxide.
Method for producing dialkylsalicylic acid. 3. The method according to claim 2, wherein the reaction between the alkali metal salt of 2,4-dialkylphenol and carbon dioxide is carried out at a temperature of 130 to 150 ° C. and a pressure from reduced pressure to near atmospheric pressure. ) Described method.