JPH013151A - Method for producing 4-hydroxybiphenyl-3-carboxylic acid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a novel method for producing 4-hydroxybiphenyl-3-carboxylic acid, which has recently attracted attention as a color developer for pressure-sensitive and thermal paper. Regarding.

[Prior Art] As for a method for industrially producing 4-hydroxybiphenyl-3-carboxylic acid, the so-called Kolbe-Schmidt reaction (Chem, Rev., 57.583 (19
57)) is optimal. A specific production method utilizing this reaction includes, for example, a method of heating 4-hydroxybiphenyl with excess potassium carbonate at a temperature of 200 to 250°C under carbon dioxide gas pressure (J, Ge
n, chem, (υ, S, S, R,), 8.424
(1938) ).

After heating 4-hydroxybiphenyl and sodium hydroxide in an aqueous solvent, the water is distilled off to produce the sodium salt of 4-hydroxyhyphenyl.
160-170 under carbon dioxide gas pressure of Kg/cri・G
A method of heating at a temperature of °C (U.S. Patent No. 1.941,20
7@specification), 4 produced by reacting 4-hydroxybiphenyl and sodium hydroxide in a lower alcohol solvent
- Separate and dry the sodium salt of hydroxybiphenyl, pulverize it to a particle size of 20 mesh or less, and pressurize this sodium salt with carbon dioxide gas at a concentration of about 2 to 40 KI/~.G.
Method of heating at a temperature of 10°C (Japanese Patent Application Laid-open No. 62-45.55
Publication No. 8) etc. have been proposed.

[Problems to be solved by the invention] However, the first method described above requires an excessive amount of potassium carbonate, and requires a reaction under high-pressure carbon dioxide gas of approximately 30 kg/cut・G. There is a problem in that the manufacturing cost is high due to equipment and other factors, making it unsuitable for mass production.

Further, although the second and third methods described above are preferable in terms of raw material cost, they have the following problems in terms of equipment and actual production. In other words, the first method is to use both methods, and as in the first method, the reaction with carbon dioxide gas is carried out under pressure, so a pressurized reaction device is required, which increases the cost in terms of equipment and makes it difficult to mass produce. is not suitable.

The second problem is that both methods involve a solid-gas reaction without a solvent, but in general, the yield of the Kolbe-Schmidt reaction decreases significantly when water is contained.

Therefore, it is necessary to once isolate the sodium salt of 4-hydroxybiphenyl, dry it, and pulverize it. Since this sodium salt is hygroscopic, it absorbs moisture when charged into a pressurized reaction vessel, so it is necessary to dry it again in the reaction vessel.

Therefore, the present invention was devised to solve such problems, and its purpose is to reduce raw material cost,
- A novel 4-hydroxybiphenyl-3- which is advantageous in terms of equipment cost, easy to operate, and suitable for mass production.
An object of the present invention is to provide a method for producing carboxylic acid.

[Means for Solving the Problems] That is, the present invention dehydrates a reaction mixture obtained by reacting 4-hydroxybiphenyl and potassium hydroxide, and then heats the reaction mixture at 150 to 250°C in the presence of a hydrophobic solvent. This is a method for producing 4-hydroxybiphenyl-3-carboxylic acid, which is reacted with carbon dioxide gas.

In the method of the present invention, first, 4-hydroxybiphenyl and potassium hydroxide are reacted to form a potassium salt of 4-hydroxybiphenyl. In this method, for example, potassium hydroxide is mixed with 4-hydroxybiphenyl as a solid in the form of flakes or pellets or dissolved in water and/or a lower alcohol such as methanol or ethanol, and the mixture is reacted with heating. There is a method to make potassium salt of 4-hydroxybiphenyl.

In this case, the amount of potassium hydroxide used is 1 mol per 1 mol of 4-hydroxy phenyl, but it is advantageous to use it in slightly excess, preferably in the range of 1 to 2 mol. . However, if the amount is too large, dehydration becomes difficult or the yield of the final product decreases. Further, when potassium hydroxide is used as a solution of water and/or lower alcohol, it is preferably used as a 10 to 50% solution. This reaction can easily proceed in a short time even at room temperature when a solution of potassium hydroxide is used; however, especially when using solid potassium hydroxide, it is best to heat it to 50°C or higher. If a solvent is used, it is preferable to heat it to near its boiling point.

Further, in the process of producing the potassium salt of 4-hydroxybiphenyl, a hydrophobic solvent similar to the hydrophobic solvent used in the next reaction process with carbon dioxide gas can also be used as a reaction solvent. This allows sufficient dispersion and contact of the reaction raw materials by stirring,
Moreover, it is possible to prevent the crystals from becoming too large or from solidifying, and the reaction proceeds favorably. This effect is particularly remarkable when no other solvent is added.

Note that the reaction between 4-hydroxybiphenyl and potassium hydroxide proceeds in the next dehydration step, so even if this reaction is still incomplete, there is no problem in proceeding to the next dehydration step.

-〇- According to the studies of the present inventors, when sodium hydroxide, potassium carbonate, etc. are used in the process of producing an alkali salt of 4-hydroxybiphenyl, not only the yield is low, but also A high reaction pressure is required in the manufacturing process, and a large amount of 4-hydroxybiphenyl as a raw material is mixed in, making purification difficult.

A method for dehydrating by-produced water or water used as a solvent for potassium hydroxide from the reaction product obtained by reacting 4-hydroxybiphenyl with potassium hydroxide is to dehydrate the reaction mixture under reduced pressure or at normal temperature. There is a method of distilling water off by heating under pressure. At this time, if an azeotropic solvent is used, dehydration can be completed more quickly and completely. Examples of azeotropic solvents used for this purpose include various solvents such as benzene, toluene, methanol, and ethanol. It is advantageous to add a solvent. When the reaction mixture is solid, this hydrophobic solvent has the effect of dispersing the reaction mixture, improving thermal conductivity, and accelerating the rate of dehydration.

After the preparation of the potassium salt of 4-hydroxybiphenyl and the dehydration of the reaction mixture, 1
4-hydroxybiphenyl-3-carboxylic acid is produced by reacting with carbon dioxide gas at 50 to 250°C.

The hydrophobic solvent used for this purpose may be one that does not participate in the reaction between the potassium salt of 4-hydroxybiphenyl and carbon dioxide gas, and may include various aromatic hydrocarbons, heteroaromatic compounds, ethers, etc. However, when the reaction between the potassium salt of 4-hydroxybiphenyl and carbon dioxide gas is carried out at normal pressure, the reaction temperature is 150 to 25°C.
Since the temperature needs to be 0°C, the boiling point is 150°C or higher. Examples of such hydrophobic solvents include triisopropylbenzene, tri-tert-butylbenzene, naphthalene, methylnaphthalene, ethylnaphthalene, dimethylnaphthalene, biphenyl, diphenylmethane, diphenylethane, ethylbiphenyl, diethylbiphenyl, quinoline, diphenyl ether, and dimethylnaphthalene. Benzyl ether, etc. can be mentioned, and these are one of them.
In addition to being able to use only the seeds alone, it is also possible to use a mixed solvent in which two or more types are combined. The amount of hydrophobic solvent used for this purpose is 4-hydroxybiphenyl 1
0.1 to 50 parts by weight, preferably 1 to 2 parts by weight
A range of 0 parts by weight is preferable.

The reaction conditions for the reaction of the potassium salt of 4-hydroxybiphenyl with carbon dioxide gas are as follows:
The temperature is 0 to 250°C, preferably 160 to 220°C, and the carbon dioxide pressure is not particularly limited, but from the viewpoint of equipment costs, etc., it is preferably normal pressure to 2Kg/crA-G.
, more preferably normal pressure. Slight pressurization within a range that does not significantly affect equipment costs is advantageous in terms of reaction rate.

After the reaction is completed, water is added to the reaction mixture to dissolve the reaction product by heating, the water layer and the hydrophobic solvent layer are separated, and a mineral acid such as hydrochloric acid or sulfuric acid is added to the water layer to obtain the desired product (4). After precipitating -hydroxybiphenyl-3-carboxylic acid and separating it by filtration, purification operations such as solvent washing and recrystallization are performed as necessary,
4-Hydroxybif-12-3-carboxylic acid is isolated.

[Function] According to the method of the present invention, 4-hydroxybiphenyl is made into a potassium salt and reacted with carbon dioxide gas in the presence of a hydrophobic solvent, so the contact efficiency and reaction rate between the potassium salt and carbon dioxide gas are improved. However, it is believed that 4-hydroxybiphenyl-3-carboxylic acid can be easily produced in high yield.

[Example] Hereinafter, the method of the present invention will be specifically explained based on Examples and Comparative Examples.

Example 1 14.4 g of potassium hydroxide was dissolved in 40 d of methanol, and then 34.09 d of 4-hydroxybiphenyl and 300 d of a mixed solvent (boiling point 257° C.) of biphenyl:diphenyl ether (3 nia) as a hydrophobic solvent were added. This suspension was heated from 80°C to 210°C over 2 hours.
Dehydration distillation was carried out while raising the temperature to ℃ to remove methanol and by-produced water.

Next, while introducing carbon dioxide gas into the reaction mixture under normal pressure, the reaction mixture was heated at 165°C for 2 hours with stirring, and further heated to 195°C.
The temperature was raised to 5°C, and the mixture was heated and stirred for 8 hours to react.

After the reaction was completed, it was cooled and 300 d of warm water was added to produce 4.
Transfer the potassium salt of -hydroxybiphenyl-3-carboxylic acid into the aqueous layer, separate the aqueous layer, add concentrated hydrochloric acid to the aqueous layer to adjust the pH to below 1, and filter out the precipitated crystals. Dry, purity 98°1% (HPLC), melting point 215
4-Hydroxybiphenyl-3-carboxylic acid at 30°C.
5y (70% yield) was obtained.

Comparative Example 1 9.3 g of sodium hydroxide was dissolved in methano-6 (M), and then 34.0 g of 4-hydroxybiphenyl and 300 g of a mixed solvent of biphenyl:diphenyl ether (3N) was dissolved.
and reacted in the same manner as in Example 1, and the reaction mixture was dehydrated by distilling off methanol and by-produced water.

Next, while introducing carbon dioxide gas into the reaction mixture under normal pressure, the reaction mixture was heated at 165°C for 2 hours with stirring, until the
The temperature was raised to 5° C., and the mixture was heated and stirred for 12 hours to cause a reaction.

After the reaction was completed, it was cooled and 900 m of warm water was added to produce 4.
Transfer the sodium salt of -hydroxybiphenyl-3-carboxylic acid into the aqueous layer, separate the aqueous layer, add concentrated hydrochloric acid to the aqueous layer to adjust the concentration to 1) H1 or less, and remove the precipitated crystals. The mixture was filtered and dried to obtain 29.2 g (yield: 31%) of 4-hydroxybiphenyl-3-carboxylic acid with a purity of 45.5% (HPLC). The remainder was filled with unreacted 4-hydroxybiphenyl.

Example 2 300mf as a hydrophobic solvent! 28.7 g of 4-hydroxybiphenyl-3-carboxylic acid was obtained in the same manner as in Example 1 above, except that ethyl biphenyl was used. The obtained 4-hydroxybiphenyl-3-carboxylic acid had a purity of 96.8% (HPLC), a melting point of 214°C, and a yield of about 65%.

Example 3 30.3 g of 4-hydroxybiphenyl-3-carphonic acid was obtained in the same manner as in Example 1 above, except that 30'Od β-methylnaphthalene was used as the hydrophobic solvent. The obtained 4-hydroxybiphenyl-3-carboxylic acid is
The purity was 97.8% (HPLC), the melting point was 215°C, and the yield was about 69%.

Example 4 To 34.0!7 of 4-hydroxybiphenyl, 14.4 g of potassium hydroxide, 300 d of a mixed solvent of biphenyl:diphenyl ether (3 nia) as a hydrophobic solvent, and 60 d of toluene were added, and the resulting suspension was 120-130℃
Heat for 1 hour to react, then 1.5 hours to react.
4-Hydroxybiphenyl-
31.2 g of 3-carboxylic acid was obtained. The obtained 4-hydroxybiphenyl-3-carboxylic acid had a purity of 98.7% (
HPLC) with a melting point of 215°C and a yield of about 7.
It was 2%.

Example 5 4-Hydroxybifu-denyl-3- 29.6 g of carboxylic acid was obtained. The obtained 4-hydroxybiphenyl-3-carboxylic acid has a purity of 98.3% (HPLC)
The melting point was 215°C, and the yield was about 68%.

[Effect of the invention] According to the method of the present invention, 4-hydroxybiphenyl is converted into its potassium salt, and then carbon dioxide gas is reacted with the potassium salt to form 4-hydroxybiphenyl.
-The process of producing -hydroxybiphenyl-3-carboxylic acid can be carried out continuously in one ordinary reaction apparatus, and the target product, 4-hydroxybiphenyl-3-carboxylic acid, can be produced with high purity and high yield. can be easily manufactured.

Patent applicant: Iwaki Pharmaceutical Co., Ltd. Same as above Nippon Steel Corporation Same as above Nippon Steel Chemical Co., Ltd.

Claims (5)

[Claims] (1) 4- characterized in that the reaction mixture obtained by reacting 4-hydroxybiphenyl and potassium hydroxide is dehydrated and then reacted with carbon dioxide gas at 150 to 250°C in the presence of a hydrophobic solvent. Method for producing hydroxybiphenyl-3-carboxylic acid. (2) The method for producing 4-hydroxybiphenyl-3-carboxylic acid according to claim 1, wherein the hydrophobic solvent has a boiling point of 150°C or higher. (3) 4-hydroxybiphenyl-3 according to claim 1 or 2, wherein a hydrophobic solvent is present from the reaction step of 4-hydroxybiphenyl and potassium hydroxide.
-Production method of carboxylic acid. (4) The method for producing 4-hydroxybiphenyl-3-carboxylic acid according to claim 1 or 2, wherein a hydrophobic solvent is present from the step of dehydrating the reaction mixture. (5) The method for producing 4-hydroxybiphenyl-3-carboxylic acid according to any one of claims 1 to 4, wherein the reaction with carbon dioxide gas is carried out under normal pressure.