JPS59164751A - Preparation of aromatic hydroxycarboxylic acid - Google Patents

Abstract

PURPOSE:To prepare the titled compound useful as a raw material of pharmaceuticals, agricultural chemicals, etc., in high yield, by reacting an aromatic hydroxy compound alkali metal salt with carbon dioxide using a reaction comprising a polycyclic aromatic hydrocarbon which has a high boiling point and is a liquid at normal temperature. CONSTITUTION:The objective compound is prepared by reacting an aromatic hydroxyl compound alkali metal salt (e.g. potassium phenolate, sodium 2-naphtholate, etc.) with carbon dioxide using a polycyclic aromatic hydrocarbon as a reaction medium, at >=100 deg.C, preferably 150-300 deg.C under a carbon dioxide gas pressure of <=30kg/cm<2>, preferably 2-10kg/cm<2>(G). The polycyclic aromatic hydrocarbon is e.g. diaryl, triphenyl, dibenzyltoluene, etc., preferably those having a boiling point of >=250 deg.C. The amount of the polycyclic aromatic hydrocarbon is preferably 1-5pts.wt. per 1pt.wt. of the aromatic hydroxyl compound alkali metal salt.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for the preparation of aromatic hydroxycarboxylic acids by reaction of aromatic hydroxy compound alnometallic salts with carbon dioxide in suspension.

Aromatic hydroxycarboxylic acids, especially paraoxybenzoic acid, salicylic acid, and 3-oxy-2-naphthoic acid,
Its usefulness has long been known as a raw material for preservatives, antifungal agents, medicines, dyes, and pigments, and in recent years its importance has increased as a synthetic raw material for agricultural chemicals, color developers for thermal recording paper, and monomers for aromatic polyesters. are doing.

These aromatic hydroxycarboxylic acids have conventionally been produced by a gas-solid phase reaction between an alkali metal salt of an aromatic hydroxy compound and carbon dioxide, the so-called Kolbe-Schmidt process, but in recent years, one of the present inventors has This gas-solid phase method was improved to a gas-liquid phase reaction using a suspended phase, and a method was achieved that enabled industrial mass production.

The present inventors further improved the Kolbe-N-Schmidt method (
As a result of repeated research, we found that i'JI' is a liquid at room temperature and
The present invention was achieved by discovering that diaryl or triaryl aromatic hydrocarbons having a temperature of 250 DEG C. or higher have the following 1:5 superior properties.

1) Since the alkali metal salt of the aromatic hydroxy compound is well suspended, complete dehydration of the alkali metal salt of the aromatic hydroxy compound is carried out quickly and at a relatively low temperature.

Therefore, the anhydrous version of the aromatic hydroxide compound Al) IJ metal salt can be easily prepared using λ oil.
The yield of the product in the reaction with carbon dioxide is significantly improved.

2) In the Kolbe-Schmidt reaction, 3iT1
An aromatic hydroxide compound is produced as a by-product along with the Al1 line of the normal reaction. Appropriate distribution of this by-product in the aromatic hydroxy compound alnoy IJ metal salt layer and the reaction medium layer is important for improving the speed of the reaction process, the yield of the target product, and the ratio. Since the reaction medium described in -1- makes this distribution appropriate, the yield and ratio of the target product are significantly improved. Therefore, in the reaction process, it is not necessary to add an aromatic hydroxy compound to liquefy the raw material yarn or to improve the yield and ratio of the target product.

6) It suppresses tarring of the product in the reaction process and further dissolves tarry by-products in the reaction medium layer.
Very little tar-like substance is mixed into the aromatic hydroxy compound alkali metal salt layer. As a result, the reaction rate, yield and ratio of the target product do not decrease due to the contamination of the tar-like substances.

4) Since the above reaction medium has a good distribution ratio of the aromatic hydroxy compound, it is easy to recover the aromatic hydroxy compound dissolved in the aqueous layer in the finishing process. Since it is usually liquid even at room temperature, it does not solidify during the finishing process. Therefore, in this process, there is no need to heat the line to prevent caking, which is thermoeconomically advantageous.

3-6) Furthermore, the above-mentioned reaction medium usually has a high boiling point and there is no pressure increase due to the vapor pressure of the solvent during the reaction process.
It also has the advantage of not requiring pressure higher than that of carbon dioxide because of its pressure resistance.

The present invention produces aromatic hydroxycararyl, diarylalkane, triaryl, Mention may be made of aryl or triaryl alkanes or their hydrides or mixtures thereof, such as 1-phenyl-1-(2,!,-dialkylphenyl)-alkanes, triphenyl, dibenzyltoluene, hydrogenated triphenyls or A mixture of these is preferred, and 2
Those having a high boiling point of 50°C or higher are excellent.

Examples of the alkali metal salts of aromatic hydroxy compounds include potassium phenol, sodium phenol, and sodium 2-naphthol.

In the Kolbe-N-Schmidt method, one of the important issues is complete dehydration of the alkali metal salt of the aromatic hydroxide compound as a raw material, and if the dehydration of the raw material is incomplete, the reaction yield will be drastically reduced. The above raw materials can be prepared by conventional methods from phenol or 2-naphthol and sodium hydroxide or potassium hydroxide, but it is especially advantageous to completely dehydrate them in the presence of the reaction medium mentioned above.

According to the present invention, the reaction between the alkali metal salt of the aromatic hydroxy compound and carbon dioxide is carried out at a temperature of 100° C. or higher, preferably 100° C.
20-300℃, especially 150-300℃? ! 171 degrees,
and 3 o kg/cm” (G) or less, preferably 1 to 15 kg/crn2 (G), especially 2 to 1' O
k! ? It is carried out at a carbon dioxide pressure of 7 m2 (G). The reaction medium used is usually at least 0.5 times the weight of the alkali metal salt of the aromatic hydroxy compound, preferably from 0.5 to 10 times, especially from 1 to 5 times the weight.

The reaction can be carried out either batchwise or continuously, but for mass production it is preferable to carry out the reaction continuously.

The reaction time or residence time can be appropriately selected from several minutes to 15 hours, preferably from 10 minutes to 10 hours, particularly from 20 minutes to 10 hours.

Since the method of the present invention has the various advantages mentioned above, it has extremely high industrial value.

Example 1 Potassium phenol 1009 and 400 g of a hydrogenated triphenyl mixture are placed in a pressure-resistant reactor and reacted with stirring at 260° C. and a carbon dioxide pressure of 7 kg/crn2 (G) for 20 minutes. Cool the reaction mixture and then add 200 ml of water.
The reaction medium layer and the aqueous layer are separated at 85°C. The aqueous layer is further extracted with 20.9 g of xylene, and phenol is recovered from the reaction medium layer and extraction solvent layer with potassium hydroxide solution.

After recovering the phenol, the aqueous layer was made acidic with dilute sulfuric acid, and paraoxybenzoic acid 80.8. ! i+ is obtained. The yield based on phenol potassium was 77.3%, the recovered phenol potassium was 21.8 g, and the selectivity was 991%.
It is.

Example 2 Sodium phenol 100 &amp; 1-phenol #-1
-(2,3-dimethylphenyl)ethane 5009 was placed in a pressure-resistant reactor and heated to 170°C and carbon dioxide pressure 111k.
g/cm2(C)) and react for 2 hours with stirring. The reaction mixture was cooled and then added to 7-500 ml of water, and the reaction medium layer and the water layer were separated at 90°C. The aqueous layer is further acidified with xylene 50I oil to yield salicylic acid 94.39.

The yield based on phenol sodium was 90.2%, the recovered phenol potassium was 8.2 g, and the 1 selectivity was 98.
It is 5%.

Example 3 166 g of sodium 2-naphthol and 464 g of a dibenzyltoluene mixture were placed in a pressure-resistant reactor and reacted with stirring at 260°C and a carbon dioxide pressure of 5 kg7 cm2-(G) for 4 hours. Pour the reaction mixture into 850 ml of water! The reaction medium layer and the aqueous layer are separated at 85°C. The reaction medium layer is extracted with 48% sodium hydroxide and recovered as a sodium 2-naphthol solution. pH5 the aqueous layer with dilute sulfuric acid.
, 5, and then the tar layer that settles at the same temperature is separated. The aqueous layer was then adjusted to pH 2.0 with dilute sulfuric acid at 85°C.
-2-Hydroxynaphthalene-6-carboxylic acid 89
．． 3; zo is obtained. The yield based on sodium β-naphthol is 4'7.5%. 55.6 g of β-naphthol was recovered from the reaction medium layer and the tar layer, with a selectivity of 86.1%.

Example 4 The reaction and finishing treatment are carried out in a continuous manner using the apparatus shown in the drawings. 2-naphthol sodium 83 per hour to mixer 1
Step 9: Supply 166 kfl of hydrogenated triphenyl mixture and mix and disperse. This mixed dispersion 249 k/hour
g is sent to reaction tank 2 in which the carbon dioxide pressure is maintained at 5 kg/Crn2 (G), and reacted at 270°C. Residence time is 4 hours. After cooling the reaction mixture in the reaction tank 2 in a heat exchanger 3, it is placed in a stirring tank 4 at 420 ml of water per hour. The temperature is adjusted to 85°C, and then sent to a liquid separation tank 5, where the liquid is separated into a reaction medium layer and an aqueous layer at 85°C. The 2-naphthol component is recovered as sodium 2-naphthol from the upper reaction medium layer using a recovery device (not shown). The lower aqueous layer is adjusted to pH 5.5 with dilute sulfuric acid in a pH adjustment tank 6, and then separated in a separation tank 7 at 85°C. 2-naphthol is recovered from the lower tar layer separated in the separation tank 7 using a vacuum distillation apparatus (not shown). Separation tank 7
The upper layer inside is sent to acid (1) tank 8 and acid precipitated with dilute sulfuric acid at 85°C to a pn of 2.0. 44.7 kg/hour
2-hydroxynaphthalene-3-carboxylic acid is obtained. β-naphtho-luna) Yield based on IJium is 4.7
．． It is 6%. 4IJ hour β-naphthol 27.8k
g was recovered and the first selection IR rate was 86.2%.

[Brief explanation of the drawing]

The drawing is a process diagram for explaining an embodiment of the present invention, in which 1 and 4 are stirring tanks, 2 is a reaction tank, 6 is a heat exchanger, and 5
and 7 is a liquid separation tank, 6 is a pI-I adjustment tank, and 8 is an acid precipitation layer. Applicant Ueno Pharmaceutical Applied Research Institute Co., Ltd. Agent Patent Attorney Masao Kobayashi 11- Procedural amendment (method) % formula % 2. Name of the invention Process for producing aromatic hydroxycarboxylic acid 3. Relationship with the person making the amendment case /F'Y Applicant Address 4, Agent 8, Contents of Amendment Submit one official drawing as shown in the attached sheet.

Claims (1)

[Scope of Claims] 1. A method for producing an aromatic hydroxycarboxylic acid, which is characterized by carrying out a reaction between an aromatic hydroxy compound, a metal salt, and carbon dioxide using a polycyclic aromatic hydrocarbon as a reaction medium. 2. The method according to claim 1, wherein the aromatic hydrocarbon is diaryl, diarylalkane, triaryl, triarylalkane, hydride thereof, or a mixture thereof. 6. Claim 1, characterized in that the alkali metal salt of an aromatic hydroxy compound is sodium phenol, potassium phenol, or sodium 2-naphthol.
2. The method according to any one of paragraphs 1 and 2.