JPH0219340A - Production of biphenyl-4,4'-dicarboxylic acid dialkali metal salt - Google Patents

Abstract

PURPOSE:To obtain the subject compound in high yield by the thermal rearrangement reaction of a biphenylcarboxylic acid alkali metal salt and/or diphenic acid di-alkali metal salt in pressurized carbon dioxide atmosphere in the presence of a catalyst and biphenyl. CONSTITUTION:The objective biphenyl-4,4'-dicarboxylic acid di-alkali metal salt useful as a raw material for engineering plastics can be produced in extremely high yield by heating a biphenylcarboxylic acid alkali metal salt and/or diphenic acid di-alkali metal salt (preferably potassium salt) together with a catalyst (preferably a cadmium compound) and biphenyl in pressurized carbon dioxide atmosphere (preferably under 10-150kg/cm<2>.G) preferably at a temperature higher than the melting point of the raw material.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an alkali metal salt of biphenylcarboxylic acid and/or
Alternatively, biphenyl-4,4 is produced by using a dialkali metal salt of diphenic acid as a raw material and subjecting it to a thermal transfer reaction together with a catalyst and biphenyl under substantially moisture-free conditions and under pressure of carbon dioxide gas.
The present invention relates to a method for producing a dialkali metal salt of '-dicarboxylic acid. The target product of the present invention is polycondensed with dihydric alcohol, dihydric phenol, dihydric amine, etc. and is used as a raw material for engineering plastics.

[Prior Art] Conventionally, there is a known method (see West German Patent No. 953071) in which a diphenoic acid dipotassium salt is used as a raw material and subjected to a heat transfer reaction together with a catalyst at a temperature above the melting point of the raw material. The yield of biphenyl-4,4ξ dicarboxylic acid dialkali metal salt was only about 10%. Alternatively, the same raw material may be dried together with a catalyst under reduced pressure at a temperature near the melting point of the raw material, and then subjected to a heat transfer reaction under pressure of carbon dioxide at a temperature above the melting point of the raw material (Japanese Patent Publication No. 58-4G49G, No. 61).
9299) is also known, but the yield of the desired product is about 40%, and it is hard to say that either method can be titrated industrially.

[Problems to be Solved by the Invention] One of the causes of low yield in conventional methods is carbonization of raw materials. Although this is an example of a thermal transition reaction of an alkali metal naphthoate, there is also a method of simply adding a solvent to compensate for this drawback.

However, it is obvious that no further improvement in yield can be expected by simply adding a solvent.

[Means for Solving the Problems] In order to solve this problem, the inventor conducted extensive studies and discovered a method of adding biphenyl to have some influence on the thermal transition reaction.

According to the present invention, a biphenyl-4,4'-dicarboxylic acid dialkali metal salt is characterized by heating an alkali metal salt of biphenylcarboxylic acid and/or a dialkali metal salt of diphenic acid together with a catalyst and biphenyl under pressure of carbon dioxide gas. A manufacturing method is provided.

The raw material of the present invention is an alkali metal salt of biphenylcarboxylic acid and/or a dialkali metal salt of diphenic acid. Preferably it is a dialkali metal salt of diphenic acid. As the alkali metal salt, potassium salt is preferred as in the usual Henkel method.

The catalyst used in the present invention is cadmium oxide (CdO
), cadmium compounds such as cadmium iodide (Cdlz), cadmium red, or zinc halides such as zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc compounds such as zinc oxide, zinc sulfate, and metal halides. For example, it can be used in combination with Preferred is a cadmium compound such as cadmium oxide or cadmium iodide.

The amount used is 0.5 to 20 mol%, preferably 1-
It is 10 mol%.

As the metal halide used in combination with the zinc compound, chloride, bromide, and iodide are effective, and use of bromide and iodide is particularly preferred.

As metals, alkali metals and alkaline earth metals (excluding zinc) are effective.

In the present invention, the reaction temperature is not particularly limited as long as it is a liquid phase higher than the melting point of dipotassium diphenic acid salt, but is preferably 380 to 385°C.

The reaction time in the present invention is 2 hours or more, preferably [1
- About IG time.

The higher the carbon dioxide pressure in the present invention, the more preferable it is, but 50K
Even if it exceeds g/cm"·G, no significant improvement in yield is observed.

In the present invention, it is preferable to stir the contents sufficiently during the reaction.

In the present invention, a solvent may be added as necessary.

Naphthalene, lower alkylnaphthalenes such as dimethylnaphthalene and methylnaphthalene, diaryl ethers such as diphenyl ether, terphenyl, anthracene, phenanthrene, etc. are used, and mixtures thereof can also be used. The amount used is 0.5 to 10 times the weight of the raw material, preferably i to 5 times the weight of the raw material.

In any case, it is preferable that the reaction system in the present invention is substantially free of water. Therefore, each material to be supplied to the reaction system should be sufficiently dried by heating or dehydration in advance. Of course, a method may also be used in which the material is first charged into a reactor, dried, and then reacted.

After the reaction is completed, the target product, biphenyl-4,4'-dicarboxylic acid dialkali metal salt, is recovered by cooling and separating by recrystallization or other appropriate separation method. Biphenyl-4,4'-dicarboxylic acid can be obtained from this metal salt by a conventionally known method.

[Example] The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Thoroughly dried biphenyl (12 g), cadmium iodide (0.38 g, 8 mol%) as a catalyst, and dipotassium diphenate (4 g) as a raw material were charged into a 1001 reactor equipped with a stirrer. . Next, dry carbon dioxide gas was injected (carbon dioxide pressure 50Kg/cm2・G), and the temperature was lowered to 380℃.
℃, and was maintained at this temperature for 6 hours to react. After the reaction was completed, the reaction mixture was maintained at 200°C and taken out in the form of a slurry. The mixture was cooled to room temperature and toluene+0
01 and 100 ml of water were added and thoroughly stirred. Insoluble matter in both layers was filtered off, and an aqueous solution containing biphenyldicarboxylic acid dipotassium salt was obtained by branching operation.

A portion of this aqueous solution was collected and analyzed using high performance liquid chromatography to determine the biphenyl-4,
The yield was calculated by adding a fixed amount of 4'-dicarboxylic acid potassium salt.

Table 1 also shows the results obtained using naphthalene and diphenyl ether instead of biphenyl.

The amount added was <12 g, the same as in the case of biphenyl, and the other conditions were also the same.

Naphthalene 28 diphenyl ether 25 biphenyl
50 [Effects of the Invention] As shown in Table 1, when biphenyl is used, the yield of the target product is specifically improved, and although the detailed reason is unknown, biphenyl is primarily used as an intermediate in the reaction. It is believed that biphenyl is involved in the reaction and therefore shows a specifically high yield in the case of biphenyl.

Claims (5)

[Claims] (1) A biphenyl-4,4'-dicarboxylic acid dialkali metal salt is prepared by heating an alkali metal biphenylcarboxylate salt and/or a dialkali metal salt of diphenic acid together with a catalyst and biphenyl under pressure of carbon dioxide gas. Production method. (2) The method according to claim 1, wherein the reaction temperature is higher than the melting point of the raw materials. (3) Carbon dioxide pressure is 10 to 150 kg at reaction temperature
/cm^2·G. (4) The method according to claim 1, wherein the alkali metal is potassium. (5) The method according to claim 1, wherein the catalyst is a cadmium compound.