JPH04257542A - Method for producing aromatic polycarboxylic acids - Google Patents

Abstract

PURPOSE:To economically and advantageously obtain aromatic polyfunctional carboxylic acids useful as a monomer, etc., for polyimide resins from halogenated aromatic carboxylic acids in good yield and high selectivity in one step. CONSTITUTION:Halogenated aromatic carboxylic acids, preferably 4-halogeno-o- phthalic acids, 4-halogenonaphthalic acids or 4-halogenobenzoic acids are dehalogenated and dimerized in the presence of a catalyst containing Pd and a metal of a different kind, preferably Sn, Rh, Au, Ag or Pt, especially the Sn or Rh supported on a carrier in an alkaline aqueous solution containing a base, preferably oxide, carbonate or bicarbonate of an alkali metal or an alkaline earth metal, especially KOH and a reducing agent such as formic acid, a polyhydric alcohol, an amino-alcohol or CO present therein to afford the objective aromatic polyfunctional carboxylic acids.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention is a method for producing aromatic polyhydric carboxylic acids by subjecting halogenated aromatic carboxylic acids to dimerization coupling through a dehalogenation reaction.

0002

BACKGROUND OF THE INVENTION Aromatic polycarboxylic acids consisting of aromatic polycarboxylic acids, their anhydrides, their salts, or their nuclear alkyl substituted products are important compounds as monomers for polymer synthesis. Among these, 3,4,3',4'-biphenyltetracarboxylic acids, 4,4'-bisnaphthalic acids, and the like are useful compounds as raw materials for heat-resistant polyimide resins. Conventionally, many methods for producing aromatic polyhydric carboxylic acids have been reported. Among these, regarding the dehalogenation dimerization reaction of aromatic polyhydric carboxylic acids using a palladium catalyst, production of 3,4,3',4'-biphenyltetracarboxylic acids by coupling of 4-chlorophthalic acids Many methods have been reported. For example, a method of dehalogenating monosodium 4-chloroorthophthalate in an alkaline aqueous solution in the presence of a catalyst in which metallic palladium is supported on activated carbon and formate as a reducing agent (Japanese Patent Application Laid-Open No. 1983-1992) 137838) and a method of coupling in an alkaline aqueous solution in the presence of a metal palladium-activated carbon catalyst, a polyhydric alcohol, and formaldehyde (Japanese Unexamined Patent Publication No. 62-26238). In addition, as improvements to these methods, there is a method in which carbon monoxide is present (Japanese Unexamined Patent Publication No. 63-179834) and a method in which chloroform is used as a reducing agent (Japanese Unexamined Patent Publication No. 63-26773).
5 Publications) etc. Furthermore, there are methods using amino alcohol (Japanese Patent Application Laid-Open No. 13036/1982) and methods using a palladium-activated carbon catalyst which has been immersed in hydrohalic acid (Japanese Patent Application Laid-Open No. 1-250328).

However, these methods do not provide a sufficiently high yield of the desired 3,4,3',4'-benyltetracarboxylic acid salt. The reason for this is that 4-halogenorthophthalate does not dimerize and generates dehalogenated orthophthalate, which is the target product 3,4,3'
, 4'-benyltetracarboxylic acid salt is not high. Therefore, halogenorthophthalic acids are coupled with high selectivity to 3,4,3',4
There is a need for a production method that can obtain '-bienyltetracarboxylic acids in high yield. In addition, regarding the dehalogen dimerization reaction of other halogenated aromatic polycarboxylic acids, for example, a method for dimerization of halogenated benzoic acid has been reported (
JP-A-62-72629, JP-A-64-1303
6). However, dehalogenation occurs and the selectivity of the coupling reaction is not high. Furthermore, there are some reports on methods for producing bisnaphthalic acids by coupling reactions of halogenonaphthalic acids, but the selectivity and yield are not sufficiently high.

0004

[Problems to be Solved by the Invention] Therefore, the present inventors conducted intensive research to solve the above problems.
By improving a known method using a palladium catalyst, aromatic polycarboxylic acids can be produced in a practical manner with high selectivity and high yield through a coupling reaction of halogenated aromatic carboxylic acids. They discovered this and completed the present invention. Therefore, an object of the present invention is to provide a manufacturing method that can economically and economically advantageously produce aromatic polycarboxylic acids, which are dimerization products, from halogenated aromatic carboxylic acids as raw materials. It is about providing.

[0005]

[Means for Solving the Problems] That is, the present invention involves reacting halogenated aromatic carboxylic acids in an alkaline aqueous solution in the presence of a base and a reducing agent in the presence of a catalyst in which palladium and a different metal are supported on a carrier. This is a method for producing aromatic polycarboxylic acids by dimerizing the aromatic polycarboxylic acids.

The halogenated aromatic carboxylic acids used in the present invention may be those having at least one aromatic nuclear-substituted halogen and at least one nuclear-substituted carboxyl group. The halogen may be any of iodine, bromine, and chlorine, but chlorine and bromine are preferred because they are economically cheap and easily available industrially. Further, the halogenated aromatic carboxylic acid may have an alkyl substitution at its core. Preferred alkyl groups include methyl group, ethyl group, propyl group, etc., and the number of alkyl groups is 0.
-2 is preferred. These halogenated aromatic carboxylic acids are thought to become alkali salts and participate in the reaction in a reaction system conducted in an alkaline aqueous solution, so the materials used as raw materials should not be acids or salts. Any acid anhydride or acid anhydride may be used as long as it can be converted into a salt. Preferred raw materials include halogenated aromatic carboxylic acids, their anhydrides, dialkali metal salts or monoalkali metal salts thereof, and monocarboxylic acids (the alkali metal is preferably sodium or potassium). Specific examples of halogenated aromatic carboxylic acids used in the present invention include 4-chloroorthophthalic acid, 4-bromonaphthalic acid, 4-chloronaphthalic acid, and 4-chlorobenzoic acid. The halogenated aromatic carboxylic acids are not limited to these.

Regarding the catalyst used in the reaction of the present invention, since zero-valent palladium and a metal different from palladium act on the reaction, either a homogeneous catalyst or a heterogeneous catalyst may be used as long as it is compatible with zero-valent palladium and a metal different from palladium. However, economically, a heterogeneous catalyst in which palladium and a different metal are supported on a carrier is preferable. Activated carbon is preferable as a carrier for this supported catalyst. The dissimilar metal is a metal different from palladium, and may be any metal that can maintain a metallic state in the reaction system, but preferable examples include transition metals from Group 8, Group 1B, and Group 2B, and Group 3B and Group 4B transition metals. metals. Among them, tin, rhodium, gold, silver, platinum, etc. are good, especially tin,
Rhodium is preferred because it has high selectivity in the dimerization reaction.

The reaction of the present invention requires the presence of a base and a reducing agent in the reaction system, and must be carried out in an alkaline aqueous solution in which the base and reducing agent are present. That is, in the reaction system of the present invention, since the reaction involves dehalogenation, a base is required to capture the halogen that is eliminated, and
Zero-valent palladium acts as a catalyst species, but after the reaction it is oxidized to divalent palladium, so formic acid, polyhydric alcohol, amino alcohol, carbon monoxide, etc. are added to the reaction system as reducing agents. There is a need to. In this reaction, palladium acts as a catalyst for the coupling reaction, but when a catalyst in which a different metal is supported together with palladium is used as a promoter, dehalogenation that proceeds as a side reaction is suppressed, and the coupling reaction is selected. becomes more sexual. The base used is preferably an alkali metal or alkaline earth metal oxide, carbonate or bicarbonate, more preferably potassium hydroxide or potassium hydroxide. When formic acid is used as the reducing agent, an alkaline water-soluble formate is preferable, and sodium formate and potassium formate are particularly preferable. When polyhydric alcohol is used, examples include ethylene glycol and glycerin. Furthermore, amino alcohols can also be used, and ethanolamine is particularly preferred. In addition, carbon monoxide can also be used.

The amount of catalyst used in the reaction of the present invention is:
1 to 50% by weight based on halogenated aromatic carboxylic acids
The amount may range from 2 to 20% by weight, but preferably from 2 to 20% by weight. As the amount of catalyst used increases, the selectivity of the coupling reaction increases. In this case, the content of palladium and different metal in the catalyst is preferably 0.5 to 10% by weight, respectively. Further, the ratio of palladium and different metals in the catalyst is preferably such that the amount of different metals is 1 to 200% by weight relative to palladium,
More preferably, it is 30 to 150% by weight. The amount of the base used in the reaction of the present invention is usually 1 equivalent or more per equivalent of the halogenated aromatic carboxylic acid, preferably in the range of 1 to 5 equivalents. If it is less than 1 equivalent, the conversion rate of halogenated aromatic carboxylic acids will be low;
When the amount is equal or more, dehalogenation, which is a side reaction, takes priority;
The selectivity of the coupling reaction becomes low. Further, the amount of the reducing agent used may be equal to or more than the equivalent amount of the halogenated aromatic carboxylic acid, and is preferably in the range of 1 to 5 times the equivalent amount.

In the reaction of the present invention, the reaction system is 80 to 12
This is done by heating to 0°C. At this time, the reaction is usually carried out at normal pressure, but depending on the reaction temperature, the system may be sealed to raise the vapor pressure of the solvent above atmospheric pressure. Moreover, the inside of the reaction system may be carried out under an inert gas atmosphere such as nitrogen. The reaction time depends on the amount of catalyst, base, reducing agent, reaction temperature, etc., but is usually 0.5 to 48 hours. The reaction product obtained after the completion of the reaction exists as an aromatic polycarboxylic acid or its alkali salt in the reaction mixture, but the salt can be converted into a monomer as a free aromatic polycarboxylic acid by acid treatment using a conventional method. Furthermore, by heating this with acetic anhydride, nitric acid, etc., it can be easily converted into an acid anhydride. The aromatic polycarboxylic acids obtained by the production method of the present invention include biphenyltetracarboxylic acid and biphenyldicarboxylic acid, which are dimerization reaction products in which the aromatic nuclei of the halogenated aromatic carboxylic acids used as raw materials are directly bonded. , carboxylic acids such as bisnaphthalic acid, acid anhydrides and salts thereof, and nuclear alkyl substituted products thereof.

[0011]

[Examples] The method of the present invention will be specifically explained below based on Examples. Example 1 25 g of chlorinated phthalic anhydride (56% by weight of 4-chloroorthophthalic anhydride, 9.2% by weight of 3-chloroorthophthalic anhydride, 3,4-dichloroorthophthalic anhydride) in 50 g of water. 5.0% by weight of dichloromethane, 0.7% by weight of 3,6-dichloroorthophthalic anhydride, 4.6% by weight of 4,5-dichloroorthophthalic anhydride) and 24.2 g of 86% potassium hydroxide were added. and dissolved. 6.5 g of ethanolamine was added to this aqueous solution, and 5% by weight Pd-2% by weight was prepared by adding palladium and tin to activated carbon as a catalyst.
Add 5.0 g of Sn/C catalyst and heat at 100°C.
Allowed time to react. After the reaction is completed, the Pd-Sn/C catalyst is collected by filtration, and concentrated hydrochloric acid is added to the mother liquor until the pH becomes 1.0 to precipitate crystals.
-13.4 g of crude crystals of biphenyltetracarboxylic acid were obtained. As a result of analyzing this crude crystal and mother liquor by liquid chromatography, the conversion rate of 4-chloroorthophthalic anhydride was 1.
The selectivity for 3,4,3',4'-biphenyltetracarboxylic acid was 94.1%, and the yield was 94.1%.

[0012] Here, the conversion rate is calculated as the ratio of the consumption amount of 4-chloroorthophthalic anhydride to the amount of 4-chloroorthophthalic anhydride in the chloride of phthalic anhydride used, and the selectivity is are 4-chloroorthophthalic anhydride, 3,4-dichloroorthophthalic anhydride and 4,5-
Calculated as the ratio of the amount of 3,4,3',4'-biphenyltetracarboxylic acid produced (mol) to the consumed amount (mol) of dichloroorthophthalic anhydride x 2, and the yield is calculated based on the amount of phthalic anhydride used. The consumption of 4-chloroorthophthalic anhydride, 3,4-dichloroorthophthalic anhydride and 4,5-dichloroorthophthalic anhydride in the chloride of
It is calculated as the ratio of the production amount (mol) of 3,4,3',4'-biphenyltetracarboxylic acid to (mol) x 2.

Examples 2 to 5 Palladium-different metal/C
Experiments were conducted using various catalysts, and the conversion rate of 4-chloroorthophthalic anhydride and the selectivity and yield of 3,4,3',4'-biphenyltetracarboxylic acid were calculated. In addition, in these experimental examples, palladium-different metal/C
The amount of catalyst used is 10% per chloride of phthalic anhydride.
The reaction temperature was 100° C. for 8 hours. The results are shown in Table 1.

[0014]

Comparative Example 1 The reaction was carried out in the same manner as in Example 1, except that the catalyst was replaced with 5% Pd/C. As a result, the conversion rate was 100% and the selectivity was 60%.
．． The yield was 60.3%.

Example 6 26.9 g of water to 2.97 g of 4-bromonaphthalic anhydride
After adding and dissolving 1.46 g of 86% KOH, 0.69 g of ethanolamine and 0.6 g of 2.5 wt.% Pd-2.5 wt.
Heated to 0°C. After reacting for 12 hours, the catalyst was filtered and the mother liquor was acidified with concentrated hydrochloric acid to obtain 2.73 g of crude crystals of 4,4'-bisnaphthalic acid. Analysis of the isolated crystals by liquid chromatography revealed that the conversion rate of 4-bromonaphthalic anhydride was 100%, the selectivity of 4,4'-bisnaphthalic acid was 82.2%, and the yield was 82.2%.

Example 7 15.6 g of p-chlorobenzoic acid, 45 g of water and 86% KO
After adding and dissolving 6.84 g of H, 6.41 g of ethanolamine and 2.5 wt% Pd-2.5 wt% Rh/C
5.58 g of catalyst was added and heated to 100° C. with stirring. After reacting for 12 hours, the catalyst was filtered and the mother liquor was acidified with concentrated hydrochloric acid to obtain 13.3 g of crude crystals of 4,4'-biphenyldicarboxylic acid. Analysis of the isolated crystals by liquid chromatography revealed that the conversion of p-chlorobenzoic acid was 100%, the selectivity of 4,4'-biphenyldicarboxylic acid was 61.4%, and the yield was 61.4%.

[0018]

[Effects of the Invention] According to the production method of the present invention, aromatic polycarboxylic acids can be produced in a high yield in one step using halogenated aromatic carboxylic acids as raw materials, and are useful as monomers for polyimide resins. Aromatic polycarboxylic acids can be economically advantageously produced.

Claims (3)

[Claims] Claim 1: Reacting halogenated aromatic carboxylic acids in an alkaline aqueous solution containing a base and a reducing agent in the presence of a catalyst in which palladium and a different metal are supported on a carrier,
A method for producing aromatic polycarboxylic acids, which comprises dehalogenating and dimerizing. 2. The method for producing aromatic polyvalent carboxylic acids according to claim 1, wherein the different metal is tin, rhodium, gold, silver or platinum. 3. The method for producing aromatic polyhydric carboxylic acids according to claim 1, wherein the halogenated aromatic carboxylic acids are 4-halogenorthophthalic acids, 4-halogenonaphthalic acids, or 4-halogenobenzoic acids.