JPH03157371A - Production of quinolinic acid - Google Patents

Abstract

PURPOSE:To obtain a compound useful as an intermediate for pressuresensitive dyestuff, drugs, agricultural chemicals, etc., from inexpensive, readily obtainable raw materials by oxidizing quinoline with chlorite ion in the presence of a ruthenium compound. CONSTITUTION:Quinoline is oxidized with chlorite ion in an acidic water medium (e.g. sulfuric acid) in the presence of a ruthenium compound (e.g. ruthenium trichloride) at 40-80 deg.C to give the objective quinolinic acid, namely 2,3- pyridinedicarboxylic acid. 3-8mol chlorite ion is used based on 1mol quinoline, the amount of the acid used as a solvent is 0.4-10 acid equivalent and 10<-5> to 10<-2>mol ruthenium compound is used. 10-50% aqueous solution of sodium chlorite is preferable as the chlorite ion. Since the oxidizing agent is the chlorite having three or more times as much effective chlorine amount as a hypochlorite, reaction volume per yield is reduced.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a novel method for producing 2,3-pyridinedicarboxylic acid, i.e., quinolinic acid, which is an intermediate useful in pressure-sensitive dyes, medicines, agricultural chemicals, etc. It is something.

(Prior Art) A general method for synthesizing quinolinic acid is to oxidize quinoline or a derivative thereof. However, conventional synthesis methods have had various problems.

For example, oxidation of quinoline with potassium permanganate in an alkaline medium (Ber, Dtsch, Chem, Ge
s.

No. 12.747 (1879)) has the drawbacks of severe reaction conditions, very low yield, and production of large amounts of by-products.

Method of oxidizing quinoline with hydrogen peroxide in the presence of copper ions (
Chem, Ber,, 65. 11 (1932)
) is extremely difficult to operate, and even though an excess of oxidizing agent is used, the yield is insufficient.

Method for oxidizing 8-hydroxyquinoline with nitric acid (Che
m, Ber,, 80. 505 (1947))
However, unlike what is described in the literature, a large amount of by-products are produced, the yield is low, and a large amount of nitrogen oxide gas is produced.

A method of oxidizing 8-hydroxyquinoline with chlorate ions in an acidic aqueous medium in the presence of vanadium ions (JP-A-58-1
05964) poses an industrial problem because it is difficult to control the temperature and requires a hydroxyl group to activate the benzene ring, making the raw material expensive. Similarly, the method of oxidizing 8-hydroxyquinoline-5-sulfonic acid with sodium chlorite in the presence of vanadium ions (West German Patent No. 945147) is also difficult to obtain raw materials and cannot be said to be an industrially valuable method.

A method in which quinoline is preoxidized with hydrogen peroxide in an acidic aqueous medium in the presence of cations such as vanadium-11 ions, and then oxidized with chlorate or chlorite (JP-A-6O-156673)
In addition to being extremely difficult to control the temperature of the reaction, it requires two-step oxidation, making the operation cumbersome.

In the method of oxidizing quinoline with hypochlorite in a basic aqueous medium in the presence of a ruthenium compound (JP-A-60-84270 and JP-A-6L-212563), sodium hypochlorite, which is easily available industrially, is used. , since its concentration is dilute at 5 to 15%, it has the disadvantage that the reaction volume per yield is large.

The method of oxidizing quinoline with chlorate in an acidic aqueous medium (JP 62-209063) must be carried out in the presence of copper ions in order to obtain an industrially valuable yield; Obtained in salt form. Therefore, in order to obtain quinolinic acid, an alkali decomposition step is required, and the obtained quinolinic acid contains a large amount of copper ions, which affects the subsequent reaction.

In the method of oxidizing 8-hydroxyquinoline using hydrogen peroxide in a basic aqueous medium (Japanese Unexamined Patent Publication No. 63-119466), it is difficult to control the temperature when adding hydrogen peroxide, and the benzene ring is not replaced by a hydroxyl group. It has the disadvantage that it requires activation and the raw materials are expensive.

(Problems to be Solved by the Invention) In order to improve the above-mentioned drawbacks, the present inventor has made efforts to obtain a method for producing quinolinic acid in good yield under mild conditions from inexpensive and easily available starting materials. investigated. As a result, they discovered that quinolinic acid can be produced from quinoline by chlorite ion in the presence of a ruthenium compound without activating the benzene ring, leading to the completion of the present invention.

(Means for Solving the Problems) The present invention is a method for producing quinolinic acid, which is characterized by oxidizing quinoline with chlorite ions in an acidic aqueous medium in the presence of a ruthenium compound.

As the source of chlorite ions used in the present invention, common water-soluble chlorite metal salts can be used. Although there are no restrictions on the type of metal salt, alkali metal salts are generally suitable, particularly aqueous sodium chlorite solutions, which are industrially available at low cost. The concentration of the chlorite aqueous solution is usually in the range of 10 to 50% from the viewpoint of ease of handling, but preferably in the range of 20 to 30%.

The amount of chlorite ion used is 3 to 8 per mole of quinoline.
The mole amount is preferably 4 to 6 moles. If it is less than 3 moles, the yield of quinolinic acid is poor and a large amount of unreacted quinoline is recovered. Further, even if more than 8 mol is used, there is no significant change in the yield, but the excess chlorite ion is only decomposed, which is not economical.

The reaction is carried out in an acidic aqueous medium. Suitable acids for use in the present invention are mineral acids such as hydrochloric acid, nitric acid, phosphoric acid, especially sulfuric acid. The amount of acid used is 0.00% per mole of quinoline.
Acid equivalents of 4 to 10, preferably 1.0 to 8.0. If the amount is less than 0.4 equivalent, the reaction rate will be extremely low;
If the amount exceeds 0 equivalent, the amount of by-products increases and the yield decreases.

Examples of the ruthenium compound used in the present invention include ruthenium tetroxide, ruthenium trichloride, and ruthenium dioxide. The presence of a ruthenium compound is essential for carrying out the present invention; without the ruthenium compound, the reaction will not proceed at all and only the raw material quinoline will be recovered.

Also, when oxidizing 8-hydroxyquinoline-5-sulfonic acid with sodium chlorite (West German patent 945147)
Ammonium vanadate, which was an effective catalyst in the present invention, has no catalytic effect at all in the reaction of the present invention.

The amount of ruthenium compound used is 1 mole of quinoline.
The amount is from 0-5 to 10-'' mol, preferably from 10-4 to 101 mol.If it is less than 10-5 mol, the effect is not sufficient;
If the amount used exceeds 0-'' mol, an even faster reaction rate can of course be obtained, but this poses a problem in terms of cost.

One useful embodiment of the present invention is to heat an acidic aqueous medium containing the quinoline and ruthenium compound to a suitable addition temperature, and add the aqueous chlorite solution dropwise thereto. After the dropwise addition is completed, the mixture is heated to the reaction temperature to complete the reaction.

The addition temperature at which the chlorite aqueous solution is added dropwise is important in carrying out the present invention;
Preferably it is 50 to 70°C.

If the dropwise addition is carried out at a temperature below 40°C, the reaction will proceed rapidly upon heating to the reaction temperature, making temperature control difficult.

Furthermore, if the temperature exceeds 80° C., the decomposition of chlorite becomes significant and the yield decreases.

The reaction temperature is preferably in the range from 80°C to the reflux temperature of the acidic aqueous medium. If the temperature is lower than 80°C, the reaction rate is slow and the decomposition of chlorite occurs preferentially, which is not preferable.

After the reaction is completed, the reaction solution is cooled to room temperature, and quinolinic acid is precipitated. After separating and washing the crystals, a small amount of quinolinic acid remaining in the furnace solution can be isolated as a copper salt by adding copper ions. In this case, the required amount of copper ions is 20% of the amount required when the total amount of quinolinic acid produced is isolated as a copper salt.
It is also 10% or less of the method of oxidizing quinoline with chlorate in the presence of copper ions (Japanese Patent Application Laid-Open No. 62-209063). As described above, according to the present invention, the amount of copper ions used and the amount of copper ions mixed in the product quinolinic acid can be suppressed to a very small amount.

(Effect of the invention) The present invention has the following features.

(1) Quinoline, which is inexpensive and easily available, can be used as a raw material, and does not need to have an active group.

(2) The amount of the ruthenium compound used in the present invention is extremely small and is effective.

(3) Since the oxidizing agent used in the present invention is a chlorite having an effective chlorine amount about three times or more than that of hypochlorite, the reaction volume per yield can be small.

(4) Most of the quinolinic acid produced by the reaction is obtained as crystals at room temperature, and only a portion is recovered as a copper salt. Therefore, the copper content is also extremely low.

As described above, the present invention can be said to be an extremely advantageous industrial manufacturing method.

(Example) The present invention will now be described in more detail with reference to Examples. Note that all concentrations in the examples are based on weight.

Example 2 in which 17.0 g (0,132 mol) of quinoline was dissolved.
4.6×10-”mol/1 in 150ml of 5% sulfuric acid aqueous solution
Ruthenium trichloride aqueous solution 1°25mj! (5,8XIO
-2 mol) was added and heated to 50° C. with stirring.

In this, 238 g of 25% sodium chlorite aqueous solution (0
, 658 mol) was added dropwise, and after the addition was completed, the mixture was gradually heated to reflux. After refluxing for 3 hours and allowing to cool, quinolinic acid precipitated. The crystals were filtered, washed with water and dried to yield 13.4 g of quinolinic acid.
I got it.

Further, 2.5 g (0.01 mol) of copper sulfate Mikiwade was added to the filtrate, and the mixture was stirred at 60° C. for 3 hours. After cooling, the quinolinic acid copper salt was filtered, washed with water, and dried to obtain 3.1 g of copper salt (total yield: 72.3% based on the starting quinoline).The filtrate was further made alkaline to remove unreacted quinoline. 3.2 g of quinoline was recovered.

The above examples show that highly pure quinolinic acid can be obtained in good yield by a simple method.

Claims (1)

[Claims] A method for producing quinolinic acid, which comprises oxidizing quinoline with chlorite ions in the presence of a ruthenium compound in an acidic aqueous medium.