JPH0248575A - Production of thiophene 2-5-dicarboxylic acid - Google Patents

Abstract

PURPOSE:To simply obtain the title compound useful as an intermediate for production of fluorescent coating material in one process and good yield by subjecting 2,2'-dihalomuconic acid relatively readily available as an industrial raw material to ring closure reaction with an alkali metal salt sulfide. CONSTITUTION:2,2'-Dihalomuconic acid expressed by formula II (X is halogen) such as 2,2'-dichloromuconic acid obtained by reacting tetraoxyadipic acid expressed by formula I with thionyl chloride and then hydrolyzing the reaction product is reacted with an alkali metal salt sulfide such as Na2S, as necessary in a solvent such as water or water-containing alcohol in the presence or absence of a base such as NaOH at 50-120 deg.C to provide the aimed compound useful as a compound intermediate of benzazolyl compound expressed by formula III[R is (CH3)3C or H]. The alkali metal salt sulfide is used at amounts of 1.0-1.5 times mol in the presence of the base and 2.0-5.5 times mol in absence of the base based on the compound expressed by formula II.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a novel method for producing thiophene 2,5-dicarboxylic acid. This compound can be used, for example, in JP-A-56-9
Fluorescent paint described in No. 2278 (Zazuryl compound represented by the following formula) (wherein R is (C1h)ic
It is a compound useful as an important intermediate in the production of (or H).

(Prior Art) Several methods for producing thiophene 2,5-dicarboxylic acid have been known.

■J, A, C, S-703416 (194B), thiofu-noene is reacted with formalin and hydrogen chloride to produce 2.5-cyclochloromethylthiophene, and then reacted with potassium acetate to produce 2.5-chloromethylthiophene. -diacetoxymethylthiophene,
A method is described in which 2,5-dihydroxymethylthiophene is further hydrolyzed and finally oxidized using potassium permanganate.

However, in this method, the intermediate 2,5-dichloromethylthiophene is a structurally unstable compound that is prone to polymerization and tar formation, and not only does it use expensive raw materials such as potassium permanganate, Since the process is long, it is difficult to say that it is an industrially advantageous method.

■Japanese Patent Publication No. 39-3434 discloses that tetrahydrothiophene 2,5-dicarboxylic acid obtained from α,α-dichloroadipic acid and sodium sulfide is chlorinated to give tetrahydrothiophene 2,5-dicarboxylic acid dichloride, and this is It describes how to disassemble it.

However, this method also uses many auxiliary raw materials and the process is long, so it cannot be said to be an industrially advantageous method.

East German Patent No. 1294488 describes a method in which adipic acid and thionyl chloride are reacted and the reaction is hydrolyzed with water, but this method also results in severe tar formation and therefore has a low yield.

(Problems to be Solved by the Invention) The present inventors have found a method for industrially producing thiophene 2,5-dicarboxylic acid easily and inexpensively by eliminating the drawbacks of such conventional methods. As a result of intensive research, we came up with the idea of using 2,2'-dihalomuconic acid as a raw material. This is because if 2,2'-dihalomuconic acid is reacted with an inorganic sulfide, especially an alkali metal sulfide,
It is no wonder that the cyclization reaction by sulfur atoms occurs simultaneously with the dehalogenation reaction, and that the desired thiophene 2,5-dicarboxylic acid can be produced in fewer steps than in conventional methods.

As a result, there is no tar-like by-product, which is often seen in conventional methods, and the dehalogenation and cyclization reaction with the alkali metal sulfide salt is followed by the resulting alkali metal salt of 2,5-dicarboxylic acid. The present invention was achieved by discovering that thiophene 2,5-dicarboxylic acid can be produced in good yield through a relatively simple reaction of acid precipitation with a mineral acid.

The 2,2'-dihalomuconic acid used as a raw material can be easily obtained, for example, by halogenating tetraoxyadipic acid, which is easily available industrially.

(Means for Solving the Problems) An object of the present invention is to provide a novel method for producing thiophene-2,5-dicarboxylic acid, the gist of which is represented by the general formula (1) (where X is a halogen atom). This is a method for producing thiophene 2,5-dicarboxylic acid, which is characterized by reacting 2,2'-dihalomuconic acid represented by the following formula with an alkali metal sulfide salt in the presence or absence of a base.

2.2'-Dihalomuconic acid is obtained by hydrolyzing 2,2'-dihalomuconic acid dichloride obtained by reacting tetraoxyacybic acid with thionyl chloride, thionyl bromide, phosphorus pentachloride, etc. as shown in the following formula. This can be obtained by

Such 2,2'-dihalomuconic acid includes 2,2'-
Dichloromuconic acid, 2,2'-dibromomuconic acid, etc. can be mentioned.

(Here, X represents a halogen atom.) The reaction of the present invention proceeds as follows, and 2.2'-/\romuconic acid and equimolar N
Since azS first reacts with -COOH, it is consumed in the reaction with this and does not react with halogen, so twice the mole is required for complete cyclization. However, if a causative base is present to neutralize -COOH, NatS becomes 1.
It is economically advantageous because it requires only 0 mole. Therefore, although this reaction can be carried out even in the absence of a base, it is usually carried out in the presence of a base.

In either case, the alkali metal salt produced is precipitated with a mineral acid, separated as thiophene 2,5-dicarboxylic acid, and collected at the bottom of the furnace. The mineral acid used is not particularly limited, but hydrochloric acid, sulfuric acid, etc. are suitable.

Examples of the alkali metal sulfide salt used in the present invention include sodium sulfide and potassium sulfide, but sodium sulfide is usually used. These alkali metal sulfides are 2
．． 1 for 2'-dihalomuconic acid in the presence of a base.
．． It is used in the range of 0 to 1.5 times the mole, preferably 1.0 to 1.3 times the mole, and in the absence of a base, it is used in the range of 2.0 to 2.5 times the mole.
It is preferably used in a range of 2.0 to 2.3 times the mole. If it is too small, the yield will decrease, and if it is too large, there will be no significant effect.

When a base is used, usually alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate and potassium carbonate can be used as the base, but sodium hydroxide is often used.

The reaction temperature is usually in the range of 50°C to 120'C, preferably in the range of 80°C to 100'C.When the reaction temperature is higher than 120'C, side reactions are likely to occur; “When it is lower than C, the reaction rate is substantially too slow by one point, which is industrially disadvantageous.

Examples of reaction solvents include water, lower alcohols such as methanol, ethanol, isopropanol, ethers such as tetrahydrofuran and dioxane, polar solvents such as NN-dimenalformamide and dimethyl sulfoxide, and mixtures thereof. However, water or hydrous alcohol is usually preferably used from an economical point of view.

(Effects of the Invention) According to the method of the present invention, 2,2'-dihalomuconic acid, which is relatively easily available as an industrial raw material, is used in one step by a cyclization reaction with an alkali metal sulfide. In comparison, the target product, thiophene 2,5-dicarboxylic acid, can be produced easily and in good yield.

(Example) The present invention will be specifically explained below with reference to Examples.

Example-1 21.1 g of 2,2'-dichloromuconic acid (0,
10 mol) and 140 mff of water, and then 42 g of 20% aqueous sodium hydroxide solution (0.21 mff) were added at room temperature.
mol) was added dropwise. Add sodium sulfide nonahydrate 2 to this solution.
100 g of an aqueous solution containing 5.2 g (0,105 mol)
was added dropwise at room temperature, and the mixture was further stirred at 90°C for 5 hours.

After that, it was cooled to room temperature and 35.0 g of 35% hydrochloric acid was added dropwise.
The precipitated thiophene 2,5-dicarboxylic acid was poured into the bottom of the furnace.

Yield: 14.9 g, yield based on 2,2'-dichloromuconic acid was 86.6%. In addition, the purity measurement result by liquid chromatography (LC) is 99.0%.
That was it.

Example-2 21.1 g of 2,2'-dichloromuconic acid (0,1
0 mol) and 140 mA of water were added, and 200 g of an aqueous solution in which 50.4 g (0.21 mol) of sodium sulfide nonahydrate was dissolved was added dropwise at room temperature, followed by further stirring at 90° C. for 5 hours.

After that, the same operation as in Example-1 was performed to obtain thiophene 2,
15.1 g of 5-dicarboxylic acid was obtained. The yield based on 2.2' dichloromuconic acid was 87.8%. Also, L
The purity measured by C was 99.0% or more.

Example-3 21.1 g (0.10 mol) of 2,2'-dichloromuconic acid was mixed with 30.0 g (0.1 mol) of 2,2'-dichloromuconic acid.
The same operation as in Example 1 was performed except that the amount was changed to 0 mol) to obtain 15.3 g of thiophene 2,5-dicarboxylic compound M.

Yield based on 2.2'-dibromomuconic acid is 89.0%
Met. The purity measurement result by LC was 99.0% or more.

Patent applicant: Steel Chemical Industry Co., Ltd. Representative Yuji Masuda

Claims (5)

[Claims] (1) General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼………………(I) (Here, X represents a halogen atom) 2,2'-dihalomuconic acid and alkali sulfide A method for producing thiophene 2,5-dicarboxylic acid, which comprises reacting a metal salt in the presence or absence of a base. (2) The method according to claim (1), wherein X is a chlorine atom. (3) The method according to claim (1), wherein the alkali metal sulfide salt is sodium sulfide. (4) The method according to claim (1), wherein the base is sodium hydroxide. (5) The method according to claim (1) or (2), wherein the 2,2'-dihalomuconic acid is 2,2'-dichloromuconic acid obtained by reacting tetraoxyadipic acid with thionyl chloride.