JPH0465057B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a method for producing dicarboxylic acid dianilide. According to the method of the present invention, the desired dicarboxylic acid dianilide can be produced in high yield under conditions where coloring of the desired product is suppressed and loss of raw material aniline is reduced. Dicarboxylic acid dianilide is an industrially useful substance that serves as a flow improver for thermoplastic resins such as polyphenylene ether resins (see, for example, Japanese Patent Application Laid-open No. 60-44547). Prior art Monocarboxylic acid anilides can be produced using, for example, a method in which a mixture of benzoic acid and aniline is heated and by-produced water is distilled out of the reaction system by azeotropic distillation with aniline [Organic Synthesis, vol I, 82 (1941 )], or a method in which a mixture of formic acid and N-methylaniline is heated in the presence of toluene, and by-produced water is distilled out of the reaction system by azeotropic distillation with toluene [Organic
Synthesis, vol. 590 (1955)], but in the former case, aniline is dissolved in the distilled water and is lost, and in the latter case, formic acid is distilled out together with toluene and water, so when formic acid is lost, It has some drawbacks. Moreover, the above-mentioned document does not describe anything about the method of using dicarboxylic acid as a starting material. On the other hand, it is already well known that dicarboxylic acid dianilide can be produced by reacting the corresponding dicarboxylic acid chloride with anline. However, in this case, it is considered to be disadvantageous for industrial production because the carboxylic acid chloride is generally expensive and hydrogen chloride is produced as a by-product. Therefore, there is a need for a method for producing dicarboxylic acid dianilides using materials other than dicarboxylic acid chlorides as starting materials, and this has also been studied for some time. for example,
Method of mixing and heating dicarboxylic acid and diphenyl urea [Chem.Ber., 86 , 945 (1953)], method of reacting dicarboxylic acid and diphenylsulfamide in the presence of pyridine [Chem.Abstr., 899h ( 1955)]
have been proposed, but in either case, the amidation reagent had to be synthesized from aniline and was not at an industrially satisfactory level. Problems to be Solved by the Invention The present inventors have studied a method for producing dicarboxylic acid dianilide by directly reacting dicarboxylic acid and aniline. However, it has been found that when the reaction is carried out by directly reacting only the dicarboxylic acid and aniline and distilling by-product water out of the system by azeotroping with the aniline, the following drawbacks occur. In other words, firstly, when by-product water is efficiently distilled out of the system, the reaction temperature becomes higher.
Therefore, side reactions such as thermal deterioration due to aniline increase and the hue of the dicarboxylic dianilide product deteriorates. Furthermore, when unreacted aniline or dicarboxylic acid monoanilide is recycled and reused, the color of the product becomes even worse. Secondly, aniline is dissolved in the water distilled out of the reaction system, resulting in a large amount of loss, which is disadvantageous in industrial implementation. SUMMARY OF THE INVENTION The present invention aims to solve the above problems. That is, the present invention provides the general formula, HOOC-R-
A method for producing a dicarboxylic acid dianilide by subjecting a dicarboxylic acid represented by COOH (wherein R represents a C _{1 to 10} alkyl group, alkenyl group, or aryl group) to a heating condensation reaction with aniline in the presence of a solvent, The boiling point at atmospheric pressure at which the solvent azeotropes with water is
A dicarboxylic carbon having a temperature range of 80 to 200°C, the amount used thereof being in a range of 5 to 70% by weight relative to the reaction mixture, and the heating condensation reaction being carried out in a range of 120 to 200°C. A method for producing acid dianilide is provided. Effects of the Invention According to the method of the present invention, side reactions that may deteriorate the hue of the target product can be suppressed, and dicarboxylic acid dialinide with a good hue can be obtained, so that it is colored when used as a fluidity improver for resins, etc. No such problems arise. In addition, by using a specific solvent, the loss of aniline, one of the raw materials, can be reduced, and even if the residual liquid after separating the target product from the reaction mixture is recycled and reused, the problem of deterioration of the hue of the target product does not occur. . DETAILED DESCRIPTION OF THE INVENTION The solvent used in the method of the present invention has a boiling point in the range of 80 to 200° C. under atmospheric pressure, which is azeotropic with water. Specific examples include ethylbenzene, xylene, kyumene, diethylbenzene, and n-decane, but xylene, ethylbenzene, or diethylbenzene is preferred, and ethylbenzene or diethylbenzene is particularly preferred. The amount of the solvent used is preferably in the range of 5 to 70% by weight based on the reaction mixture, particularly 10 to 70% by weight.
A range of ~40% is preferred. If the weight ratio is less than 5%, it is undesirable that side reactions may occur due to deterioration of aniline or that the dicarboxylic acid dianilide product may be colored. Also, the weight percentage
When it exceeds 70%, the reaction rate decreases, which is industrially disadvantageous. The reaction temperature varies depending on the weight ratio of the dicarboxylic acid, aniline, and solvent used, but is generally between 120 and
A range of 200°C is preferred. General formula used in the present invention, HOOC-
Examples of dicarboxylic acids represented by R-COOH include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, dodecanedioic acid, where R is a _C1-10 alkyl group, alkenyl group, or aryl group. Examples include itaconic acid, fumaric acid, maleic acid, and phthalic acid. The molar ratio of raw material dicarboxylic acid and aniline used is preferably in the range of 1/2 to 1/10, particularly 1/2 to 1/10.
The range of 2.5 to 1/5 is preferable. If the molar ratio exceeds 1/2 and the amount of dicarboxylic acid increases, the amount of unreacted dicarboxylic acid remaining will increase, which is not preferable. Furthermore, if the molar ratio exceeds 1/10 and the amount of aniline is large, the amount of reaction liquid will increase, the pot yield will decrease, and economic efficiency will deteriorate, which is disadvantageous for industrial implementation. A specific method for implementing the present invention is to heat a reaction mixture consisting of a dicarboxylic acid, aniline, and a solvent, and distill by-produced water out of the reaction system by azeotropy with the solvent, thereby forming a solvent layer and an aqueous layer. A preferred method is to separate the solvent layer and then circulate the solvent layer to the reaction system. Aniline is distilled out together with the azeotrope, but it is particularly preferable to use an aromatic hydrocarbon such as ethylbenzene as the solvent because the loss of aniline to the aqueous layer can be suppressed to a very low level. After the reaction is completed, the reaction mixture is cooled and the dicarboxylic acid dianilide is crystallized and separated to obtain a crude dicarboxylic acid dianilide. Methanol,
Lower alcohols such as ethanol or toluene,
By washing with aromatic hydrocarbons such as xylene and ethylbenzene, a white purified dicarboxylic acid dianilide is obtained. The liquid obtained by filtration after crystallizing the target product from the reaction mixture contains aniline, dicarboxylic acid, dicarboxylic acid monoanilide, dicarboxylic acid dianilide, and reaction solvent, so this is recycled to the reaction process to obtain dicarboxylic acid. It can be reused as a raw material for acid dianilide. Experimental Examples Examples 1 to 11 Dicarboxylic acid, aniline, and reaction solvent were charged in the amounts shown in Table 1 into a three-necked flask with an internal capacity of 300 ml, and the water produced was distilled out of the reaction system as an azeotrope with the reaction solvent. While stirring, the mixture was heated and stirred for a predetermined period of time. After the reaction was completed, the reaction mixture was cooled to 40°C or lower to precipitate crystals. The crystals were separated, stirred and washed with a solvent, and then dried under reduced pressure. The obtained crystals were confirmed to be dicarboxylic acid dianilide by IR, mass spectra, nmr spectra, etc. Aniline in the distilled water was analyzed by gas chromatography. The results of the reaction and analysis are shown in Table 1. Here, the reaction temperature is the temperature of the reaction mixture when by-product water begins to distill out of the system by azeotropy with the reaction solvent, and the temperature of the reaction mixture immediately after stirring for a predetermined period of time. In addition, the dicarboxylic acid anilide yield is expressed as the amount of dicarboxylic acid charged (mol)
Amount of dicarboxylic acid dianilide produced (mol)
It is expressed as a percentage. The aniline concentration in distilled water is expressed as the weight percent of aniline based on the sum of the weight of distilled water and the weight of distilled aniline.

【table】

[Table] Comparative example 1 Adipic acid 43.8g (0.3mol), aniline 176.7g
The reaction was carried out in the same manner as in Examples 1 to 11, except that (1.9 mol) was used and no reaction solvent was added. The reaction temperature was 161-220°C, the dianilide yield was 86.5%, and the color of the product remained grayish brown. The amount of distilled water is
At 9.8 g, the aniline concentration in the distillate water was 2.8% by weight. Example 12 Adipic acid 43.8g (0.3mol), aniline 139.5g
The reaction was carried out in the same manner as in Examples 1 to 11 using (1.5 mol) and 26.7 g of ethylbenzene. After the reaction is completed, the reaction mixture is cooled to 40°C or less, the crystals that have crystallized are separated, and the obtained liquid is washed with methanol, and the washed liquid obtained separately is concentrated. The resulting residues were combined as recovered unreacted materials, and adipic acid, aniline, and ethylbenzene were newly added and reacted four times. 5
The average yield of adipic acid dianilide in the reactions carried out twice was 95.4% based on adipic acid, and the dicarboxylic acid dianilide products were all white in color.

Claims (1)

[Claims] 1 General formula, HOOC-R-COOH (wherein R is
A method for producing a dicarboxylic acid dianilide by subjecting a dicarboxylic acid represented by C _{1 to 10} alkyl group, alkenyl group, or aryl group to a heating condensation reaction with aniline in the presence of a solvent, in which the solvent is azeotropic with water. The boiling point under atmospheric pressure is in the range of 80 to 200°C, the amount used is in the range of 5 to 70% by weight of the reaction mixture, and the heating condensation reaction is carried out in the range of 120 to 200°C. A method for producing a dicarboxylic acid dianilide, characterized in that: