JPS62149650A - Production of aromatic bisaniline - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful for production of heat-resistant polyamide or polyimide resin in high yield, by reacting an aromatic ketone with an aniline while removing water condensed by the reaction from the reaction system. CONSTITUTION:An aromatic ketone (e.g., fluorenone, 1-indanone, 2-tetralone or benzophenone) is reacted with an aniline at 75-200 deg.C, preferably 120-150 deg.C while removing water condensed by the reaction from the reaction system (by azeotropic reaction) to give the aimed compound shown by formula I (X is halogen or lower aliphatic hydrocarbon group; R<1> and R<2> are phenyl or aromatic ketone residue shown by formula II - formula IV bonded to valences of R<1> and R<2>). 1mol aromatic ketone is preferably reacted with 2-100mol, especially 2-15mol aniline in 1/40-40mol based on 1 aniline of an aromatic solvent (e.g., benzene or toluene).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing aromatic bisanilines.

BACKGROUND OF THE INVENTION It is widely known that the reaction of a carbonyl compound with a primary amine yields a Schiff base. This reaction is a specific reaction in that the carbonyl compound and aniline give a diamine compound rather than a Schiff base.

An example of producing aromatic bisanilines from aromatic ketones and anilines has been reported by Steele et al.
1ecu 1es), Dan, 486, 1981).

That is, in the reaction of Steele et al., fluorenone and aniline were mixed at 511 rM in an aniline solvent at a high temperature of 185°C.
Although 9,9-bis(4-aminophenyl)fluorene was obtained by carrying out this process, the yield was as low as 54%.

Problems to be Solved by the Invention The present invention aims to improve the yield under milder reaction conditions in the reaction of aromatic ketones and anilines, and also aims to establish an industrial production method.

Means to solve the problem Conventional methods are carried out at high temperatures, which underestimates the effect of water generated, and the amount of water generated is minimal compared to the amount of raw materials used and the yield of the target product. Therefore, attempts to improve yield through dehydration have been largely ignored.

However, the inventor of the present invention attempted to improve the yield of one reaction by extracting this small amount of water from the thread using an appropriate solvent, for example, using an azeotrope. It was discovered that the temperature could be lowered and the reaction time could also be shortened. Furthermore, it was also discovered that since the reaction can be carried out at low temperatures and in a short time, side reactions can be reduced and the purification step can be extremely simplified.

That is, the present invention provides a method for producing an aromatic bisaniline represented by the general formula CI), which is characterized in that when an aromatic ketone and an aniline are reacted, the reaction is carried out while removing water produced by condensation from the reaction system. It is.

The aromatic bisaniline produced in the present invention is typically represented by the following general formula CI).

General formula (D Here, X represents a lower aliphatic hydrocarbon group such as a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or a butyl group.

R1 and R2 are, for example, aromatic ketone residues shown in Table 1, each of which is bonded to two bonds.

(Margin below) Table 1 Good too.

In the present invention, aromatic ketones as shown in Table 1 and anilines react, for example, according to the following reaction formula (TI) to form aromatic bisanilines as shown in general formula (I).

In this example, fluorenone and aniline hydrochloride react with 9
．． The reaction formula for producing 9-bis(4-aminephenyl)fluorene is 6. In addition to fluorenone, aromatic ketones include benzophenone, indanone, and tetraone.

Anilines used as raw materials typically include the unsubstituted aniline mentioned above, but aniline derivatives, such as those in which the hydrogen atom of an aromatic nucleus or amine group is substituted with a halogen atom or a hydrocarbon group such as a methyl group or an ethyl group, are used as raw materials. It may be something.

If it has a reactive hydrogen at the para position, an inert substituent such as a methyl group or halogen may be present at the ortho position.

The appropriate molar ratio of aniline to aromatic ketone is stoichiometric, that is, twice the molar amount, but it is desirable to use an excess of aniline in order to improve the reaction yield.

However, even if a large excess amount is used, the yield will not be improved.From this viewpoint, the amount of aniline is preferably about 2 to 100 moles, more preferably about 2 to 15 moles, per mole of aromatic ketone. Although the reaction of the present invention proceeds either in the absence of a solvent or in a solvent, excess aniline conveniently acts as a reaction solvent in a normal system.

As the reaction solvent, the above-mentioned aniline may be used alone, or an azeotropic solvent that is azeotropic with water may be used together.

As the azeotropic solvent, aromatic solvents such as benzene, toluene, and xylene are suitable. These solvents are added to the system and the water produced is removed under appropriate reduced pressure and controlled reaction temperature. When an azeotropic solvent such as benzene is added, the reaction temperature can be significantly lowered, side reactions such as oxidation at high temperatures are suppressed, and purification becomes easier. Furthermore, since xylene, toluene, etc. have a somewhat higher boiling point than benzene, the reflux temperature may be adjusted by reducing the pressure of the reaction system.

The amount of the azeotropic solvent to be used is desirably 1/40 to 40 moles per mole of the aniline used.

If the amount of azeotropic solvent used is less than 1/40 mol, it is insufficient to azeotropically distill water, and the reflux temperature decreases as the amount of azeotropic solvent increases, so it is preferable to use up to about 40 mol in relation to the reaction temperature. For example, 130°C, which is the preferred reaction temperature in the present invention.
To achieve a similar value, use approximately 1 mole of bencef per 3 moles of akoline.

The reaction temperature is variable within a wide range of 75 to 200°C, but from the viewpoint of lowering the temperature, which is the objective of the present invention, it is preferably 10°C.
The temperature is 0 to 170°C, more preferably 120 to 150°C.

The reaction time varies depending on other reaction conditions, but under the above-mentioned preferred conditions, 2 to 5 hours is appropriate; the reaction is sufficiently completed within this time, and even if the reaction is carried out for a longer time, no yield will be obtained. It does not have much effect on rate improvement.

In the reaction between aromatic ketones and anilines, the reaction can be further promoted by using an acid catalyst. As an acid catalyst, the purpose can be achieved by using a compound such as aniline hydrochloride, by blowing hydrogen chloride gas into the reaction system, or by adding hydrochloric acid, sulfuric acid, or the like.

After the reaction is completed, the solvent is removed by suction filtration to obtain a crude product. For this purification, recrystallization using a less polar solvent such as toluene or xylene is appropriate, and toluene is particularly preferred.

The aromatic bisanilines produced according to the present invention are used for various purposes, such as the production of heat-resistant polyamides, polyimide resins, and the like.

Example 1 A reaction vessel equipped with a stirring device and an ester condensation dehydration tube was charged with 37 g of fluorenone, 210 g of aniline, 110 g of aniline hydrochloride as a catalyst, and 80 g of benzene as an azeotropic solvent, and refluxed at 130° C. for 3 hours. 6 pieces were dehydrated. The reaction product was mixed with 8 wt% potassium hydroxide (KOH
) After neutralization, the mixture was poured into an aqueous solution, washed with warm water, cooled, and the aniline contained in the crude product was filtered to obtain a crude product.

After drying, the crude product was recrystallized with toluene to give a yield of 9.
A purified product was obtained at 0% (layer, p, 234-235 °C, OS
C purity 88.6%).

In place of fluorenone in Example 1, 1-indanone, 2-
Similar results were obtained when the reaction was performed using tetralone and benzophenone.

Example 2 37 g of fluorenone and 110 g of aniline hydrochloride were placed in the same apparatus as in Example 1, and dissolved in 7210 g of aniline. Furthermore, 50 g of toluene was added and the mixture was refluxed at 140°C.

The reaction was stopped when the theoretical amount of water had been distilled off. The reaction time required 6 hours. Purification was carried out in the same manner as in Example 1. The yield was 80% and the melting point was 234-235°C.

Example 3 A reaction similar to Example 2 was carried out under slightly reduced pressure. 13
The reaction was refluxed at a temperature below 0°C and the reaction was stopped when the theoretical amount of water was distilled off.The zero reaction time required 6 hours.

Purification was carried out in the same manner as in Example 1. Yield 80%, melting point 23
The temperature was 4-235°C.

Example 4 A test was conducted on the same scale as Examples 1 to 3, except that xylene was used as the azeotropic solvent. In this case, the reaction was carried out at various reaction temperatures (140 to 160° C.) with the system under slightly reduced pressure.

Further, the reaction was carried out without adding any azeotropic solvent other than aniline.

Purification was carried out in the same manner as in Example 1. In either case, the yield is 7
5%, melting point 233-235°C.

Comparative example 1 9-fluorenone 73.0 g, aniline hydrochloride 22
A mixture of 2 g of aniline and 420 g of aniline was stirred and refluxed for 5 hours without removing the condensed water.

While still warm, the reaction mixture was poured into two drops of 10% aqueous potassium hydroxide solution. After heating the mixture for 10 minutes, the dark red aqueous layer was decanted. This operation was repeated twice using 2Q of water, followed by suction filtration.

The red-white solid was washed with 1.751 g of benzene. Since washing with benzene alone did not improve the purity and also lowered the yield, the red-white solid was recrystallized from toluene using activated carbon. However, the yield never exceeded 60%. Further, recrystallization was performed three times to obtain a purity of 98.5%.

Effects of the Invention The present invention enables low-temperature synthesis with higher yield than conventional techniques, and has fewer side reactions and coloring, and is excellent as an industrial manufacturing method, and has great industrial value.

Claims (4)

[Claims] (1) A method for producing aromatic bisanilines represented by general formula (I), which is characterized in that when reacting an aromatic ketone and an aniline, the reaction is carried out while removing water produced by condensation from the reaction system. . General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, X is a hydrogen atom, a halogen atom, or a lower aliphatic hydrocarbon group, and R^1 and R^2 are each a phenyl group. It is any of the aromatic ketone residues shown below that binds to the bonds of R^1 and R^2. ▲There are mathematical formulas, chemical formulas, tables, etc.▼▲There are mathematical formulas, chemical formulas, tables, etc.▼▲There are mathematical formulas, chemical formulas, tables, etc.▼ (2) In a method for producing aromatic bisanilines from an aromatic ketone and an aniline, 2 to 100 mol of aniline per 1 mol of aromatic ketone, and 1 mol of aniline
Using aromatic solvent 1/40 to 40 mol based on mol 7
The manufacturing method according to claim 1, characterized in that condensed water is removed by an azeotropic reaction at a heating temperature of 5 to 200°C. (3) the aromatic ketone is any one of fluorenone, 1-indanone, 2-tetralone, and benzophenone,
The manufacturing method according to claim (1) or (2), wherein the aniline is unsubstituted aniline. (4) The manufacturing method according to claim (2), characterized in that the reaction product is purified by a recrystallization method using toluene or xylene.