JP2835231B2 - Aromatic diamine and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel aromatic diamine which can be used as a raw material for an aromatic polythiazole precursor, and a method for producing the same.

[0002]

2. Description of the Related Art A polymer having a heterocyclic ring such as a thiazole ring, an imidazole ring, an oxazole ring and an oxazinone ring in a repeating unit has high rigidity, high strength, high elastic modulus, It is attracting attention as a high heat-resistant polymer.

[0003] Among them, aromatic polythiazole having a thiazole ring is expected to be used as a plastic material as a substitute for a metal material, alone or in combination with other engineering plastics, due to its excellent mechanical strength. .

However, aromatic polythiazoles generally have poor solubility due to their high rigidity, and have problems in molding because they are soluble only in some strong acids such as methanesulfonic acid and chlorosulfonic acid. .

[0005] Aromatic polythiazoles have hitherto been produced from an aromatic diaminodithiol compound and a dicarboxylic acid derivative, particularly chloride. Sex problems remain, which is not preferable. Therefore, a method of first synthesizing a precursor of an aromatic polythiazole and then performing a ring-closing reaction to obtain an aromatic polythiazole has been generally adopted. If a precursor of an aromatic polythiazole soluble in an organic solvent can be produced, it can be easily molded at the stage of the precursor. Then, if the thiazole ring-closing reaction is performed by heating the molded precursor, a molded article having a desired shape can be obtained by avoiding the above-mentioned problem of moldability.

The precursor of the aromatic polythiazole is prepared by heating a mixture of an aromatic diaminodithiol compound or a salt thereof and a dicarboxylic acid or a derivative thereof to a temperature of 160 ° C. or more in the presence of polyphosphoric acid or the like. However, when an aromatic polythiazole precursor is produced using polyphosphoric acid, it is difficult to control the polymerization reaction, and in many cases, there is a problem that the reaction proceeds to polythiazole. For this reason,
Various attempts have been made to obtain precursors of aromatic polythiazoles.

For example, as a method for stably producing a precursor of an aromatic polythiazole, a method in which an aromatic diaminodithiol compound or a salt thereof and a dicarboxylic acid derivative are polymerized by an interfacial polymerization method (Japanese Patent Laid-Open Publication No. (103230)
And a salt of an aromatic diaminodithiol compound and a dicarboxylic acid derivative in the presence of a phosphoric acid compound at 70 to 140 ° C.
(Japanese Patent Application Laid-Open No. 1-311127).

[0008] According to the above two methods, an aromatic polythiazole precursor can be produced stably and efficiently as compared with the conventional methods. However, in these methods, an aromatic diaminodithiol compound or a salt thereof is used as a starting material, and in the production of a precursor, the thiol group may react with a dicarboxylic acid derivative. Further, during the process of producing the precursor, there was a possibility that a thiol group partially caused a ring-closing reaction, and as a result, an insoluble component was generated.

Accordingly, an object of the present invention is to provide an aromatic diamine as a raw material of an aromatic polythiazole precursor, which is free from the above-mentioned insoluble components in the production of the precursor, and is stable. An object of the present invention is to provide an aromatic diamine capable of efficiently producing a precursor.

[0010] Another object of the present invention is to provide a method capable of producing such an aromatic diamine with high purity and high yield.

[0011]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have found that a carboxyl group, an ester group,
If an aromatic diamine obtained by bonding an alkylthio group substituted by a cyano group or a benzene group, or an unsubstituted alkylthio group to an aromatic residue is used, there is no need to worry about by-producing insoluble components, and stable and efficient. It has been found that aromatic polythiazole precursors can be produced well.
When the aromatic diaminodithiol compound or a salt thereof is reacted with an alkyl halide having the substituted or unsubstituted alkyl group in an alkaline aqueous solvent, the aromatic diamine is produced with high purity and high yield. The inventors have discovered that the present invention can be performed and completed the present invention.

That is, the aromatic diamine of the present invention has the following general formula:

Embedded image (However, Ar is the following general formula;

Embedded image And R is a substituted or unsubstituted alkyl group, and in the case of a substituted alkyl group, an alkyl group substituted by a carboxyl group, an ester group, a cyano group, or a benzene group. A non-substituted alkyl group, an ethyl group, an isopropyl group, an n-
Propyl, n-butyl, sec-butyl and te
It is selected from the group consisting of rt-butyl groups. An aromatic diamine represented by any of the above.

The method of the present invention for producing an aromatic diamine having the above-mentioned structure comprises an aromatic diaminodithiol compound or a salt thereof, and a compound represented by the general formula: XR (where X is a halogen element and R is a substituted Or an unsubstituted alkyl group, a carboxyl group, an ester group, a cyano group, or an alkyl group substituted by a benzene group in the case of a substituted alkyl group, and an ethyl group, isopropyl in the case of an unsubstituted alkyl group. Group, n-propyl group, n-butyl group,
It is selected from the group consisting of a sec-butyl group and a tert-butyl group. Wherein the hydrogen atom of the thiol group of the aromatic diaminodithiol compound or a salt thereof is replaced with the alkyl group of the alkyl halide by reacting the alkyl halide represented by the formula (1) with an alkaline aqueous solvent. .

Hereinafter, the present invention will be described in detail. The aromatic diaminodithiol compound used in the method of the present invention is a compound having an amino group and a thiol group on both sides of an aromatic residue, respectively. As the aromatic residue, the following formula:

Embedded image And the like. Among the above Chemical Formula 7,

Embedded image Is preferably an aromatic residue.

The positional relationship between the amino group and the thiol group bonded to both sides of the aromatic residue may be symmetric or point-symmetric about the aromatic residue. For example, when a benzene ring is selected as the aromatic residue, the aromatic diaminodithiol compound includes

Embedded image Any of these may be used.

When the aromatic diamine of the present invention is produced from these aromatic diaminodithiol compounds, the aromatic diaminodithiol compound is preferably used in the form of a salt such as hydrochloride in order to prevent deterioration.

In the method of the present invention, the above-mentioned aromatic diaminodithiol compound or a salt thereof is reacted with an alkyl halide in an alkaline aqueous solvent to convert the hydrogen atom of the thiol group of the aromatic diaminodithiol compound into an alkyl group. Replace with

The alkyl group in the alkyl halide may be substituted by another organic group or may be an unsubstituted alkyl group. Examples of the unsubstituted alkyl group include an isopropyl group, an ethyl group, an n-propyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group. Among the unsubstituted alkyl groups, secondary and tertiary alkyl groups are particularly preferred.

As the substituted alkyl group, an alkyl group substituted with a carboxyl group, an ester group, a cyano group or a benzene group (eg, a benzyl group) is preferable. In addition, when it has such a substituent, the alkyl group does not need to be particularly secondary. As the alkyl group having a substituent, for example,

Embedded image And the like.

In the six substituted alkyl groups described in Chemical formula 1, in which the upper two ester groups are substituted, the alkyl group bonded to the oxygen atom in the ester bond is not limited to a methyl group. It may be a chain alkyl group (an alkyl group having about 6 or less carbon atoms).

As the above-mentioned alkyl halide having an alkyl group, bromides, chlorides, iodides and the like of the respective alkyl groups can be used. Preferably, a bromide or chlorinated product is used.

The reaction between the aromatic diaminodithiol compound or a salt thereof and the alkyl halide is carried out in an alkaline aqueous solvent. As the alkaline aqueous solvent used at this time, a solution in which a basic salt such as sodium hydroxide is dissolved in water or a mixed solvent of water and an alcohol (ethanol and / or methanol) can be used.

The above-mentioned starting materials are easily dissolved in the alkaline aqueous solvent, and the reactivity becomes good. Further, in the alkaline aqueous solvent, the thiol group becomes a thiolate ion to increase the reactivity at this site, thereby promoting the reaction with the halide (alkyl halide). further,
In an alkaline aqueous solvent, the reaction product easily precipitates, and the recovery and generation of the reaction product become easy, and a high-purity aromatic diamine is obtained.

The alkali concentration of the alkaline aqueous solvent is 3 to
The content is preferably 20% by weight, more preferably 5 to 10%.
% By weight.

The concentration of the aromatic diaminodithiol compound or its salt and the concentration of the alkyl halide in the alkaline aqueous solvent are 5 to 15% by weight and 5 to 15% by weight, respectively.
The content is preferably 15% by weight.

The reaction between the salt of the aromatic diaminodithiol compound and the alkyl halide in the alkaline aqueous solvent proceeds as follows. In the following reaction, 2,5-diamino-1,4-benzenedithiol dihydrochloride is used as an example of a salt of an aromatic diaminodithiol compound. In the formula, X-R represents an alkyl halide.

Embedded image

This substitution reaction can be carried out in the range of 0 ° C. to 100 ° C. If the temperature is lower than 0 ° C., the reaction rate is undesirably reduced. On the other hand, when the temperature exceeds 100 ° C., a side reaction occurs, which is not preferable. A more preferred reaction temperature is 0 ° C to 95 ° C.

The reaction time is not particularly limited, but generally ranges from 2 to
About 24 hours is fine.

It is preferable to stir the solution in order to increase the reaction rate. The reaction rate can be increased by increasing the amount of the alkyl halide.

Further, in the above reaction, when cetyltrimethylammonium chloride, n-butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, 18-crown-6, cetyltrimethylammonium bromide, etc. are added as a phase transfer catalyst, Speed can be increased. Such a phase transfer catalyst causes the reaction between the salt of the aromatic diaminodithiol compound and the alkyl halide to proceed rapidly. Preferred phase transfer catalysts include cetyltrimethylammonium chloride,
Cetyltrimethylammonium bromide.

By performing the substitution reaction under the above conditions,
An aromatic diamine in which a hydrogen atom of a thiol group of a salt of an aromatic diaminodithiol compound is substituted with an alkyl group of an alkyl halide is obtained. This aromatic diamine has the following general formula:

Embedded image (However, Ar and R are the same as described above.) In other words, the compound represented by Chemical Formula 12 is an aromatic diamine in which two substituted or unsubstituted alkyl groups (—SR) are bonded to an aromatic residue.

The production of an aromatic polythiazole precursor and an aromatic polythiazole using the aromatic diamine obtained above can be carried out as follows.
First, the aromatic diamine of the present invention is reacted with a derivative of a dicarboxylic acid to produce an aromatic polythiazole precursor. Examples of the dicarboxylic acid derivatives include those in which each carboxyl group is substituted as follows.

Embedded image As the aromatic residue Ar of the dicarboxylic acid derivative, for example, the following aromatic residues can be used. Of the dicarboxylic acids, terephthalic acid is particularly preferred.

Embedded image

The reaction of the aromatic diamine of the present invention with a dicarboxylic acid can be carried out in a solvent such as N-methyl-2-pyrrolidone, hexamethylphosphoric triamide, N, N-dimethylacetamide. These solvents can be used alone or as a mixture. Further, in order to enhance the reactivity, a maximum of 5% of a chloride such as LiCl or CaCl ₂ may be added. The reaction temperature is preferably between -20 ° C and + 50 ° C. In addition,
The obtained aromatic polythiazole precursor can be washed and dried by a known method.

The precursor thus obtained is soluble in many organic solvents, so that the precursor can be easily molded.

After the precursor is obtained by the above-described method, the precursor is heated to cause a thiazole ring closure reaction to produce an aromatic polythiazole. When the precursor is heated to 200 ° C. to 500 ° C., an alkyl group (an alkyl group bonded to a sulfur atom) of the precursor is eliminated, and a thiazole ring is formed at that site, whereby an aromatic polythiazole is obtained. In addition, in the precursor, when the alkyl group bonded to the sulfur atom has a cyano group, an ester group, or a carboxyl group as a substituent, the temperature at which the ring closure reaction of the precursor is lower (about 200 ° C. to 400 ° C.) Occurs in

[0036]

In the method of the present invention, the reaction of an aromatic diaminodithiol compound or a salt thereof with an alkyl halide is carried out in an alkaline aqueous solvent. Both of the above reactants are easily dissolved in the alkaline aqueous solvent to form a uniform solution, so that the reactivity is good. Further, in the alkaline aqueous solvent, the thiol group becomes a thiolate ion, the reactivity at this site increases, and the reaction with the alkyl halide easily proceeds. Furthermore, the reaction product (the aromatic diamine of the present invention) easily precipitates in the alkaline aqueous solvent, and is easily collected and formed.

The aromatic diamine of the present invention has a substituted or unsubstituted alkylthio group, and when this is polymerized with a dicarboxylic acid derivative, the amino group reacts selectively, and at the site of this amino group. A chain linked precursor is obtained. On the other hand, the thiol group is protected by the alkyl group and does not become a polymerization site. For the above reasons, the aromatic diamine of the present invention is a good raw material for a polythiazole precursor.

[0038]

The present invention will be described in detail with reference to the following specific examples. Example 1

21.6 g of sodium hydroxide was dissolved in 300 ml of distilled water, 30.0 g of 2,5-diamino-1,4-benzenethiol dihydrochloride was added thereto, and the mixture was cooled to 0 ° C. with ice water while stirring. This was dissolved.

To the resulting solution, 29.4 ml of methyl 3-bromopropionate was added dropwise with stirring. During the dropping of the methyl 3-bromopropionate, 3.0 g of cetyltrimethylammonium chloride was added. A precipitate formed shortly after the dropwise addition of cetyltrimethylammonium chloride. The temperature of the solution was gradually raised to room temperature while stirring the solution.

After keeping the solution at room temperature for 3 hours, the obtained reaction product was subjected to suction filtration through a glass filter, and the precipitate was sufficiently washed with distilled water. After washing, it was dried under vacuum at 60 ° C. The solid thus obtained was yellow. The yield was 23.6 g. The obtained solid was recrystallized using cyclohexane to obtain yellow needle crystals. The obtained crystals were dried in vacuum.

When the melting point of the obtained crystal was measured, it was 84 ° C. Elemental analysis was also performed. The results were as follows. The numerical values in the following table of elemental analysis represent percentages.

Further, when ¹ H-NMR was measured,
Single peaks were observed at 3.7 ppm and 6.8 ppm, respectively.

From the above analysis, it was confirmed that the obtained crystal had the following structure.

Embedded image

Example 2 21.6 g of sodium hydroxide was dissolved in 300 ml of distilled water, and 30.0 g of 2,5-diamino-1,4-benzenethiol dihydrochloride was added thereto.
Was added, and the mixture was cooled to 0 ° C. with ice water with stirring to dissolve it.

While stirring the resulting solution, 22.4 ml of 3-bromopropionitrile was added dropwise. During the dropping of 3-bromopropionitrile, 3.0 g of cetyltrimethylammonium chloride was added. A precipitate formed shortly after the dropwise addition of cetyltrimethylammonium chloride. The temperature of the solution was raised to room temperature while continuing to stir the solution.

After 4 hours while maintaining the solution at room temperature, the obtained reaction product was subjected to suction filtration through a glass filter, and the precipitate was sufficiently washed with distilled water. After washing, it was dried under vacuum at 60 ° C. The solid thus obtained was yellow. The yield was 51.3 g. The obtained solid was recrystallized using methylene chloride to obtain yellow crystals. It was dried in vacuum.

When the melting point of the crystal obtained above was measured, it was 130 ° C. Elemental analysis was also performed. The results were as follows.

Further, when ¹ H-NMR was measured,
Triplet peaks at 2.97 ppm and 2.67 ppm
A single peak was observed at ppm and 6.79 ppm.

From the above analysis, it was confirmed that the obtained compound was the compound shown below.

Embedded image

Example 3 14.4 g of sodium hydroxide and 200 parts of distilled water were placed in a three-necked flask.
ml and cetyltrimethylammonium chloride (4.4 g) were added, and the mixture was stirred and dissolved under a nitrogen stream. 2,5-diamino
20.0 g of -1,4-benzenethiol dihydrochloride was added and stirred until a homogeneous solution was obtained.

The solution was cooled to 0 ° C. using ice water,
Isopropyl bromide 23.0 was added dropwise. After the addition, the temperature of the solution was raised to room temperature while stirring was continued.

The obtained reaction product was subjected to suction filtration through a glass filter, and the precipitate was sufficiently washed with distilled water. After washing, it was dried under vacuum at room temperature and then at 150 ° C. under a reduced pressure of 1 mmHg. The solid thus obtained was recrystallized twice using n-hexane,
Yellow needle crystals were obtained. The obtained crystals were dried in vacuum. The yield was 10.3 g.

Elemental analysis of the obtained compound, ¹ H-NMR
The measurement (measurement using CDCL ₃ ) was performed. The results were as follows.

[0055] From the above analysis, it was confirmed that the obtained compound was a compound having a structure shown below.

Embedded image

Example 4 10 g (0.0290 mol) of 2,5-bis (methoxycarbonylethylthio) -1,4-phenylenediamine was dissolved in 400 ml of concentrated hydrochloric acid with stirring at room temperature. The solution was heated with stirring at 60-90 ° C. for 10 hours, then kept at about 5 ° C. overnight.

The solution obtained above was filtered to separate a white solid generated, and the solid was dissolved in about 1000 ml of distilled water. Sodium bicarbonate was added to this solution to adjust the pH of the solution to 3-4. Adjusting the pH to the above range resulted in a yellow precipitate. The solution was filtered to remove the precipitate, washed thoroughly with distilled water and dried in vacuum. The yield at this time was 10.0 g.

10.0 g of the substance obtained above was dissolved in 900 ml of ethanol and recrystallized.

The obtained crystals were subjected to elemental analysis. The results were as follows. The numerical values in the following table of elemental analysis represent percentages.

Further, infrared absorption analysis of this crystal showed that it was 3337 cm ^-1 , 3263 cm ^-1 , and 1635 cm ^-1.
In addition, a peak peculiar to the diamine bonded to the benzene ring was observed. At 1692 cm ⁻¹ , a peak unique to a carbonyl group was observed.

From the above, it was confirmed that the crystals obtained above were the following aromatic diamines.

Embedded image

Example 5 20.0 g of 2,5-diamino-1,4-benzenedithiol dihydrochloride was dissolved in an aqueous sodium hydroxide solution (14.4 g of NaOH, 200 ml of water) at room temperature under an argon atmosphere.
This solution was cooled on ice and 20.7 ml of benzyl chloride was added dropwise while stirring. At this time, when about half of the benzyl chloride was dropped, 1.0 g of cetyltrimethylammonium chloride was added.
Was added.

After the above solution was vigorously stirred at about 5 ° C. for 1 hour, stirring was continued at room temperature for 3 hours to obtain a precipitate. The precipitate was filtered, washed thoroughly with water and dried in vacuum.

The substance obtained above was dissolved in a 1: 1 mixture of normal hexane and methylene chloride and recrystallized to obtain needle-like crystals. The yield was 32.8% (9.43 g).

The obtained crystals were subjected to elemental analysis. The results were as follows. The numerical values in the following table of elemental analysis represent percentages.

Further, infrared absorption analysis of the crystal showed that it was 3406 cm ^-1 , 3318 cm ^-1 , and 1603 cm ^-1.
In addition, a peak peculiar to the diamine bonded to the benzene ring was observed.

From the above, it can be seen that the crystals obtained above are the following aromatic diamines.

Embedded image

[0068]

As described in detail above, in the method of the present invention, an aromatic diaminodithiol compound or a salt thereof is reacted with an alkyl halide in an alkaline aqueous solvent. Aromatic diamines (substituted hydrogen atoms of thiol groups of aromatic diaminodithiol compounds with alkyl groups) can be produced.

In the aromatic diamine of the present invention, since the sulfur atom bonded to the aromatic residue is protected by an alkyl group, the polymerization reaction of the aromatic diamine of the present invention with a dicarboxylic acid derivative is The amino group will react selectively. As a result, the aromatic diamine and the alkyl halide of the present invention are polycondensed at the amino group in the aromatic diamine to form a polythiazole precursor without by-producing insoluble components.

In particular, in the aromatic diamine of the present invention,
As an alkylthio group, a carboxyl group, an ester group,
When an alkylthio group having a cyano group or a benzene group is selected, the ring closing reaction of the precursor can be performed at a low temperature, which is preferable.

The precursor having these groups is N-
It is very well soluble in organic solvents such as methyl-2-pyrrolidone and has the advantage that polythiazole can be produced without using a strong acid.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C07C 323/38 C07C 323/38 323/52 323/52 323/65 323/65 // C07B 61/00 300 C07B 61/00 300 (56) References JP-A-64-70460 (JP, A) JP-A-64-40449 (JP, A) JP-A-55-38334 (JP, A) JP-A-55-33438 (JP, A) 62-123155 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) CA (STN) REGISTRY (STN)

Claims (7)

(57) [Claims] 1. The following general formula: (Where Ar is the following general formula; And R is a substituted or unsubstituted alkyl group, and in the case of a substituted alkyl group, an alkyl group substituted by a carboxyl group, an ester group, a cyano group, or a benzene group. A non-substituted alkyl group, an ethyl group, an isopropyl group, an n-
Propyl, n-butyl, sec-butyl and te
It is selected from the group consisting of rt-butyl groups. An aromatic diamine represented by any of the above. 2. The aromatic diamine according to claim 1, wherein said Ar is An aromatic diamine, which is an aromatic residue of any one of the above. 3. The aromatic diamine according to claim 2, wherein said Ar is a benzene ring. 4. The aromatic diamine according to claim 1, wherein R is a substituted alkyl group.
The following formula: An aromatic diamine, which is any one of the above. 5. An aromatic diaminodithiol compound or a salt thereof, and a compound represented by the general formula: XR (where X is a halogen element, R is a substituted or unsubstituted alkyl group, and Is a carboxyl group, an ester group,
An alkyl group substituted by a cyano group or a benzene group, and in the case of an unsubstituted alkyl group, an ethyl group, an isopropyl group, an n-propyl group, an n-butyl group, a sec-
It is selected from the group consisting of a butyl group and a tert-butyl group. Wherein the hydrogen atom of the thiol group of the aromatic diaminodithiol compound or a salt thereof is replaced with the alkyl group of the alkyl halide by reacting the alkyl halide represented by the formula (1) with an alkaline aqueous solvent. A method for producing an aromatic diamine. 6. The method according to claim 5, wherein the reaction between the aromatic diaminodithiol compound or a salt thereof and the alkyl halide is carried out in the presence of a phase transfer catalyst. Method. 7. The method according to claim 6, wherein the phase transfer catalyst is any of cetyltrimethylammonium chloride, n-butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, and 18-crown-6. A method for producing an aromatic diamine.