JPH09157240A - Production of azo compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an azo compound by a process advantageous from the operational and economical points of view by dispersing solid particles of a phenolic compound in water in the presence of a surfactant and subjecting the phenolic compound to a coupling reaction. SOLUTION: (A) A phenolic compound exhibiting solid particle form is made to react with (B) diazonium salt of an aromatic aniline compound in the presence of (C) a surfactant in water to obtain (D) the objective azo compound. Preferably, the component A is a phenolic compound of formula I (R1 is H, a 1-12C alkyl, a 5-6C cycloalkyl, phenyl, etc.; R2 is H, a halogen, OH or a 1-4C alkoxy; R3 is a halogen, a 1-12C alkyl, a 5-6C cycloalkyl, a 1-4C alkoxy, phenyl, etc.), the component B is an aromatic aniline compound of formula II (R4 is H, a halogen, a 1-12C alkyl, carboxy, etc.) and the component D is an azo compound of formula III.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an improved method for producing an azo compound.

[0002]

2. Description of the Related Art Azo compounds are mainly polyolefins,
It is a very important compound as an intermediate for a benzotriazole-based UV absorber, which is added to improve the oxidation resistance of general-purpose resins such as polyesters.

These can be obtained by a diazo coupling reaction between a phenol and a diazonium salt of an aniline. This reaction has been known for a long time and is a reaction that proceeds relatively easily. However, for example, when a phenol represented by the general formula (I) is reacted with a diazonium salt of an aniline represented by the general formula (II), an unreacted phenol compound is a product in the reaction system. It is very easy for the phenomenon that the reaction is stopped because the reaction system is clogged or tar-like in the system. Therefore, in a reaction using phenols with a small number of substituents that are soluble in water and an alkaline aqueous solution,
By dissolving phenols in water or the like to prepare an aqueous solution, the dispersibility is improved and the product or the like is less likely to be caught. However, the phenols used for the above-mentioned purpose have a relatively bulky substituent such as 2,4-disubstituted phenol represented by 2-t-butyl-4-methylphenol. There are many. Such phenols are almost insoluble in water or alkaline aqueous solutions.

Therefore, a method of dissolving the phenols in a soluble organic solvent (JP-A-53-37628, JP-A-55-94348, JP-A-56-125455) and the product are included. In order to avoid incorporation, the amount of phenol in the reaction system is reduced, and a solution of phenols is added dropwise to the diazonium salt aqueous solution contrary to the usual method (Japanese Patent Publication No. Sho 63-9502), and an organic solvent is used. A method has been proposed in which a phenol in a molten state is dispersed in water in the presence of a stabilizer without using it (JP-A-49-59131).

[0005]

SUMMARY OF THE INVENTION Conventionally, the techniques proposed have been the formation of tars and tars by aggregation of phenols having strong lipophilicity and solid azo compounds having weak hydrophilicity, which are products, which occur in the coupling reaction system. In order to prevent liquefaction, it is a method of supplying the phenols to the reaction system in a solution state, or a method of keeping the phenols in a molten state in the reaction system by heating. However, when the organic solvent used for solutionization is a hydrocarbon type solvent (Japanese Patent Laid-Open Nos. 53-37628 and 55-55
In JP-A-94348 and JP-A-56-125455), the distribution of phenols between the organic solvent and the aqueous solution is largely deviated from the organic solvent, so that the conditions such as stirring conditions, reaction liquid composition, and reaction temperature are slightly different. Due to such a difference, layer separation occurs and the coupling reaction with the diazonium salt existing in water is stopped.

On the other hand, in the case of a water-soluble solvent such as methanol or acetic acid (Japanese Patent Publication No. 63-9502), a stable and high yield can be obtained without forming a dumpling. The operation of separating from the reaction system is complicated,
There is a drawback in that the solvent may react with the diazonium salt and give a product other than the target product.

When the reaction is carried out in the molten state (Japanese Patent Laid-Open No. 49-59131), a large amount of a stabilizer such as naphthalene sulfonic acid is required in order to react at the melting point of phenols or higher. Even if they coexist, in many cases, a decrease in yield due to self-decomposition of the diazonium salt is unavoidable.

That is, the object of the present invention is that the reaction in the coupling reaction system does not become dumpling-like or tar-like, the reaction can be completed while maintaining the dispersion state, and a stabilizer is not required. An object of the present invention is to provide a process for producing an azo compound which has a composition as simple as possible and is advantageous in operation and economically.

[0009]

[Means for Solving the Problems] A method for smoothly coupling the strongly lipophilic phenols represented by the general formula (I) with an aqueous solution of a diazonium salt, which is a hydrophilic substance, has been earnestly studied including an additional test of the prior art. As a result of investigation, it was found that the above object can be achieved by dispersing solid particulate phenols in water in the presence of a surfactant.

That is, the present invention is a method for producing an azo compound, which comprises reacting solid particulate phenols with a diazonium salt of an aromatic aniline in water in the presence of a surfactant.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, it is important to use solid particulate phenols. Any phenol may be used as long as it can be coupled with a diazonium salt of aromatic aniline. Particularly preferable results are obtained when the phenols represented by the general formula (I) are used. Specific examples of phenols include 2-t-butyl-4-methylphenol and 2,4.
-Di-t-butylphenol, 2,4-dimethylphenol, p-cresol, 2-chloro-4-methylphenol, 2-cyclohexyl-4-methylphenol,
2,4, -di-t-amylphenol and the like can be mentioned.

Various methods are conceivable for the preparation of solid particulate phenols, but one of the powerful methods, both operationally and economically, is to use the same interface as the surfactant used for the coupling reaction. In water containing an activator, solidify the molten phenols while maintaining the dispersed state,
Raw material phenols for exhibiting the effects of the present invention can be prepared. In this case, the phenols may be gradually added to the aqueous surfactant solution or may be present in the required amount from the beginning.

Specifically, solid particulate phenols can be obtained, for example, by the following method.

The phenols are melted and gradually added with stirring to water containing a predetermined amount of surfactant. At this time, the temperature of the aqueous solution is kept at a temperature lower than the melting point of the phenols, preferably 10 ° C. or more lower than the melting point of the phenols. Uniform crystals of phenol are gradually deposited, and a slurry of fine solid particles is obtained. At this time, addition of a small amount of seed crystals is also effective for shortening the crystallization time or for reliable crystallization.

Alternatively, a phenol, a surfactant and water are stirred under heating to form an emulsion. As the heating temperature,
The range of the melting point of the phenols ± 10 ° C is preferable. When this emulsion is cooled with stirring, uniform crystals are precipitated and fine solid particles can be obtained. As in the above method, the addition of seed crystals is also effective.

It is also possible to separately prepare phenols in the form of fine solid particles, and disperse this in water containing a surfactant to prepare a slurry.

Any aromatic anilines can be used, but those represented by the general formula (II) are preferably used. More preferably, 2-nitroaniline, 4-chloro-2-nitroaniline, 4-methyl-2
-Nitroaniline, 4-t-butyl-2-nitroaniline, 4-methoxy-2-nitroaniline, 4,6-dichloro-2-nitroaniline and the like can be mentioned.

For these aromatic anilines, a diazonium salt is prepared by a known method and subjected to a coupling reaction with phenols. The reaction is preferably carried out by dropping an aromatic aniline diazonium salt as an aqueous solution into a liquid containing phenols. The reaction temperature is preferably 0 to 50 ° C.

Further, when the aromatic aniline represented by the general formula (II) is used, it is preferable to use a mineral acid as concentrated as possible when preparing the diazonium salt because of its low reactivity.

Next, in the present invention, it is another important point to carry out the reaction in the presence of a surfactant.

As the surfactant which can be used in the present method, various ones can be used as long as they can disperse the phenols in the form of fine solid particles in water, but preferably an anionic surfactant, eg Examples thereof include alkane sulfonate, alkylbenzene sulfonate, alkyl sulfate ester salt, α-olefin sulfonate, and the like.

The amount of these surfactants is preferably 0.01% by weight or more in the preparation of fine solid particles and 0.1 to 5.0% by weight in the coupling reaction with respect to water.

The amount of water in which the phenols are dispersed is not particularly limited, but it is 0.
It is preferably 5 to 10 times by weight.

The present invention will be described below with reference to Examples and Comparative Examples. The present invention is not limited to these.

[0025]

【Example】

Manufacture of solid particles 1 200 ml equipped with a half-moon type stirring blade (blade diameter 50 mm)
Liporan PJ-400 in a four-necked flask (inner diameter 80 mm)
(Lion product, α-olefin sulfonate-based surfactant) 0.8 g and water 120 g were added, and melted 2-t-butyl-4-methylphenol (Tokyo Kasei Reagent) while stirring at 35 ° C. 40.0 g (special grade purity> 98%) was added little by little using a dropping funnel. Gradually, crystals were precipitated and became a white slurry. 1 more after the dropping
Stirring was continued for hours. The obtained slurry was separated by filtration, washed with water, and dried under reduced pressure to obtain 39.5 g of fine solid particulate 2-t-butyl-4-methylphenol (recovery rate 98.8%). When a portion of this was classified using a standard sieve, the distribution shown in Table 1 was obtained. Further, the particles passing through the 100-mesh sieve were enlarged and observed with an optical microscope, and the result was as shown in FIG.

Manufacture of solid particles 2 In place of 2-t-butyl-4-methylphenol used in manufacture of solid particles 1, 40.0 g of 2,4-di-t-butylphenol (manufactured by Dainippon Ink Co., Ltd., purity> 99%) Using
The same operation was performed. 37.9 g of fine solid particle-shaped 2,4-di-t-butylphenol was obtained (recovery rate: 94.8%). The result of classification showed almost the same distribution as in the production of solid particles 1 and 42 mesh. The residual rates on 80 mesh were 4.8% and 69.2%, respectively.

Preparation of Solid Particles 3 2-t-butyl-4-methylphenol (Tokyo Kasei reagent special grade, purity> 98%) was directly subjected to classification in the same manner as in Preparation of Solid Particles 1 without treatment. The distribution is as shown in.

Manufacture of solid particles 4 2-t-butyl-4-methylphenol (Tokyo Kasei reagent special grade, purity> 98%) was finely pulverized in a mortar and then classified in the same manner as in the manufacture of solid particles 1. The distribution is shown in Table 1. Further, when the particles that passed through the 80-mesh sieve were enlarged and observed with an optical microscope, the results were as shown in FIG.

[0029]

[Table 1] Example 1 10.4 g of 4-chloro-2-nitroaniline in 33.3 g of 35% hydrochloric acid, Emulgen 106 (Kao's nonionic surfactant polyoxyethylene lauryl ether)
0.1 g was added and suspended. After stirring at 35 ° C. for about 1 hour, an aqueous solution containing 4.3 g of sodium nitrite (purity 98.5%) and 12.8 g of water was added dropwise while maintaining the temperature at 15 to 20 ° C. Furthermore, the mixture was stirred at 10 ° C. or lower for about 2 hours. A small amount of an aqueous solution of sulfamic acid was added to the obtained aqueous solution of diazonium salt to remove excess nitrous acid, and water 1
1.5g was added and diluted.

On the other hand, phenols are 2-t-butyl-
4-Methylphenol 10.3g, Liporan PJ-40
0 (manufactured by Lion, α-olefin sulfonate-based surfactant) (0.20 g) and water (24.55 g) were used to prepare solid particles by the method 1.

The above diazonium salt aqueous solution was added dropwise to the thus prepared slurry of phenol kept at 28 to 32 ° C. for 3 hours to cause a reaction. After completion of dropping, the mixture was further stirred at room temperature for 6 hours. The reaction liquid was a highly fluid slurry. The formed crystals were separated by filtration, washed and dried to give 2-nitro-4-chloro-2'-
19.5 g (purity 98.8%) of hydroxy-3'-t-butyl-5'-methylazobenzene was obtained. The yield is 9
2.1%.

Example 2 9.9 g of 2-t-butyl-4-methylphenol, 0.2 g of sodium decanesulfonate (Tokyo Kasei), water 3
9.7 g was heated to 55 ° C. to make an emulsion. This was gradually cooled with stirring, and it was confirmed that crystals were precipitated at around 36 ° C. Further cooling was continued, and the mixture was stirred at 30 ° C for 1 hour to prepare fine solid particles having the same shape as in the production of solid particles 1 A slurry was obtained.

While keeping the temperature at 28 to 33 ° C., an aqueous diazonium salt solution prepared in the same manner as in Example 1 was added dropwise over 2 hours to cause a reaction. The reaction liquid was a highly fluid slurry, and the yield of the obtained azo compound was 94.4%.
Met.

Example 3 When 12.4 g of 2,4-di-t-butylphenol was used in place of 2-t-butyl-4-methylphenol of Example 1, a similar reaction was carried out. −
4-chloro-2'-hydroxy-3 ', 5'-di-t-
20.4 g (purity 96.3%) of butylazobenzene was obtained. The reaction liquid was in the form of a highly fluid slurry, and the yield of the obtained azo compound was 85.7%.

Comparative Example 1 A reaction was carried out in the same manner except that the slurry of Example 1 was maintained at 40 to 43 ° C. (solid content was melted to form an emulsion). And the yield was 63.6%.

Comparative Example 2 Preparation of Solid Particles 2-t-Butyl-prepared by the method of 4
4-Methylphenol was dispersed in Liporan PJ-400 (manufactured by Lion, α-olefin sulfonate-based surfactant) and reacted with an aqueous diazonium salt solution prepared in the same manner as in Example 1. Became tar-like, the reaction could not be continued, and the operation was interrupted.

[0037]

INDUSTRIAL APPLICABILITY According to the present invention, the solid particulate phenols are dispersed in water in the presence of a surfactant to carry out a coupling reaction, whereby the reaction can be completed while maintaining the dispersed state, and stabilization is also achieved. Since an agent is not required and only inexpensive water is used as a solvent, the azo compound can be produced in an operationally and economically advantageous manner as compared with the conventional method.

[Brief description of the drawings]

FIG. 1 is an optical micrograph of particles obtained in Production 1 of solid particles.

FIG. 2 is an optical micrograph of particles obtained in Production 4 of solid particles.

Claims (7)

[Claims] 1. A process for producing an azo compound, which comprises reacting solid particulate phenols with a diazonium salt of an aromatic aniline in water in the presence of a surfactant. 2. Phenols are represented by the general formula (I): (In the formula, R1 represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 or 6 carbon atoms, a phenyl group, or a phenylalkyl group having 1 to 4 carbon atoms in the alkyl moiety, R2 represents a hydrogen atom, a halogen atom, a hydroxyl group, or an alkoxy group having 1 to 4 carbon atoms, and R3 represents a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 or 6 carbon atoms, or a carbon atom. Represents an alkoxy group having 1 to 4 atoms, a phenyl group, a phenylalkyl group having 1 to 4 carbon atoms in the alkyl portion, a phenyl group substituted with an alkyl group having 1 to 8 carbon atoms, or a phenoxy group) The aromatic anilines are represented by the general formula (II): (In the formula, R4 is a hydrogen atom, a halogen atom, or a carbon atom of 1
Represents an alkyl group of 1 to 12, an alkoxy group having 1 to 4 carbon atoms, a carboxyl group, or a sulfonic acid group)
The azo compound is represented by the general formula (III): (Wherein R1, R2, R3 and R4 have the above-mentioned meanings). 3. In the general formula (I), R1 is a tert-butyl group,
3. The method for producing an azo compound according to claim 2, wherein R2 represents a hydrogen atom, R3 represents a tert-butyl group or a methyl group, and R4 in the general formula (II) is a chlorine atom. 4. A solid particulate phenol is a cube,
The method for producing an azo compound according to any one of claims 1 to 3, which comprises a rectangular parallelepiped and an independent particle crystal composed of an aggregate thereof. 5. The solid particulate phenols have a particle size of 30.
The method for producing an azo compound according to any one of claims 1 to 4, which comprises 50% or more of particles having a thickness of 0 µm or less. 6. The method for producing an azo compound according to claim 1, wherein the surfactant is an anionic surfactant. 7. The surfactant is 0.01% by weight with respect to water.
2. It is present in a concentration of .about.5% by weight.
7. A method for producing an azo compound according to any one of items 6 to 6.