JPH0733356B2 - Process for producing 2,6-dichloro-4-nitroaniline - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improved process for producing 2,6-dichloro-4-nitroaniline, in particular 4-nitroaniline in a mineral acid solvent with chlorine. The present invention relates to an improved method for producing 2,6-dichloro-4-nitroaniline by reacting with an agent.

Prior Art 2,6-Dichloro-4-nitroaniline is an important intermediate for azo dyes.

Heretofore, as a method for producing 2,6-dichloro-4-nitroaniline, a method of reacting 4-nitroaniline with a chlorinating agent in a mineral acid solvent such as hydrochloric acid or sulfuric acid has been known. In order to control organisms, etc. in these manufacturing methods,
A method of adding disodium salt of dinaphthalenemethanedisulfonic acid (Polish Patent 60981) and a method of adding condensate of naphthalenesulfonic acid formalin (Japanese Patent Publication No. 58-54136) are known. It was hoped that the rate would improve.

Problem to be Solved by the Invention The present invention aims to provide a method for producing 2,6-dichloro-4-nitroaniline from 4-nitroaniline in high yield.

Means for Solving the Problems The present invention provides a reaction system in which lignin is used when 2,4-dichloro-4-nitroaniline is produced by reacting 4-nitroaniline with a chlorinating agent in a mineral acid solvent. Sulfonic acid or its salt, and / or dialkylsulfosuccinic acid ester is present in the presence of 2,6-dichloro-4
-The gist is the method for producing nitroaniline.

The ligninsulfonic acid or salt thereof used in the present invention is usually obtained by cooking wood pulp, and for example, 0.2 or more per 1 benzene nucleus,
Preferably, those having 0.4 to 0.6 sulfone groups are mentioned, and as the salt thereof, for example, calcium salt,
Examples thereof include sodium salt, ammonium salt and potassium salt.

On the other hand, examples of the dialkylsulfosuccinic acid ester include compounds represented by the following general formula.

(In the formula, R represents a C _{3 to} C ₁₂ , preferably a C _{5 to} C ₉ alkyl group, and particularly preferably a 2-ethylhexyl group.) In addition, two or more kinds of the above-mentioned additives of the present invention are used in combination. It can also be used.

The amount of these additives of the present invention to be used is usually 1 to 20% by weight, preferably 3 to 10% by weight, based on 4-nitroaniline.
Is. If the amount used is too small, the desired compound cannot be obtained in a high yield, and conversely, if the amount is too large, there is no significant difference in the effect, which is not economical.

The mineral acid used as the solvent in the present invention is usually hydrochloric acid or sulfuric acid. The concentration of the mineral acid is usually 15 to 35% by weight, preferably 20 to 35% by weight in the case of hydrochloric acid, and, in the case of sulfuric acid, usually,
The range is 50 to 90% by weight, preferably 60 to 70% by weight.

The amount of the solvent used is usually in the range of 7 to 10 times by weight with respect to 4-nitroaniline.

As the chlorinating agent, an oxidizing agent that easily generates chlorine by reacting with chlorine or a mineral acid, for example, chlorine peroxide, chloric acid or its potassium, sodium salt, hypochlorous acid or its potassium, sodium salt, etc. Is mentioned. The amount of the chlorinating agent used is usually about 2.2 to 2.4 mol times that of 4-nitroaniline.

In the present invention, the reaction temperature is usually 0 to 70 ° C,
The temperature is preferably in the range of 5 to 60 ° C. The reaction is rather slow on the low temperature side and some unreacted compounds tend to remain, but the amount of oxidative decomposition products is small. On the contrary, although the unreacted amount is small on the high temperature side, the yield tends to be somewhat low due to oxidative decomposition. Further, in the reaction, 4-nitroaniline as a raw material disappeared, and moreover, it was an intermediate 2
The reaction is carried out until the amount of chloro-4-nitroaniline becomes constant, but the reaction time is usually about 3 to 10 hours, varying depending on the temperature, solvent and chlorinating agent used.

The reaction of the present invention can be specifically carried out, for example, as follows.

That is, the raw material 4-nitroaniline was charged into a mineral acid solvent to which the ligninsulfonic acid of the present invention or a salt thereof and / or a dialkylsulfosuccinic acid ester was added, and the mixture was stirred at a temperature of 0 to 70 ° C. under a chlorine atmosphere. The reaction can be carried out by adding the agent and continuing stirring for a predetermined time. The mixture after completion of the reaction is usually, if necessary, after removing excess chlorine by adding NaHSO _3, etc., and then passed according to a conventional method, and then the separated crystals are washed with water and diluted with a dilute alkali. The desired crystals of 2,6-dichloro-4-nitroaniline can be recovered by washing with water and further drying.

The mineral acid solution (reaction mother liquor) may be recycled and used as the next reaction solvent.

EFFECTS OF THE INVENTION According to the method of the present invention, the viscosity increase of the in-system reaction liquid during the chlorination reaction is less than that in the conventional method, and as a result, the yield is high
2,6-dichloro-4-nitroaniline can be efficiently obtained.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these. In the examples, "parts" and "%" mean "parts by weight" and "% by weight".

Example 1 In a reactor equipped with a stirrer and a temperature controller, 35% hydrochloric acid 770
Was added to 100 parts of 4-nitroaniline and lignin sulfonate sun extract P-252 (Na salt and C
After adding 10 parts of a mixture with a salt, manufactured by Sanyo Kokusaku Pulp Co., Ltd., and thoroughly mixed to evenly mix,
This mixture was heated to a temperature of 40 to 50 ° C, and chlorine gas was continuously introduced at the same temperature under stirring to carry out a chlorination reaction. This reaction was carried out by chromatography until 4-nitroaniline almost disappeared and the intermediate 2-chloro-4-nitroaniline remained constant (about 4 hours).

After completion of the reaction, N ₂ gas was blown into the mixture to degas dissolved chlorine, cooled to room temperature, passed, and then the separated crystals were washed with water and 2% caustic soda water.
After washing with water and drying, 140.6 parts of a yellow crystalline powder was obtained. As a result of a purity analysis of the crystals, as shown in Table 1 below, 2,6-dichloro-4-nitroaniline was 96.3% and 2-chloro-4-nitroaniline was 0.4%, which was a pure yield from 4-nitroaniline. Was 90.3%.

Example 2 In the method of Example 1, instead of 770 parts of 35% hydrochloric acid, 6
The reaction was performed in exactly the same manner except that 990 parts of 0% sulfuric acid was used to produce 2,6-dichloro-4-nitroaniline. The results of purity, yield, etc. are shown in Table 1.

Example 3 The reaction was carried out in the same manner as in Example 1 except that the amount of 10 parts of lignin sulfonate sun extract P-252 used was reduced to 3 parts, and 2,6-dichloro-4 was used. -Nitroaniline was prepared. The results of purity, yield, etc. are shown in Table 1.

Example 4 In the method of Example 1, 58% instead of 770 parts of 35% hydrochloric acid was used.
% Sulfuric acid 496 parts was used to reduce the amount of lignin sulfonate sun extract P-25 used to 10 parts to 3 parts. Also, instead of chlorine gas as a chlorinating agent, sodium hypochlorite water (effective chlorine concentration 170 g /) and 797 parts of 98% sulfuric acid,
The same method was used to prepare 2,6-dichloro-4-nitroaniline except that the compounds were added simultaneously at a temperature of -30 ° C.
The results of purity, yield, etc. are shown in Table 1.

Example 5 In the method of Example 2, 10 parts of di-2-ethylhexyl sulfosuccinic acid sorbalite S-70 (manufactured by Kyoei Yushi-Seikagaku Co., Ltd., trade name) instead of lignin sulfonate sun extract P-252 is used. 2,6-dichloro-4-nitroaniline was produced in the same manner except that was used. The results of purity, yield, etc. are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that no lignin sulfonate was added, and 2,6-dichloro- was used.
4-Nitroaniline was produced. The results of purity, yield, etc. are shown in Table 1.

Comparative Example 2 In the method of Example 1, instead of lignin sulfonate, a formalin condensate of naphthalene sulfonic acid, Diadespers NA (manufactured by Mitsubishi Kasei Kogyo Co., Ltd., trade name)
A 2,6-dichloro-4-nitroaniline was produced in the same manner except that 10 parts were used. The results of purity, yield, etc. are shown in Table 1.

Claims (2)

[Claims] 1. When producing 2,6-dichloro-4-nitroaniline by reacting 4-nitroaniline with a chlorinating agent in a mineral acid solvent, ligninsulfonic acid or its salt and / or 2,6-dichloro-4-characterized by the presence of dialkyl sulfosuccinate
Method for producing nitroaniline. 2. Lignin sulfonic acid or its salt and / or
Alternatively, the amount of dialkyl sulfosuccinate ester present is 4-
The amount of 2,6-dichloro- according to claim 1, which is 1 to 20% by weight based on nitroaniline.
Method for producing 4-nitroaniline.