JPH0733716A - Production of halogenated mononitrobenzene - Google Patents

Abstract

PURPOSE:To provide a method for controlling the ratio of isomers of produced nitro compound in the mononitration of a halogenated benzene. CONSTITUTION:A halogenated mononitrobenzene is produced by reacting a halogenated benzene with nitrogen oxide and an ozone-containing oxygen or air. In this process, the isomer ratio of the produced nitro compound can be controlled by varying the kind of the solvent and/or the amount of the solvent within the range of 0-2,000 pts.wt. based on the reaction base.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing halogenated mononitrobenzene. More specifically, the present invention relates to a method for producing a halogenated mononitrobenzene which controls the isomer ratio of the produced mononitro compound without using nitric acid or a nitric acid derivative as a direct nitration reagent.

[0002]

2. Description of the Related Art Halogenated mononitrobenzene is a medicine,
It is an essential material as a starting material in the production of countless organic industrial products represented by pesticides, dyes, plastics, explosives, etc., but for its industrial synthesis, it has been consistently used with nitric acid alone or other substances since the last century. The method of using it as a nitration reagent in combination with the acid catalyst (sulfuric acid, phosphoric acid, etc.) has been adopted.

However, since these methods usually use a large amount of a high concentration of acid, they are an operational hazard, a large amount of waste acid is treated,
There have always been inherent technical problems to be solved such as the use of corrosion resistant equipment, the difficulty of continuous automation, intense heat generation, and substrate oxidation.

Further, only by the nitric acid alone method or the mixed acid method, the desired orientation of the nitrated product was constant, and it was impossible to produce each nitrated isomer according to the market conditions.

[0005]

[Problems to be Solved by the Invention] Various isomer ratios of halogenated mononitrobenzene can be efficiently adjusted according to demand by a clean method with little pollution without using troublesome inorganic acids such as nitric acid, sulfuric acid and phosphoric acid. It is desired to establish a manufacturing method that can be changed.

The present applicants have already used nitrogen oxides and ozone-containing oxygen or air as a clean method with little pollution without using a troublesome inorganic acid such as nitric acid, sulfuric acid, phosphoric acid, etc. A method for obtaining a nitro compound has been filed as Japanese Patent Application Laid-Open No. 4-217645, and as a result of subsequent research, a method for varying various isomer ratios of halogenated mononitrobenzene was found and the present invention was completed.

An object of the present invention is to provide a method for controlling the isomer ratio of a nitro compound produced when mononitrating halogenated benzene.

[0008]

That is, the present invention relates to a method for producing a halogenated mononitrobenzene by reacting halogenated benzene with oxygen or air containing nitrogen oxides and ozone, and a solvent species and / or The present invention relates to a method for producing a halogenated mononitrobenzene, which is characterized by controlling the isomer ratio of the produced nitro compound by changing the substrate concentration.

The present invention will be described in detail below. Examples of the halogenated benzene used as a raw material in the method of the present invention include fluorobenzene, chlorobenzene, bromobenzene, and iodobenzene.

The solvent used in the method of the present invention is
Dichloromethane, chloroform, carbon tetrachloride and 1,2
-Aliphatic halogenated hydrocarbons represented by dichloroethane and the like, aliphatic nitro compounds represented by nitromethane and nitroethane, aliphatic cyano compounds represented by acetonitrile and propionitrile, and n-pentane, n Examples include aliphatic hydrocarbons represented by hexane and n-heptane.

Among these solvents, dichloromethane and 1,2-dichloroethane have a high ortho orientation, and carbon tetrachloride, n-hexane, acetonitrile and nitromethane have a high para orientation.

The amount of solvent used is 2000 with respect to the substrate.
It is not more than 1 times by weight, preferably 0 to 1500 times by weight. When the solvent is dichloromethane, 1,2-dichloroethane, etc., the ortho-orientation increases with an increase in the amount of solvent, that is, the substrate concentration decreases. It is almost constant. Further, when the amount of the solvent is 0, that is, when the raw material is a liquid without using the solvent, the nitration reaction proceeds and the meta-orientation is increased.

NO, NO ₂ , N ₂ O as nitrogen oxides
₃ , N ₂ O ₄ , N ₂ O _{5 and the} like can be used alone or in combination. Oxygen or air containing ozone can be obtained, for example, by passing it through a silent discharge tube.

The reaction is carried out, for example, as follows. First, the raw materials to be reacted are dissolved or suspended in the above-mentioned solvent at room temperature or lower, preferably under ice cooling. Next, oxygen or air containing ozone obtained by passing gaseous nitrogen oxides and oxygen or air through the silent discharge tube is blown in while stirring. Also, nitrogen oxides can be charged in a liquid form. In this case, it is preferable to blow oxygen containing ozone or air in a state where nitrogen oxides are excessively present in the reaction system. The amount of nitrogen oxides varies slightly depending on the above-mentioned mixed composition, but is 0.2 to 0.2 in terms of nitrogen atom based on the starting aromatic compound.
5 mol times is sufficient, and the amount of ozone is 0.1 to 2 mol times the aromatic compound as the raw material. Further, it is preferable that oxygen or air containing ozone is blown as fine bubbles using, for example, a sinter glass ball or the like.

The reaction temperature is usually room temperature or lower, but mild heating is preferred for low-reactivity raw materials. The reaction time is determined by analyzing the content of the target substance in the reaction product by, for example, gas chromatography. As the reaction method, in addition to the usual batch system, a plurality of reactors are arranged side by side, and oxygen or air containing nitrogen oxides and ozone is first blown into the first reactor, and an excess of those discharged from the first reactor is used. It can also be carried out in a continuous mode, in which the gas of the above is introduced into the second reactor, and in this way the nitrogen oxides are completely consumed.

When the reaction is completed, the desired product can be efficiently obtained by a usual method such as neutralizing the reaction solution, removing the solvent by distillation and filtration, if necessary, and then fractionating and crystallization. In the production method of the present invention, since the reaction temperature is low, heat consumption is small and the ozone concentration to be acted on can be easily changed by changing the silent discharge voltage of the ozone generator. In addition to the advantage that the setting is easy, the solvent used in the reaction is washed with sodium carbonate aqueous solution containing urea to remove by-produced nitric acid or residual nitrogen oxides, or passed through a sodium carbonate powder layer. This has the advantage that it can be reused.

[0017]

EXAMPLES The production method of the present invention will be described more specifically by way of examples.

Example 1 1.12 g (10 mmol) of chlorobenzene, 1.20 g (13 mmol) of liquid dinitrogen tetroxide and 50 ml of 1,2-dichloroethane were charged into a Pyrex reaction flask, and oxygen gas was added at 0 ° C. with stirring. 1 ozone generated in
Pumping was carried out for 1 hour at a flow rate of 0 mmol / hour. After completion of the reaction, dissolved nitrogen oxides were removed through air, the reaction mixture was washed with an aqueous sodium carbonate solution, and the solvent was distilled off to obtain a crude product of chloronitrobenzene. The crude product was analyzed by an internal standard substance quantification method by gas chromatography, and the following results were obtained.

Yield 99.0% Composition ratio (%) o-Chloronitrobenzene 46.0 m-Chloronitrobenzene 0 p-Chloronitrobenzene 54.0 (O / P = 0.85) Examples 2 to 13 Example 1 Table 1 shows the results of the yield and isomer ratio of chloronitrobenzene examined by changing the chlorobenzene concentration for each solvent shown in Table 1 in the same manner as in. In addition, Example 8 does not use a solvent.

[0020]

[Table 1]

Examples 14 to 17 As in Example 1, the substrates shown in Table 2 were used, and the orientation was observed with and without the use of a dichloromethane solvent (50 ml) (Examples 14 and 16). Dinitrogen tetraoxide was introduced as a gas at a rate of 40 mmol / hour. The results of yield and isomer ratio are shown in Table 2.

[0022]

[Table 2]

Comparative Example 1 While stirring a mixed solution of 3.4 g of chlorobenzene and 0.80 g of 95% sulfuric acid at 5 ° C., 2.2 g of 94% nitric acid was added over 15 minutes. After that, gradually return to room temperature (25 ° C), and
The stirring was continued for 30 minutes. The analysis results of the reaction solution at the end were as follows.

Yield 60.0% Composition ratio (%) o-Chloronitrobenzene 31.7 m-Chloronitrobenzene 0 p-Chloronitrobenzene 68.3 (O / P = 0.46) Comparative Example 2 Chlorobenzene 3.4 g While stirring a mixed solution of 4.30 g of 95% sulfuric acid and 30 g of dichloromethane at 5 ° C.,
2.2 g of 4% nitric acid was added in 15 minutes. After that, the temperature was gradually returned to room temperature (25 ° C.), and stirring was continued for 7 hours. The analysis results of the reaction solution at the end were as follows.

Yield 99.0% Composition ratio (%) o-Chloronitrobenzene 31.0 m-Chloronitrobenzene 1.0 p-Chloronitrobenzene 68.0 (O / P = 0.46) Examples 18 to 25 Implementation As in Example 14, using the substrates shown in Table 2 and using a dichloromethane solvent (50 ml) and not using it (Examples 21, 23 and 25), the change in O / P ratio depending on the reaction time was measured by gas chromatography. It was analyzed by chromatography. The results are shown in Table 3.

[0026]

[Table 3]

[0027]

In the nitration reaction of halogenated benzene of the method of the present invention, in the method of reacting oxygen or air containing nitrogen oxide and ozone, by changing the solvent species and / or the substrate concentration, Unlike the mixed acid method of (1), the ratio between the isomers of the nitrated product formed can be easily controlled.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Maeda 1 722, Tsuboi-cho, Funabashi-shi, Chiba Central Research Institute of Nissan Chemical Industries, Ltd. (72) Isao Hashiba 1 722, Tsuboi-cho, Funabashi, Chiba Nissan Chemical Central Research Institute Co., Ltd.

Claims (3)

[Claims] 1. A method for producing halogenated mononitrobenzene by reacting halogenated benzene with oxygen or air containing nitrogen oxides and ozone, which is produced by changing the solvent species and / or solvent amount. A method for producing a halogenated mononitrobenzene, which comprises controlling the isomer ratio of a nitro compound. 2. The solvent species is an aliphatic halogenated hydrocarbon,
The method for producing a halogenated mononitrobenzene according to claim 1, wherein the solvent is at least one solvent selected from an aliphatic nitro compound, an aliphatic cyano compound and an aliphatic compound. 3. The method for producing a halogenated mononitrobenzene according to claim 1, wherein the amount of the solvent is 2000 times or less the weight of the reaction substrate.