JPS6151576B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing m-nitro-ω-bromoacetophenone.

m-Nitro-ω-bromoacetophenone is used as a slime control agent in the paper industry. Its production methods include (a) nitration of ω-bromoacetophenone with a mixture of sulfuric acid and fuming nitric acid, and (b) dissolution of m-nitroacetophenone in an organic solvent such as carbon tetrachloride, chloroform or glacial acetic acid. , a method of bromination with bromine is known. However, method (a) is dangerous because it uses a large amount of fuming nitric acid, which is difficult to handle, and the large amount of water used after the reaction becomes strongly acidic, so wastewater must be treated with a neutralizing agent. It won't happen. Method (b) has drawbacks such as poor absorption of bromine and the need for reaction at relatively high temperatures for a long period of time, resulting in bromine volatilization and an increase in the amount of bromine required.

The present inventors conducted extensive research to eliminate such drawbacks, and as a result, they arrived at the present invention.

The present invention is a method for producing m-nitro-ω-bromoacetophenone, which is characterized by brominating m-nitroacetophenone in an aqueous medium.

As a method for producing organic compounds in the chemical industry, it is generally advantageous to carry out the reaction in a homogeneous system from the viewpoint of the reaction rate and the purity of the product. Therefore, in this reaction, an organic solvent in which m-nitroacetophenone, the starting material, is easily dissolved should normally be used; however, in the present invention, the reaction is carried out in a heterogeneous system using an insoluble solvent. It was unexpected that the reaction time could be shortened and the yield could be improved.

In carrying out the present invention, m-nitroacetophenone is preferably dispersed as a fine powder in an aqueous medium, and this aqueous suspension is treated with a brominating agent.

Bromine is usually preferred as the brominating agent, and can be used as it is or diluted with an inert solvent. If bromine is added little by little while stirring the mixture, the reaction will proceed rapidly. By-product hydrogen bromide dissolves in water, preventing the generation of hydrogen bromide gas. The reaction temperature is room temperature to 100℃, preferably
The temperature is 60-90℃.

The aqueous medium may be water itself, but adding an acid or salt to it can promote bromine absorption and shorten the reaction time. Acids include hydrochloric acid, sulfuric acid,
Hydrobromic acid and the like are used. As the salt, sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium sulfate, etc. are used. acid is m
-0.01 to 1 per mole of nitroacetophenone
It is preferably used in a mole ratio of 0.05 to 0.5 mole. A relatively large amount of salt can be used.

Compared to the known method of brominating m-nitroacetophenone by dissolving it in an organic solvent, the method of the present invention has the following advantages:
The reaction time can be shortened, the amount of brominating agent used can be reduced, and the yield can also be improved.

Example 1 m-nitroacetophenone 16.5 g (0.1 mol),
50 g water and 2.75 g (0.016 mol) 47% hydrobromic acid
was charged into a reactor equipped with a four-necked flask, a thermometer, and a cooling tube, and when the internal temperature reached around 80℃,
Dropwise addition of 15.9 g (0.1 mol) of bromine is started. Continue dropping with care for about 20 minutes while keeping the temperature at 80-85°C on a water bath, and after finishing dropping, keep at the same temperature for about 1 hour. When the mixture is then gradually cooled to room temperature, the oil gradually turns into fine crystals and precipitates out. After passing through this crystal,
After washing with water several times and drying under reduced pressure, the melting point is 92-93.
°C m-nitro-ω-bromoacetophenone 22.9
g (yield 93.8%) is obtained.

Example 2 m-nitroacetophenone 16.5 g (0.1 mol),
When the reaction was carried out in the same manner as in Example 1 using 50 g of water and 1.67 g (0.016 mol) of 35% hydrochloric acid, 20.7 g of the target substance with a melting point of 91 to 93°C was obtained.
(yield 84.8%) is obtained. The time required for dropping bromine is approximately 35 minutes.

Example 3 m-nitroacetophenone 16.5 g (0.1 mol),
Using 50 g of water and 1.6 g (0.016 mol) of 98% sulfuric acid,
When the reaction was carried out using the same equipment and operation as in Example 1, 21.3 g of the target substance with a melting point of 91-93°C (yield 87.3
%) is obtained. The time required for dropping bromine is approximately 42 minutes.

Example 4 m-nitroacetophenone 16.5g (0.1 mol)
When the reaction is carried out using the same equipment and operation as in Example 1 using 50 g of a saturated aqueous solution of sodium bromide and
21.1 g (yield: 86.5%) of the target substance with a melting point of 92-93°C is obtained. The bromine addition time is 50 minutes.

Example 5 m-nitroacetophenone 16.5g (0.1 mol)
When the reaction is carried out using the same apparatus and operation as in Example 1 using 50 g of a saturated aqueous solution of potassium chloride, 20.6 g (yield: 84.4%) of the target substance with a melting point of 91 to 93°C is obtained. The bromine addition time is 50 minutes.

Example 6 m-nitroacetophenone 16.5g (0.1 mol)
When the reaction is carried out using the same equipment and operation as in Example 1, using 50 g of water and without adding acid or salt,
21.0 g (yield: 86%) of the target substance with a melting point of 93-94°C is obtained. The time required for dropping bromine is 1 hour.

Comparative example 1 m-nitroacetophenone 16.5g (0.1 mol)
and 50 g of glacial acetic acid were placed in a 100 ml four-necked flask equipped with a thermometer, condenser, and dropping funnel, heated on a water bath, and when the internal temperature reached around 80° C., addition of bromine was started. At this time, the internal temperature rose slightly, so it was cooled and kept at around 80°C. Since bromine absorption is slow in organic solvents, care must be taken to prevent bromine from volatilizing from the upper end of the cooling tube. Therefore, the reaction time required 130 minutes, and the amount of bromine used was 19.2g.
(0.12 mol), an increase of 1.2 times that in Example 1. Note that hydrogen bromide gas generated during the reaction was absorbed into water. After the addition of bromine, to prevent decomposition of the target substance, immediately cool the reaction solution, and then cool the reaction solution for about 10 minutes.
When poured into twice the volume of ice water, a slightly sticky precipitate was obtained. After washing this with water until the acetic acid odor disappears and drying under reduced pressure, the desired substance with a melting point of 92-93℃ is obtained.
17.5g (yield 72.8%) was obtained.

Comparative example 2 m-nitroacetophenone 16.5g (0.1 mol)
and 50 ml of chloroform were charged into the same apparatus as in Comparative Example 1, and when the internal temperature reached around 61°C, dropping of bromine was started. The following operation was carried out in the same manner as in Comparative Example 1, and 18.0 g (yield: 73.7%) of the target substance having a melting point of 91 to 92°C was obtained. The amount of bromine used is 20g (0.125mol).
The time required for dropping was 2 hours and 15 minutes.

Claims (1)

[Claims] 1. A method for producing m-nitro-ω-bromoacetophenone, which comprises brominating m-nitroacetophenone in an aqueous medium. 2 Claim 1, characterized in that water containing acid and/or salt is used as the aqueous medium.
The method described in section.