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Method for synthesizing 2,4-dichloroaniline

A technology of dichloroaniline and p-chloronitrobenzene, applied in chemical instruments and methods, preparation of organic compounds, preparation of amino compounds, etc., can solve problems such as difficult cost control, reduce raw material consumption and production costs, and reduce reaction side effects The effect of less product and mild reaction conditions

Inactive Publication Date: 2009-02-11
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this method needs to react under pressure and high temperature, and also uses various chemicals such as methyl ethyl ketone, triphenylphosphine, carbon monoxide and expensive palladium chloride catalyst, which involves the treatment and recovery of various chemicals, and industrial production The cost in is not easy to control

Method used

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  • Method for synthesizing 2,4-dichloroaniline

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Add 20ml of ethanol and 6.3g of p-chloronitrobenzene into the 50ml three-necked flask, stir and dissolve, then add 12.6ml of 5% ammonium chloride aqueous solution. Stir and heat under the protection of nitrogen, add 6.5g of zinc powder in batches, control the temperature 75°C during the process of adding zinc powder, and keep stirring at this temperature after the addition is complete until the reaction solution is colorless and transparent.

[0033] After the above reaction solution was cooled to a temperature lower than 60°C, 95 g of concentrated hydrochloric acid was slowly added dropwise under nitrogen protection, while the temperature was controlled at 55-60°C and stirred. After the concentrated hydrochloric acid was added dropwise, the reaction was carried out at 60°C for 1 hour. Cool to room temperature, filter, discard the yellow filter residue, and neutralize the filtrate with ammonia water to pH = 7 under ice-bath conditions, a solid precipitates, and recrysta...

Embodiment 2

[0035] Add 20ml of ethanol and 6.3g of p-chloronitrobenzene into the 50ml three-necked flask, stir and dissolve, then add 12.6ml of 5% ammonium chloride aqueous solution. Stir and heat under the protection of nitrogen, control the temperature at 80°C, add 10g of zinc powder in batches, continue to maintain the temperature after the addition, and stir until the reaction solution is colorless and transparent.

[0036] Filtrate while hot, wash the filter cake with an appropriate amount of hot water, combine the filtrate and washing liquid, add crushed ice and let it stand for cooling to precipitate crystals. The obtained crystals were filtered and washed with petroleum ether to obtain 4.5 g of p-chlorophenhydroxylamine crystals, and the yield of hydroxylamine was 78%.

[0037] Dissolve 4.5g of hydroxylamine crystals in 25ml of ethanol, under nitrogen protection and stirring, use a constant pressure dropping funnel to drop the hydroxylamine ethanol solution into a three-necked bot...

Embodiment 3

[0039] Replace the Zn powder in embodiment 1 with stannous chloride as reducing agent, stannous chloride consumption is 14g, and the charging amount of all the other reagents is all identical with embodiment 1, operates final by the identical reaction condition of embodiment 1 and operating method 5.2 g of 2,4-dichloroaniline was obtained, and the yield of 2,4-dichloroaniline was 80%.

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Abstract

The invention discloses a method for synthesizing 2, 4-dichloroaniline, which adopts parachloronitrobenzene as raw material and comprises the steps as follows: firstly, nitro-benzene is reduced into the corresponding hydroxylamine in the alcohol-water solution of ammonium chloride; secondly, chloro of benzene ring and reduction of hydroxylamine are carried out simultaneously in the hydrochloric acid solution; and thirdly, the pH value is adjusted until the solids are precipitated, and 2,4-dichloroaniline can be obtained after recrystallization by using the alcohol-water solution. The hydrochloric acid in this invention is adopted not only as a source of hydrogen for reduction reaction, but also as a chlorination agent for chlorination reaction, the reduction reaction and the chlorination reaction can be finished at the same time, the invention has the advantages of short process route, no high requirement for devices, simple operation, and high yield of 2,4-dichloroaniline, no usage of expensive catalysts, low raw material and production cost and being suitable for industrial production.

Description

technical field [0001] The invention relates to a method for synthesizing 2,4-dichloroaniline. Background technique [0002] 2,4-Dichloroaniline is an important dye and pharmaceutical intermediate, widely used in pesticides, medicines, dyes, photosensitive materials and other fine chemical industries. At present, this product in our country mainly relies on imports. The main reason for this situation is that the production process of 2,4-dichloroaniline in my country is relatively long, the cost is high, and its competitiveness is low compared with foreign products. Using nitrobenzene as raw material, the traditional method of preparing 2,4-dichloroaniline requires four steps of reduction, acylation, chlorination and deacylation. In addition to monochlorine and polychlorinated by-products, the product of this process also has positional isomers of 2,4-dichloroaniline, which is relatively difficult to separate and affects product quality. At the same time, the process uses...

Claims

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Application Information

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IPC IPC(8): C07C211/52C07C209/36
Inventor 朱京科刘佳沈晶馨
Owner ZHEJIANG UNIV
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