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Prepn process of 2,5-dichloro-p-phenylenediamine

A technology of dichloro-p-phenylenediamine and dichloroaniline, which is applied in two fields, can solve the problems of unfavorable environmental protection and low total yield of four-step reaction, and achieve the effects of low cost, low production cost, and reduced production cost

Inactive Publication Date: 2007-06-06
上海染料研究所有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The fourth reduction reaction is to reduce 4-nitro-2,5-dichloroaniline with iron powder in hydrochloric acid and ethanol, and the yield of the product 2,5-dichloro-p-phenylenediamine is 79.0%. This reaction The biggest disadvantage is that a large amount of waste residue "iron mud" is produced, which is detrimental to environmental protection
[0008] The total yield of the four-step reaction of this method is low, only 59%

Method used

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Embodiment 1

[0031] Embodiment 1 2, the preparation of 5-dichloro-p-phenylenediamine

[0032] (a) Acylation of 2,5-dichloroaniline

[0033] Add 30 grams (0.3 mol) of 99% 1,2-dichloroethane into a 250ml four-neck flask equipped with stirring, reflux condenser, and thermometer, and add 10.3 grams (0.062 mol) of 98% 2,5-dichloroaniline under stirring. mol), after 2,5-dichloroaniline is dissolved, add 7.2 grams (0.069mol) of acetic anhydride dropwise at room temperature, raise the temperature to 70-80°C and react for one hour, then add 50ml of water, and distill 1,2-dichloroaniline The azeotrope of ethane and water, the recovered 1,2-dichloroethane 27.4 grams (91.3% recovery rate) can be used mechanically in the next reaction. When the temperature rose to 95°C, the heating was stopped, and the reactant was cooled to room temperature. Filter, wash the filter cake, drain and dry at 75-80°C to obtain 12.6 g of 2,5-dichloroacetanilide with a yield of 98%, a purity of 99.3% as determined by HPLC,...

Embodiment 2

[0041] Embodiment 2 2, the acylation test of 5-dichloroaniline

[0042] Add 42 grams (0.32mol) of 95% 1,1,1-trichloroethane into a 250ml four-neck flask equipped with stirring, reflux condenser, and thermometer, and add 10.3 grams of 98% 2,5-dichloroaniline under stirring (0.062mol), after 2,5-dichloroaniline was dissolved, 7.2 grams (0.069mol) of acetic anhydride was added dropwise at room temperature, and the temperature was raised to 70-80°C to react for one hour, then 80ml of water was added, and 1,1 was evaporated. The azeotrope of 1-trichloroethane and water, the recovered 1,1,1-trichloroethane can be recycled and used mechanically. When the temperature rose to 90°C, the heating was stopped, and the reactant was cooled to room temperature. Filter, wash the filter cake, drain and dry at 75-80°C to obtain 12.4 g of 2,5-dichloroacetanilide with a yield of 97%, a purity of 99.2% by HPLC, and a M.P. of 134-135°C.

Embodiment 3

[0043] The reduction test of embodiment 3 4-nitro-dichloroaniline

[0044] Weigh respectively 6.4 grams (0.03mol) of 4-nitro-2,5-dichloroaniline, 128 grams (2.64mol) of 95% ethanol, 1.2 grams of ferric chloride and activated carbon (mass ratio 1: 5), and put into In a 250ml four-neck flask equipped with a stirring, reflux condenser, and a thermometer, stir and heat up to reflux, add 3.6 grams (0.061mol) of 85% hydrazine hydrate, and keep refluxing for two hours. Cool to 60°C and filter, collect the filtrate and distill ethanol out (ethanol recovery is applied mechanically, the recovery rate is 80%), add an appropriate amount of water to the material, cool and crystallize, filter, wash and drain, and dry at 78-80°C to obtain 2. 3.0 g of 5-dichloro-p-phenylenediamine, 93% yield, 99.6% measured by HPLC, M.P.164-165°C.

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Abstract

The process of preparing 2, 5-dichloro-p-phenylene diamine adopts 2, 5-dichloroaniline as main material, and includes four reaction steps of acylation, nitration, hydrolysis and reduction. The present invention has improved acylation reaction performed in halogenated hydrocarbon as solvent, and improved catalytic reduction of hydrazine hydrate with the catalyst ferric chloride and active carbon performed in alcohol as solvent. The improved process has no exhausted waste acid effluent from acylation reaction and waste iron slime from reduction, high product yield, mild reaction condition, high product purity and low production cost, and is suitable for industrial production.

Description

technical field [0001] The invention belongs to the technical field of chemical intermediate synthesis, and in particular relates to a preparation method of 2,5-dichloro-p-phenylenediamine. technical background: [0002] 2,5-dichloro-p-phenylenediamine is an important organic synthesis intermediate, which can be used in the synthesis of dyes and pigments, and can also be widely used in the production of photographic chemicals, polymers, hair dyes, etc. [0003] Regarding the preparation method of 2,5-dichloro-p-phenylenediamine, due to the use of different starting materials, various methods have been reported in the literature. In consideration of the source of raw materials, usually 2,5-dichloroaniline is used as a raw material to prepare 2,5-dichloro-p-phenylenediamine through acylation, nitration, hydrolysis and reduction in four steps (see Zygmunt Boruszczak & Jan Kraska, Dye and pigment. Vol. 36. No. 4, pp. 339-342, 1998). [0004] The purpose of the first acylation ...

Claims

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Application Information

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IPC IPC(8): C07C211/52C07C209/36
Inventor 费振荣顾乃祁
Owner 上海染料研究所有限公司
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