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Preparation method of 4-chlorophenylhydrazine hydrochloride

A technology of chlorophenylhydrazine hydrochloride and p-chloroaniline, which is applied in the field of preparation of p-chlorophenylhydrazine hydrochloride, can solve the problems of high solubility of ammonium chloride and ammonium bisulfate, late crystallization of products, loose crystallization of products, etc. , to achieve the effect of high solubility, good fluidity and loose crystallization

Inactive Publication Date: 2013-03-27
天津市天川化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The main purpose of the present invention is to overcome the above-mentioned shortcoming that existing product exists, and provide a kind of preparation method of p-chlorophenylhydrazine hydrochloride, adopt aqueous solution of ammonium sulfite as reductant, overcome existing technology and use sodium sulfite solid to feed and easy to condense The defect that the block is not easy to operate; the ammonium chloride and ammonium bisulfate generated in the acidification reaction have a high solubility in water, which makes the crystallization of the product late, which is beneficial to the acidification reaction in the solution and reduces side reactions; the product crystallization is loose and has good fluidity. Easy to discharge and wash, effectively improve product quality and yield

Method used

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preparation example Construction

[0014] The preparation method of p-chlorophenylhydrazine hydrochloride of the present invention, it comprises the steps:

[0015] (1) For diazotization reaction, put p-chloroaniline into water, start stirring, add hydrochloric acid solution dropwise and then heat up to 60±5°C. After the p-chloroaniline hydrochloride is completely dissolved, cool down to 5-10°C, and then drop The weight percent concentration is 20% sodium nitrite aqueous solution, the end point of dropping is that the starch kI test paper turns blue, and the temperature is maintained for 1 hour, and the pH of the reaction solution is 1 to 2, and the diazonium chloride-p-chlorobenzene aqueous solution is obtained;

[0016] (2) Reduction reaction, under normal temperature conditions, add dropwise the diazonium chloride p-chlorobenzene aqueous solution obtained in the diazotization reaction to the ammonium sulfite aqueous solution, control the pH=6.5 to 8, the reaction solution is yellow and turbid, after dropping,...

Embodiment

[0020] (1) Add 82kg of tap water to the reaction tank, then add 38.7kg of p-chloroaniline, start stirring, dropwise add 106kg of hydrochloric acid solution with a concentration of 31% by weight, after the drop is completed, heat up to 60°C, and wait for p-chloroaniline hydrochloride After all dissolved, cool down to 10°C, at this time, small crystals of p-chloroaniline hydrochloride can be seen; then dropwise add sodium nitrite aqueous solution (sodium nitrite 21.5kg) with a concentration of 20% by weight, and the end point of the addition is starch kI The test paper turns blue, keep the temperature of the reaction system at 8±2°C, keep it warm for 1 hour, keep the pH of the reaction system at 1 to 2, and obtain diazo-p-chlorobenzene chloride.

[0021] (2) At normal temperature, put 250 kg of ammonium sulfite aqueous solution into the reaction tank, containing 750 mol of ammonium sulfite, and drop the diazonium chloride-p-chlorobenzene aqueous solution obtained in step (1) into...

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PUM

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Abstract

The invention provides a preparation method of 4-chlorophenylhydrazine hydrochloride. The preparation method of the 4-chlorophenylhydrazine hydrochloride includes a diazotization reaction, a reduction reaction and an acidizing reaction. The diazotization reaction includes throwing 4-chlorophenylhydrazine to water; dropping hydrochloric acid to enable the 4-chlorophenylhydrazine hydrochloride to dissolve completely; and dropwise adding a sodium nitrite aqueous solution to obtain a chlorination diazonium parachloroaniline aqueous solution. The reduction reaction includes dropwise adding the chlorination diazonium parachloroaniline aqueous solution to an ammonium sulfite aqueous solution and obtaining diazonium parachloroaniline disulfonate. The acidizing reaction includes dropping the hydrochloric acid to the diazonium parachloroaniline disulfonate; filtering; washing; discharging; stoving; and obtaining a 4-chlorophenylhydrazine hydrochloride end product. The preparation method of the 4-chlorophenylhydrazine hydrochloride is easy to operate by using the sodium nitrite aqueous solution as a reducing agent; and the product seeds out late and side reactions are reduced due to the fact that ammonium chloride and ammonium bisulfate generated in the acidizing reaction have high solubility in the water; and furthermore product quality and product yields are improved effectively due to the fact that the product is incompact in crystallization, good in flow-ability and easy to discharge and wash.

Description

technical field [0001] The invention relates to a preparation method of p-chlorophenylhydrazine hydrochloride. Background technique [0002] p-Chlorophenylhydrazine hydrochloride is an important pharmaceutical and pesticide intermediate. The existing preparation method of p-chlorophenylhydrazine hydrochloride uses p-chloroaniline as raw material, and obtains p-chlorophenylhydrazine hydrochloride through the steps of diazotization reaction, sodium sulfite reduction, and acidification and hydrolysis. The specific process flow is as follows: 1. Under acidic conditions, 20% by weight sodium nitrite aqueous solution is added dropwise to p-chloroaniline at 0 to 10° C. to generate diazo-p-chlorobenzene chloride. 2. Under the condition of strong stirring at normal temperature, slowly add sodium sulfite solid into the water, dropwise add the diazonium chloride p-chlorobenzene obtained in step 1, and keep the temperature for 4 hours. 3. Add industrial hydrochloric acid dropwise to t...

Claims

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Application Information

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IPC IPC(8): C07C241/02C07C243/22
Inventor 王怀恩苏玉清薛金枝刘刚
Owner 天津市天川化工有限公司
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