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Preparation method for 4-chlorophenylhydrazine hydrochloride

A technology of chlorophenylhydrazine hydrochloride and chloroaniline hydrochloride, which is applied in the field of preparation of p-chlorophenylhydrazine hydrochloride, can solve the problems of poor washing and sticky crystals, achieve high solubility, late crystallization, and reduce The effect of production costs

Inactive Publication Date: 2014-07-09
TIANJIN QIDONG CHEM PLANT
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] 3. The crystal is sticky and not easy to wash

Method used

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Embodiment 1

[0028] A preparation method of p-chlorophenylhydrazine hydrochloride, comprising the steps of:

[0029] 1) Diazotization reaction: Put 38.7kg of p-chloroaniline into 82kg of water, start stirring, dropwise add 109kg of hydrochloric acid solution with an amount three times that of p-chloroaniline, after the drop is completed, heat up to 60°C, and wait for p-chloroaniline salt After the acid salt is completely dissolved, lower the temperature to 5-10°C. At this time, fine crystals of p-chloroaniline hydrochloride can be seen. Add 20% sodium nitrite aqueous solution dropwise. At the end of the dropwise addition, the starch kI test paper turns blue. Maintain this temperature and keep the reaction system warm. 1 hour, keep the pH of the system at 1-2;

[0030] 2) Reduction reaction: At room temperature, put 220 kg of ammonium sulfite aqueous solution into the reaction tank, containing 750 mol of ammonium sulfite, and dropwise add the diazonium salt solution obtained in step 1 into ...

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PUM

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Abstract

A provided preparation method for 4-chlorophenylhydrazine hydrochloride comprises the following steps: 1) under an acidic condition, at 5-10 DEG C, dropwise adding a sodium nitrite aqueous solution with a concentration of 20% into 4-chloroaniline to perform a diazo reaction and to generate a diazo salt; 2) under a room temperature condition, dropwise adding an ammonium sulfite aqueous solution into a solution of the diazo salt obtained in the step 1, heating to 50-60 DEG C and keeping the temperature for 3-4 h; and 3) at 50-70 DEG C, dropwise adding a hydrochloric acid solution with a concentration of 20% into the solution obtained in the step 2, keeping the temperature for 1-2 h, reducing the temperature, filtering, washing, discharging the material, and drying to obtain a finished product. The beneficial effects comprise that by using ammonium sulfite aqueous solution as a reducing agent in the reduction reaction, the problems are solved that sodium sulfite solid is easy to cake during material charging in a conventional technology and material charging is not easy to operate; ammonium chloride and ammonium hydrogen sulfate which are generated in the acidification reaction have high solubility in water, and crystallization precipitation is late, thereby facilitating performing of the acidification reaction in the solution and reducing side reactions; and the product crystallizes loosely, is good in fluidity, easy for material discharging and washing, and product quality and yield are both better than conventional production levels.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a method for preparing p-chlorophenylhydrazine hydrochloride. Background technique [0002] p-Chlorophenylhydrazine hydrochloride is an important medicine and pesticide intermediate. In the prior art, p-chloroaniline is used as raw material, and p-chlorophenylhydrazine hydrochloride is prepared through diazotization reaction, sodium sulfite reduction, acidification and hydrolysis. The raw material that adopts is reacted for p-chloroaniline, hydrochloric acid, sodium nitrite, sodium sulfite, and concrete technological process is [0003] 1. P-Chloroaniline is reacted dropwise with 20% sodium nitrite aqueous solution at 0-10°C under acidic conditions to form diazonium salt; [0004] 2. At room temperature, slowly add solid sodium sulfite into water under strong stirring, raise the temperature to 70°C, add diazonium salt dropwise, and keep warm for 4 hours. [0005] 3. Add industr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C243/22C07C241/02
Inventor 马荣洁
Owner TIANJIN QIDONG CHEM PLANT
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