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How is phenylhydrazine hydrochloride synthesized

Phenylhydrazine hydrochloride is a solid powder with pink odor and pungent odor at room temperature. It is a highly toxic substance. It is mainly used as an organic intermediate in the dye, pharmaceutical and agrochemical industries. For example, it can produce naphthol g, antipyrine, cationic dyes and developers.

For some small and medium-sized enterprises, due to the limitation of production process conditions, the purity of the product is not high, so the product is mainly used in the pesticide industry. In addition, due to incorrect determination of certain synthesis conditions, the reaction is abnormal, which has a certain impact on the yield and quality of the product.

1 Synthesis process

Phenylhydrazine hydrochloride is prepared by diazotization reaction of aniline and sodium nitrite in acid medium at low temperature to generate diazonium chloride. Then it is reduced with ammonium bisulfite and ammonium bicarbonate to form sodium diazodisulfonate. After acid precipitation, phenylhydrazine hydrochloride is formed. It mainly includes the two-step process of aniline diazotization and diazobenzene chloride.

In a reaction unit in the synthesis of phenylhydrazine, that is, in the process of preparing diazonium chloride from aniline by deamination, abnormal reactions often occur due to improper determination of certain reaction conditions, resulting in the yield and quality of the reaction Have a certain impact. product. Therefore, to determine the ratio of raw material input, the reaction temperature and the feed rate of the sodium nitrite solution are important factors.

The sodium diazobenzene sulfonate produced by the diazonium salt reduction reaction reacts with water to form sodium phenylhydrazine sulfonate, and then reacts with hydrochloric acid to form phenylhydrazine hydrochloride. After adding hydrochloric acid, keep the temperature between 80~85° and stir for 60 minutes. After lowering the temperature, phenylhydrazine hydrochloride can be filtered or dried to obtain the product phenylhydrazine hydrochloride.

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