Preparation method of 2-bromophenylhydrazine sulfate

一种2-溴苯肼硫酸盐的制备方法

Abstract

本发明涉及一种2-溴苯肼硫酸盐的制备方法,包括重氮化、还原、纯化、成盐的步骤。在重氮化和还原的步骤中,采用浓盐酸保持反应液呈强酸性,保证反应的顺利完全进行。在还原步骤中,采用锌粉-浓盐酸作为还原剂,代替硫代硫酸钠、亚硫酸氢钠、氯化亚锡-盐酸等,不但还原性能好,收率高,缩短反应时间,反应后生成的氢氧化锌等杂质便于去除,使产品杂质少,纯度高。在成盐步骤中用丙酮淋洗,既提高产品的纯度,又保证了产品的外观。本制备方法工艺稳定可靠,易于操作,产品纯度高(高效液相色谱测其含量≥99.2%),收率≥42%,完全满足市场对2-溴苯肼硫酸盐的需要。
The invention relates to a preparation method of 2-bromophenylhydrazine sulfate. The preparation method comprises the following steps of diazotization, reduction, purification and salt formation. In the diazotization and reduction steps, concentrated hydrochloric acid is adopted, so that a reaction liquid is kept to be strong acidic, and the reaction is kept smoothly and completely. In the reduction step, zinc powder and the concentrated hydrochloric acid are used as reducing agents to replace sodium thiosulfate, sodium hydrogen sulfite, stannous chloride and hydrochloric acid and the like, so that good reducing property and high yield are realized, the reaction time is shortened, impurities such as zinc hydroxide and the like generated after the reaction are convenient to remove, and a product is few in impurities and high in purity. In the salt formation step, acetone is used for leaching, so that not only is the purity of the product increased, but also the appearance of the product is ensured. The preparation method is stable and reliable in process, easy to operate, high in product purity (larger than or equal to 99.2% measured by a high performance liquid chromatography), high in yield (larger than or equal to 42%) and capable of completely meeting the requirement of the market for 2-bromophenylhydrazine sulfate.

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