Preparation of 4-Methylbenzenesulfonhydrazide

At present, the synthesis method of 4-Methylbenzenesulfonhydrazide is mainly prepared by reacting p-toluenesulfonyl chloride with hydrazine hydrate (or hydrazine salt) in a benzene medium, and the process steps are as follows:

Hydrazine hydrate is diluted with water to form a 10% aqueous solution, put into an enamel reactor, and sulfuric acid is added under stirring to react to generate a hydrazine sulfate solution. After benzene and p-toluenesulfonyl chloride are stirred and dissolved, they are added to the reactor and mixed with hydrazine sulfate, and stirred continuously at room temperature to cause a condensation reaction to generate p-toluenesulfonyl hydrazide. Because p-toluenesulfonyl hydrazide is insoluble in benzene and only slightly soluble in water, it precipitates as a solid. The hydrogen chloride produced during the reaction is drawn out and absorbed by water to obtain hydrochloric acid as a byproduct. After the p-toluenesulfonyl hydrazide generation reaction is complete, the stirring is stopped, the reaction product is filtered, and the filtrate is allowed to stand for stratification. The upper layer is benzene and can be recycled, and the water layer recovers the unreacted hydrazine sulfate. The filter cake is washed with water to remove the acid and water-soluble substances, and then dehydrated and dried at about 60°C to obtain the finished product.