Method for preparing maleic hydrazide

Abstract

The invention discloses a method for preparing maleic hydrazide. The method is characterized in that after dilute sulfuric acid reacts with hydrazine hydrate to produce a hydrazine sulfate water solution, the hydrazine sulfate water solution conducts cyclization reaction with maleic anhydride under the effect of an organic acid catalyst and is then neutralized to a pH (hydrogen ion concentration) value of 5.0 to 7.0 by using an inorganic base; after the hydrazine sulfate water solution is washed and dried, the maleic hydrazide is acquired; the temperature at which the cyclization reaction is conducted is 70 DEG C to 96 DEG C, and the reaction time is 1.0 hour to 4.0 hours; and the molar ratio of hydrazine hydrate to organic acid catalyst to sulfuric acid to maleic anhydride is 1 to 0.01-0.3 to 1.0-3.0 to 1.0-1.5. The method disclosed by the invention has the advantages that the operation is safe, simple and convenient, the yield is high, the product quality satisfies the international standard, so that the method is very suitable for industrialized production.

Description

A kind of preparation method of maleic hydrazide technical field The invention relates to a preparation method of a selective and temporary plant growth inhibitor, in particular to a preparation method of maleic hydrazide. Background technique The maleic hydrazide of nafloxacin, referred to as MH, also known as Yiyadan, the chemical name is maleic hydrazide, which is a selective and temporary plant growth inhibitor, and the drug can enter through the cuticle of the leaf surface. For plants, it can inhibit the cell division of plants and reduce the photosynthetic effect, thereby strongly inhibiting the formation of buds and the growth of stems, improving cold resistance, and inhibiting the growth of tobacco axillary buds and the germination of potatoes, potatoes, onions, etc. during storage. At present, the process route for synthesizing maleic hydrazide is mainly prepared by reacting maleic anhydride and hydrazine hydrate in solvents such as water, ethanol, acetic acid an...

AI Technical Summary

Problems solved by technology

Due to the incomplete reaction of the traditional method, the amount of residual hydrazine in maleic hydrazide is very high, it is difficult to meet the above requirements, and it is difficult for domestic products to meet the requirements of the international market. Therefore, it is very hopeful to have a more advanced method to increase the yield and reduce the cost.

Images