1 results about "Dichlorobutane" patented technology

This invention relates to the field of pharmaceutical synthesis technology, and in particular to a method for removing viscous impurities during the synthesis of hexahydropyridazine, comprising the following steps: 1,2-dicarboxyhydrazide reacts with 1,4-dichlorobutane in stages under alkaline and potassium bromide catalytic conditions. After the reaction is complete, the mixture is filtered and distilled under reduced pressure to obtain a concentrated tetrahydropyridazine-1,2-dicarboxaldehyde solution. The concentrated tetrahydropyridazine-1,2-dicarboxaldehyde solution is then subjected to ethyl acetate extraction, dehydration and decolorization, cooling for impurity removal, and reduced pressure distillation to obtain purified tetrahydropyridazine-1,2-dicarboxaldehyde. The purified tetrahydropyridazine-1,2-dicarboxaldehyde is dissolved in anhydrous ethanol, and ethanol-hydrochloride is added dropwise while maintaining the temperature for reaction. After the reaction is complete, the mixture is crystallized, filtered, washed, and dried to obtain hexahydropyridazine dihydrochloride. This invention not only reduces and prevents side reactions and effectively removes viscous impurities, but also has low energy consumption and improves the product yield and purity of hexahydropyridazine dihydrochloride.