A method for improving the yield and purity of crude alprazolam

Abstract

The present application provides a preparation method for improving the yield and purity of crude alprazolam. First, benzodiazepine and acetylhydrazine undergo hydrazinolysis and cyclization reaction in n-butanol to obtain an n-butanol solution with alprazolam as the main solute. After the reaction is completed, a specific amount of n-butanol is distilled under reduced pressure. Then, the temperature is lowered for crystallization, filtration, and elution with a mixed solvent composed of n-butanol and a solvent that is miscible with n-butanol in a specified ratio to obtain crude alprazolam with higher yield and purity. The method is simple to operate, the amount of n-butanol solvent distilled is controlled to ensure the yield of alprazolam, and the selection of the mixed washing solvent ensures the removal of various impurities.

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