A method of cleaning and recovering sildenafil citrate mother liquor

Abstract

The invention provides a method for performing clean recovery on a sildenafil citrate mother liquor. Based on a production process in the prior art, the method comprises the steps of concentrating and separating a primary crystallization mother liquor by using a nanofiltration membrane to obtain a concentrated liquid; separating the concentrated liquid to obtain an initial reaction material-sildenafil, wherein the content of sildenafil reaches 99.80% and the purity of sildenafil reaches 99.97%; and directly discharging a residual nanofiltration dialysis fluid into a rectifying tower, and recovering an organic solvent-ethanol through a vapor permeation membrane. According to the clean environment-friendly recycling process for the sildenafil citrate mother liquor, the difficult problem in nearly 100% recycling of the initial material-sildenafil is solved, the heavy environmental protection burden of production enterprises is eliminated, the potential considerable economic benefits are brought for producers, and very high economic and social values are achieved.

Description

technical field [0001] The invention belongs to the technical field of medicinal chemistry, and more particularly relates to a method for cleaning and recycling sildenafil citrate mother liquor. Background technique [0002] Sildenafil citrate (Sildenafil citrate), chemical name is 5-[2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl)phenyl]-1-methyl-3 - n-Propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7one citrate, a selective inhibitor of V-type cGMP phosphodiesterase in human cavernosal. Sildenafil citrate, as an oral drug, can effectively treat erectile dysfunction, and it has achieved good clinical results. [0003] The existing sildenafil citrate synthesis process can be summarized as the following two in general: [0004] One is 2-ethoxybenzoyl chloride and compound 4-[2-ethoxybenzamido]-1-methyl-3-n-propyl-5-carboxamide after oxidative cyclization, sulfonyl chloride Sildenafil citrate is obtained by sulfonamization, sulfonamidation and salt formation. In this synthesis ...

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Problems solved by technology

In order to improve the yield and purity of the synthetic product according to this synthesis method, in the patent application with the application number 201410620801.8 and the name "Preparation Method of Sildenafil Citrate", through the chlorosulfonation reaction of thionyl chloride, etc. , using chemical methods to improve the yield and purity of the product, but it is impossible to realize the economic and environmental recovery of the active ingredients in the mother liquor, let alone the efficient and energy-saving recovery of the organic solvent in the mother liquor

[0006] Therefore, above-mentioned two kinds of synthetic routes all have handling defect on the last salt-forming step, and sildenafil and citric acid part dissociate in the mother liquor, and this can cause the reduction of product yield, and the produced in the production preparation process Wastewater contains too many organic substances, which causes environmental pollution. For example, it is almost impossible to effectively recover sildenafil with economic value by using traditional treatment methods, and the organic solvent ethanol in the mother liquor cannot be economically and effectively recovered, and it will also increase Corporate Environmental Burden

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