Valsartan Refining via pH-Adjusted Extraction
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Solution Overview
Problem
Current methods fail to effectively recover valsartan with a pharmaceutically eligible configuration from mother liquor containing high levels of D-isomers, typically above 10%, 20%, or 30%, as existing techniques are inefficient and unable to reduce D-isomer content to acceptable levels.
Innovation Solution
A refining method involving the use of a mixed solvent system, such as acetonitrile/water or methanol/water, with an inorganic base like NaOH, followed by pH adjustment and extraction with an organic solvent like ethyl acetate, to crystallize and concentrate valsartan, thereby reducing D-isomer content to less than 0.5%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If crystallization is used to obtain valsartan with fewer isomers, then the purity of L-isomer is improved, but the D-isomer content in mother liquor increases to more than 10%
Solution Approach 1:
The patent changes the chemical parameters of the mother liquor by adding inorganic base to adjust pH, followed by acidification to pH 2-4. This parameter change transforms the chemical environment to enable effective separation and removal of D-isomers through extraction, converting the harmful high D-isomer content into an opportunity for purification.
Solution Approach 2:
The patent extracts D-isomers from the mother liquor using organic solvents after pH adjustment. The D-isomer is selectively extracted into the organic phase, separating it from the L-isomer in the aqueous phase. This extraction process effectively removes the harmful D-isomer component while preserving the valuable L-isomer.
2Ease of manufacture
If no refining method is applied to mother liquor with high D-isomer content, then the process is simple, but the recovery of pharmaceutically eligible valsartan is inefficient
Solution Approach 1:
The patent performs preliminary pH adjustment by adding inorganic base before the main extraction step. This preliminary action modifies the chemical environment to optimize subsequent extraction efficiency, ensuring that D-isomers are in the appropriate form for effective separation. This preparatory step enables high recovery efficiency without significantly complicating the overall process.
Solution Approach 2:
The patent uses inorganic base and acid as intermediary substances to mediate the pH adjustment process. These intermediaries facilitate the transformation of valsartan between different ionization states, enabling effective separation. The intermediaries are easily removable and do not complicate the process, maintaining ease of manufacture while dramatically improving productivity.
3Ease of operation
If conventional methods are used to handle mother liquor with more than 10% D-isomers, then the process is straightforward, but the yield of refined valsartan is insufficient
Solution Approach 1:
The patent employs periodic action through multiple extraction steps and controlled pH adjustments. The process involves sequential operations: adding inorganic base, filtering, adding acid to adjust pH, extracting with organic solvent, and repeating if necessary. This periodic approach systematically increases yield while maintaining operational simplicity through standardized, repeatable steps.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining the valsartan in solution throughout the process and performing extraction in sequence rather than discarding intermediate materials. The mother liquor is continuously processed through pH adjustment and extraction, maximizing recovery yield without interrupting the operational flow or requiring complex batch processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly reduces D-isomer content to less than 0.5% while achieving a yield of over 40% with low recovery costs, making it suitable for industrial production and environmentally friendly.
Implementation Method 1
adding a certain amount of inorganic base, separating solids out after salification
Implementation Method 2
adjusting the pH of the filtrate with an acid, extracting with an organic solvent
Implementation Method 3
extracting with an organic solvent
Implementation Method 4
cooling to crystallize, and obtaining the product
Data Source
AI summary
The present invention relates to a method of refining valsartan comprising more than or equal to 10% D-isomers, the method comprising: adding a solvent to valsartan comprising more than or equal to 10% D-isomers to dissolve it, then adding a certain amount of inorganic base, separating solids out after salification, distilling a filtrate after filtration, and distilling the filtrate to remove the organic solvent; adjusting the pH of the filtrate with an acid, extracting with an organic solvent, concentrating most of the organic solvent, cooling to crystallize, and obtaining the product. The method enables isomers of the product to be below 0.5%, and produce a yield of more than or equal to 40%, being suitable for industrial production.