Esomeprazole Optical Resolution via Inclusion Complex Crystallization
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Solution Overview
Problem
Existing methods for preparing optically pure esomeprazole are inefficient due to the need for excessive and expensive optical resolution agents, use of toxic solvents, coloration issues, unsuitable chromatography for mass production, and low optical purity, leading to yield reduction and additional purification requirements.
Innovation Solution
A method involving dissolving (S)-(-)-binol and racemic omeprazole in a water-compatible organic solvent and water mixture, followed by crystallization and filtration to form an inclusion complex, which is then treated with a weak base to remove the binol moiety, reducing the amount of binol required and avoiding toxic solvents, resulting in a high optical purity of at least 98% ee without further purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If (S)-(-)-binol is used in excess amount (1.5 mole equivalents) to obtain high optical purity, then the optical purity of esomeprazole is improved, but the production cost increases due to expensive optical resolution agent
Solution Approach 1:
The patent changes the physical-chemical parameters of the resolution system by introducing a water-compatible organic solvent mixture and controlling temperature (30-70°C dissolution followed by cooling to -5°C to room temperature), which improves the efficiency of (S)-(-)-binol in resolving racemic omeprazole, allowing lower binol usage while maintaining high optical purity
Solution Approach 2:
The patent utilizes phase transition through controlled cooling of the reaction mixture from dissolution temperature (30-70°C) to crystallization temperature (-5°C to room temperature), which promotes selective crystallization of the inclusion complex and improves resolution efficiency, reducing the need for excess binol
2Reliability
If benzene is used as solvent to perform the resolution reaction, then the reaction proceeds effectively, but toxicity issues arise due to benzene being a Class I carcinogenic solvent
Solution Approach 1:
The patent replaces toxic benzene with water-compatible organic solvents (such as methanol, ethanol, isopropanol, acetone, acetonitrile, or their mixtures with water) that are less toxic and can be easily removed, maintaining reaction effectiveness while eliminating carcinogenic risks
Solution Approach 2:
The patent changes the solvent system parameters from pure benzene to water-compatible organic solvent mixtures, adjusting solubility and crystallization properties to maintain effective resolution while eliminating toxicity concerns
3Reliability
If the inclusion complex is formed using conventional methods, then the resolution reaction occurs, but the solution becomes pitch-black requiring decolorization steps that complicate the process
Solution Approach 1:
The patent changes the reaction parameters by using water-compatible organic solvents and controlling temperature (30-70°C dissolution, then cooling to -5°C to room temperature for crystallization), which prevents pitch-black coloration while maintaining effective inclusion complex formation, eliminating the need for decolorization steps
4Manufacturing precision
If chromatography is used to remove (S)-(-)-binol from the inclusion complex, then the binol is removed effectively, but the method is not suitable for mass production due to high cost and complexity
Solution Approach 1:
The patent employs extraction methods using water-compatible organic solvents to remove (S)-(-)-binol from the inclusion complex, replacing chromatography with a simpler, more scalable extraction process that is suitable for mass production while maintaining effective binol removal
Solution Approach 2:
The patent changes the separation methodology from chromatography to extraction/crystallization by adjusting solvent system parameters and temperature, achieving effective binol removal through phase separation that is economically viable for large-scale production
5Manufacturing precision
If conventional optical resolution methods are used, then the resolution process occurs, but the optical purity is only about 90% ee requiring further purification that lowers the overall yield
Solution Approach 1:
The patent changes the resolution parameters by using water-compatible organic solvents and precise temperature control (dissolution at 30-70°C, crystallization at -5°C to room temperature), which improves optical purity to ≥98% ee in a single step, eliminating the need for additional purification that would reduce yield
Solution Approach 2:
The patent utilizes controlled phase transitions through temperature-dependent solubility changes, dissolving at elevated temperatures (30-70°C) and crystallizing at lower temperatures (-5°C to room temperature), which enhances the selectivity of the resolution process and achieves high optical purity with improved overall yield
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 achieves high optical purity of esomeprazole and its salt with reduced costs, eliminates coloration issues, and allows for efficient recycling of the binol optical resolution agent, meeting pharmaceutical purity standards.
Implementation Method 1
reacting the racemic form of omeprazole with (S)-(−)-binol (a levorotatory isomer of β-binaphthol) as an optical resolution agent to form the inclusion complex of esomeprazole and (S)-(−)-binol
Implementation Method 2
cooling the resulting solution to a temperature of −5° C. to room temperature to allow the crystallization of the inclusion complex of esomeprazole and (S)-(−)-binol
Data Source
AI summary
Optically pure esomeprazole and its salt can be simply prepared by dissolving (S)-(−)-binol, a weak base and the racemic form of omeprazole in a mixture of a water-compatible organic solvent and water at a high temperature, cooling the mixed solution to crystallize the inclusion complex of esomeprazole and (S)-(−)-binol, and removing the (S)-(−)-binol moiety from the crystallized inclusion complex.