Asenapine Maleate Crystallization via Phosphate Salt Conversion
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Solution Overview
Problem
Current methods for purifying asenapine, particularly in industrial scales, face challenges with low yields and impurity issues due to its oil-like nature and limited crystallization capabilities, making it difficult to obtain high-purity crystalline forms of asenapine maleate.
Innovation Solution
The development of asenapine phosphate, which is synthesized through treatment of crude asenapine with phosphoric acid in organic solvents, resulting in a high-purity, crystalline form with improved filterability and stability, and subsequent conversion to a novel monoclinic polymorphic form of asenapine maleate with enhanced chemico-physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If asenapine is purified by conventional crystallization methods, then some purification is achieved, but the yield is low and purity is insufficient due to its oil-like nature
Solution Approach 1:
The patent changes the chemical parameter by converting asenapine base into asenapine phosphate salt through reaction with phosphoric acid. This parameter change transforms the oil-like asenapine base into a crystalline salt form that can be effectively purified by crystallization, thereby achieving both high purity and high yield simultaneously
Solution Approach 2:
The patent utilizes phase transition by converting asenapine from its oil phase (base form) to solid crystal phase (phosphate salt form). This phase transition enables the application of crystallization techniques for purification, resolving the contradiction between achieving high purity and maintaining high yield
2Ease of manufacture
If asenapine base is used directly, then no salt conversion is needed, but it cannot be purified by crystallization and remains impure
Solution Approach 1:
The patent applies parameter change by converting asenapine base to asenapine phosphate salt, enabling crystallization-based purification. The process simplicity is maintained through a straightforward acid-base reaction followed by crystallization, achieving both ease of manufacture and high purity
3Manufacturing precision
If conventional purification methods are used, then some impurities are removed, but filterability is poor and stability is insufficient
Solution Approach 1:
The patent utilizes phase transition to convert asenapine from oil phase to crystalline solid phase through salt formation. The crystalline structure of asenapine phosphate provides excellent filterability and enhanced stability, resolving the contradiction between purification effectiveness and operational ease
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
This approach allows for the production of asenapine maleate with high yields and purity exceeding 99.5%, along with improved stability and filterability, facilitating its use in pharmaceutical compositions.
Implementation Method 1
asenapine phosphate, which is synthesized through treatment of crude asenapine with phosphoric acid
Implementation Method 2
the product is characterised by crystallinity, high HPLC purity (exceeding 99.5%), excellent filterability
Implementation Method 3
its use to prepare asenapine maleate
Data Source
AI summary
Disclosed is asenapine phosphate of formula (I) and its enantiomer (I) which can be used to prepare asenapine maleate. Further disclosed is a monoclinic crystalline form of asenapine maleate.