Crystalline Candesartan Intermediate Purification via Phase Transition
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Solution Overview
Problem
The existing processes for preparing 1-(cyclohexyloxycarbonyloxy)ethyl 1-((2'-cyanobiphenyl-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate result in an oily-resinoid form, making it difficult to purify and handle, leading to the persistence of impurities in the production of candesartan cilexetil.
Innovation Solution
A crystalline form of 1-(cyclohexyloxycarbonyloxy)ethyl 1-((2'-cyanobiphenyl-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate is achieved through a process involving dissolution in an unpolar organic solvent, optional heating and cooling, followed by crystallization, to produce a stable form suitable for transforming into candesartan cilexetil without impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the compound is prepared using conventional methods, then the reaction can be completed, but the product is obtained in oily-resinoid form which is difficult to purify and handle
Solution Approach 1:
The patent changes the physical state parameter of the product from oily-resinoid to crystalline form by controlling the purification process. The compound is dissolved in a suitable solvent and subjected to crystallization by controlling temperature and filtration, transforming it into a stable crystalline form that is easy to purify and handle.
Solution Approach 2:
The patent utilizes phase transition from liquid (oily-resinoid) to solid (crystalline) state. Through controlled cooling and filtration during the purification process, the compound undergoes phase transition to form stable crystals, which fundamentally changes its physical properties and makes it easier to manipulate and purify.
2Reliability
If the compound is obtained in oily form, then the reaction yield can be achieved, but impurities persist and complicate further transformation
Solution Approach 1:
The patent extracts and removes impurities from the oily-resinoid product through crystallization process. By dissolving the compound in a suitable solvent and controlling crystallization, pure crystals are formed while impurities remain in the mother liquor or are filtered out, achieving high purity that facilitates efficient subsequent transformation.
Solution Approach 2:
The patent changes the physical state parameter to crystalline form, which inherently provides better purity and stability. The crystalline structure allows for effective separation from impurities through filtration and recrystallization, ensuring high purity that is essential for efficient transformation into the final product.
3Ease of operation
If the compound is in crystalline form, then it is easy to purify and handle, but requires additional purification steps
Solution Approach 1:
The patent changes the physical state parameter to crystalline form, which fundamentally improves ease of handling. Crystalline compounds are solid, stable, and can be easily manipulated, filtered, and stored compared to oily-resinoid forms. The crystallization process, while requiring some steps, is a standard and well-controlled procedure that ensures product quality.
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 crystalline form enables efficient and straightforward transformation into candesartan cilexetil, reducing impurities and facilitating the production of a stable solid pharmaceutical composition for treating hypertension and related conditions.
Implementation Method 1
A crystalline form of 1-(cyclohexyloxycarbonyloxy)ethyl 1-((2'-cyanobiphenyl-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate is achieved through a process involving dissolution in an unpolar organic solvent, optional heating and cooling, followed by crystallization
Data Source
Figure 1
AI summary
The present invention relates to 1-(cyclohexyloxycarbonyloxy)ethyl 1-((2'-cyanobiphenyl-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate in crystalline form and a process for its preparation, which is useful intermediate in the preparation of candesartan cilexetil. The present invention also relates to the preparation of candesartan cilexetil and pharmaceutical composition comprising candesartan cilexetil.