Ropinirole Hydrochloride Purification Process
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Solution Overview
Problem
Current processes for purifying Ropinirole hydrochloride are costly, not feasible on an industrial scale, and utilize hazardous reagents, posing safety risks and environmental concerns.
Innovation Solution
A process involving the use of sodium dithionate as a bleaching agent and activated charcoal to remove colored impurities, followed by trituration and reaction with a base in a water-immiscible solvent, then treatment with ethanolic HCl to achieve high purity Ropinirole hydrochloride, utilizing less hazardous reagents and improving yield and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If crystallization from hot acetonitrile is used to purify Ropinirole hydrochloride, then purity is improved, but production cost increases and industrial scalability deteriorates due to excessive solvent volume required
Solution Approach 1:
The patent changes the purification parameters by replacing hot acetonitrile crystallization with a base treatment method using water-immiscible solvents. The process treats the crude compound with a base in a water-immiscible solvent to form a salt, separates the salt from colored impurities, and then acidifies to recover the pure compound. This parameter change eliminates the need for excessive solvent volumes while achieving high purity.
Solution Approach 2:
The patent extracts colored impurities from the crude Ropinirole hydrochloride through selective base treatment. By forming a salt with the base, the colored impurities remain in the organic layer while the pure salt forms in the aqueous layer, allowing separation and purification without requiring large volumes of crystallization solvent.
2Manufacturing precision
If hazardous reagents like hydroxylamine hydrochloride, phenyl hydrazine, or hydrazine are used for purification, then purity is improved, but safety risks and environmental harm increase
Solution Approach 1:
The patent employs readily available, less hazardous bases such as sodium hydroxide, potassium hydroxide, or ammonia for the purification process. These common, inexpensive bases effectively remove colored impurities without the severe safety risks associated with hydroxylamine hydrochloride, phenyl hydrazine, or hydrazine, while maintaining high product purity.
Solution Approach 2:
The patent converts the harmful effect of colored impurities into a beneficial separation process. By using base treatment, the colored impurities are selectively removed through formation of water-soluble salts, transforming what was a contamination problem into an effective purification mechanism that enhances product quality while using safer reagents.
3Manufacturing precision
If conventional purification methods are used, then purity is achieved, but production cost increases due to excessive solvent consumption and hazardous reagent requirements
Solution Approach 1:
The patent fundamentally changes the purification parameters by using water-immiscible solvents with base treatment instead of conventional hot acetonitrile crystallization. This approach requires significantly less solvent volume while achieving the same purity level, thereby reducing solvent consumption and associated costs.
Solution Approach 2:
The patent employs a multi-functional base treatment process that simultaneously achieves several objectives: removing colored impurities, separating from non-dopaminergic metabolites, and purifying the final product. This single process step performs multiple purification functions that would otherwise require multiple separate operations with additional solvents.
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 process achieves a purity of above 99.7% with quantitative yield, making it suitable for industrial-scale production while minimizing the use of hazardous substances and reducing production costs.
Implementation Method 1
treating Ropinirole hydrochloride with sodium dithionate and charcoal in suitable alcoholic solvent
Implementation Method 2
treating Ropinirole hydrochloride with sodium dithionate and charcoal in suitable alcoholic solvent
Implementation Method 3
reacting the triturated solid with base in water immiscible solvent and isolating the free base
Implementation Method 4
treating the free base obtained in step (iii) with ethanolic HCl to give Ropinirole hydrochloride
Data Source
AI summary
The present invention provides an improved process for the purification of Ropinirole hydrochloride of formula (Ia) comprising steps of: (i) treating Ropinirole hydrochloride with sodium dithionate and charcoal in suitable alcoholic solvent; (ii) triturating Ropinirole hydrochloride obtained in step (i) with ethanol; (iii) reacting the triturated solid with base in water immiscible solvent and isolating the free base; (iv) treating the free base obtained in step (iii) with ethanolic HCl to give Ropinirole hydrochloride.