Green Synthesis of Pyridine Carboxamide via Solvent Substitution
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Solution Overview
Problem
Existing processes for preparing 4-{4-[({[4-chloro-3-(trifluoromethyl)-phenyl]amino}carbonyl)amino]phenoxy}-N-methylpyridine-2-carboxamide and its tosylate salt face challenges in industrial-scale production, including low yields, inefficiency, safety concerns, and environmental impact, particularly in the steps involving solvents like methylene chloride and dimethylformamide.
Innovation Solution
The process involves reacting picolinic acid with thionyl chloride, followed by methylamine in an aqueous solution, then with 4-aminophenol in the presence of a base, and finally with 4-chloro-3-trifluoromethylphenyl isocyanate, using a non-chlorinated solvent and p-toluenesulfonic acid to enhance solubility and purity, while reducing the need for potassium carbonate and methylene chloride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the prior art process using methylene chloride and dimethylformamide is used, then the compound can be prepared, but the process efficiency is low and safety concerns arise
Solution Approach 1:
The patent changes the reaction parameters by replacing methylene chloride with ethyl acetate and dimethylformamide with water/toluene mixtures. This parameter substitution resolves the contradiction by eliminating harmful solvents while maintaining or improving process efficiency through optimized reaction conditions including temperature control and catalyst selection.
Solution Approach 2:
The patent employs readily available, non-hazardous solvents like ethyl acetate and water that can be easily disposed of or recycled, replacing expensive and hazardous solvents. This approach improves safety while maintaining productivity through simplified workup procedures and reduced environmental compliance requirements.
2Quantity of substance
If the prior art process is used, then the compound can be prepared, but the overall yield is low
Solution Approach 1:
The patent implements a continuous multi-step synthesis process where intermediates are carried forward without isolation when possible, and reaction conditions are optimized to ensure high conversion at each step. The use of ethyl acetate as a solvent throughout provides consistent solubility and reaction rates, achieving overall yields exceeding 90% compared to lower yields in the prior art.
3Manufacturing precision
If the prior art process using extraction steps is used, then the compound can be purified, but the process becomes costly and inconvenient
Solution Approach 1:
The patent eliminates the need for complex extraction steps by designing a synthesis route where impurities are naturally separated or converted. The use of ethyl acetate allows for simple filtration and crystallization to achieve high purity products, removing the need for multiple extraction operations with hazardous solvents and making the process much more convenient for industrial manufacture.
4Productivity
If hazardous solvents like methylene chloride are used, then the reaction can proceed, but environmental compatibility deteriorates
Solution Approach 1:
The patent substitutes hazardous solvents with environmentally friendly alternatives like ethyl acetate and water. The reaction efficiency is maintained or improved through optimized temperature profiles, catalyst selection, and stoichiometry control, demonstrating that green chemistry principles can achieve equal or superior productivity compared to traditional hazardous solvent systems.
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 increases overall yield, improves safety, and enhances the environmental compatibility by eliminating costly extraction steps and using less hazardous solvents, resulting in higher purity and increased industrial scalability.
Implementation Method 1
reacting in thionyl chloride with addition of dimethylformamide, to prepare the acid chloride salt
Implementation Method 2
addition of water and/or by precharging the reaction vessel with a definite amount of p-toluenesulfonic acid. Thus, pursuant to GMP production a clarifying filtration is enabled
Data Source
AI summary
The present invention relates to a process for preparing 4-{4-[({[4-chloro-3-(trifluoro-methyl)phenyl]amino}carbonyl)amino]phenoxy}-N-methylpyridine-2-carboxamide and its tosylate salt.