Pyrazole Synthesis Yield and Waste Reduction
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Solution Overview
Problem
Current methods for synthesizing 5-bromo-2-(3-chloro-pyridin-2-yl)-2H-pyrazole-3-carboxylic acid are inefficient, resulting in low yields, high waste production, and complex operation processes, which are not suitable for the production of anthranilamide compounds like chlorantraniliprole and cyantraniliprole.
Innovation Solution
A novel method involving a series of reactions starting from pyrazole derivatives, including halogenation and carboxylation steps, using readily available reagents and solvents to achieve a higher yield and simplified synthesis pathway, specifically forming compounds of Formula VI, V, IV, III, II, and VIII, ultimately leading to 5-bromo-2-(3-chloro-pyridin-2-yl)-2H-pyrazole-3-carboxylic acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used for synthesizing 5-bromo-2-(3-chloro-pyridin-2-yl)-2H-pyrazole-3-carboxylic acid, then the synthesis can be performed with existing procedures, but the overall yield is low and waste production is high
Solution Approach 1:
The synthesis is divided into distinct modular stages: (i) formation of pyrazole derivative (Formula VIII) from pyrazole and halogenated carbonyl compound, (ii) bromination to introduce bromine at position 5, (iii) carboxylation to introduce the carboxylic acid group. Each stage is optimized independently to maximize yield and minimize waste, allowing for better material utilization throughout the synthesis pathway.
Solution Approach 2:
The patent employs specific parameter optimizations including temperature control during bromination and carboxylation steps, selection of appropriate solvents and bases (e.g., using K2CO3 or Cs2CO3 in DMF or NMP), and stoichiometric control of reagents. These parameter changes collectively improve reaction efficiency and reduce material loss.
2Ease of manufacture
If conventional synthesis methods are used, then existing procedures can be followed, but the operation complexity is high
Solution Approach 1:
The patent merges multiple functional group introductions into a streamlined sequence where bromination and carboxylation are performed in succession on the same pyrazole intermediate without requiring isolation of multiple intermediates. This consolidation reduces the number of separate operational steps and simplifies the overall manufacturing process while maintaining high yields.
Solution Approach 2:
The pyrazole derivative is pre-formed with the appropriate substituents (Formula VIII) before the final bromination and carboxylation steps. This preliminary preparation of the core structure allows subsequent steps to proceed more efficiently with fewer operational complexities, as the basic framework is already in place.
3Ease of manufacture
If existing synthesis routes are used, then current knowledge can be applied, but the cost is high
Solution Approach 1:
The synthesis employs readily available commercial reagents such as pyrazole, halogenated carbonyl compounds, bromine sources (NBS or Br2), and carbonate bases that can be purchased off-the-shelf. This self-service approach eliminates the need for expensive custom-synthesized intermediates or specialized reagents, significantly reducing overall manufacturing cost while maintaining efficiency.
Solution Approach 2:
The patent uses inexpensive, easily disposable reagents and solvents (DMF, NMP, dichloromethane) that can be readily replaced without significant cost penalty. The high atom economy and yield of each step mean that reagent consumption is minimized, making the process cost-effective even with multiple transformation steps.
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 a 50% overall yield with reduced waste and operational complexity, making it more efficient and cost-effective for producing anthranilamide compounds.
Implementation Method 1
reacting the mixture with a halogenation reagent
Implementation Method 2
reacting the mixture with carbon dioxide
Implementation Method 3
a base comprising a compound comprising a metal
Data Source
AI summary
Described herein are novel methods of synthesizing 5-Bromo-2-(3-chloro-pyridin-2-yl)- 2H-pyrazole-3-carboxylic acid from pyrazole or pyrazole derivatives.