Fipronil Synthesis Using Trichloroacetic Acid Solvent
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Solution Overview
Problem
The commercial production of Fipronil, an important insecticide, is hindered by the use of corrosive and expensive trifluoro acetic acid, which causes equipment corrosion and significant economic burdens due to recovery and processing challenges.
Innovation Solution
Substituting trifluoro acetic acid with trichloro acetic acid, utilizing hydrogen peroxide as an oxidizing agent, and incorporating a melting point depressant like dichloro acetic acid to facilitate the oxidation process, making the process more economical and reducing corrosion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trifluoro acetic acid is used as solvent, then the oxidation reaction proceeds effectively, but equipment corrosion occurs and economic costs increase
Solution Approach 1:
The patent replaces expensive trifluoro acetic acid with cheaper trichloro acetic acid as the solvent medium. Although trichloro acetic acid has a higher melting point, it achieves the same oxidation effectiveness at lower cost and with reduced corrosion, making it a more economical disposable solvent option.
Solution Approach 2:
The patent changes the physical state parameter of the solvent system by using a eutectic mixture of trichloro acetic acid and melting point depressant. This parameter change allows the solid trichloro acetic acid to function as an effective liquid-like solvent medium at reaction temperature, achieving both cost reduction and corrosion mitigation while maintaining oxidation effectiveness.
2Ease of manufacture
If trichloro acetic acid is used as solvent, then cost is reduced and corrosion is minimized, but the solvent is solid at room temperature and less effective
Solution Approach 1:
The patent introduces a melting point depressant as an intermediary substance that modifies the physical properties of trichloro acetic acid. This intermediary agent lowers the melting point of the solvent system, enabling trichloro acetic acid to function effectively as a liquid-like medium at reaction temperature while maintaining its cost and corrosion advantages.
Solution Approach 2:
The patent creates a composite solvent system by combining trichloro acetic acid with a melting point depressant. This composite medium synergistically combines the cost-effectiveness and low corrosion properties of trichloro acetic acid with the fluidity-enhancing properties of the melting point depressant, achieving both economic viability and reaction effectiveness.
3Reliability
If melting point depressant is added to trichloro acetic acid, then solvent effectiveness is improved, but process complexity increases
Solution Approach 1:
The patent uses a simple parameter change approach by selecting a melting point depressant that forms a eutectic mixture with trichloro acetic acid at readily achievable ratios. This parameter adjustment (adding a small amount of depressant) achieves the desired solvent effectiveness without requiring complex process equipment or multi-step procedures, thus minimizing process complexity while improving reliability.
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 enables the efficient and cost-effective production of Fipronil with high yield and purity, avoiding corrosion problems and reducing the need for costly corrosion inhibitors, thus making the manufacturing process more viable.
Implementation Method 1
The present invention relates to an improved process of oxidation of 5-amino-1-phenyl-3-cyano-4-trifluoromethyl sulphinyl pyrazoles using an oxidizing agent, preferably hydrogen peroxide
Implementation Method 2
it has been found that this compound can be made to be an effective solvent in the proposed manufacturing process through the use of a compatible melting point depressant
Data Source
AI summary
This invention relates to a process for the preparation of 5-amino-1-phenyl-3-cyano-4-trifluoromethyl sulphinyl pyrazoles as defined by Formula-I,wherein: R1=trifluoromethyl or trifluoromethoxy, and R2, R3=individually hydrogen, chlorine or bromine, the process comprising the step of oxidizing a compound of Formula-II,wherein: R1=trifluoromethyl or trifluoromethoxy, and R2, R3=individually hydrogen, chlorine or bromine, in a medium comprising at least one oxidizing agent and trichloro acetic acid, and/or the reactions product (s) of the at least one oxidizing agent and trichloro acetic acid, and at least one melting point depressant. The preferred pyrazole is Fipronil, preferably prepared using hydrogen peroxide and dichloro acetic acid at room temperature.