Fipronil Synthesis Using Hydrogen Peroxide Oxidation
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Solution Overview
Problem
Current methods for synthesizing Fipronil, a novel pesticide, are inefficient due to the use of expensive, toxic, or rare oxidizing agents and suffer from poor selectivity, making them unsuitable for commercial-scale production.
Innovation Solution
A process involving the halogenation of aromatic compounds, followed by ammonolysis, halogenation, diazotization, sulfenylation, and oxidation using hydrogen peroxide in a specific solvent system to produce Fipronil, utilizing easily available raw materials and reducing the need for costly reagents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If expensive, toxic, or rare oxidizing agents are used for Fipronil synthesis, then oxidation reaction can proceed, but the process becomes unsuitable for commercial-scale production due to cost and safety concerns
Solution Approach 1:
The patent replaces expensive, toxic, or rare oxidizing agents with hydrogen peroxide, which is a cheap, readily available, and environmentally benign oxidant. This substitution enables commercial-scale production by eliminating the cost and safety concerns associated with traditional oxidizing agents while maintaining effective oxidation of the sulfide to sulfoxide conversion.
2Manufacturing precision
If traditional oxidizing agents are used for Fipronil synthesis, then oxidation can occur, but selectivity is poor leading to by-product formation
Solution Approach 1:
The patent employs trifluoroacetic acid and trichloroacetic acid as oxidation media, which significantly enhance the regioselectivity of the oxidation reaction. These acidic media create favorable reaction conditions that direct the oxidation to the desired sulfide to sulfoxide conversion while minimizing by-product formation, thereby improving manufacturing precision and reducing substance loss.
3Manufacturing precision
If trifluoroacetic acid is used as oxidation medium, then regioselectivity is improved, but recovery becomes complex due to water miscibility and corrosion issues
Solution Approach 1:
The patent addresses the recovery complexity of trifluoroacetic acid by implementing a systematic approach: the reaction mixture is neutralized with a base, allowing the acid to be converted to its salt form for easy separation. The regenerated trifluoroacetic acid can then be recovered and reused, reducing waste and simplifying the overall process despite the acid's water miscibility and corrosive properties.
4Productivity
If 3,4,5-trichlorobenzotrifluoride is synthesized by chlorination of p-chlorobenzotrifluoride, then conversion is achieved, but the process requires tedious fractionation and crystallization to separate isomers
Solution Approach 1:
The patent improves the synthesis of 3,4,5-trichlorobenzotrifluoride by optimizing the chlorination conditions of p-chlorobenzotrifluoride. By carefully controlling reaction parameters such as temperature, catalyst selection, and chlorination sequence, the process favors the formation of the desired 3,4,5-trichloro isomer over other possible isomers. This selective approach reduces the need for extensive fractionation and crystallization steps, thereby simplifying the separation process while maintaining high conversion efficiency.
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 process achieves high yields and purity of Fipronil, overcoming the limitations of existing methods by using commercially available materials and minimizing by-product formation, thus providing a more economical and efficient synthesis route.
Implementation Method 1
oxidation of 5-amino-1-(2,6-dichloro-4-trifluoromethylphenyl)-3-cyano-4-trifluoromethylthio-pyrazole with hydrogen peroxide in the presence of boric acid
Data Source
AI summary
The present disclosure relates to a process for trifluoromethylsulfinyl pyrazole compound of formula I,from a compound of formula III, wherein, R, R1 and R2 represent a group containing halogen group respectively and R3 represents a perhaloalkyl.