Sulfinylation of Pyrazole Derivative for Fipronil
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Solution Overview
Problem
Current industrial processes for producing fipronil, a crucial insecticide, face challenges such as low yield, impurity issues, and the use of hazardous reagents, particularly CF3Br, which is environmentally toxic and difficult to handle, making large-scale production inefficient and unsafe.
Innovation Solution
A novel sulfinylation process involving 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-1H-pyrazole-3-carbonitrile reacted with a sulfinylating agent and a halogenating agent in the presence of a cyclic secondary amine acid complex, specifically using sulfonic acid derivatives and avoiding gaseous reagents like dimethylamine, to achieve high purity and yield while minimizing environmental and health risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CF3Br is used as a reagent in the sulfinylation process, then the reaction can proceed, but environmental toxicity and handling difficulty increase
Solution Approach 1:
The patent removes the harmful CF3Br reagent from the reaction system and replaces it with alternative reagents (CF3S(O)ONa, CF3S(O)OK, or CF3S(O)Cl combined with halogenating agents), thereby extracting the toxic element while maintaining the sulfinylation function
Solution Approach 2:
The patent employs readily available, stable reagents such as sodium or potassium trifluoromethylsulfinate and common halogenating agents instead of the expensive and hazardous CF3Br, using materials that are easier to handle and dispose of safely
2Productivity
If gaseous reagents like dimethylamine are used, then the reaction proceeds, but safety risks and handling complexity increase
Solution Approach 1:
The patent extracts the problematic gaseous dimethylamine from the reaction system and replaces it with stable solid or liquid reagents such as cyclic secondary amine acid complexes, eliminating the need for specialized gas handling equipment and procedures
Solution Approach 2:
The patent uses stable, non-gaseous reagents that are easier to store, handle, and dispose of compared to volatile gaseous amines, improving operational safety and simplifying plant operations
3Productivity
If traditional sulfinylation methods are used, then production can continue, but yield and purity remain low
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by using specific reagent combinations (trifluoromethylsulfinate salts with halogenating agents or CF3S(O)Cl) and optimized conditions to achieve both high conversion and high selectivity, thereby improving yield and purity simultaneously
Solution Approach 2:
The patent employs composite reagent systems combining sulfinylating agents with halogenating agents and amine acid complexes, where the synergistic interaction of multiple components achieves superior reaction outcomes compared to single reagents
4Productivity
If CF3S(O)Cl is used as the sulfinylating agent, then reaction yield improves, but reagent instability and handling difficulty increase
Solution Approach 1:
The patent segments the sulfinylation process into two stages: first generating CF3S(O)Cl in situ from stable CF3S(O)ONa/CF3S(O)OK and halogenating agents, then using the generated CF3S(O)Cl for sulfinylation, thereby handling the unstable intermediate only when needed and in controlled amounts
Solution Approach 2:
The patent uses stable salts (CF3S(O)ONa or CF3S(O)OK) as intermediary reagents that can be stored and handled safely, which then react with halogenating agents to generate the active CF3S(O)Cl species in situ, acting as a mediator between stable storage forms and reactive functional forms
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 high yield and purity of fipronil, avoiding hazardous reagents and environmental toxicity, facilitating safe and efficient large-scale industrial production suitable for agricultural and animal health applications.
Implementation Method 1
5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-1H-pyrazole-3-carbonitrile (II) is reacted with a sulfinylating agent S
Implementation Method 2
in the presence of at least one amine acid complex wherein the amine(s) are selected from cyclic secondary amines and the acid(s) are selected from sulfonic acid derivatives
Implementation Method 3
with the addition of a halogenating agent
Data Source
AI summary
The present invention relates to a process for the sulfinylation of a pyrazole derivative, characterized in that 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-1H-pyrazole-3-carbonitrile (II) is reacted with a sulfinylating agent S in the presence of at least one amine acid complex wherein the amine(s) are selected from cyclic secondary amines and the acid(s) are selected from sulfonic acid derivatives, and with the addition of a halogenating agent, wherein S is [CF3S(O)]2O; or CF3S(O)X wherein X means fluoro, chloro, bromo, iodo, a hydroxy group, or an alkaline or alkaline earth metal salt of the hydroxy group; or mixtures thereof.