Sulfinylation Process for Fipronil Using Amine Acid Complexes
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Solution Overview
Problem
Current processes for the sulfinylation of 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-1H-pyrazole-3-carbonitrile face challenges in large-scale industrial production, including low yield, impurity issues, and the use of toxic reagents, which complicates reaction control and product purity, especially due to temperature and kinetic changes during scale-up.
Innovation Solution
A novel process involving the reaction of 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-1H-pyrazole-3-carbonitrile with a sulfinylating agent and an amine acid complex in the presence of a halogenating agent, maintaining a reaction temperature below 39°C, utilizes specific sulfinylating agents like trifluoromethylsulfinic acid and chlorinating agents like thionylchloride, with an amine acid complex to achieve high yield and purity of fipronil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional sulfinylation processes are used with reagents like CF3S(O)Cl or CF3S(O)ONa, then the reaction can proceed at higher temperatures (30-60°C), but the yield is low and impurity formation increases
Solution Approach 1:
The patent changes the temperature parameter to below 39°C and modifies the reagent system by using CF3S(O)OH combined with specific amine acid complexes (secondary/tertiary amines with hydrofluoric, hydrochloric, hydrobromic, hydroiodic acid or sulfonic acid derivatives), which fundamentally alters the reaction kinetics and selectivity to achieve both high yield and high purity
Solution Approach 2:
The patent introduces amine acid complexes as intermediaries that mediate between the sulfinylating agent and the pyrazole derivative. These complexes (formed from secondary/tertiary amines and acids) act as catalysts or reaction mediators that enable the transformation to proceed with high efficiency and selectivity at controlled temperatures
2Speed
If the reaction temperature is raised to 30-60°C as in conventional processes, then the reaction rate increases, but side reactions occur and product purity decreases
Solution Approach 1:
The patent optimizes the temperature parameter to below 39°C (specifically 0-39°C in some embodiments) and combines it with the amine acid complex system to maintain high reaction rate while suppressing side reactions. This parameter optimization resolves the contradiction between speed and precision
Solution Approach 2:
The patent employs controlled temperature maintenance (keeping reaction mixture below 39°C) as a feedback control mechanism to prevent thermal runaway and side reactions, ensuring the reaction proceeds at optimal rate while maintaining high product purity
3Ease of manufacture
If toxic reagents like CF3S(O)Cl are used, then the sulfinylation can be achieved, but the process becomes complicated and requires careful control to avoid harmful byproducts
Solution Approach 1:
The patent extracts or removes the toxic components (CF3S(O)Cl and other harmful reagents) from the reaction system and replaces them with less toxic alternatives (CF3S(O)OH combined with amine acid complexes), thereby simplifying the process and eliminating harmful byproducts
Solution Approach 2:
The patent converts potentially harmful reagents into beneficial ones by using CF3S(O)OH with amine acid complexes, which provide the necessary reactivity while being less toxic and producing fewer harmful byproducts, thus turning a harmful process into a beneficial one
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 purity and yield of fipronil, avoiding toxic reagents and side products, and ensures efficient large-scale production by maintaining controlled reaction conditions, thereby improving the industrial viability of fipronil as a pesticide and animal health product.
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 secondary and/or tertiary amines and the acid(s) are selected from hydrofluoric, hydrochloric, hydrobromic and hydroiodic acid and 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 secondary and/or tertiary amines and the acid(s) are selected from hydrofluoric, hydrochloric, hydrobromic and hydroiodic acid and 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, wherein the temperature of the reaction mixture at no time exceeds 39°C.