Tefluthrin Crystalline Form II: Reducing Aquatic Toxicity
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Solution Overview
Problem
Commercial tefluthrin in a non-crystalline state has high toxicity against aquatic organisms, and existing crystalline forms require complex preparation processes, leading to high production costs.
Innovation Solution
A new crystalline form of tefluthrin (crystalline form II) is developed, characterized by specific X-ray powder diffraction patterns and prepared through methods involving acid washing, base treatment, and controlled cooling of amorphous tefluthrin, which reduces toxicity and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If tefluthrin is manufactured in a non-crystalline state according to conventional methods, then production is simple and direct, but toxicity against aquatic organisms is high
Solution Approach 1:
The patent applies parameter changes by transforming tefluthrin from a non-crystalline state to a specific crystalline form (crystalline form II). This phase change modifies the physical and chemical parameters of the substance, resulting in reduced toxicity against aquatic organisms while maintaining pesticidal activity. The crystallization process changes the molecular arrangement and solubility characteristics, directly addressing the toxicity issue.
Solution Approach 2:
The invention utilizes phase transitions by converting amorphous tefluthrin into crystalline form II through controlled cooling and temperature cycling. This phase transition from disordered non-crystalline structure to ordered crystalline structure is the core mechanism that reduces aquatic toxicity. The patent specifically describes cooling the amorphous product to obtain the crystalline form, leveraging this phase change to achieve the desired environmental safety profile.
2Object-affected harmful factors
If crystalline form I of tefluthrin is prepared through recrystallization, then toxicity against aquatic organisms is reduced, but production costs increase due to complex processes
Solution Approach 1:
The patent extracts the essential crystallization step from the complex recrystallization process used for crystalline form I. By isolating and applying only the critical cooling phase transition step, the method achieves the same toxicity reduction effect without requiring multiple recrystallization cycles, solvent treatments, and extended processing time, thereby reducing production costs while maintaining environmental safety.
Solution Approach 2:
Instead of following the conventional approach of recrystallizing from solvent to obtain crystalline form I, the patent inverts the process by directly cooling the amorphous product to induce crystallization. This reverse approach achieves crystalline form II with reduced toxicity without going through the traditional recrystallization route, simplifying the manufacturing process and reducing costs.
3Manufacturing precision
If crystalline form I is produced through multiple recrystallization steps, then product purity is improved, but production time and resource consumption increase
Solution Approach 1:
The patent applies preliminary action by performing a single controlled cooling step that pre-establishes the crystalline structure. This preliminary crystallization step, performed by cooling the amorphous product to specific temperatures, achieves both purification and crystallization in one operation, eliminating the need for multiple subsequent recrystallization steps and improving production efficiency.
Solution Approach 2:
The invention merges the purification and crystallization functions into a single phase transition step. By combining what would traditionally require separate recrystallization operations into one controlled cooling process, the method achieves both product purity improvement and crystalline form formation simultaneously, thereby enhancing productivity and reducing resource consumption.
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 crystalline form II of tefluthrin exhibits lower toxicity comparable to or lower than crystalline form I, with simplified production processes that conserve equipment, raw materials, and human resources, while maintaining effective pest control.
Implementation Method 1
cooling the amorphous product synthesized to a low temperature, thereby obtaining the crystalline form II
Implementation Method 2
after being formulated into a preparation, tefluthrin in a non-crystalline state has a higher toxicity against aquatic organisms
Implementation Method 3
an X-ray powder diffraction (X-RPD) pattern recorded by using Cu-Ka radiation at 25° C. of the crystalline form II
Implementation Method 4
an X-ray powder diffraction (X-RPD) pattern recorded by using Cu-Ka radiation at 25° C. of the crystalline form II shows at least 3 reflections
Data Source
AI summary
The present invention belongs to the technical field of fine chemicals and relates to a new crystalline form of tefluthrin, a preparation method therefor and the use thereof. The preparation method specifically comprises: taking an amorphous tefluthrin or a solid tefluthrin other than the tefluthrin as described in the present invention as a raw material, firstly preparing the raw material into an amorphous substance at room temperature, and then allowing the amorphous substance to cool to 5° C. to −24° C. to obtain a white or light yellow solid, i.e., a new crystalline form of tefluthrin.