Type 2 Benzoxazole Crystal Stability via Recrystallization
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Solution Overview
Problem
The existing crystal forms of 2-(3-ethanesulfonylpyridin-2-yl)-5-(trifluoromethanesulfonyl)benzoxazole are not stable enough to maintain effective control efficacies against pests, leading to potential decreases in pesticide formulation stability and efficacy.
Innovation Solution
A more stable crystal form, referred to as the type 2 crystal, is produced through specific recrystallization methods involving solvents like 2-propanol or mixed solvents such as xylene and n-heptane, with controlled temperature and seed crystal techniques to achieve diffraction peaks at 2θ values of 14.0 ± 0.2° to 22.3 ± 0.2°, enhancing stability and control efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If type 1 crystal is used for pesticide formulation, then the compound can be produced and applied, but the formulation stability and control efficacy decrease over time
Solution Approach 1:
The patent applies parameter changes by transforming the crystal structure of the compound from type 1 to type 2 through controlled recrystallization processes. This structural parameter change results in a more stable crystal form that maintains formulation stability and control efficacy over extended periods, directly resolving the contradiction between initial formulation capability and long-term stability.
Solution Approach 2:
The patent utilizes phase transitions by inducing a transformation from type 1 crystal phase to type 2 crystal phase through specific recrystallization conditions (solvent selection, temperature control, seeding). This phase transition creates a more stable crystalline structure that prevents degradation and maintains pest control efficacy throughout the formulation's shelf life and application period.
2Ease of manufacture
If type 1 crystal is used, then the compound can be crystallized from various solvents, but the crystal form lacks sufficient stability for reliable pesticide performance
Solution Approach 1:
The patent applies preliminary action by introducing seed crystals of type 2 into the recrystallization process before the crystal formation is complete. This seeding approach guides the crystallization process to produce the desired stable type 2 crystal form rather than type 1, ensuring reliability while maintaining manufacturing flexibility through controlled initiation of crystal growth.
Solution Approach 2:
The patent changes crystallization parameters including solvent selection (2-propanol, xylene-n-heptane mixtures), temperature profiles (65-67°C precipitation), and seeding conditions to transform the crystal form from type 1 to type 2. These parameter changes enable reliable production of the stable crystal form while preserving ease of manufacture through well-defined procedural steps.
3Reliability
If recrystallization is performed to improve crystal stability, then formulation stability improves, but the production process becomes more complex
Solution Approach 1:
The patent defines specific recrystallization parameters (solvent types, temperature ranges, seeding conditions) that transform type 1 to type 2 crystal. By establishing well-defined parameter ranges rather than requiring complex multi-step procedures, the process achieves improved formulation stability while maintaining reasonable production simplicity through standardized operational conditions.
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 type 2 crystal form of the compound results in a more stable pesticide formulation that maintains control efficacies against a wide range of pests, including insects, acarina, and nematodes, with improved stability and prolonged effectiveness when applied in various agricultural settings.
Implementation Method 1
having diffraction peaks at 2θ = 14.0 ± 0.2°, 14.3 ± 0.2°, 16.5 ± 0.2°, 16.9 ± 0.2°, 17.6 ± 0.2°, 18.8 ± 0.2°, 19.9 ± 0.2°, and 22.3 ± 0.2°
Implementation Method 2
A type 2 crystal may be produced by dissolving a type 1 crystal into 2-propanol, followed by precipitating a crystal at the temperature of 65 to 67°C
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A type 2 crystal of 2-(3-ethanesulfonylpyridin-2-yl)-5-(trifluoromethanesulfonyl)benzoxazole having diffraction peaks at 2θ = 14.0 ± 0.2°, 14.3 ± 0.2°, 16.5 ± 0.2°, 16.9 ± 0.2°, 17.6 ± 0.2°, 18.8 ± 0.2°, 19.9 ± 0.2°, and 22.3 ± 0.2° in powder X-ray diffraction using Cu-Kα radiation is a stable crystal.