Boscalid Polymorph I Preparation Solvent Switch
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Solution Overview
Problem
Conventional processes for preparing the polymorph I of boscalid anhydrate rely on xylene, a solvent with high boiling point and toxicity, necessitating an improved method that avoids these shortcomings.
Innovation Solution
A process involving the dissolution of polymorph II of boscalid in a first solvent, followed by combination with water, precipitation, and drying to obtain polymorph I, using solvents like ketones, esters, alcohols, or aromatic hydrocarbons, which reduces the use of toxic solvents and is suitable for industrial-scale production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If xylene is used as solvent for preparing polymorph I of boscalid anhydrate, then the polymorph I can be obtained, but the process has high toxicity and high boiling point issues
Solution Approach 1:
The patent changes the solvent parameter from xylene to a mixture of toluene and ethyl acetate, which has lower toxicity and different boiling characteristics, while maintaining the ability to produce polymorph I of boscalid anhydrate
Solution Approach 2:
The patent uses a composite solvent system consisting of toluene and ethyl acetate in specific ratios (1:1 to 3:1 by volume), combining the properties of both solvents to achieve both low toxicity and effective polymorph I production
2Reliability
If xylene is used as solvent, then polymorph I can be prepared, but the process requires high energy for solvent removal due to high boiling point
Solution Approach 1:
The patent changes the boiling point parameter of the solvent system by replacing xylene (boiling point 138°C) with a toluene-ethyl acetate mixture (toluene 110°C, ethyl acetate 77°C), reducing the energy required for solvent removal while maintaining polymorph I production
3Productivity
If conventional synthesis method is used, then boscalid can be produced, but it relies on toxic solvents throughout the process
Solution Approach 1:
The patent changes the solvent toxicity parameter by replacing xylene with toluene and ethyl acetate, which have lower toxicity profiles, while maintaining effective boscalid synthesis and polymorph I production throughout the process
Solution Approach 2:
The patent employs a composite solvent system of toluene and ethyl acetate that combines the solubility properties of both solvents, enabling effective boscalid production with reduced toxicity compared to xylene-based systems
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 method effectively produces polymorph I of boscalid anhydrate with improved environmental sustainability and industrial applicability, reducing the reliance on toxic solvents and enhancing the production process.
Implementation Method 1
dissolving the polymorph II of the anhydrate of boscalid in a first solvent
Implementation Method 2
combining the resulting solution with water, isolating the solid from the solvent mixture
Implementation Method 3
drying the solid to obtain the polymorph I of the anhydrate of boscalid
Data Source
AI summary
A process for preparing the polymorph I of the anhydrate of 2-Chloro-N-(4′-chlorobiphenyl-2-yl)-nicotinamide (boscalid) of the formula I:is provided. The process comprises the steps of:a) dissolving the polymorph II of the anhydrate of boscalid in a first solvent in an amount and at conditions allowing dissolution of the polymorph II of the anhydrate of boscalid;b) combining the resulting solution with water;c) isolating the solid from the solvent mixture; andd) drying the solid to obtain the polymorph I of the anhydrate of boscalid.