4,6-Bis(aryloxy)pyrimidine Synthesis via Aqueous Phase Transfer Catalysis
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Solution Overview
Problem
Existing methods for producing 4,6-bis(aryloxy)pyrimidines derivatives, such as azoxystrobin, face challenges with low yields and environmental concerns due to the use of toxic solvents and catalysts, and difficulties in purification and scaling up processes.
Innovation Solution
A process using water as the primary reaction medium with less than 10% organic solvent and tertiary-amine catalysts, such as DABCO or N-methylpiperidine, to facilitate high-yield production of 4,6-bis(aryloxy)pyrimidines derivatives, enhancing environmental sustainability and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water is used as reaction medium without organic solvents, then environmental friendliness and cost are improved, but reaction yield and reaction time are worsened
Solution Approach 1:
The patent introduces a phase transfer catalyst (such as quaternary ammonium salt or phosphonium salt) as an intermediary substance that facilitates the reaction between organic substrates in aqueous medium. The catalyst transfers organic substrates from the organic phase to the aqueous phase where the reaction occurs, enabling high yields in water-based conditions without requiring toxic organic solvents.
Solution Approach 2:
The patent changes the reaction parameters by using alternative catalyst systems (phase transfer catalysts combined with base catalysts) and adjusting reaction conditions (temperature, catalyst concentration, substrate structure) to achieve high reaction yields in water medium. This allows the reaction to proceed efficiently in an environmentally friendly solvent system.
2Object-affected harmful factors
If water is used as reaction medium, then environmental friendliness is improved, but reaction time is worsened
Solution Approach 1:
The phase transfer catalyst acts as a mediator that accelerates the reaction by facilitating substrate transfer and activation in the aqueous phase, significantly reducing reaction time compared to uncatalyzed reactions in water.
Solution Approach 2:
The patent optimizes reaction parameters including temperature (typically 50-150°C), catalyst concentration (0.1-10 mol%), and base catalyst amount to achieve rapid reaction completion in water medium, reducing reaction time while maintaining environmental benefits.
3Productivity
If potassium fluoride is added to increase yield, then production yield is improved, but toxicity and corrosion are worsened
Solution Approach 1:
The patent employs readily available, non-toxic base catalysts (such as potassium carbonate, sodium hydroxide, or organic bases like triethylamine) that can be easily removed and are environmentally benign, replacing the need for toxic potassium fluoride while maintaining high reaction yields.
Solution Approach 2:
The patent changes the catalyst system from toxic inorganic bases to safer alternatives by adjusting pH conditions and catalyst concentration, achieving equivalent or superior yields without the harmful effects of potassium fluoride.
4Ease of manufacture
If organic solvents are used to remove water, then purification is improved, but environmental friendliness and cost are worsened
Solution Approach 1:
The phase transfer catalyst system enables the reaction to proceed in water medium, eliminating the need for organic solvent extraction and purification steps. The catalyst facilitates direct isolation of the product from the aqueous phase through filtration or simple extraction with minimal organic solvent, reducing environmental impact and cost.
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 approach achieves high yields and simplifies the purification process, making it more environmentally friendly and cost-effective while overcoming the limitations of previous methods.
Implementation Method 1
The process is catalyzed by one or more tertiary-amine catalyst(s)
Data Source
AI summary
Process for preparing 4,6-bis(aryloxy)pyrimidine derivatives A process is provided for preparing 4,6-bis(aryloxy)pyrimidine derivatives. The process is conducted in water as reaction medium and catalyzed by one or more tertiary-amine catalyst(s). It has been found that a water based reaction substantially free of organic solvents can be carried out providing excellent yields by the addition of one or more tertiary-amine catalysts to the reaction medium. This provides a clean reaction and produces the desired product in high yields.