Phosphoric Ester Mediator for Oxime Synthesis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for preparing oximes and oxime O-methyl ethers from poorly water-soluble carbonyl compounds face challenges due to low reactivity of hydroxylammonium salts and complex reaction mixtures, requiring expensive solvents and phase transfer catalysts, especially when handling carbonyl compounds with low water solubility.
Innovation Solution
A method involving a biphasic reaction system with a phosphoric ester as a reaction mediator and cation scavenger, using hydroxylamine salts or hydroxylamine O-methyl ether salts, and controlling the pH between 2 to 10, allows for efficient conversion of poorly water-soluble carbonyl compounds into oximes or oxime O-methyl ethers with high yield and conversion rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydroxylammonium salts are used as starting material, then handling and cost-effectiveness improve, but reactivity decreases particularly with poorly water-soluble carbonyl compounds
Solution Approach 1:
A phase transfer catalyst is introduced as an intermediary substance that facilitates the reaction between hydroxylammonium salts and poorly water-soluble carbonyl compounds. The catalyst transfers the hydrophilic hydroxylammonium ion into the organic phase where the carbonyl compound resides, enabling the reaction to proceed at acceptable rates while maintaining the advantages of using salt forms.
Solution Approach 2:
The reaction conditions are optimized by adjusting parameters such as pH, temperature, and catalyst concentration to enhance the reactivity of hydroxylammonium salts. The pH is controlled to maintain the hydroxylammonium ion in a reactive state while managing the solubility issues of poorly water-soluble carbonyl compounds.
2Productivity
If polar solvents are used to dissolve hydroxylammonium salts, then reactivity improves, but workup complexity and cost increase
Solution Approach 1:
The phase transfer catalyst serves as a mediator that enables the reaction to proceed in a biphasic system without requiring large amounts of polar solvents. The catalyst shuttles reactants between phases, allowing the use of minimal polar solvent while maintaining reaction efficiency.
Solution Approach 2:
The reaction is conducted in a biphasic system where the product partitions into the organic phase upon formation. This phase transition behavior simplifies workup as the product can be separated by simple phase separation followed by solvent removal, avoiding complex purification procedures.
3Productivity
If perfluorinated carboxylic acids are used as phase transfer catalysts, then reaction efficiency improves for liquid carbonyl compounds, but cost increases and applicability is limited
Solution Approach 1:
The patent employs conventional, inexpensive phase transfer catalysts such as quaternary ammonium salts or crown ethers that can be used in small catalytic amounts. These catalysts are much cheaper than perfluorinated carboxylic acids and work effectively for a broad range of substrates including solids, liquids, and oils.
Solution Approach 2:
The selected phase transfer catalysts exhibit broad substrate scope and can effectively catalyze reactions with various carbonyl compounds regardless of their physical state (solid, liquid, or oil). This universal applicability replaces the need for specialized expensive catalysts limited to specific substrate types.
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 enables the efficient and economic preparation of oximes and oxime O-methyl ethers from carbonyl compounds with low water solubility, simplifying the workup process and reducing costs by using a biphasic system with phosphoric esters, achieving high chemical yield and conversion rates.
Implementation Method 1
the reaction takes place in a mixture of at least 2 liquid phases (at least a biphasic system), and in which the desired oxime or the desired oxime O-methyl ether can be prepared with high chemical yield and high conversion rates
Implementation Method 2
the reaction takes place in a mixture of at least 2 liquid phases (at least a biphasic system)
Data Source
AI summary
Method for preparing certain oximes and oxime O-methyl ethers by reacting poorly water-soluble carbonyl compounds with salts of hydroxylamine or hydroxylamine O-methyl ether or the free base of hydroxylamine in the presence of certain phosphoric esters or salts thereof of the formula (I)wherein R1, R2 and X are defined as specified in the description.