2-Hydroxyphenyl Benzotriazole Synthesis via Phase-Transfer Catalysis
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Solution Overview
Problem
Current processes for preparing 2-hydroxyphenyl alkenyl benzotriazole compounds have unsatisfactory yields and use toxic and environmentally unfriendly solvents, necessitating a more efficient and environmentally friendly method.
Innovation Solution
A two-step process involving etherification of a 2-hydroxyphenylbenzotriazole compound with an alkenyl halide in the presence of a phase-transfer agent and base, followed by a Claisen rearrangement at elevated temperatures, achieving yields greater than 80% and purity greater than 99% without the need for toxic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current processes are used for preparing 2-hydroxyphenyl alkenyl benzotriazole compounds, then the synthesis can be completed, but the yield is unsatisfactory and toxic solvents are required
Solution Approach 1:
The patent changes the reaction parameters by using a phase-transfer catalyst system with specific bases (alkali metal carbonates or hydroxides) and water-immiscible organic solvents, transforming the reaction conditions to achieve both high yield (>80%) and environmental friendliness. The Claisen rearrangement is performed at elevated temperatures (170-250°C) which improves the yield while the phase-transfer catalysis eliminates the need for toxic solvents.
2Manufacturing precision
If current processes are used for preparing 2-hydroxyphenyl alkenyl benzotriazole compounds, then the synthesis can be completed, but the purity is insufficient
Solution Approach 1:
The patent optimizes reaction parameters including temperature (170-250°C for Claisen rearrangement), catalyst loading (3-15 mol% phase-transfer catalyst), and base equivalents (0.7-1.5 equivalents) to simultaneously achieve high purity (>99%) and high yield (>80%). The controlled heating rate and reaction time are also optimized to prevent side reactions.
3Ease of manufacture
If etherification is performed with alkenyl halide and base, then the intermediate compound is formed, but the reaction requires toxic solvents
Solution Approach 1:
The patent introduces a phase-transfer catalyst as an intermediary substance that enables the etherification reaction to proceed in water-immiscible organic solvents without requiring toxic solvents. The phase-transfer catalyst facilitates the reaction between the hydroxy compound and alkenyl halide by transferring ions between phases, simplifying the manufacturing process while eliminating harmful solvents.
4Productivity
If Claisen rearrangement is performed at elevated temperatures, then the final product is formed with high yield, but energy consumption increases
Solution Approach 1:
The patent uses a phase-transfer catalyst as an intermediary to lower the activation energy barrier of the Claisen rearrangement, enabling the reaction to proceed at lower temperatures (170-250°C instead of higher temperatures) while maintaining high yield. This reduces the energy consumption while achieving the desired productivity.
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 process enhances the yield and purity of 2-hydroxyphenyl alkenyl benzotriazole compounds while eliminating the use of harmful solvents, offering a more efficient and environmentally friendly synthesis.
Implementation Method 1
etherification is performed on a 2-hydroxyphenylbenzotriazole compound in water and/or at least one suitable organic solvent by reacting an alkenyl halide in the presence of at least one phase-transfer agent and of at least one base
Implementation Method 2
a Claisen rearrangement is performed on the 2-O-alkenylphenylbenzotriazole compound thus obtained, by heating the reaction mixture to a temperature above 170° C. with at least one suitable organic solvent
Data Source
AI summary
The process for preparing 2-hydroxyphenyl alkenyl benzotriazole compounds and the process for preparing siloxane compounds containing 2-hydroxyphenyl benzotriazole function are disclosed.