Host-Guest Catalyst Recovery via Azobenzene Isomerization
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Solution Overview
Problem
Homogeneous catalysts are difficult to recover from reaction solutions due to their solubility, which hinders their reuse and recycling.
Innovation Solution
Formation of a host-guest compound between the catalyst and an inclusion compound, such as cyclodextrin, allows for the isolation and subsequent release of the catalyst by isomerization, enabling efficient recovery and reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If homogeneous catalysts are used to catalyze chemical reactions, then catalytic activity is improved, but catalyst recovery becomes difficult due to solubility
Solution Approach 1:
The patent employs a soluble support molecule as an intermediary carrier that temporarily holds the homogeneous catalyst. The support molecule has specific binding sites that reversibly bind the catalyst, allowing it to be transported and recovered from the reaction mixture. After catalyst recovery, the bound catalyst can be released back into solution for reuse, thus resolving the contradiction between maintaining catalytic activity and enabling easy recovery.
Solution Approach 2:
The patent utilizes photoisomerization of azobenzene groups within the support molecule to change its binding parameters. By irradiating with light of specific wavelengths, the support molecule transitions between cis and trans isomers, which alters its affinity for the catalyst. This parameter change enables controlled binding and release of the catalyst, facilitating both recovery and reuse while maintaining catalytic functionality.
2Ease of operation
If conventional recovery techniques are used for homogeneous catalysts, then catalyst isolation is attempted, but catalytic activity is lost or reduced
Solution Approach 1:
The soluble support molecule acts as a protective intermediary during the isolation process. When the support-catalyst complex is isolated from the reaction mixture, the catalyst remains bound to the support, preventing aggregation, precipitation, or degradation that would otherwise occur during isolation. This protective binding maintains the catalyst's active species integrity throughout the isolation and storage process.
Solution Approach 2:
The patent uses light-induced isomerization to control catalyst release after isolation. The isolated support-catalyst complex can be stored in the bound state, and when catalytic activity is needed, irradiation with appropriate light triggers isomerization that releases the active catalyst back into solution, thus maintaining catalytic activity through controlled parameter changes rather than harsh chemical treatments.
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 allows for the effective separation and recovery of homogeneous catalysts from reaction solutions, maintaining their catalytic activity and facilitating their reuse in various chemical reactions.
Implementation Method 1
The catalyst may be released from the inclusion compound by converting the first isomer of the catalyst to a second isomer of the catalyst. Converting the first isomer of the catalyst to a second isomer of the catalyst may include applying electromagnetic radiation.
Implementation Method 2
The host portion of the host-guest compound binds to the soluble catalyst, allowing the catalyst to be isolated from the solution. forming a host-guest compound between a first isomer of the catalyst and inclusion compound in the solution
Data Source
AI summary
A method for separating a homogeneous catalyst from a solution includes forming a host-guest compound between a first isomer of the catalyst and inclusion compound in the solution and isolating the host-guest compound from the solution. The catalyst may be released from the inclusion compound by converting the first isomer of the catalyst to a second isomer of the catalyst.