Stereoretentive Ruthenium Complexes With Lower-Loading Metathesis Catalysis
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Solution Overview
Problem
The high cost and complexity of synthesizing stereoretentive ruthenium complexes with dithiocatechol-based ligands, along with their low thermal stability and high catalyst loading requirements, hinder their industrial application in olefin metathesis reactions, particularly for controlling the C=C bond configuration.
Innovation Solution
Development of ruthenium complexes with novel ligands such as N-heterocyclic carbenes (NHCs), cyclic alkylaminocarbenes (CAACs), or phosphines, combined with zinc complexes, which exhibit stereoretentive properties even under elevated temperatures, reducing the need for high catalyst loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dithiocatechol-based ligands are used in ruthenium complexes, then stereoretentive properties are achieved, but synthesis cost and complexity increase
Solution Approach 1:
The patent uses NHC and CAAC ligands as alternative structures that replicate the stereoretentive function of dithiocatechol ligands. These alternative ligands provide similar catalytic performance with simpler synthesis routes and lower costs, effectively copying the desired functionality without the manufacturing complexity.
Solution Approach 2:
The patent employs readily available and inexpensive ligand precursors such as imidazolium salts for NHC ligands and amino-carbonyl compounds for CAAC ligands. These materials can be synthesized through straightforward procedures using common reagents, making the overall catalyst preparation more cost-effective compared to dithiocatechol-based systems.
2Manufacturing precision
If dithiocatechol-based ruthenium complexes are used, then stereoretentive properties are achieved, but thermal stability decreases
Solution Approach 1:
The patent changes the chemical parameters of the ligand system by transitioning from dithiocatechol to NHC/CAAC ligands. This parameter change results in complexes with enhanced thermal stability while preserving stereoretentive properties, as the NHC and CAAC ligands form stronger bonds with the ruthenium center and resist thermal degradation.
Solution Approach 2:
The patent creates composite catalyst systems combining ruthenium centers with NHC or CAAC ligands, along with ancillary ligands such as phosphines or pyridines. This composite approach allows optimization of both thermal stability and stereoretentive properties through synergistic interactions between different ligand components.
3Manufacturing precision
If dithiocatechol-based catalysts are used, then stereoretentive properties are achieved, but catalyst loading requirements increase
Solution Approach 1:
The patent modifies the electronic and steric parameters of the ligand system by using NHC and CAAC ligands, which provide stronger donation to the ruthenium center. This enhances the catalytic activity and stability of the active species, allowing the catalyst to maintain high stereoretentive performance at lower loadings compared to dithiocatechol-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
The new ruthenium complexes achieve higher yields and selectivity in olefin metathesis reactions, overcoming the limitations of existing catalysts by providing cost-effective and thermally stable alternatives.
Implementation Method 1
new stereoretentive ruthenium complexes useful as catalysts and/or (pre)catalysts for olefin metathesis reaction
Data Source
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AI summary
The subject matter of the invention is a stereoretentive ruthenium complex of the general formula 1a-Ru and/or 1b-Ru, in which all variables have the meanings defined in the description. The subject matter of the invention is also a method of preparing the ruthenium complex, an intermediate used in preparing the ruthenium complex, and the use of this ruthenium complex as a (pre)catalyst in olefin metathesis reactions such as ring-closing metathesis (RCM), homometathesis (self-CM), cross-metathesis (CM), and stereoretentive processes in olefin metathesis.