Dual-Supported Olefin Metathesis Catalysts Preventing Leaching
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Solution Overview
Problem
Current supported olefin metathesis catalysts face limitations in catalyst lifetime and efficiency due to bimolecular decomposition and leaching issues, which hinder their performance and recyclability, especially in flow-through technologies.
Innovation Solution
Development of dual-supported catalyst complexes with specific linker structures that anchor non-labile and labile ligands to a silica support, enhancing stability and preventing leaching, thereby improving catalyst lifetime and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If catalysts are anchored onto solid support via chelating alkylidene ligand, then catalyst lifetime is improved by preventing bimolecular decomposition, but catalyst leaching occurs reducing overall efficiency
Solution Approach 1:
The patent divides the catalyst anchoring system into two separate functional components: a non-labile ligand (such as NHC or phosphine) that provides strong, stable attachment to the support preventing leaching, and a labile alkylidene ligand that maintains catalytic activity. This segmentation allows each ligand type to fulfill its specific role without compromise - the non-labile ligand anchors the catalyst while the labile ligand enables metathesis reactions.
Solution Approach 2:
The patent introduces a linker as an intermediary component that connects the ligands to the solid support. The linker acts as a mediator between the catalyst complex and the support surface, providing optimal attachment geometry and strength. This intermediary layer allows the catalyst to be firmly anchored while maintaining its catalytic functionality, preventing both leaching and decomposition.
2Stability of the object's composition
If phosphine ligands are exchanged with phosphines on polystyrene-divinylbenzene polymer, then catalyst immobilization is achieved, but catalyst performance is reduced compared to homogeneous equivalents
Solution Approach 1:
The patent changes the key parameter of ligand lability - using non-labile ligands (strongly bound phosphines or NHCs) for support attachment instead of labile phosphines. This parameter change fundamentally improves the catalyst-support interaction strength, preventing leaching while maintaining catalytic activity through the separate labile alkylidene ligand. The strong sigma-donor properties of NHC ligands particularly enhance this effect.
Solution Approach 2:
The patent creates a composite catalyst system combining multiple ligand types with different properties: non-labile ligands for stable support attachment, labile alkylidene ligands for catalytic activity, and linker molecules for optimal connection. This composite approach leverages the strengths of each component to achieve both immobilization stability and high catalytic performance.
3Reliability
If NHC ligands are used to replace ancillary chlorides, then strong bonding to ruthenium center is achieved increasing substitutional inertness, but catalyst complexity increases
Solution Approach 1:
The patent makes the non-labile ligand serve multiple functions simultaneously: it provides strong sigma-donor stabilization of the ruthenium center, ensures substitutional inertness to prevent unwanted ligand exchange, and enables firm anchoring to the solid support through the linker. This multi-functionality of the non-labile ligand reduces the need for additional components, simplifying the overall catalyst design despite the advanced ligand chemistry.
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 dual-supported catalysts demonstrate increased catalyst lifetimes and improved efficiency in olefin metathesis reactions, maintaining activity and preventing leaching, even under spiking conditions, and show effective performance in both batch and flow-through processes.
Implementation Method 1
The linker has the structure -A-Si(O(CH2)nCH3)3, wherein n is an integer ranging from 0-3
Implementation Method 2
which is known to prevent bimolecular decomposition via site isolation
Implementation Method 3
NHC ligands generally form strong bonds to the ruthenium center and are often the most substitutionally inert ligand within the catalyst coordination sphere
Data Source
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AI summary
Supported olefin metathesis catalysts are disclosed, and more particularly, a supported catalyst complex comprising a catalyst composed of a Group 8 transition metal complex comprising a labile ligand and a non-labile ligand and a support, wherein the metal complex and the support are linked together by one or more linkers, in which one of the linkers connects the labile ligand of the complex to the support and the same or a different linker connects the non-labile ligand of the complex to the support. A method for preparing a supported catalyst complex is further disclosed, comprising contacting at least one non-labile ligand precursor and at least one labile ligand precursor with at least one Group 8 transition metal complex having multiple coordinated ligands, in which the non-labile ligand and the labile ligand precursors are exchanged via ligand exchange reactions with the coordinated ligands of the metal complex. Both the non-labile and the labile ligands comprise linkers for attachment to a support. The metal complex is further contacted with a support in order to link the metal complex to the support via the linkers connected to the labile and the non-labile ligands. The invention further relates to the use of the supported olefin metathesis catalyst in performing metathesis reactions. The invention has utility in the fields of catalysis, organic synthesis, polymer chemistry, and industrial and fine chemicals chemistry.