Supported Transition Metal Complex for Olefin Metathesis
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Solution Overview
Problem
The challenge in olefin metathesis is to maintain high activity and selectivity of homogeneous transition metal catalysts when immobilized on supports, while minimizing metal and impurity contamination, especially in supercritical carbon dioxide where catalyst solubility is low, leading to potential 'leaching' issues.
Innovation Solution
The use of supported transition metal complexes, specifically bound to organic and inorganic carriers like polystyrene and silica gel matrices via stable ether, ester, or amide bonds, which enhance catalyst stability and reduce leaching in supercritical carbon dioxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If homogeneous transition metal catalysts are used in olefin metathesis, then high activity and selectivity are achieved, but catalyst separation and reuse become difficult
Solution Approach 1:
The patent introduces a support structure (carrier) as an intermediary between the homogeneous catalyst and the reaction medium. The transition metal complex is immobilized on the support via functional groups, creating a heterogeneous catalyst that maintains the high activity of homogeneous catalysts while enabling easy separation through filtration or decantation.
Solution Approach 2:
The patent employs porous support materials with specific surface areas and pore structures to immobilize the catalyst. The porous structure provides high surface area for catalyst attachment while allowing substrate and product diffusion, maintaining catalytic activity and enabling separation.
2Ease of operation
If catalysts are immobilized on supports, then separation and reuse are improved, but activity and selectivity decrease
Solution Approach 1:
The patent applies local quality by functionalizing specific regions of the support surface with specific chemical groups that match the catalyst's binding requirements. This localized functionalization ensures optimal catalyst-support interaction while maintaining the bulk properties of the support that facilitate separation.
Solution Approach 2:
The patent creates composite material systems combining the support matrix with functional groups and the transition metal complex. This composite structure integrates the separation benefits of heterogeneous catalysts with the high activity of homogeneous catalysts through carefully designed material composition.
3Quantity of substance
If perfluorinated ligands are used to increase catalyst solubility in supercritical carbon dioxide, then solubility improves, but catalyst leaching increases
Solution Approach 1:
The support structure acts as an intermediary that anchors the catalyst, preventing leaching into the supercritical carbon dioxide medium. The catalyst is immobilized on the support surface, allowing it to function in the nonpolar solvent without requiring perfluorinated ligands for solubility.
Solution Approach 2:
The patent changes the physical state and binding parameters of the catalyst by immobilizing it on the support. This transformation from a soluble homogeneous catalyst to an immobilized heterogeneous catalyst eliminates the need for solubility-enhancing perfluorinated ligands while preventing leaching.
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 allows for high conversion rates with low catalyst bleeding, maintaining activity and selectivity, and enabling efficient reuse of the catalysts in olefin metathesis reactions.
Implementation Method 1
the supported transition metal complexes according to the invention are used in olefin metathesis
Implementation Method 2
The type of connection of the transition metal complex via the group X depends on the type of complex and in particular the functional groups provided by it for the purpose of connection. As a rule, ether, ester, amide or urethane bonds are preferred because of their easy synthetic accessibility, as long as they ensure a stable connection of the transition metal complex under the application conditions.
Data Source
AI summary
The invention relates in particular to supported transition metal complex based on a polystyrene matrix which comprises structural units of the formula (Ia), or supported transition metal complex based on a silica gel matrix which comprises structural units of the formula (II), in which the radicals and indices are each defined as specified in the description. The invention also relates to the use of the supported transition metal complexes in catalysis, and to corresponding processes for transition metal-catalyzed conversion of reactant(s) to product(s). In particular, the invention relates to the field of olefin metathesis.