Metal-Carbene Catalyst for 1,7-Diolefin Hydrodimerization
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Solution Overview
Problem
Prior art processes for hydrodimerizing 1,3-butadiene to produce 1,7-octadiene suffer from low productivity, activity, and selectivity, with phosphorus-modified palladium catalysts being oxygen-sensitive, expensive, and difficult to recycle, and trialkylphosphines being pyrophoric and costly.
Innovation Solution
A process using a metal-carbene complex with a metal of group 8 to 10 and at least one carbene ligand, which stabilizes non-cyclic olefins with alkylated phenols or stable N-oxyl radicals, allowing for higher catalyst productivity and selectivity, and reducing the need for excess phosphine ligands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphorus-modified palladium catalysts are used for hydrodimerization, then catalytic activity is achieved, but the catalyst becomes oxygen-sensitive, expensive, and difficult to recycle
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst system by replacing phosphorus-modified palladium catalysts with metal-carbene complexes featuring N-heterocyclic carbene ligands. This fundamental parameter change eliminates oxygen sensitivity while maintaining high catalytic activity and productivity for hydrodimerization reactions.
Solution Approach 2:
The invention employs catalysts that are more stable and easier to handle than prior art catalysts, reducing the need for expensive protective measures and complex recycling infrastructure. The metal-carbene complexes offer a balance between activity and stability that reduces overall process costs.
2Productivity
If trialkylphosphines are used as ligands, then catalyst activity is enhanced, but the ligands become pyrophoric and costly
Solution Approach 1:
The patent replaces hazardous trialkylphosphine ligands with N-heterocyclic carbene ligands that are not pyrophoric. This substitution eliminates the fire hazard while maintaining the ability to enhance catalyst activity, making the process safer and reducing costs associated with handling and storage.
Solution Approach 2:
The invention changes the ligand type from phosphine-based to carbene-based, fundamentally altering the chemical properties of the catalyst system. This parameter change eliminates pyrophoricity while preserving or enhancing catalytic performance through the unique electronic properties of N-heterocyclic carbenes.
3Productivity
If conventional catalysts are used, then hydrodimerization proceeds, but selectivity and productivity remain low
Solution Approach 1:
The patent employs metal-carbene complexes with specific N-heterocyclic carbene ligands that fundamentally change the catalytic parameters of the system. This results in simultaneously enhanced selectivity for 1,7-diolefins and improved productivity, overcoming the limitations of conventional catalysts.
Solution Approach 2:
The invention uses composite catalyst systems comprising metal centers coordinated with specifically designed N-heterocyclic carbene ligands. This composite structure combines the reactivity of the metal with the stabilizing and directing effects of the carbene ligand, achieving high selectivity and productivity simultaneously.
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 achieves high selectivity and productivity for 1,7-diolefins, with catalyst productivities exceeding 10,000 and low by-product formation, enhancing process reliability and reducing catalyst requirements.
Implementation Method 1
a process for preparing substituted or unsubstituted 1,7-diolefins by hydrodimerizing non-cyclic olefins having at least two conjugated double bonds in the presence of a reducing agent and of a metal-carbene complex
Implementation Method 2
hydrodimerizing non-cyclic olefins having at least two conjugated double bonds in the presence of a reducing agent
Data Source
AI summary
The invention relates to a process for preparing substituted or unsubstituted 1,7-diolefins by hydrodimerizing non-cyclic olefins having at least two conjugated double bonds in the presence of a reducing agent and of a catalyst, wherein the catalyst used is a metal-carbene complex.