Pincer-Based Cobalt Catalyst for Stereoselective Alkyne Hydrogenation
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Solution Overview
Problem
Existing methods for the selective hydrogenation of alkynes to achieve specific stereochemistry require elevated temperatures and phosphine-based ligands, which are tedious to synthesize and need an inert atmosphere, while there is a need for a phosphine-free, nitrogen-ligated cobalt complex that can perform stereoselective hydrogenation at room temperature.
Innovation Solution
Development of a pincer-based cobalt catalyst of formula (I) that uses ammonia borane as a hydrogen source and is prepared by reacting an anhydrous CoX2 salt with a nitrogen-ligated ligand in a suitable solvent at room temperature, allowing for the hydrogenation of substituted alkynes to Z-alkenes with high selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosphine-based ligands are used for stereoselective hydrogenation, then high selectivity for Z-alkenes is achieved, but the synthesis becomes tedious and requires inert atmosphere
Solution Approach 1:
The patent extracts the problematic phosphine-based ligands from the catalytic system and replaces them with nitrogen-based ligands (pyridine, pyrimidine, triazole, or tetrazole). This extraction eliminates the need for tedious multi-step synthesis and inert atmosphere requirements while maintaining the catalytic activity and stereoselectivity for Z-alkene production
Solution Approach 2:
The patent changes the chemical parameter of the ligand from phosphine-based to nitrogen-based (pyridine, pyrimidine, triazole, or tetrazole). This parameter change fundamentally alters the catalyst's properties, enabling operation under atmospheric conditions and simplifying the synthesis procedure while preserving high stereoselectivity
2Productivity
If elevated temperature (60-80°C) is used for hydrogenation, then reaction proceeds efficiently, but energy consumption increases
Solution Approach 1:
The patent changes the temperature parameter from elevated (60-80°C) to room temperature (20-25°C). This parameter change is enabled by the novel nitrogen-based ligand system, which maintains catalytic activity at lower temperatures, thereby reducing energy consumption while preserving reaction efficiency and productivity
3Reliability
If phosphine-based ligands are used, then catalytic activity is maintained, but synthesis complexity increases
Solution Approach 1:
The patent extracts the complex phosphine-based ligand system and replaces it with simpler nitrogen-based ligands (pyridine, pyrimidine, triazole, or tetrazole). This extraction maintains catalytic activity while dramatically simplifying the synthesis procedure and eliminating the need for inert atmosphere
Solution Approach 2:
The patent employs commercially available nitrogen-based ligands that can be used directly without extensive purification or special handling requirements. These ligands replace the complex, expensive phosphine-based alternatives, simplifying the overall catalytic system while maintaining effectiveness
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 catalyst achieves high selectivity for Z-alkenes at room temperature (27°C) without the need for special experimental setups, tolerating sensitive functionalities and reducing energy consumption, with yields ranging from 68-95% and improved energy efficiency.
Implementation Method 1
pincer-based cobalt catalysts for hydrogenation reaction
Implementation Method 2
hydrogenation of substituted alkynes to Z-alkenes
Data Source
AI summary
The present invention relates to a pincer-based cobalt catalyst of formula (I) for hydrogenation of alkynes, and its process of preparation thereof. More particularly the present invention also relates to a process for the hydrogenation of alkynes to alkenes.