Cobalt Dimethylglyoxime Double-Bond Isomerization at Low H2 Pressure
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Solution Overview
Problem
Existing methods for C-C double bond isomerization, such as those used to convert 3-formylbut-3-enyl acetate to 4-acetoxy-2-methylbut-2-enal, are costly, complex, and require high hydrogen pressures, leading to catalyst complexity, corrosion issues, and unsatisfactory yields, and are not applicable to other structures.
Innovation Solution
A method using a cobalt dimethylglyoxime catalyst (Co(dmgX)2•L2) under 1 to 10 bar hydrogen pressure, without metal chlorides or halides, to perform double-bond isomerization of compounds of formula (II) to formula (I), allowing for simpler reactor conditions and catalyst recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal chlorides (FeCl2, FeCl3, SnCl2, SnCl4, CuCl, CuCl2, ZnCl2) are used as co-catalysts with Co(dmgBF2)2•L2, then conversion rates and selectivities are improved, but system complexity increases and corrosion risk increases
Solution Approach 1:
The patent removes the metal chloride co-catalysts from the catalytic system, retaining only the cobalt dimethylglyoxime complex. This extraction eliminates the need for separate co-catalyst addition, simplifies the system, and removes corrosion risks while maintaining catalytic activity through the hydrogen-active cobalt complex alone.
Solution Approach 2:
The patent replaces expensive and corrosive metal chloride co-catalysts with a more stable, reusable cobalt dimethylglyoxime complex that does not require additional co-catalysts. This substitution reduces material costs, eliminates corrosion issues, and simplifies catalyst recovery and recycling processes.
2Manufacturing precision
If metal chlorides are used as co-catalysts, then conversion rates and selectivities are improved, but corrosion of steel reactors increases
Solution Approach 1:
The patent eliminates the harmful corrosive effect of metal chlorides by designing a catalytic system based on cobalt dimethylglyoxime complexes that are inherently non-corrosive to steel reactors. This conversion replaces a harmful chemical system with a benign one that maintains catalytic effectiveness without compromising reactor integrity.
3Productivity
If hydrogen pressure of 30 to 60 atm is applied, then isomerization reaction efficiency is improved, but costs increase
Solution Approach 1:
The patent optimizes the hydrogen pressure parameter to a lower range (1 to 10 bar) compared to conventional methods (30 to 60 atm). This parameter change reduces equipment requirements, lowers operational costs, and simplifies safety considerations while the cobalt catalyst maintains high isomerization efficiency at these milder conditions.
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 method achieves excellent yields and selectivities at lower hydrogen pressures, avoiding metal chlorides and reducing reactor complexity, while being applicable to a broader range of structures.
Implementation Method 1
a double-bond isomerization reaction in the presence of hydrogen and a cobalt dimethylglyoxime catalyst
Implementation Method 2
in the presence of hydrogen and a cobalt dimethylglyoxime catalyst
Data Source
AI summary
The present invention relates to a method for preparing a compound of the formula (I) wherein R1, R2 and R3 are as defined in the claims and the description, by subjecting a compound of the formula (II) to a double-bond isomerization reaction in the presence of hydrogen and a cobalt dimethylglyoxime catalyst.