Acrolein Co-oxidant and Carbon Nanotube Catalyst for Caprolactone
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Solution Overview
Problem
The existing methods for preparing ε-caprolactone using molecular oxygen as an oxidant in the Baeyer-Villiger oxidation of cyclohexanone face challenges with low efficiency and high cost due to the use of benzaldehyde as a co-oxidant, which limits the economic feasibility and complicates separation and purification.
Innovation Solution
The method employs acrolein as a co-oxidant and nitrogen-doped carbon nanotubes as a metal-free catalyst, facilitating the synthesis of ε-caprolactone with improved efficiency, easy catalyst recovery, and reduced costs, while producing valuable acrylic acid that aids in separation and purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If benzaldehyde is used as a co-oxidant in the Baeyer-Villiger oxidation of cyclohexanone, then the oxidation reaction can proceed, but the efficiency is low and the cost is high
Solution Approach 1:
The patent changes the chemical parameter of the co-oxidant from benzaldehyde to acrolein, which has different molecular structure and reactivity characteristics. Acrolein's α,β-unsaturated aldehyde structure enables more efficient oxidation of cyclohexanone, achieving over 90% conversion rate and 95% selectivity, while reducing co-oxidant consumption and improving overall process efficiency.
2Ease of manufacture
If benzaldehyde is used as a co-oxidant, then the oxidation reaction can proceed, but separation and purification become complicated
Solution Approach 1:
The patent extracts the problematic benzaldehyde component from the reaction system and replaces it with acrolein. The acrolein oxidation system produces different by-products with distinct physical and chemical properties, enabling simpler separation and purification processes. The acrylic acid produced can be easily separated from ε-caprolactone through distillation or other standard separation techniques.
3Reliability
If molecular oxygen is used as an oxidant, then safety and cost are improved, but the oxidizing ability is weak and satisfactory results cannot be achieved
Solution Approach 1:
The patent introduces an aldehyde co-oxidant (acrolein) as an intermediary substance that mediates between molecular oxygen and cyclohexanone. The aldehyde acts as a reactive intermediate that enhances the oxidizing capability of molecular oxygen, enabling efficient Baeyer-Villiger oxidation while maintaining the safety and cost advantages of using molecular oxygen as the primary oxidant.
4Productivity
If a catalyst is used to enhance molecular oxygen oxidizing ability, then oxidation efficiency is improved, but separation and purification become difficult and cost increases
Solution Approach 1:
The patent employs a solid catalyst that can be easily separated from the reaction mixture through filtration or decantation. The catalyst, such as metal oxides or supported catalysts, provides the necessary catalytic activity for efficient oxidation while being inexpensive and disposable, eliminating the need for complex separation and purification procedures required for homogeneous catalysts.
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 achieves high yield and selectivity of ε-caprolactone with 100% efficiency of acrolein when the molar ratio of aldehydes to ketones exceeds 4, significantly reducing co-oxidant consumption and simplifying the process, and the nitrogen-doped carbon nanotubes provide high catalytic activity and environmental benefits.
Implementation Method 1
nitrogen-doped carbon nanotubes as a metal-free catalyst, facilitating the synthesis of ε-caprolactone
Implementation Method 2
Baeyer-Villiger oxidation reaction is an important reaction to oxidize a cyclic ketone or a linear ketone into a more complicated and valuable linear ester or lactone
Data Source
AI summary
The present invention discloses a method for preparing ε-caprolactone. The method comprises the steps of: adding cyclohexanone, a co-oxidant and a certain amount of catalyst into a certain amount of organic solvent, using molecular oxygen as an oxidant, implementing a reaction with stirring for 0.1 to 24 hours under a pressure of 0.1 to 2 MPa and at a temperature of 60° C. to 100° C., wherein the co-oxidant is acrolein, and the catalyst is a carbon material. The present invention has the advantages of high-efficiency co-oxidant, easily available and recovered catalyst, environmental-friendly oxidant, simple operation and low cost.