Liquid Phase Hydrogenolysis of Cyclic Acetals for Selective Hydroxy Ether Production
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Solution Overview
Problem
Existing methods for producing hydroxy ether compounds through hydrogenolysis of cyclic acetals and ketals suffer from low selectivity and high by-product formation, requiring co-catalysts and stabilizers that complicate purification and increase costs, while traditional alkoxylation processes produce undesirable byproducts and are inefficient.
Innovation Solution
A liquid phase hydrogenolysis process using a noble metal catalyst supported on silica or carbon, without acidic co-catalysts or stabilizers, where cyclic acetal or ketal compounds are reacted with hydrogen in the presence of a reactive solvent with a molar ratio of at least 2:1, enhancing selectivity towards hydroxy mono-ether compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional alkoxylation reactions are used to produce hydroxy ether compounds, then the process can proceed with conventional catalysts, but the selectivity is poor and undesirable byproducts are formed
Solution Approach 1:
The patent changes the fundamental reaction parameters by switching from alkoxylation to hydrogenolysis of cyclic acetals/ketals. This involves changing the reactants (from alcohol+alkyl epoxide to cyclic acetal/ketal), the reaction type (from nucleophilic substitution to catalytic hydrogenolysis), and the catalyst system (from base/acid catalysts to noble metal catalysts like Pd, Pt, or Rh). These parameter changes achieve high selectivity (90-98%) to hydroxy ether compounds while eliminating the formation of polyether byproducts that plague traditional alkoxylation processes.
2Manufacturing precision
If hydrogenolysis of cyclic acetals is performed with noble metal catalysts, then selectivity improves, but co-catalysts and stabilizers are required which complicate purification
Solution Approach 1:
The patent removes (extracts) the co-catalysts and stabilizers from the reaction system. Specifically, it eliminates the need for phosphoric acid co-catalysts and hydroquinone stabilizers that were previously required in hydrogenolysis processes. By using only the noble metal catalyst on an inert support (alumina, silica, or carbon), the reaction achieves high selectivity without requiring additional chemical additives, thereby simplifying the purification process and eliminating the need to remove these auxiliary substances from the product.
Solution Approach 2:
The patent employs a disposable inert support material (alumina, silica, or carbon) for the noble metal catalyst. These supports are inexpensive, stable, and can be easily separated from the product mixture through filtration or decantation. The inert nature of these supports means they do not participate in the reaction or require complex removal procedures, making them ideal disposable carriers for the catalytic active sites.
3Productivity
If phosphoric acid co-catalysts are used in hydrogenolysis, then reaction activity increases, but corrosion and separation difficulties occur
Solution Approach 1:
The patent replaces the corrosive phosphoric acid co-catalyst with an inert, disposable support material (alumina, silica, or carbon) that carries the noble metal catalyst. These supports are chemically stable, non-corrosive, and can be easily disposed of or regenerated by simple filtration and washing procedures. They provide the necessary catalytic activity through the noble metal sites while eliminating all the harmful effects associated with phosphoric acid, including corrosion of equipment and difficulty in product separation.
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 (at least 90%) and yield of hydroxy mono-ether compounds, reducing by-product formation and eliminating the need for co-catalysts and stabilizers, making it more efficient and economically viable for continuous production.
Implementation Method 1
reacting at least a portion of the hydrogen and at least a portion of the cyclic compounds in the presence of: (i) a noble metal catalyst supported on carbon or silica
Implementation Method 2
a noble metal catalyst supported on carbon or silica
Data Source
AI summary
A liquid phase hydrogenolysis of acetal compounds, such as cyclic acetals and cyclic ketals, is disclosed. The acetal compounds are fed to a reaction zone and reacted in the presence of a noble metal catalyst supported on a carbon or silica support to make hydroxy mono-ether compounds in high selectivity, without the necessity of using acidic co-catalysts such as phosphorus containing acids or stabilizers such as hydroquinone.