Phosphorous Acid Derivatives for Olefin Metathesis Isomerization Control
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Solution Overview
Problem
The olefin metathesis reaction is hindered by double bond isomerization due to residual metathesis catalysts, which is exacerbated by heating and distillation, and current inhibitors like tris(hydroxymethyl) phosphine (THMP) are not viable on an industrial scale due to carcinogenic byproducts and explosive hazards.
Innovation Solution
The use of a salt and/or ester of a phosphorous oxo acid, or a derivative where a P—H bond is replaced by a P—C bond, as an isomerization suppression agent to passivate residual metathesis catalysts, allowing for further processing without removal, including heating and distillation, without generating carcinogenic byproducts or explosive gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tris(hydroxymethyl) phosphine (THMP) is added to suppress isomerization, then isomerization is inhibited, but carcinogenic formaldehyde is generated as a byproduct
Solution Approach 1:
The patent replaces THMP with phosphorous acid derivatives (H3PO3 and its esters) that are commercially available, non-carcinogenic, and can be used in stoichiometric amounts. These alternatives achieve the same isomerization suppression function without generating harmful byproducts, effectively substituting a problematic reagent with a safer one.
Solution Approach 2:
The patent changes the chemical structure parameter of the isomerization suppressor from THMP (which generates formaldehyde) to phosphorous acid derivatives (H3PO3 and its esters). This structural parameter change eliminates the formation of carcinogenic formaldehyde while maintaining the isomerization suppression function through the P=O group's ability to coordinate with metal catalysts.
2Reliability
If THMP is prepared from precursor salts, then isomerization suppression is achieved, but explosive hydrogen gas is formed
Solution Approach 1:
The patent uses phosphorous acid derivatives (H3PO3 and its esters) that are already in their active form, eliminating the need for preliminary conversion steps that generate hydrogen gas. By starting with the ready-to-use suppressor rather than requiring in-situ generation from precursors, the hazardous hydrogen evolution step is avoided entirely.
3Productivity
If residual metathesis catalyst is present in the reaction mixture, then metathesis reaction proceeds, but double bond isomerization occurs
Solution Approach 1:
The patent adds phosphorous acid derivatives to the reaction mixture to selectively bind and remove the active metal catalyst species that cause isomerization. The P=O group coordinates with the metal center, effectively extracting the harmful catalytic activity while allowing the metathesis reaction to proceed with controlled catalyst deactivation.
Solution Approach 2:
The phosphorous acid derivative acts as an intermediary substance that mediates between the metathesis catalyst and the olefin product. It selectively interacts with the catalyst to suppress isomerization without interfering with the primary metathesis reaction, serving as a protective mediator that preserves product integrity.
4Manufacturing precision
If the metathesis mixture is heated and/or distilled, then product purification is achieved, but isomerization is exacerbated
Solution Approach 1:
The patent applies preliminary anti-action by adding phosphorous acid derivatives to the reaction mixture before heating and distillation. This pre-treatment passivates the residual catalyst that would otherwise promote isomerization during thermal processing, allowing subsequent heating and distillation to proceed without exacerbating double bond migration.
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 method effectively suppresses isomerization, preserving the integrity of olefin metathesis products and enabling their subsequent processing without compromising the product, even under high-temperature conditions, and is commercially scalable without safety hazards.
Implementation Method 1
adding an isomerization suppression agent to a mixture that includes the olefin metathesis product and residual metathesis catalyst from the metathesis reaction under conditions that are sufficient to passivate at least a portion of the residual metathesis catalyst
Data Source
AI summary
A method for suppressing isomerization of an olefin metathesis product produced in a metathesis reaction includes adding an isomerization suppression agent to a mixture that includes the olefin metathesis product and residual metathesis catalyst from the metathesis reaction under conditions that are sufficient to passivate at least a portion of the residual metathesis catalyst. The isomerization suppression agent includes (i) a salt and/or an ester of a phosphorous oxo acid, and/or (ii) a derivative of the phosphorous oxo acid in which at least one P—H bond has been replaced by a P—C bond, and/or (iii) a salt and/or an ester of the derivative. Methods of refining natural oils are described.