In-situ Activation of Iron Hydrosilylation Catalysts
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Solution Overview
Problem
Existing hydrosilylation catalysts, particularly precious metal complexes, are inefficient in catalyzing certain reactions, prone to catalyst poisoning, and costly, while non-precious metal-based catalysts are air and moisture sensitive, making them challenging to use in industrial settings.
Innovation Solution
In-situ activation of five-coordinate non-precious metal complexes containing terpyridine, pyridinediimine, or quinoline-based terdentate nitrogen ligands using reducing agents to generate effective catalysts for hydrosilylation reactions, allowing for selective catalysis of silyl hydrides and unsaturated hydrocarbons without the need for inert conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precious metal complex catalysts are used for hydrosilylation reactions, then catalytic activity is achieved, but catalyst efficiency is insufficient and excess reactant is required
Solution Approach 1:
The patent modifies the ligand structure by introducing electron-withdrawing groups (such as fluorine atoms) at specific positions (R2 and R6) of the diimine ligand. This parameter change in the electronic properties of the ligand enhances the catalytic efficiency of the iron complex, allowing complete conversion of silicone hydride without requiring excess allyl polyether.
Solution Approach 2:
The patent replaces expensive precious metal catalysts (platinum, rhodium) with iron-based catalysts that are cheaper and can be used in lower amounts. The iron complex serves as a cost-effective alternative that maintains catalytic activity without requiring large excesses of reactants.
2Reliability
If precious metal complex catalysts are used for hydrosilylation reactions, then catalysis is achieved, but catalyst cost is high
Solution Approach 1:
The patent substitutes expensive precious metals with iron, a abundant and inexpensive metal. The iron complex catalyst achieves comparable catalytic activity to precious metal catalysts while dramatically reducing the cost of the catalyst system, making the overall process more economically viable.
Solution Approach 2:
The patent creates an iron-based catalyst that copies the functional behavior of precious metal catalysts in hydrosilylation reactions. By designing the iron complex with appropriate ligands (terpyridine, pyridinediimine, or quinoline-based terdentate nitrogen ligands), it replicates the catalytic activity previously only achievable with expensive precious metals.
3Ease of manufacture
If non-precious metal complexes are used as catalysts, then catalyst cost is reduced, but air and moisture sensitivity increases
Solution Approach 1:
The patent introduces electron-withdrawing groups (such as fluorine atoms) at specific local positions (R2 and R6) of the ligand structure. This localized modification creates regions of altered electron density that stabilize the iron center against oxidation by air and hydrolysis by moisture, while maintaining catalytic activity.
Solution Approach 2:
The patent creates a composite catalyst system combining iron metal center with specially designed organic ligands containing electron-withdrawing groups. This composite structure provides both the low cost of iron and the stability against air and moisture through the protective electronic effect of the ligand design.
4Ease of manufacture
If conventional iron complexes are used for hydrosilylation, then catalyst cost is reduced, but unwanted by-products are formed
Solution Approach 1:
The patent modifies the electronic parameters of the ligand by introducing electron-withdrawing groups that alter the electron density at the iron center. This parameter change in the catalyst's electronic structure enhances its selectivity for the desired hydrosilylation pathway while suppressing the dehydrogenative silylation pathway that produces unwanted unsaturated silyl olefin by-products.
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 in-situ activation method enables efficient and selective hydrosilylation reactions at room temperature, reducing the formation of unwanted by-products and avoiding the need for costly precious metals, while being more stable in air and moisture, thus suitable for industrial-scale applications.
Implementation Method 1
In-situ activation of five-coordinate non-precious metal complexes containing terpyridine, pyridinediimine, or quinoline-based terdentate nitrogen ligands using reducing agents to generate effective catalysts for hydrosilylation reactions
Implementation Method 2
reacting the silyl hydride and the compound containing at least one unsaturated group in the presence of the activated catalyst to produce a hydrosilylation product
Data Source
AI summary
Disclosed herein is a process for the hydrasilylation of a composition containing a silyl hydride and a compound containing at least one unsaturated group, the process comprising contacting a non-previous metal based complex as a catalyst precursor with an activator being a reducing agent shortly before, simultaneously or after contacting the complex with the composition, to cause the siiyl hydride to react with the compound containing at least one unsaturated group to produce a hydrosilylation product.