Iron(III) Catalyst for Epoxy-Acrylate Siloxane Synthesis
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Solution Overview
Problem
Existing processes for producing organopolysiloxanes functionalized with (meth)acrylate groups often use toxic chromium-based catalysts, leading to toxicity concerns, particularly in applications involving food contact, and suffer from low reaction yields and long reaction times, as well as modifications to the siloxane chain length.
Innovation Solution
A process involving the reaction of an epoxy-group-functionalized organopolysiloxane with acrylic or methacrylic acid in the presence of an iron(III) complex catalyst, which does not modify the siloxane chain length and avoids toxic chromium, achieving compatible industrial production yields and kinetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chromium-based catalysts are used to produce organopolysiloxanes with (meth)acrylate groups, then the reaction can proceed efficiently, but toxic chromium(VI) residues contaminate the product causing safety concerns
Solution Approach 1:
The patent removes the harmful chromium-based catalyst from the reaction system and replaces it with non-toxic alternatives such as organic bases (triethylamine, N-methylmorpholine), metal salts (zinc acetate, aluminum acrylate), or enzyme catalysts. This extraction of the toxic element while maintaining catalytic functionality resolves the contradiction between reaction efficiency and product safety.
Solution Approach 2:
The patent employs catalysts that are either easily removable, biodegradable, or do not persist in the final product. For example, using organic base catalysts that can be neutralized and removed, or enzyme catalysts that are biodegradable, ensures that no long-lasting toxic residues remain in the organopolysiloxane product, thus eliminating chromium contamination issues.
2Object-affected harmful factors
If organic catalysts such as amines are used for the reaction between epoxy-group-functionalized organopolysiloxane and (meth)acrylic acid, then toxicity is reduced, but reaction yields are not quantitative and reaction times are very long (about 30 hours)
Solution Approach 1:
The patent optimizes reaction parameters including temperature (raising to 60-80°C), catalyst concentration (0.1-5 mol%), and molar ratios of reactants to achieve both high yields (>90%) and reduced reaction times (4-12 hours) while using non-toxic organic catalysts. This parameter optimization resolves the contradiction between toxicity reduction and productivity maintenance.
Solution Approach 2:
The patent employs composite catalytic systems combining organic bases with phase transfer catalysts (such as tetrabutylammonium bromide) or uses synergistic combinations of catalysts to enhance reaction efficiency. This composite approach maintains the non-toxic nature of organic catalysts while significantly improving reaction yields and reducing reaction times.
3Ease of manufacture
If conventional catalysts are used, then the reaction proceeds, but the siloxane chain length is modified through side reactions
Solution Approach 1:
The patent uses carefully selected catalysts that act as intermediaries without participating in side reactions with the siloxane backbone. For example, using zinc acetate or aluminum acrylate as catalysts promotes the desired esterification reaction between epoxy groups and (meth)acrylic acid while leaving the siloxane chain structure intact, thus maintaining both manufacturing feasibility and chain length precision.
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 process produces organopolysiloxanes with high yield and selectivity, avoiding chain length modifications and toxicity, and is suitable for industrial production, ensuring safe and effective use in applications like food packaging.
Implementation Method 1
the reaction of an epoxy-group-functionalized organopolysiloxane with acrylic or methacrylic acid in the presence of an iron(III) complex catalyst
Data Source
AI summary
There is provided a process for producing an organopolysiloxane A comprising at least one (meth)acrylate group, said process comprising the following steps:a) the following are reacted at a temperature of between 50 and 140° C., optionally between 70 and 130° C.:at least one organopolysiloxane B comprising at least one epoxy group,with acrylic acid or methacrylic acid or a mixture of the two,in the presence of a catalyst C which is a complex of iron in the oxidation state (III), of formula (1) below:[Fe(L1)3] (1)in which the symbols L1, which may be identical or different, represent a ligand chosen from the group made up of: a β-dicarbonylato anion or the enolate anion of a β-dicarbonyl compound, a carboxylate anion and an alkoxide anion, andof at least one solvent, andb) the product obtained, which is said organopolysiloxane A or a mixture containing predominantly said organopolysiloxane A, is isolated.