3-Halopropyltrihalosilane Hydrosilylation With Platinum Cocatalysts
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Solution Overview
Problem
Existing methods for synthesizing 3-halopropyltrihalosilane compounds suffer from low selectivity and yield, leading to the formation of undesired side-products such as propyltrihalosilanes and silicontetrahalides, and require additional steps that increase time and cost.
Innovation Solution
A method involving the reaction of allyl halide or methallyl halide with H-silane in the presence of a Karstedt catalyst and a cocatalyst of formula (A) enhances the selectivity and yield of 3-halopropyltrihalosilane compounds, using a catalyst composition that includes a Karstedt catalyst and a cocatalyst of formula (A): where R1 is an aryl group, R2 is an alkyl group, and n is 0 or 1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional platinum catalysts are used for hydrosilylation of allyl halide and H-silane, then the reaction can proceed, but the selectivity and yield are moderate with formation of side-products
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by introducing specific cocatalysts (amines, amides, nitriles, isocyanates, carbamates) in combination with platinum catalysts. This parameter change transforms the moderate-selectivity conventional system into a high-selectivity system that suppresses side-reactions such as reduction of allyl halide to propene and isomerization of unsaturated compounds.
Solution Approach 2:
The patent employs composite catalyst systems combining platinum catalysts with organic cocatalysts (such as triethylamine, N,N-dimethylacetamide, acetonitrile). This composite approach creates a synergistic effect where the cocatalyst enhances the selectivity of the platinum catalyst, achieving high yield and selectivity for 3-halopropyltrihalosilane compounds while minimizing harmful side-products.
2Manufacturing precision
If additional preparation steps are added to improve catalyst performance, then selectivity and yield improve, but the time and cost of preparation increase
Solution Approach 1:
The patent merges the catalyst activation step with the main hydrosilylation reaction by using cocatalysts that can be directly added to the reaction mixture. This eliminates the need for separate catalyst preparation steps described in prior art (such as preparing catalysts in advance as mentioned in US 4,292,434), thereby reducing preparation time and costs while maintaining high selectivity and yield.
Solution Approach 2:
The cocatalysts are designed to be pre-selected from specific chemical classes (amines, amides, nitriles, isocyanates, carbamates) with known properties that enhance platinum catalyst activity. This preliminary selection of appropriate cocatalysts allows direct addition to the reaction system without requiring complex preparatory steps, thus saving time while achieving improved catalytic performance.
3Productivity
If conventional catalyst systems are used, then the reaction proceeds, but propene is formed which reacts further to produce unwanted propyltrihalosilanes
Solution Approach 1:
The patent applies preliminary anti-action by using cocatalysts that prevent the reduction of allyl halide to propene in the first place. The cocatalyst-modified platinum catalyst system selectively promotes the desired hydrosilylation pathway while suppressing the reduction side-reaction, thereby preventing the formation of propene and subsequent unwanted propyltrihalosilane by-products before they can form.
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 method achieves high yields and improved selectivity of 3-halopropyltrihalosilane compounds with reduced side-products, facilitating purification and being ecologically benign and atom-efficient.
Implementation Method 1
They describe the addition of Si-H bonds across unsaturated bonds. An important group of silanes produced by this reaction are 3-halopropyltrihalosilane compounds such as 3-chloropropyltrichlorosilane (also referred to as trichloro(3-chloropropyl)silane). They are conventionally prepared by hydrosilylation of an allyl halide such as allylchloride and a H-silane such as a trihalosilane (e.g. trichlorosilane) in the presence of platinum catalysts.
Data Source
AI summary
The present invention relates to a method for synthesizing at least one 3-halopropyltrihalosilane compound, use of a novel catalyst system and a novel composition.