Cationic Germanium(II) Catalyst for Siloxane Synthesis
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Solution Overview
Problem
Existing methods for preparing siloxanes, such as the Piers-Rubinsztajn reaction, face challenges with noble metal catalysts being expensive and unstable, leading to inefficient and unsafe processes, and cationic silicon(II) compounds are sensitive to air and moisture, complicating the reaction management.
Innovation Solution
The use of cationic germanium(II) compounds in the presence of oxygen as a catalyst system for the Piers-Rubinsztajn reaction, which is more stable and efficient, and can be used in air, providing a safer and more reproducible process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If noble metal catalysts are used for dehydrocondensation of Si-H-containing silanes and silanols, then selective linkage and uniform product are achieved, but the cost increases significantly due to expensive noble metals
Solution Approach 1:
The patent replaces expensive noble metal catalysts with a cheaper alternative catalyst system that can be used in sub-stoichiometric amounts. The catalyst described in WO 2019/068357 is consumed during the reaction but at much lower cost than noble metals, and can be added in controlled amounts to achieve the desired conversion without requiring expensive precious metals.
Solution Approach 2:
The patent changes the catalyst type from noble metals to a different chemical system with different properties. The new catalyst operates under modified reaction conditions (controlled temperature, stoichiometric ratios) to achieve similar selective linkage without the high cost of noble metals.
2Productivity
If B(C6F5)3 is used as catalyst in the Piers-Rubinsztajn reaction, then the reaction proceeds, but the catalyst is consumed and deactivated, requiring repeated addition which complicates the process and reduces reproducibility
Solution Approach 1:
The patent accepts that the catalyst will be consumed but uses a cheaper catalyst system that can be added in controlled stoichiometric amounts. This avoids the need for complex monitoring and repeated addition procedures, simplifying the overall process while maintaining productivity.
Solution Approach 2:
The patent calculates and adds the precise stoichiometric amount of catalyst needed for the reaction at the beginning. This preliminary calculation and addition eliminates the need for repeated catalyst additions during the reaction, simplifying the process and improving reproducibility.
3Reliability
If relatively large amounts of catalyst are used at the start of the reaction, then catalyst consumption is compensated, but the reaction becomes difficult to control due to rapid initial phase and exothermic nature, posing safety risks
Solution Approach 1:
The patent uses a catalyst system that allows for controlled reaction progression. The catalyst activity and reaction rate can be monitored and controlled by adjusting the amount of catalyst added and the reaction conditions (temperature, stoichiometry), providing feedback control to prevent runaway reactions.
Solution Approach 2:
The patent optimizes the catalyst amount to be stoichiometric rather than large excess, and controls reaction parameters (temperature, addition rate) to manage the exothermic nature of the reaction. This allows the reaction to proceed at a controlled rate without dangerous temperature spikes.
4Productivity
If cationic silicon(II) compounds are used as catalyst, then high catalytic activity is achieved, but the compounds are highly sensitive to air and humidity, increasing technical complexity
Solution Approach 1:
The patent employs cationic silicon(II) compounds that are sufficiently stable to be handled and stored in air or under mild protective atmospheres, eliminating the need for complex inert gas handling systems while maintaining high catalytic activity. The catalyst can be used in standard laboratory or industrial equipment without requiring specialized air-free techniques.
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 approach results in a highly active catalyst system that efficiently catalyzes the Piers-Rubinsztajn reaction, maintaining stability in air and reducing the need for expensive noble metals, thus enhancing process control and safety while improving the reproducibility and cost-effectiveness of siloxane production.
Implementation Method 1
cationic germanium(II) compounds catalyze the Piers-Rubinsztajn reaction very efficiently
Implementation Method 2
cationic germanium(II) compounds in the presence of oxygen, resulting in a highly active catalyst system
Data Source
AI summary
The subject matter of the present invention is a mixture M containing (a) at least one compound A, selected from (a1) a compound of general formula (I): R1R2R3Si-H, and/or (a2) a compound of general formula (I'): (SiO4/2) a (RxSiO3/2) b (HSiO3/2) b ' (Rx2SiO2/2) c (RxHSiO2/2) c' (H2SiO2/2) c" (RX 3SiO1/2) d (HRx 2SiO1/2) d' (H2RxSiO1/2) d" (H3SiO1/2) d"'; and (b) at least one compound B, selected from (b1) a compound of general formula (II): R4R5R6Si-O-R7, and/or (b2) a compound of general formula (II'): Rx 3Si-O[-SiRx 2-O] m- [Si (OR7) Rx-O] n-SiRx 3, and (c) at least one compound C, selected from cationic germanium (II) compounds of general formula (III): ( [Ge(II)Cp]+) a Xa-