Thiocarboxylate Silane Synthesis via Alkylguanidinium Catalyst
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Solution Overview
Problem
Current processes for preparing thiocarboxylate silane are complex, uneconomical, and result in low yields and impure products due to the need for stoichiometric amounts of amines, phase transfer catalysts, and hazardous materials, with slow reaction rates and complicated purification procedures.
Innovation Solution
A process involving the reaction of an aqueous solution of thiocarboxylic acid salt with a haloalkyl silane in the presence of a catalytically effective amount of alkylguanidinium salt phase transfer catalyst, allowing for higher reaction temperatures and significantly improved kinetics, reduced catalyst usage, and simplified purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stoichiometric amounts of amine catalyst are used, then the reaction can proceed, but the process becomes complex and uneconomical with requiring large amounts of catalyst and complicated purification procedures
Solution Approach 1:
The patent changes the chemical parameter of the catalyst from conventional amines to alkylguanidinium salts, which fundamentally alters the reaction mechanism. This parameter change enables the reaction to proceed at higher temperatures with significantly reduced catalyst loadings (from stoichiometric to catalytic amounts), thereby simplifying the process while maintaining productivity
Solution Approach 2:
The patent employs a reusable catalytic amount of alkylguanidinium salt that can be recycled after treatment with caustic to the corresponding hydrochloride, eliminating the need for stoichiometric amounts of amine catalyst. This reduces material consumption and simplifies purification procedures while maintaining high reaction rates
2Ease of operation
If phase transfer catalyst such as quaternary ammonium salt or phosphonium salt is used, then the reaction can proceed in aqueous process, but the rate of reaction is low requiring large amounts of catalyst
Solution Approach 1:
The patent changes the catalyst parameter from conventional quaternary ammonium salts or phosphonium salts to alkylguanidinium salts. This parameter change results in significantly higher thermal stability and reaction rates, allowing the use of much smaller catalyst amounts while maintaining aqueous process capability
Solution Approach 2:
Instead of using large amounts of conventional phase transfer catalysts to achieve acceptable reaction rates, the patent inverts the approach by using a different catalyst class (alkylguanidinium salts) that inherently provides superior catalytic activity, thereby reducing the catalyst loading requirement while maintaining or improving reaction rate
3Productivity
If higher reaction temperatures are used, then the overall kinetics of the reaction is dramatically improved, but the thermal stability of conventional catalysts is insufficient
Solution Approach 1:
The patent changes the catalyst parameter to alkylguanidinium salts, which possess superior thermal stability compared to conventional catalysts. This parameter change enables the reaction to be conducted at higher temperatures (e.g., 50-100°C) without catalyst decomposition, thereby dramatically improving reaction kinetics while maintaining catalyst integrity
Solution Approach 2:
The patent employs alkylguanidinium salts as catalysts that remain stable under high-temperature reaction conditions, eliminating the need to use large amounts of catalyst or conduct the reaction at lower temperatures. The catalyst's thermal stability allows it to function effectively at elevated temperatures where conventional catalysts would decompose
4Productivity
If large amounts of catalyst are used in previous systems, then the reaction rate can be improved, but a rag layer forms between aqueous and organic phases requiring complicated purification
Solution Approach 1:
The patent changes the catalyst parameter to alkylguanidinium salts with superior catalytic activity, which allows the reaction to proceed at high rates with much smaller catalyst loadings. This parameter change eliminates the formation of rag layers between phases, as the reduced catalyst amount prevents excessive emulsion formation, thereby simplifying the separation and purification processes
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 process dramatically improves reaction kinetics, yield, and product quality, eliminating the need for hazardous materials and solvent use, while reducing catalyst usage and purification complexity by more than 50%, resulting in a more efficient and cost-effective production of thiocarboxylate silane.
Implementation Method 1
reacting an aqueous solution of salt of thiocarboxylic acid with a haloalkyl silane in the presence of a catalytically effective amount of alkylguanidinium salt phase transfer catalyst
Implementation Method 2
The rag layer usually present between the aqueous and the organic phases due to the high level of catalyst usage in the previous systems is completely absent herein
Data Source
AI summary
An improved process for the preparation of thiocarboxylate silane comprises reacting an aqueous solution of salt of thiocarboxylic acid represented by the formula: R-Y-SM, wherein R is selected from the group consisting of an alkyl, alkynyl, aryl and aralkyl group containing from 1 to 30 carbon atoms and hydrogen; Y is carbonyl, C(=O); and M is selected from the group consisting of an alkali metal, ammonium, mono-, di-, and tri- substituted ammonium, with a haloalkyl silane represented by the formula: LfG2(-SiX3)c (5), wherein G2 is a polyvalent group derived from an alkyl, alkenyl, aryl or aralkyl group containing from 1 to 40 carbon atoms; each occurrence of L is independently a halogen atom, sulfonate group, sulfinate group, or carboxylate group; each occurrence of X is independently selected from the group consisting of RO-, R2C=NO-, R2NO-, R2N-, -R, and -(OSiR2)t(OSiR3), wherein each R is independently an alkyl, alkynyl, aryl or aralkyl group containing from 1 to 30 carbon atoms or hydrogen, with the proviso that at least one X is not -R; the subscript c is an integer from 1 to 6; and, the subscript f is an integer from 1 to 6, in the presence of a catalytically effective amount of alkylguanidinium salt phase transfer catalyst to provide thiocarboxylate silane.