A kinetic modeling for the ultrasound-assisted and oxalic acid-catalyzed hydrolysis of 3-glycidoxypropyltrimethoxysilane

Abstract

Abstract: Instantaneous hydrolysis rates of the ultrasound-assisted and oxalic acid-catalyzed hydrolysis of 3-glycidoxypropyltrimethoxysilane (GPTMS) have been obtained at several temperatures by using a dynamic ultrasound-adapted calorimetric method. Hydrolysis starts by ultrasound action because of the initial immiscibility gap between GPTMS and water. The hydrolysis process is a complex result of dissolution between GPTMS and H2O, which increases the hydrolysis rate, and reaction within the phases, which diminishes the hydrolysis rate as the reactants are consumed. The experimental hydrolysis rates were very well fitted by a modified version of an earlier kinetic model based on a dissolution and reaction mechanism. The rate constants for the ultrasound and methanol producing dissolution and the rate constants for the GPTMS hydrolysis were obtained by fitting the modeling to the overall heterogeneous/homogeneous hydrolysis pathway at each temperature studied. The hydrolysis rate constants were found in good agreement with those obtained previously on basis of a non-modeling method applied exclusively to the final homogeneous step of the reaction. Ultrasound producing mixture was found much more effective than methanol producing dissolution during the heterogeneous step of the GPTMS hydrolysis. Graphical Abstract: [Figure not available: see fulltext.]