Studies on dialkoxysilane hydrolysis kinetics under alkaline conditions

The Fourier transform infrared spectroscopy (FTIR) was employed to study the hydrolysis reaction of dimethyldimethoxysilane (DMDMS) in aqueous solution by following the changes of Si–OCH3 characteristic peak. A series of hydrolysis rate constants were achieved by linear regression analysis in various reaction conditions. The results showed that the hydrolysis reactions are affected obviously by the pH value of catalyst and the initial DMDMS concentration. 29Si NMR was also used to ‘in situ’ monitor this system and the results were in an agreement with those from FTIR. It indicated that FTIR is a powerful tool for providing ‘in situ’ information regarding the hydrolysis of alkoxysilane for the high sensitivity and fast scanning ability. The reaction mechanism of nucleophilic displacement with the formation of a pentacoordinate intermediate was suggested.