Hydrolysis and condensation of alkoxysilanes investigated by internal reflection FTIR spectroscopy

The hydrolysis of a series of alkyl-substituted alkoxysilanes and an antimicrobial quaternary ammonium silane was investigated in water-acetone solvents by Fourier transform infrared (FTIR) spectroscopy. An internal reflectance cell was employed for the investigation. Rates of sequential hydrolysis of the first, second, and in one case the third alkoxy groups were extracted by nonlinear regression of curves of methanol concentration plotted versus time using data obtained from the FTIR spectra of the reaction mixture. Acid catalysis of the hydrolysis was observed. Condensation of the silanol groups produced by the hydrolysis was investigated using similar techniques and rate data are presented.