Picture of UK Houses of Parliament

Leading national thinking on politics, government & public policy through Open Access research

Strathprints makes available scholarly Open Access content by researchers in the School of Government & Public Policy, based within the Faculty of Humanities & Social Sciences.

Research here is 1st in Scotland for research intensity and spans a wide range of domains. The Department of Politics demonstrates expertise in understanding parties, elections and public opinion, with additional emphases on political economy, institutions and international relations. This international angle is reflected in the European Policies Research Centre (EPRC) which conducts comparative research on public policy. Meanwhile, the Centre for Energy Policy provides independent expertise on energy, working across multidisciplinary groups to shape policy for a low carbon economy.

Explore the Open Access research of the School of Government & Public Policy. Or explore all of Strathclyde's Open Access research...

Esterification, condensation, and deprotonation equilibria of trimethylsilanol

Sefcik, J and Rankin, S E and Kirchner, S J and McCormick, A V (1999) Esterification, condensation, and deprotonation equilibria of trimethylsilanol. Journal of Non-Crystalline Solids, 258 (1-3). pp. 187-197. ISSN 0022-3093

Full text not available in this repository.Request a copy from the Strathclyde author

Abstract

We investigate by Si-29 NMR the equilibrium behavior of trimethylsilanol in both acidic and alkaline ethanol/water solutions. This system is of interest not only for passivation (silylation) of organic and inorganic hydroxide-containing compounds, but also as a model of higher silane functionality systems yielding silica coatings, silicones, gels, and zeolites. Because silanol esterification, condensation, and deprotonation reactions are often coupled, one cannot easily monitor the individual reaction equilibria in multifunctional silane systems. Here, though, we measure the equilibrium species distribution in a monofunctional model system to estimate the equilibrium constants-including for the first time the esterification equilibrium constant of a silanol in alkaline conditions. Our main findings are: (1) the measured esterification equilibrium constants agree with previous values from dioxane-based solutions and with pseudoequilibrium data for multi-functional silanes in ethanol-water solutions (suggesting that substitution effects for silanol esterification equilibrium coefficients are negligible), (2) the measured equilibrium deprotonation constant agrees with silanol acidities reported in a dioxane-based system, and (3) the solvent environment affects the apparent silanol condensation equilibrium constants significantly. In alkaline systems, while silanol deprotonation affects solution pH even at low base concentrations, it affects the silicate speciation only at high base concentrations. Finally, we find a strong and nearly linear correlation between 29Si NMR chemical shift and the degree of trimethylsilanol deprotonation.