Trimethylsilyl derivatives for the study of silicate structures. Part III. Sodium silicate hydrates

Abstract

A study was made of the yield and distribution of the products formed when Na₂H₂SiO₄,4H₂O, Na₂H₂SiO₄,5H₂O, and Na₂H₂SiO₄,8H₂O were treated by a direct method of trimethylsilylation reported previously. These soluble silicates are particularly prone to side reactions due to polymerisation of silicate ions in solution, yielding a distribution of products many of which are undetected chromatographically.

Quantitative yields of the expected orthosilicate derivatives were obtained only when vanishingly small concentrations of silicate were used. Further experiments with the mineral hemimorphite confirmed that, for a unified method of trimethylsilylation applicable to different structures, careful control of the water content in the reaction medium is essential. Improvements in the trimethylsilylation and chromatographic procedures are described.