Convenient two step synthesis of 29Si labelled tetraalkoxysilanes.

29 Si enrichment would be advantageous for many NMR studies of the structural properties of sol–gel derived materials. The required starting materials (29Si enriched alkoxysilanes), however, are expensive and difficult to provide. Here we present a scalable, reliable synthesis of 29Si enriched tetraethoxysilane starting from silicon dioxide or elemental silicon with a total yield up to 75%.