Preparation of alkyl-substituted partial trimethylsilyl silicates from olivine

The direct trimethylsilylation reaction of olivine has yielded partial trimethylsilyl derivatives of ortho- and di-silicates whose unsilylated silanol groups have been esterified with the alcohol used as the organic solvent in the trimethylsilylating reagent. Gas chromatographic-mass spectroscopic measurements indicate the presence of the tri-, di-, and mono-alkyl-substituted trimethylsilyl derivatives of monosilicic acid [SiO₄(SiMe₃)_4-nR_n; n = 1-3] in addition to the fully silylated monomeric derivative [SiO₄(SiMe₃)₄]. Dimeric derivatives have also been detected which contain both the completely trimethylsilylated derivative [Si₂O₇(SiMe₃)₆] and alcohol-esterified derivatives [Si₂O₇(SiMe₃)_6-nR_n; n = 1-4]. The ratio of the esterified products varies with the volume of alcohol or water in the silylating reagent as well as with the reaction time.