Silylation - Silylation of Organic Compounds

Silylation of Organic Compounds

Alcohols, carboxylic acids, amines, thiols, phosphates can be derivatized by silylation. The process involves the replacement of a proton with a trialkylsilyl group, typically trimethylsilyl (-SiMe₃). A general technique is to deprotonate the substrate with a suitable strong base (e.g. butyl lithium), and allow it to react with a silyl chloride (e.g. trimethylsilyl chloride). The base used in this reaction mustn't form any HCl as it will hydrolyze the silyl protecting group. Therefore, butyl lithium or a Grignard reagent is usually the base of choice since the reaction products are a protonated (gaseous) alkane and an inert salt (lithium chloride or magnesium bromide and chloride).

Silyl derivatives are generally less polar and more volatile and more thermally stable than their precursor organic compound. The introduction of a silyl group(s) gives derivatives of enhanced volatility, making the derivatives suitable for analysis by gas chromatography and electron-impact mass spectrometry (EI-MS). For EI-MS, the silyl derivatives give more favorable diagnostic fragmentation patterns of use in structure investigations, or characteristic ions of use in trace analyses employing selected ion monitoring and related techniques.

Similarly, silylation is used to introduce silyl ethers as protecting groups for organic synthesis.