Alkylsilanes

Alkylsilanes are organosilicon compounds in which the silicon atom is bonded to one or more alkyl groups and typically to hydrogen or other substituents. They are a broad class of silanes that differ from arylsilanes by the presence of alkyl rather than aryl substituents. General forms include RnSiH(4−n) for n = 1–4, with specific examples such as methylsilane (CH3SiH3), dimethylsilane (CH3)2SiH2, trimethylsilane (CH3)3SiH, and tetramethylsilane (CH3)4Si. Depending on substitution, alkylsilanes may be mono-, di-, tri-, or tetra-alkyl silanes.

Synthesis of alkylsilanes can be achieved by several routes. Hydrosilylation of alkenes or alkynes with silanes bearing Si–H bonds is a common method to form Si–C bonds. Another route involves substitution reactions on halosilanes or silanols with organomagnesium or organolithium reagents to install alkyl groups onto silicon. Reduction or coupling of silicon-centered intermediates can also furnish alkylsilanes. Catalysts from platinum, rhodium, or nickel families are often employed for hydrosilylation processes.

Reactivity and properties of alkylsilanes center on the Si–C bonds and the silicon center. They can undergo typical organosilicon transformations, including hydrosilylation, oxidation to silanols or siloxanes, and, in the presence of halogens or strong reagents, displacement on silicon. Hydrolysis of more reactive silane derivatives (such as halosilanes or alkoxysilanes) is common, whereas simple alkylsilanes are relatively inert to air but moisture-sensitive under certain conditions.

Applications of alkylsilanes include use as intermediates in organic synthesis, precursors to silicon-containing polymers, and surface-modifying reagents (for example, alkylsilane coupling agents for silanization of oxide surfaces). Safety considerations emphasize moisture sensitivity and flammability for many low-molecular-weight species; proper handling under inert conditions is recommended.