Group X is usually a halide such as Cl???, an alkoxide, such as CH3O???, or another transfer group, such as RNH. For example, CF3CH2OSi(CH3)3 can be prepared in greater than 90% yield from CF3CH2OH and ((CH3)3Si)2NH, with NH3 being the only byproduct (N. R. Patel et. al.