= Solution
First hydrolyse both Si–Cl groups to give a <silanol> of <monomer functionality> two, then condense Si–OH groups to form the Si–O–Si backbone:
$$
\mathrm{R_2SiCl_2+2H_2O\longrightarrow R_2Si(OH)_2+2HCl},
$$
$$
\mathrm{{\equiv}Si{-}OH+HO{-}Si{\equiv}\longrightarrow{\equiv}Si{-}O{-}Si{\equiv}+H_2O}.
$$
\b[<monomer functionality> two favours chains, with cyclic oligomers also possible.] Removal of condensation products or equilibration under appropriate conditions favours high <molar mass>. The <hydrolysis> and condensation can overlap in a one-pot process; the equations distinguish their chemical functions rather than requiring isolation of every silanediol.
Back to article page
