Kinetic studies of the reaction of tetraethoxysilane with oxygen atoms

The temperature dependent kinetics of the reaction of tetraethoxysilane (TEOS) with O atom have been determined by fast flow reactor molecular beam sampling. The rate of constant has the form k = 3.4 x 10 (-11) exp (-1304 K/T) cm(3) s(-1) over the temperature range 300 to 673 K and similar to that of H atom abstraction from carbon-bonded ethoxy groups. Gas-phase products of the chemistry have been analyzed which suggest that following formation of the primary radical, subsequent reactions lead to the formation of R3SiO and/or RnSi(OH)(4-n) (n < 4). These species are believed to undergo both four center elimination of ethylene and addition reactions to produce Si-O-Si ligands by dehydration.