Kinetic study for the reactions of chlorine atoms with hexamethyldisiloxane, 1,1,3,3-tetramethyldisiloxane, and 1,3-dimethyldisiloxane

The absolute rate constants for the reactions of chlorine atoms with (CH3)(3)SiOSi(CH3)(3), (CH3)(2)HSiOSiH(CH3)(2), and (CH3)H2SiOSiH2(CH3) were measured in the gas phase over the temperature range 273-363 K, using the very low pressure reactor (VLPR) in a molecular flow system. The absolute rate constants were temperature independent and take the values (in cm(3) molecule(-1) s(-1), 2 sigma uncertainties): k(1) = (1.00 +/-0.19) x 10(-10), k(2) = (1.98 +/-0.29) x 10(-10), and k(3) = (2.42 +/-0.25) x 10(-10). All title reactions proceed via the abstraction of C-H and/or Si-H hydrogen leading to the formation of HCL The results show that the reactivity of Si-H bond towards Cl atom attack is higher than the reactivity of the C-H bond. (C) 2001 Elsevier Science BN. All rights reserved.