Kinetics of the reactions of C2H5, n-C3H7, and n-C4H9 radicals with Cl2 at the temperature range 190-360 K

The kinetics of the C2H5 +Cl-2, n-C3H7+Cl-2, and n-C4H9 +Cl-2 reactions has been studied at temperatures between 190 and 360 K using laser photolysis/photoionization mass spectrometry. Decays of radical concentrations have been monitored in time-resolved measurements to obtain reaction rate coefficients under pseudo-first-order conditions. The bimolecular rate coefficients of all three reactions are independent of the helium bath gas pressure within the experimental range (0.5-5 Tort) and are found to depend on the temperature as follows (ranges are given in parenthesis): k(C2H5 + Cl-2) = (1.45 +/- 0.04) x 10(-11) (T /300 K)-1.73 +/- 0.09 cm(3) molecule(-1) s(-1) (190-359 K), k(n-C3H7 + Cl-2) = (1.88 +/- 0.06) x 10(-11) (T /300 K)(-)1.57 +/- 0.14 cm(3) molecule(-1) s(-1) (204-363 K), and k(n-C4H9 + Cl-2) = (2.21 +/- 0.07) x 10(-11) (T/300 K) -2.38:+/- 0.14 cm(3) molecule(-1) S-1 (202-359 K), with the uncertainties given as one-standard deviations. Estimated overall uncertainties in the measured bimolecular reaction rate coefficients are 20%. Current results are generally in good agreement with previous experiments. However, one former measurement for the bimolecular rate coefficient Of C-2 H-5 + Cl-2 reaction, derived at 298 K using the very low pressure reactor method, is significantly lower than obtained in this work and in previous determinations. (C) 2007 Wiley Periodicals, Inc.