Rate Coefficients and Products of Ethyl and Vinyl Cross-Radical Reactions

Published

November 1, 2002

Author(s)

Askar Fahr, D C. Tardy

Abstract

Rate constant and products of vinyl (H₂C=CH) and ethyl (C₂H₅) cross-radical reactions have been determined at ambient temperature and 93 kPa (700 Torr) pressure. Vinyl and ethyl radicals were produced simultaneously through the 193-nm excimer laser photolysis of dilute mixtures of C₂H₅COC₂H₃/He. Time-resolved UV absorption spectroscopy and gas chromatographic/ mass spectrometric (GC/MS) product analysis methods were employed for kinetics and product studies. Analysis of the temporal absorptions at 230 nm and 235 nm through kinetic modeling of the reaction system resulted in an over-all rate constant of (9.6 1.3)x10^-11 cm³molecule^-1s^-1 for the C₂H₅+C₂H₃ cross-radical reaction. The major reaction products, identified and quantified using GC/MS analysis, consisted of butane, 1-butene, 1,3-butadiene which are formed through the combination reactions: C₂H₅+C₂H₅ --> n- butane (1c), C₂H₃+C₂H₃ -->1,3-butadiene (2c) and C₂H₅+C₂H₃ -->1-butene (3c) and ethane, ethylene and acetylene, products of the disproportionation reactions. Using a comparative method and the yields of the combination products for the reactions (1c), (2c) (3c) and k_1C = 2.0 x10^-11 cm³ molecule^-1s^-1, k_2C =9.3x10^-11 a rate constant value of k_3C = (6.5 1)10^-11 cm³ molecule^-1s^-1 for the combination channel of the reaction C₂H₅+C₂H₃ has been determined.

Citation

Journal of Physical Chemistry A

Volume

106

Issue

No. 46

Pub Type

Journals

Keywords

cross-reactions, ethyl radicals, ethylvinylketone, products, reaction kinetics, UV photolysis, UV-absorption, vinyl radicals

Citation

Fahr, A. and Tardy, D. (2002), Rate Coefficients and Products of Ethyl and Vinyl Cross-Radical Reactions, Journal of Physical Chemistry A (Accessed July 26, 2024)