Chemical activation analysis of the reaction of methyl, ethyl, propyl and butyl radicals with O2

Author

Hsing-Hui Yu, New Jersey Institute of Technology

Document Type

Thesis

Date of Award

5-31-1990

Degree Name

Master of Science in Environmental Science - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Joseph W. Bozzelli

Second Advisor

Barbara B. Kebbekus

Third Advisor

Richard B. Trattner

Abstract

The addition reactions of methyl, ethyl, propyl and butyl radicals with molecular oxygen to form the energized adducts CH3OO#, CCOO#, CCCOO#, C₂COO#, C*CCOO#, CCCCOO#, CCCOO.C#, C2CHCOO#, C₃C00#, C*CCCOO#, CC*CCOO# and C*CCOO.C# and the reactions of the adducts to varied products have been analyzed using the bimolecular version of the quantum Rice-Ramsperger-Kassel (QRRK) theory. The analysis encompassed a temperature range from 200 to 2000 K and pressures between 0.001 to 10 Atm in argon (CH₃ + O₂ reaction only), helium and nitrogen bath gases. The calculations satisfactorily explain the experimentally observed rate constants for loss of methyl radical as a function of pressure. The calculations also explain the observed low pressure (0.5 to 13 Torr) rate constants of Slagle et. al. for loss of ethyl and production of ethylene over in the temperature range (300 - 900 K) in addition to the room temperature data for C₂H₄ formatiopn of Kaiser et. al. over pressures of 1 to 6000 Torr. We present a complete description of the complex pressure and temperature dependence of the methyl and ethyl radical reaction with O₂. A small fraction of the adduct CH₃O₂# undergoes a H atom shift through a cyclic (4 member ring) intermediate to an alkyl hydroperoxy radical which then undergoes dissociation to product. The C₂H₅O₂# adduct from ethyl + O₂ reaction undergoes a H atom shift through a cyclic (5 member ring) intermediate to an alkyl hydroperoxy radical which then undergoes beta scission to products. There is no need to invoke a direct hydrogen transfer pathway to explain the observed data. Apparent rate constants are presented for stabilization and reaction to the products over the above temperature and pressure ranges.

The most important reaction for the three and four carbon alkyl radicals + O₂ reaction system and their apparent rate constants at 1 Atm and 300 K are listed as following: Reactionk (cm³ / mole-sec)CCC. + O₂ ----> C₃H₆ + HO₂3.60E+12CC.C + O₂ ----> C₃H₆ + HO₂5.00E+12C*CC. + O₂ ----> C₂H₂ + CH₂O + OH3.43E+12CCCC. + O₂ ----> CCC*C + HO₂4.90E+12CCC.C + O₂ ----> CC*CC + HO₂1.00E+13C₃.CH + O₂ ----> C₂C*C + HO₂4.87E+12C₃C. + O₂ ----> C₂C*C + HO₂1.40E+13C*CCC. + O₂ ----> C*CC*C + HO₂3.97E+12CC*CC. + O₂ ----> C₃H4 + CH₂O + OH4.84E+12C*CC.C + O₂ ----> C₂H₂ + CCHO + OH9.74E+12

Recommended Citation

Yu, Hsing-Hui, "Chemical activation analysis of the reaction of methyl, ethyl, propyl and butyl radicals with O2" (1990). Theses. 3022.
https://digitalcommons.njit.edu/theses/3022