Chlorination Chemistry. 2. Rate Coefficients, Reaction Mechanism, and Spectrum of the Chlorine Adduct of Allene

Published

January 12, 2000

Author(s)

D B. Atkinson, Jeffrey W. Hudgens

Abstract

Cavity ring-down (CRD) spectroscopy and ab initio calculations have determined the reaction rate coefficients, mechanism, and thermochemistry relevant to the addition of a chlorine atom to allene. Chlorine atoms were produced by laser photolysis at 351 nm and the addition reaction products were probed at a variable delay by CRD spectroscopy using a second laser pulse. Ab initio results indicate that the only product is the 2-chloroallyl (C₃H₄Cl) radical. We measured the continuum spectrum of the 2-chloroallyl radical between 238 and 252 nm and determined the absorption cross-section, ς₂₄₀(C₃H₄Cl) = (2.5 ± 0.5) x 10^-17 cm². By fitting the C₃H₄Cl absorption data to complex kinetic mechanisms, rate coefficients at 298 K were found to be k(Cl + C₃H₄; 656 Pa, N₂) = (1.61 ± 0.27) x 10^-10 cm³ molec^-1 s^-1, k(Cl + C₃H₄; 670 Pa, He) = (1.34 ± 0.24) x 10^-10 cm³ molec^-1 s^-1, and k(Cl + C₃H₄; 1330 Pa, He) = (1.75 ± 0.25) x 10^-11 cm³ molec^-1 s^-1. The recombination reaction displayed no pressure dependence between 434 Pa and 1347 Pa in N₂ buffer giving k(C₃H₄Cl + C₃H₄Cl) = (3.7 ± 1.0) x 10^-11 cm³ molec^-1 s^-1. A study of the addition reaction of 2-chloroallyl radical and oxygen molecule determined ς₂₄₀ (C₃H₄ClO₂) = (3.6 ± 0.7) x 10^-18 cm² and k(O₂ + C₃H₄Cl, 705 Pa N₂) = (3.5 ± 0.5) x 10^-13^ cm³ molec^-1 s^-1. Quoted uncertainties denote two standard deviations and include the propagated uncertainties of absorption cross-sections.

Citation

Journal of Physical Chemistry A

Volume

104

Issue

No. 4

Pub Type

Journals

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Keywords

2-chloroallyl radical, 2-chloroallyl radical+O₂ reaction, cavity ring-down spectroscopy, Cl+ O₂ reaction, reaction rate coefficient, self-reaction rate coefficient

Citation

Atkinson, D. and Hudgens, J. (2000), Chlorination Chemistry. 2. Rate Coefficients, Reaction Mechanism, and Spectrum of the Chlorine Adduct of Allene, Journal of Physical Chemistry A, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=831574 (Accessed April 19, 2024)