Gas phase reaction of Cl atoms with a series of oxygenated organic species at 295 K

Abstract

The relative rate technique has been used to determine the rate constants for the reaction of chlorine atoms with a series of oxygenated organic species. Experiments were performed a t 295 t 2 K and atmospheric pressure of synthetic air or nitrogen. The decay rates of the organic species were measured relative to that of ethane or n-butane. Using rate constants of 5.7 x lo-" cm3 molecule-'s-', and 2.25 x lo-'' cm3 molecule-' s-l for the reaction of C1 with ethane and n-butane respectively the following rate constants were derived, in units of lo-" cm3 molecule-' s-': propane, (16.0 2 0.4); i-butane, (15.1 -t 0.9); n-pentane, (31.0 .t 1.6); n-hexane, (34.5 2 2.3); cyclohexane, (36.1 f 1.5); methanol, (4.57 2 0.40); ethanol, (8.45 t 0.91); n-propanol, (14.4 f 1.2); tbutylalcohol, (3.26 f 0.19); acetaldehyde, (8.45 t 0.79); propionaldehyde, (11.3 2 0.9); dimethylether, (20.5 t 0.8); diethylether, (35.6 t 2.8); and methyl-t-butylether, (16.6 2 1.2). Quoted errors represent 20, and do not include any errors due to uncertainties in the rate constants used to place our relative measurements on an absolute basis. The results are discussed with respect to the mechanisms of these reactions and to previous literature data.

Kinetic study of the gas-phase reaction of atomic chlorine with a series of aldehydes

“…From the analysis of the data given in Table 1, reaction rate constants are of the order of 10 −10 cm 3 molecule −1 s −1 and they increase when the length of the organic chain increases in both saturated and unsaturated aldehydes, k n−pentanal < k n−hexanal < k n−heptanal k trans−2−pentenal < k trans−2−hexenal < k trans−2−heptenal A similar behavior, the increase of the rate constant value with the number of methylene groups, was also found in the reactions of Cl atoms with alkanes (Wallington et al, 1988;Hooshiyar and Niki, 1995;Qian et al, 2001).…”

Rate coefficients for the reactions of chlorine atoms with methanol and acetaldehyde

“…Literature data for k 1 and k 2 are given in Table III, together with the latest evaluations of the NASA and IUPAC panels and our current recommendation. In arriving at a recommendation for k 1 we reduced the weighting of the original absolute study by Michael et al [14], which lies considerably above the mean of the other values, and that of Wallington et al [17] which is not thought to be as reliable as the present study. Several of the studies [16,20] were not explicitly designed to measure k 1 and these studies have been given weights of 0.5 in the analysis, as has the study by Lightfoot et al [18] [17,21 -24].…”

Design of and initial results from a Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC)

“…The errors in Table 1 are those obtained from the regression analysis, and reflect the fact that the error in measurement of the compound of interest and the reference compound are similar, as discussed in the previous section. Using the data in Table 1, and taking the pressure independent rate coefficients for Cl + chloroethane and Cl + isobutane to be (1.15±0.15)×10 −11 cm 3 molecule −1 s −1 (Wallington et al, 1990a) and (1.51±0.09)×10 −10 cm 3 molecule −1 s −1 (Wallington et al, 1988), the ratios of the rate coefficients may be converted to absolute rate coefficients, and fitted to a Troe expression (Troe, 1974) weighted by the experimental uncertainties as shown in Fig. 12.…”