Gas-phase reactivity study of (E)-3-pentenenitrile and 4-pentenenitrile towards OH radicals and Cl atoms at atmospheric pressure

摘要

The relative-rate technique has been used to obtain rates coefficients for the reactions of (E)-3-pentenenitrile (CH_3CH=CHCHCN) and 4-pentenenitrile (CH_2=CHCH_2CH_2CN) with OH radicals and Cl atoms at 298 K and (760 ± 10) Torr total pressure of synthetic air using different reference compounds. The experiments were performed in an environmental chamber with "in situ" FTIR spectroscopy to monitor the reactants concentrations. The following room temperature rate coefficients (in cm~3 molecule~(-1)s~(-1)) were obtained: k_1 (OH + CH_3CH=CHCHCN) = (5.05 ± 1.10) × 10~(-11), k_2 (Cl + CH_3CH=CHCHCN) = (2.60 ± 0.26) × 10~(-10), k_3 (OH + CH_2=CHCH_2CH_2CN) = (2.90 ± 0.64) × 10~(-11) and k_4 (Cl + CH_2=CHCH_2CH_2CN) = (2.56 ± 0.26) × 10~(-10). This is the first kinetic study for all of these reactions. The effect of atom or group substituent on the overall rate coefficients is analyzed and the reactivity of nitriles is compared with those of other unsaturated compounds in the literature. In addition, a comparison between the experimentally determined rate coefficients from this work and the k_(OH) and k_(Cl) predicted from k vs Ehomo correlations is presented. The atmospheric lifetimes at room temperature of these compounds has been estimated using the rate coefficients determined in this work.