Kinetics of the reactions of the nitrate radical with a series of halogenobutenes. A study of the effect of substituents on the rate of addition of NO3 to alkenes

Abstract

Rate coefficients for the reaction of NO₃ with a series of halogenobutenes have been measured using the discharge-flow technique coupled to optical-absorption detection of NO₃. The following room-temperature rate coefficients and Arrhenius parameters (cm³ molecule^–1 s^–1) were measured: 1-chlorobut-1-ene, 1.2 × 10^–14; 2-chlorobut-1-ene, 7.0 × 10^–14; 2-chlorobut-2-ene, 11.0 × 10^–14; 1-chloromethylpropene, 9.0 × 10^–14; 3-bromobut-1-ene, 0.4 × 10^–14; 4-bromobut-1-ene, 0.5 × 10^–14; 2-bromobut-2-ene, 13.4 × 10^–14; 3-chlorobut-1-ene, 2.4 × 10^–12 exp(–1992/T); 1-chlorobut-2-ene, 6.0 × 10^–13 exp(–981/T); 3-chloromethylpropene, 1.7 × 10^–12 exp(–1277/T). Trends in the reactivities of the compounds towards NO₃ are discussed in terms of the relative energies of the interacting orbitals, and the data are used to calculate group reactivity factors. These factors can be used to estimate rate constants which have not, as yet, been measured.