Rates of reaction between the nitrate radical and some aliphatic alcohols
Abstract
Rate coefficients for the gas-phase reaction of NO3 with methanol, ethanol and propan-2-ol have been determined. Absolute rates were measured at temperatures between 258 and 367 K using the fast flow–discharge technique. The measured rate coefficients (in units of 10–15 cm3 molecule–1 s–1) at 295 K are: 0.132 ± 0.024, 1.37 ± 0.10 and 3.13 ± 0.64 for methanol, ethanol and propan-2-ol, respectively. The temperature dependence of the rate coefficients can be expressed as Arrhenius equations: kmethanol=(1.06 ± 0.51)× 10–12 exp[–(2093 ± 803)/T], kethanol=(6.99 ± 1.21)× 10–13 exp[–(1815 ± 419)/T] and kpropan-2-ol=(1.54 ± 0.75)× 10–12 exp[–(1743 ± 1009)/T](in units cm3 molecule–1 s–1). An attempted product study, using N2O5, as the NO3 source, failed since the alcohols react with N2O5, producing alkyl nitrates. The estimated upper limit for rate coefficients for reaction of N2O5 with methanol, ethanol and propan-2-ol at 296 K in the gas phase were (2.0 ± 1.0)× 10–19, (3.9 ± 2.0)× 10–19, and (4.8 ± 2.5)× 10–19 cm3 molecule–1 s–1, respectively. The error limits correspond to the 95%-confidence interval.