Kinetic measurements of methyl and ethyl nitrate reactions with OH radicals

Abstract

Reaction rate coefficients of methyl and ethyl nitrates with OH radicals were determined by the relative rate method in 1 atmosphere of oxygen. Reactions were initiated by the photochemical formation of OH radicals utilizing the reaction: H2O+O(1D)2OH. O(1D) was obtained through a stationary photolysis of excess ozone in an experimental system under black light irradiation. Measurements were carried out for various combinations with different reference materials. Rate coefficients obtained were (0.30±0.032 (2σ)×10−13 cm3molecule−1s−1 (Temp.: 304–310 K) for methyl nitrate and (2.0±0.70)× 10−13 cm3molecule−1s−1 (298–310 K) for ethyl nitrate. For methyl nitrate, this data indicates the preference of a smaller rate coefficient between the two values reported in the literature [1,2], which have shown large discrepancies of more than one order of magnitude. For ethyl nitrate, only one measurement has been reported [2]. However, the present result suggests that the reported value was overestimated by a factor of more than two. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet: 29: 933–941, 1997.