ChemInform Abstract: Rate Constants for the Gas-Phase Reactions of OH Radicals and Cl Atoms with n-Alkyl Nitrites at Atmospheric Pressure and 298 K.

Abstract

Rate constants for the reactions of OH radicals and Cl atoms with CH3ONO, C2H5ONO, n-C3H7ONO, n-C4H9ONO, and n-C5H11ONO have been determined at 298 ± 2 K and a total pressure of approximately 1 atm. The OH rate data were obtained using both the absolute rate technique of pulse radiolysis combined with kinetic spectroscopy and a relative rate method involving simultaneous measurement of the loss of the nitrite and the reference compound. The Cl rate constants were measured using the relative rate method. Values of the rate constants in units of 10−13 cm3 molecule−1 s−1 are: Text Table Text. Relative Cl Relative OH Absolute OH CH3ONO 94.4 ± 7.4 3.0 ± 1.0 2.6 ± 0.5 C2H5ONO 295 ± 13 7.0 ± 1.5 7.0 −1.1 n-C3H7ONO 646 ± 58 11.0 ± 1.5 12.0 ± 0.5 n-C4H9ONO 1370 ± 58 22.7 ± 0.8 27.2 ± 6.0 n-C5H11ONO 2464 ± 444 37.4 ± 5.0 42.5 ± 8.0 When compared to rate data for the corresponding alkanes the results show that the -ONO group decreases the rate constant for H atom abstraction by the OH radical from groups bonded to the -ONO group and also decreases that for groups in the β position. Similar results were found for the reaction of Cl atoms with these compounds. The results are discussed in terms of reactivity trends.