KINETICS AND PRODUCTS OF THE REACTIONS OF NO3 WITH MONOALKENES, DIALKENES, AND MONOTERPENES

Rate constants for the reactions of NO3 with a number of aliphatic mono- and dialkenes and monoterpenes have been determined in a 420 1 reaction chamber at 1-bar total pressure of synthetic air by 298 K with a relative kinetic method. The products of these reactions have been investigated also at 1-bar total pressure of synthetic air with in situ FT-IR spectrometry and gas chromatography. In all cases, the initial formation of thermally unstable nitrooxy-peroxynitrate-type compounds containing the difunctional group -CH(OONO2)-CH(ONO2)- has been observed. The experimental results are consistent with a mechanism involving the formation of nitrooxy-alkoxy radicals, -CH(O)-CH(ONO2)-, via the self-reaction of the nitrooxy-peroxy radicals. The further reactions of the nitrooxy-alkoxy radicals then determine the final products. The main reaction pathways are (i) reaction with O2 to form nitrooxy-aldehydes or -ketones and HO2 and (ii) thermal decomposition forming aldehydes/ketones and NO2. The mechanisms leading to the final products are discussed, and their possible relevance for the chemistry in the troposphere is considered. © 1990 American Chemical Society.