Reaction of NO(2) with selected conjugated alkenes.

ABSTRACT

The gas phase reactions of selected alkenes (isoprene, myrcene, ocimene, and 1,3-cyclohexadiene) with NO2 under dark condition have been investigated at T ∼ 298 K and P ∼ 760 Torr of purified air. The kinetic studies were performed under pseudo-first-order conditions using a large excess of NO2 concentration to those of the alkenes. The rate coefficients (in 10(-19) cm(3) molecule(-1) s(-1)) obtained are 1.1 ± 0.2 for isoprene, 2.5 ± 0.3 for myrcene, 8.5 ± 1.2 for ocimene, and 15 ± 1 for 1,3-cyclohexadiene. Several products were identified by using in situ Fourier transform infrared (FT-IR) spectrometry, and acetone was found to be the major product from the reactions of NO2 with myrcene and ocimene, with a formation yield of 22 ± 3% and 26 ± 7%, respectively. The oxidation products from the reactions of NO2 with isoprene and 1,3-cyclohexadiene were found to be mainly nitro compounds identified by FT-IR spectroscopy. Reaction mechanisms were proposed to account for the products observed.