Kinetics of t-2-hexenyl acetate and 4-methyl-3-penten-2-one with OH and Cl radicals at 298 K and atmospheric pressure.

ELIZABETH GAONA-COLMÁN, MARÍA B. BLANCO AND MARIANO A. TERUEL

ATMOSPHERIC ENVIRONMENT

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2017 vol. 151 p. 155 - 166

1352-2310

Rate coefficients for the reactions of hydroxyl radicals and chlorine atoms with two biogenic volatile organic compounds as (E)-2-hexenyl acetate and 4-methyl-3-penten-2-one have been determined at 298 K and atmospheric pressure. The decay of the organics was followed using a chromatograph with a flame ionization detector (GC-FID) and the rate constants were determined using a relative rate method.Rate coefficients are found to be (in cm3 molecule1 s1): k1(OH þ (E)-2-hexenylacetate) ¼ (6.88 ± 1.41) 1011, k2(Cl þ (E)-2-hexenyl acetate) ¼ (3.10 ± 1.13) 1010, k3(OH þ 4-methyl-3-penten-2-one) ¼ (1.02 ± 0.20) 1010 and k4(Cl þ 4-methyl-3-penten-2-one) ¼ (2.66 ± 0.90) 1010 at 298 K. This is the first kinetic experimental study for these reactionsstudied under atmospheric pressure. The rate coefficients are compared with previous determinationsfor other unsaturated and oxygenated compounds and reactivity trends are presented. Products identification studies were performed using solid-phase microextraction (SPME) method employing on-fiber products derivatization with o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride using gas chromatograph with a mass spectrometer detector (GC-MS) for the reactions studied. In addition, atmospheric lifetimes of the unsaturated compounds studied are estimated and compared with other tropospheric sinks for these compounds