OH and Cl radicals initiated oxidation of Amyl Acetate under atmospheric conditions: Kinetics, products and mechanisms

STRACCIA C, VIANNI C; BLANCO, MARÍA BELÉN; TERUEL, MARIANO ANDRES

Environmental Science: Atmospheres

RSC

Año: 2023

The relative rate coefficients of the gas-phase reaction of amyl acetate, (AA), CH₃COO(CH₂)₄CH₃with OH radicals and Cl atoms were determined at (298 ± 2) K and 1000 mbar of pressure. Theexperiments were developed in two different atmospheric Pyrex chambers coupled with “in situ”Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography equipped with flameionization detection (GC-FID). The rate coefficients obtained from the average of differentexperiments were (in units of cm3.molecule-1.s-1): kAA + OH-FTIR = (6.00 ± 0.96)×10-12; kAA + OH-GC-FID =(6.37 ± 1.50)×10-12 and kAA + Cl-GC-FID = (1.35 ± 0.14)×10-10. Additionally, product studies werecompleted for the Cl –initiated oxidation of AA, in similar conditions of the kinetic experiments byGas Chromatography coupled with a mass detector (GC-MS) with Solid Phase Micro Extraction(SPME). Acetic acid, formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde were themain products identified. Complementary Structure activity relationships (SAR) were developed tocompare with the experimental kinetic results and to clarify the individual reactivity sites of theester. The atmospheric oxidation pathways of the AA are postulated and discussed taking intoaccount the observed products and the SAR estimations. The initial pathway for the degradation ofAA initiated by Cl atoms and OH radicals occurs via H-atom abstraction at -C(O)OCH2- (C1); -CH2- (C2); -CH2- (C3); and -CH2CH3- (C4) moieties.