| Abstract
| - Kinetic and mechanistic studies of the reactions of OH radicals and ozone with acetylacetone performed in photoreactors at atmospheric pressure and different temperatures are reported.
- A kinetic study on the reactions of the OH radical and ozone with acetylacetone (AcAc) has been performed in a 1080 L quartz glass reaction chamber using in situ FTIR spectroscopy analysis. Temperature dependent rate coefficients for the reaction of AcAc with the OH radical were determined over the temperature range 285−310 K using the relative kinetic method. The following Arrhenius expression was derived: k = 3.35 × 10−12 exp((983 ± 130)/T) cm3 molecule−1 s−1, where the indicated error is the two least-squares deviation. A rate coefficient (in units of cm3 molecule−1 s−1) of (1.03 ± 0.31) × 10−18 has been obtained at (298 ± 3) K for the reaction of ozone with AcAc. A product investigation on the gas-phase reaction of OH radical with AcAc was conducted in a 405 L borosilicate glass chamber using in situ FTIR spectroscopy to monitor reactants and products. Methylglyoxal, acetic acid, peroxy acetic nitrate (PAN) were positively identified as products with molar yields of (20.8 ± 4.5)%, (16.9 ± 3.4)%, and (2.0 ± 0.5)%, respectively. From the residual infrared spectrum the main products are attributed to 2,3,4-pentantrione (CH3COCOCOCH3) and its hydrated analogue pentan-2,3-dione-4-diol (CH3COCOC(OH)2CH3). Based on the observed products, a simplified mechanism for the reaction of the OH radical with AcAc is proposed.
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