NASA - National Aeronautics and Space Administration

Rate coefficients, k1 (T), for the gas-phase reaction of the OH radical with furan2,5-dione (maleic anhydride (MA), C4 H2 O3 ), a biomass burning related compound, were measured under pseudo–first-order conditions in OH using the pulsed laser photolysis–laser-induced fluorescence method over a range of temperature (283-374 K) and bath gas pressure (50-200 Torr; He or N2 ). k1 (T) was found to be independent of pressure over this range with k1 (283-374 K) = (1.55 ± 0.20) × 10−12 exp[(−410 ± 44)/T) cm3 molecule−1 s−1 and k1 (296 K) = (3.93 ± 0.28) × 10−13 cm3 molecule−1 s−1 , where the uncertainties are 2σ and the preexponential term includes the estimated systematic error. The atmospheric lifetime of MA with respect to OH reactive loss is estimated to be ∼15 days. The present results are compared with a previous room temperature relative rate study of the OH + MA reaction, and the significant discrepancy between the studies is discussed; the present results are approximately a factor of 4 lower. It is also noteworthy that the experimentally measured k1 (296 K) value obtained in this work is nearly a factor of 110 less than estimated by a structure activity relationship based on trends in ionization potential. Based in part on a computational evaluation, an atmospheric degradation mechanism of MA is proposed.