Products of the gas-phase reactions of NO3 radicals with the furan and tetramethylfuran

Furan and substituted furans were found to be atmospheric reaction products of the OH radical-initiated degradation of conjugated dienes, such as 1,3-butadiene, cis-13-pentadiene, and isoprene. They are also products of combustion processes. The purpose of this work is to identify the primary formed stable reaction products of the reaction of NO3 radicals toward furan and tetramethylfuran. Experiments were performed under flow conditions in the pressure range 5.5 < P (mbar) < 100 at 298 K. GC-MS/FID, direct MS, and long-path FT-IR served as detection techniques. cis-Butenedial and 3H-furan-2-one were found as main products of the reaction of NO3 radicals with furan in N-2 with averaged formation yields of 0.77 and 0.19, respectively, independent of total pressure in the tube. In experiments with a maximum O-2 concentration of 2.2 x 10(18) molecule cm(-3), an increase of the 3H-furan-2-one yield was observed up to 0.38. There were no indications for the formation of nitrates or peroxynitrates. In the reaction of NO3 radicals with tetramethylfuran, the detected reaction product was assigned to cis-3,4-dimethylhex-3-en-2,5-dione, tentatively. Using the relative rate method, the rate constant for the reaction of NO3 radicals with 3H-furan-2-one was determined to be (1.76 +/- 0.23) x 10(-13) cm(3) molecule(-1) s(-1).