PRODUCT AND KINETIC-STUDY OF THE OH-INITIATED GAS-PHASE OXIDATION OF FURAN, 2-METHYLFURAN AND FURANALDEHYDES AT APPROXIMATE-TO-300 K

The products of the OH-initiated gas-phase oxidation of furan and 2-methylfuran were studied at 298 +/- 2 K in the absence of NOx at 1000 mbar pressure of air using in situ long-path FTIR absorption spectroscopy to monitor reactants and products; the 254nm photolysis of H2O2 was used as the OH-radical source under NOx-free conditions. The major products were cis/trans-butenedial and cis/trans-4-oxo-2-pentenal for the oxidation of furan and 2-methylfuran with estimated carbon balances of approximate to 100 and approximate to 87% C, respectively. This study represents the first product determination for both furan and 2-methylfuran; a mechanism is proposed to explain the results. Rate coefficients have also been determined for the gas-phase reaction of OH radicals with the aromatic heterocyclics furan-2-aldehyde, furan-3-aldehyde, and 5-methylfurfural at 300 +/- 2 K in 1000 mbar of synthetic air, using a relative kinetic technique. The rate coefficients obtained using trans-2-butene as reference compound are (units of 10(-11) cm(3) molecule(-1)s(-1)): furan-2-aldehyde, 3.51 +/- O.11; furan-3-aldehyde, 4.85 +/- 0.16; 5-methylfurfural, 5.10 +/- 0.21. This study represents the first determination of the rate coefficients for these compounds.