THE REACTIONS OF THE CYCLIC HYDROCARBON RADICALS C-C3H5, C-C5H9, AND C-C6H11 WITH O ATOMS IN THE GAS-PHASE

The production of the cyclic hydrocarbon radicals c-C3H5, c-C5H9, and c-C6H11 by the reactions of c-C3H6, c-C5H10, and c-C6H12 with F atoms and the reactions of the cyclic hydrocarbon radicals with O atoms were studied at low pressure (around 1 mbar) and low temperature (290-300 K) using the discharge flow method. Stable and labile species were detected by mass spectrometry combined with molecular beam sampling. The rate constants of the reactions c-C3H5 + O (4), c-C5H9 + O (5), and c-C6H11 + O (6) were determined: k4 = 1.4. 10(14), k5 = 1.7. 10(14), k6 = 1.4. 10(14) cm3/mol.s. One main reaction route is interpretated by the formation of a highly excited adduct, decomposing to H + oxygen containing ring products; at high strain energy (reaction (4)) total ring cleavage, at low strain energy (reaction (6)) partial ring cleavage was observed. A second reaction route leads to OH + alkene. The rate constant for the reaction F + c-C6H12 (3) was found as k3 = 5.7.10(13) cm3/mol.s.