REACTIVITY OF HO2 RADICALS IN ALCOHOLS

Photoinitiated liquid phase oxidation of 1-phenyl ethanol and benzyl alcohol have been investigated in the temperature range of 50-70-degrees-C using the intermittent illumination (rotating sector) technique. The rate of oxidation was followed by gas chromatography while the rate of initiation was determined by the inhibitor method. Results were explained by assuming HO2. radicals to be the main chain carriers, supported by comparison of the results with literature data. - The termination rate constant of HO2. was calculated from the average lifetime of radicals in both alcohols: 2k(t) = 9.91.10(12) exp(-29.2 kJ.mol-1/RT) in 1-phenyl ethanol and 2k(t) = 8.98.10(12) exp(-31.3 kJ.mol-1/RT) in benzyl alcohol. (in l.mol-1.s-1, the uncertainties given by the covariance matrix, see in the text.) - The rate constants for hydrogen abstraction by HO2. from the substrate molecules have also been determined in the case of both alcohols: k(p) = 4.61.10(8) exp(-52.0 kJ.mol-1/RT) in 1-phenyl ethanol, k(p) = 1.04.10(9) exp(-54.3 kJ.mol-1/RT) in benzyl alcohol, (in l.mol-1.s-1, uncertainties see in the text.)