An electron paramagnetic resonance spectroscopic investigation of hydroxyl-radical attack on allyl alcohol

Allyl alcohol has been subjected to hydroxyl-radical attack at 25 ± 2 °C within the cavity of an X-band electron paramagnetic resonance (e.p.r.) spectrometer by use of an aqueous flow system in which the hydroxyl radicals were generated by mixing solutions of titanous chloride and hydrogen peroxide containing sulfuric acid. The reaction conditions were varied over a considerable range. At low allyl alcohol concentrations the e.p.r. absorption observed arose chiefly from the two possible addition products CH2(OH)CHCH2OH, I, and ·CH2CH(OH)CH2OH, II, present in roughly equal steady-state molar concentrations; a relatively weak signal from the hydrogen-atom abstraction product CH2:CHCHOH, III, was also observed. As the allyl alcohol concentration was raised, the relative contribution from I and II fell while that from the products of the addition of I and II to allyl alcohol became increasingly evident. These results considerably extend and clarify those previously reported for allyl alcohol by earlier workers using this reaction system.