Kinetic Studies on the Reactions of Hydroxyl Radicals with Cyclic Ethers and Aliphatic Diethers

Abstract

Rate coefficients for the reactions of hydroxyl radicals with a series of cyclic ethers and aliphatic diethers have been determined at 298 ± 2 K. Experiments were performed using a photolytic relative rate method at atmospheric pressure and the absolute rate technique of pulsed laser photolysis−laser induced fluorescence. The temperature dependence of the rate coefficients for the cyclic ethers was also studied over the temperature range 263−372 K. The rate coefficients show significant deviations from simple structure−activity relationships. The reactivity of the aliphatic diethers toward hydroxyl radicals is discussed in terms of the initial formation of a hydrogen-bonded adduct which then undergoes an intramolecular H atom transfer via five-, six-, and seven-membered-ring structures. The reactivity of cyclic ethers is also discussed in relation to adduct formation. However, because of steric restrictions, it is unlikely that the hydrogen-bonded adducts readily undergo H atom transfer via ring formation.