Radiation chemistry of alternative fuel oxygenates: Substituted ethers

Absolute rate constants for the reaction of ethyl tert-butyl, diisopropyl, and methyl tert-amyl ethers with the hydroxyl radical, hydrated electron, a nd hydrogen atom in water have been determined using electron pulse radioly sis (e(aq)(-) and . OH), absorption spectroscopy (e(aq)(-) and . OH), and E PR free induction decay attenuation (H) measurements. At room temperature t he hydroxyl radical reaction was found to be the primary loss pathway, with fate constants of (1.81 +/- 0.09) x 10(9), (2.49 +/- 0.12) x 10(9), and (2 .37 +/- 0.12) x 10(9) dm(3) mol(-1) s(-1) determined for these ethers, resp ectively. The reaction of the hydrated electron with these compounds was no t significant, with upper limit values of less than or equal to 10(7), less than or equal to6.7 x 10(6), and less than or equal to4.0 x 10(6) dm(3) mo l(-1) s(-1) determined. The corresponding rate constants for hydrogen atom reaction with these ethers were (7.04 +/- 0.11) x 10(6), (6.70 +/- 0.09) x 10(7), and (3.09 +/- 0.09) x 10(6) dm(3) mol(-1) s(-1). On the basis of the se rate constant values, the kinetic computer modeling of the free-radical removal of these ethers from NaO-saturated aqueous solution was found to be in very good agreement with experimental steady-state, Co-60, irradiation measurements.