Radiolysis of Liquid Di-n-propyl Ether: Alcohol Formation and Solvated Electrons

Abstract

In the γ radiolysis of pure di-n-propyl ether at 296 K, G(n-propanol) = 2.5 ± 0.1. The propanol yield was reduced by the addition of an electron scavenger (SF6) or proton scavenger (C3H7NH2), but was not affected by the addition of hydrogen chloride or propylene. In the absence of additives the geminate neutralization reaction [7] R2OH+ + esolv− → ROH + R gave 1.8 G units of alcohol. The charge scavenging reactions of SF6 and C3H7NH2 were consistent with the nonhomogeneous kinetics model reported earlier. The optical absorbance of solvated electrons in di-n-propyl ether increased with wavelength up to 1.6 μ, the practical limit of the detector, at all temperatures in the liquid range, including the liquid supercooled to 140 K. (f.p. = 151 K). The kinetics of electron reactions could be measured by observing the absorption at 0.9 μ. The optical absorbance observed as a function of time t at all temperatures was consistent with the kinetics model and had the general form: absorbance = b(t−1/2 + c)e−kt, where b is a proportionality constant, c is related to the free ion yield and k is a first order decay constant that describes the decay of the solvated electron free ions. At 273 K, k(esolv− + SF6) = 4.5 × 1010 M−1 s−1 and the activation energy is 3.2 ± 0.3 kcal/mol.