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

Abstract

In they radiolysis of pure di-11-propyl ether at 296 K, G(n-propanol) = 2.5 + 0.1. The propanol yield was reduced by the addition of an electron scavenger (SF,) 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] R 2 0 H + + e,,,,-+ ROH + R gave 1.8 G units of alcohol. The charge scavenging reactions of SF, and C3H7NH2 were consistent with the nonhomogeneous kinetics model reported earlier. The optical absorbance of solvated electrons in di-tz-propyl ether increased with wavelength up to 1.6 y, 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 theabsorption at 0.9 y. The optical absorbance observed as a function of time r at all temperatures was consistent with the kinetics model and had the general form: absorbance = b(t-'I2 + c)e-", 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(e,,,,-+ SF,) = 4.5 x 10" M -' s-' and the activation energy is 3.2 + 0.3 kcal/mol.Le rendement en 12-propanol, G(n-propanol) = 2.5 0.1, provenant de I'irradiation gamma du di-n-propyle ether a 296 K, diminue par I'addition d'un capteur d'electrons (SF,) ou de protons (C3H,NH,), mais n'est pas influence par I'addition d'acide chlorhydrique ou de propylene.Dans I'ether pur, la neutralisation [7] R,OH+ + e,,,,--> ROH + R a un rendement en alcool de 1.8 unite G. Les reactions decapture de charges dces au SF, et C,H7NH2 sont compatibles avec un modele de cinitique nonhomogene propose precedemment. L'absorption optique pour I'electron solvate dans le di-n-propyle ether liquide augmente en fonction de la longueur d'onde jusqu'i 1.6 y, la limite pratique du spectrophotometre, et ce mtme dans le liquide surfondu a 140 K (la temperature de fusion est 151 K). La cinetique des reactions de I'electron est suivie par ]'observation a 0.9 y de son absorption optique. La variation de celle-ci en fonction du temps r est en accord avec le modele de cinetique non homogene, et est de la forme:

Reaction rates of electrons in liquid methanol and ethanol: effects of pressure

“…It therefore appears that the volume of activation of diffusion of solvated electrons in alcohols is similar to that for the diffusion of simple ions. This is consistent with the low, ion-like mobilities of electrons in the alcohols (18)(19)(20). The present and earlier (2, 3) results suggest that AVi(e-,olv diffusion) -4 cm3 mol-1 in methanol and 6 cm3 mol-I in ethanol.…”

Electron Mobilities and Ranges in Liquid Ethers: Ion-like and Conduction Band Mobilities

“…The contribution of conduction bands in all these liquids was estimated to be negligible at room temperature and below. Electron migration is therefore ion-like, with u,/u-= 2 + 1 in water (6, 39) and alcohols (7,40). Consistent with this conclusion, the activation energies of viscous flow (13), dielectric relaxation (24), and electron mobility (7, 39) are similar to each other in water or in a given alcohol (41).…”

The Solvated Electron in Polar Organic Liquids

“…Recently this conclusion was confirmed in a study 55 where it was shown that the Walden rule holds for solvated electrons, and μ(β 8 )η = C. Fig. 4 presents the known mobilities of solvated electrons as a function of the viscosity of the polar liquid.…”

“…4 Figure 4. Variation of the mobility of the solvated electron with viscosity in polar liquids: 1) water 52 ; 2) ammonia 54 ; 3) n-propyl ether 55 ; 4) ethanol 55 ; 5) methanol 46 » 55 ; 6) ethanol 65 ; 7) glycerol 50 ; the data for the remaining limits were taken from Refs. 33, 46, 47, and 57: 8) 1,2propylene glycol; 9) dimethoxyethane; 10) hexanol; 11) 1-pentanol; 12) isobutyl alcohol; 13) isopentyl alcohol; 14) ethyl methyl ketone; 15) monobutylamine; 16) 1-butanol; 17) hexamethylphosphoramide; 18) 1-propanol; 19) isopropyl alcohol.…”