A. JOHN ELLIOT, SHAHSULTAN PADAMSHI, and JANA PIKA. Can. J. Chem. 64, 314 (1986).The radiolytic reductio? of uranyl ions in degassed sulphuric acid solutions containing various organic solutes was studied. It was shown that while COOH, C02-, and a-hydroxy-alkyl radicals reduced uranyl ions, the P-hydroxy-alkyl radicals and those derived from gluconic acid could not affect the reduction. The oxidation of uranium(1V) by hydrogen peroxide at pH 0.7 involves hydroxyl radicals in a chain mechanism but at pH 2.0 the oxidation proceeds by a non-radical reaction pathway. From the enhancement of the rate of oxidation of uranium(1V) by oxygen in the presence of 2-propanol, a mechanism involving the perhydroxyl radical, which reconciles earlier published data on kinetics and oxygen tracer studies, is proposed for the oxygenuranium(1V) reactions.A. JOHN ELLIOT, SHAHSULTAN PADAMSHI et JANA PIKA. Can. J. Chem. 64, 314 (1986). On Ctudie la reduction radiolytique des ions uranyles dans des solutions dCgazCes d'acide sulfurique contenant divers solutks organiques. On montre que, contrairement aux radicaux COOH, COz-et a-hydroxy-alkyles qui rCduisent les ions uranyles, les radicaux P-hydroxy-alkyles et ceux provenant de l'acide gluconique ne peuvent effectuer la rkduction. L'oxydation de I'uranium(1V) par le peroxyde d'hydrogtne i un pH de 0,7 fait intervenir des radicaux hydroxyles dans un mCcanisme en chaine; toutefois, i un pH de 2,0, la rCaction d'oxydation s'effectue par une voie non-radicalaire. En se basant sur le fait que la vitesse d'oxydation de l'uranium(1V) par l'oxygtne est plus grande en presence de propanol-2, on propose pour cette rCaction un mCcanisme qui implique le radical perhydroxyle. Ce mkcanisme permet de concilier les donntes publites anttrieurement tant sur la cinCtique que sur les Ctudes par marqueurs d'ox>g' ene.[Traduit par le journal]

Nitrogen-14 quadrupole interactions have been observed in the nonexchanging amino proton 1H nmr spectra of rigorously purified liquid mono- and dimethylamines over the temperature range −82 °C to +81 °C. The proton lineshapes have been analyzed to yield 14N spin-lifetimes (τ) as a function of temperature. Activation energies and correlation times for molecular reorientation in the liquids have been calculated from these data and the results compared with those from 14N nmr measurements.

. 63, 2975 (1985). Nitrogen-14 quadrupole interactions broaden the 'H nuclear magnetic resonances of the ammonium protons spin-coupled to 1 4~ in the methyl-substituted ammonium chlorides (methylammonium, dimethylammonium, and trimethylammonium). These proton lineshapes have been determined over the temperature range -8.3 to +93.6OC in 6 mol L-' aqueous HCl solution. The I4N spin-lifetimes, T , have been calculated from the Arrhenius form equation In T vs. I/T (K), and yield activation energies of 10.63 k 0.92, 10.60 ? 0.52, and 11.12 k 0.39 kJ mol-' for the mono-, di-, and tri-methyl species, respectively.

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