Exchange Reactions of Uranium Ions in Solution

Rona, Elizabeth

doi:10.1021/ja01166a001

Cited by 31 publications

(24 citation statements)

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“…One is inverse second‐order on the H + ion concentration, and the other is independent of the acidity. Considering the previous studies, the following general picture can be drawn:

U^{4 prefix+} prefix+ normalU normalO * O^{2 prefix+} prefix+ 2 H_{2} normalO \overset{K_{i p}}{⇌} ({}, ((), H_{2} normalO) U^{4 prefix+} \dots normalO * \dots {normalU normalO}^{2 prefix+} ((), H_{2} normalO))

…”

Section: Discussionmentioning

confidence: 92%

“…Direct electron exchange without H + ‐ion concentration dependence has not been observed so far. The U(IV)–U(VI) electron transfer was also extensively studied . On the basis of inverse third kinetic order on H + concentration, an HO‐UOUO 2 3+ intermediate, formed from U(OH) 3+ , UO 2 2+ and water, was suggested for the electron exchange .…”

Section: Introductionmentioning

confidence: 99%

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Simple ¹⁷O NMR method for studying electron self‐exchange reaction between UO₂²⁺ and U⁴⁺ aqua ions in acidic solution

Bányai

Farkas

Tóth

2015

Magnetic Reson in Chemistry

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(17) O NMR spectroscopy is proven to be suitable and convenient method for studying the electron exchange by following the decrease of (17) O-enrichment in U(17) OO(2+) ion in the presence of U(4+) ion in aqueous solution. The reactions have been performed at room temperature using I = 5 M ClO4 (-) ionic medium in acidic solutions in order to determine the kinetics of electron exchange between the U(4+) and UO2 (2+) aqua ions. The rate equation is given as R = a[H(+) ](-2) + R', where R' is an acid independent parallel path. R' depends on the concentration of the uranium species according to the following empirical rate equation: R' = k1 [UO(2 +) ](1/2) [U(4 +) ](1/2) + k2 [UO(2 +) ](3/2) [U(4 +) ](1/2) . The mechanism of the inverse H(+) concentration-dependent path is interpreted as equilibrium formation of reactive UO2 (+) species from UO2 (2+) and U(4+) aqua ions and its electron exchange with UO2 (2+) . The determined rate constant of this reaction path is in agreement with the rate constant of UO2 (2+) -UO2 (+) , one electron exchange step calculated by Marcus theory, match the range given experimentally of it in an early study. Our value lies in the same order of magnitude as the recently calculated ones by quantum chemical methods. The acid independent part is attributed to the formation of less hydrolyzed U(V) species, i.e. UO(3+) , which loses enrichment mainly by electron exchange with UO2 (2+) ions. One can also conclude that (17) O NMR spectroscopy, or in general NMR spectroscopy with careful kinetic analysis, is a powerful tool for studying isotope exchange reactions without the use of sophisticated separation processes. Copyright © 2015 John Wiley & Sons, Ltd.

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“…One is inverse second‐order on the H + ion concentration, and the other is independent of the acidity. Considering the previous studies, the following general picture can be drawn:

U^{4 prefix+} prefix+ normalU normalO * O^{2 prefix+} prefix+ 2 H_{2} normalO \overset{K_{i p}}{⇌} ({}, ((), H_{2} normalO) U^{4 prefix+} \dots normalO * \dots {normalU normalO}^{2 prefix+} ((), H_{2} normalO))

…”

Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Simple ¹⁷O NMR method for studying electron self‐exchange reaction between UO₂²⁺ and U⁴⁺ aqua ions in acidic solution

Bányai

Farkas

Tóth

2015

Magnetic Reson in Chemistry

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“…Irradiated materials were dissolved in 4 molar HCl containing the required U 4+ or U0 2 2+ carrier. At this acid concentration exchange between U(IV) and U(VI) is negligible [8,9]. The U(IV) fraction was separated from the U(VI) fraction by precipitations as UF 4 or as NH 4 We have noticed a very important oxidation of uranium by both the 238 U(n, 2n) 237 U and 238 U(n, y) 239 !!…”

mentioning

confidence: 89%

Szilard-Chalmers Processes in Inorganic Uranium Compounds

Aten¹,

Kapteyn²,

Kapteyn³

1968

Radiochimica Acta

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“…Uranium: UIV / UVI.-Studied (193) with U233, the exchange of uranium between the tetra-and hexavalent states in hydrochloric acid solutions pro ceeded at a rate which was first-order with respect to (UVI) , second-order with respect to (UIV) , and minus third-order with respect to hydrogen ion concentration. The rate was independent of added salt, chloride ion, and illumination, and showed an activation energy of 33.4 kcal.…”

Section: Isotope Effects)mentioning

confidence: 99%

Isotopic Tracers in Chemical Systems

Edwards¹

1952

Annu. Rev. Nucl. Sci.

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Exchange Reactions of Uranium Ions in Solution

Cited by 31 publications

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Simple ¹⁷O NMR method for studying electron self‐exchange reaction between UO₂²⁺ and U⁴⁺ aqua ions in acidic solution

Simple ¹⁷O NMR method for studying electron self‐exchange reaction between UO₂²⁺ and U⁴⁺ aqua ions in acidic solution

Szilard-Chalmers Processes in Inorganic Uranium Compounds

Isotopic Tracers in Chemical Systems

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Exchange Reactions of Uranium Ions in Solution

Cited by 31 publications

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Simple 17O NMR method for studying electron self‐exchange reaction between UO22+ and U4+ aqua ions in acidic solution

Simple 17O NMR method for studying electron self‐exchange reaction between UO22+ and U4+ aqua ions in acidic solution

Szilard-Chalmers Processes in Inorganic Uranium Compounds

Isotopic Tracers in Chemical Systems

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Simple ¹⁷O NMR method for studying electron self‐exchange reaction between UO₂²⁺ and U⁴⁺ aqua ions in acidic solution

Simple ¹⁷O NMR method for studying electron self‐exchange reaction between UO₂²⁺ and U⁴⁺ aqua ions in acidic solution