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Relevant academic research and scientific papers

Kinetic study of the oxidation of p-hydroquinone and p-toluhydroquinone by neptunium(VI) in aqueous perchlorate media

The oxidation of p-hydroquinone and p-toluhydroquinone by Np(VI) in aqueous perchlorate media can be described by the empirical rate law -d[Np(VI)]/dt = k[Np(VI)][H2Q] where H2Q is the appropriate hydroquinone. At 25° and I = 1.00 va

Reduction of Pu(IV) and Np(VI) with carbohydrazide in nitric acid solution

The reduction of Pu(IV) and Np(VI) with carbohydrazide (NH 2NH)2CO in 1-6 M HNO3 solutions was studied. The Pu(IV) reduction is described by a first-order rate equation with respect to Pu(IV). At [HNO3] ≥ 3 M, the reaction becomes reversible. The rate constants of the forward and reverse reactions were determined, and their activation energies were estimated. Neptunium(VI) is reduced to Np(V) at a high rate, whereas the subsequent reduction of Np(V) to Np(IV) is considerably slower and is catalyzed by Fe and Tc ions. The possibility of using carbohydrazide for stabilizing desired combinations of Pu and Np valence states was examined. Pleiades Publishing, Inc., 2012.

Behavior of Pu(VI) and Np(VI) in malonate solutions

Complexation of PuO22+ in solutions containing malonate anions C3H2O42- (L 2-) is studied by spectrophotometry. Mono- and bimalonate complexes are formed. The monomalonate complex was isolated as PuO2L· 3H2O. It is isostructural to UO2L·3H2O and forms rhombic crystals with the unit cell parameters a = 9.078(2), b = 7.526(2), and c = 6.2005(15) A, space group Pmn21. The electronic absorption spectrum of the monomalonate complex is characterized by a strong band at 843 nm. In malonate solutions, Pu(VI) is slowly reduced to the pentavalent state even in the cold. The reduction of Np(VI) is considerably faster and more sensitive to increasing temperature. Some kinetic features of the reduction are discussed. Pleiades Publishing, Inc., 2006.

Kinetics of Reaction between Neptunium(VI) and 3,3'-Bis(diaziridinyl)

Reaction of Np(VI) with excess 3,3'-bis(diaziridinyl) yields the corresponding diazirine and is described by the equation 4NpO2(2+)+ H2N2HCCHN2H2 = 4NpO2(1+)+ N2HCCHN2 + 4H(1+). The rate of this reaction is described by the equation -d[Np(VI)]/dt = k[Np(VI)][H2N2HCCHN2H2]/[H(1+)], wherek=132.+-.10 min**-1 at 35.7°C and the ionic strength of the solution μ = 2. The activation energy of the reaction is E = 73.1.+-.4.6 kJmol**-1.

Kinetics of reactions of Np and Pu ions with hydroxylamine derivatives: VIII. Reduction of Np(VI) with N,N-dibutylhydroxylamine

The rate of Np(VI) reduction with (C4H9)2NHOH(1+) in HC1O4 and HNO3 solutions is described by the equation -d[Np(VI)]/dt = k*[Np(VI)]*[(C4H9)2NHOH(1+)]/[H(1+)], where k = 15.6 +/- 1.1 min**-1 at 25.5°C and ionic strength μ = 2 in an HC1O4 solution and k = 16.0 +/- 1.0 min**-1 at 26.0°C in an HNO3 solution. The activation energy is E = 45.8 +/- 0.8 and 71.9 +/- 0.2 kJ*mol**-1, respectively. The reaction mechanismis discussed in comparison with that of the other Np(VI) reactions with disubstituted hydroxylamines.

Kinetics of the reduction of neptunium(VI) by dicarboxylic acids

The reduction of tracer concentrations of Np(VI) by dicarboxylic acids has been shown to proceed via formation of the 1:1 metal-ligand complex and to form Np(V) but not Np(IV). The rate constants were in the sequence oxalate alkylmalonate ? succinate ? phthalate ≥ fumarate > glutarate. The results are consistent with a mechanism in which the rate-determining step involves loss of a methylene proton from the reductant.

Kinetics of reduction of neptunium(VI) with oxalic acid in aqueous perchloric acid

The kinetics for the reduction of neptunium(VI) with oxalic acid has been studied in aqueous perchlorate media. The rate law for the reaction was found to be d[Np(V)]/dt = k [Np(VI)][total oxalate]/[H+] Specific velocity constants and activation energy have been determined. A possible mechanism has been suggested which explains the observed kinetics and the stoichiometry of the reaction.

The reduction of cobalt(III) by neptunium(V) and the neptunium(V)-chromium(III) complex

The rate law for the reaction Np(V) + Co(III) = Np(VI) + Co(II), from 5 to 25° in perchloric acid-lithium perchlorate solutions of constant ionic strength, is -d[Np(V)]/dt = k′[Np(V)] [Co(III)] where k′ = k0e-β[H+]. Under the same co

The formation of a neptunium(V)-chromium(III) complex. Kinetics and equilibria in perchlorate solutions

A value for the equilibrium quotient Q = [Np(V)·Cr(III)]/[Np(V)][Cr(III)] of 2.62 ± 0.48 at 25° has been determined spectrophotometrically. Values of ΔH = -3.3 ± 0.6 kcal, and ΔS = -9.0 ± 1.9 e.u. have been determined. The rates of formation and aquation of the complex Np(V)·Cr(III) have been measured. The complex is also formed by the reduction of Np(VI) with Cr(II).