Mary Woods

A kinetic study of the oxidation of nitrous acid by Np(VI) and Am(VI) in perchlorate media

Abstract The empirical form of the rate law for the oxidation of HNO2 by Np(VI) and Am(VI) in aqueous perchlorate media at 25° and I = 1.0 M is −d Am(VI)/dt = [Am(VI)][HNO2] (k1 + k2/[H+]). For Np(VI), k 1 = 2.01 ± 0.45 M −1 sec −1, k 2 =1.56 ± 0.07 sec −1 , ΔH 1 Psu∗ = 11.7 kcal/mol , ΔS 1 ∗ = = −17.9 e.u., ΔH 2 ∗ = 16.1 kcal/mol and ΔS 2 ∗ = −3.7 e.u. For Am(VI), k1 (11.5 ± 0.3) × 103 M−1 sec−1, k 2 = 656 ± 32 sec −1 , ΔH 1 ∗ = 9.2 kcal/mol , ΔS 1 ∗ = −9.0 ΔH 2 ∗ = 7.9 kcal/mol and ΔS 2 ∗ = -19.1 e.u. These results are compared with those obtained for Mn(III) and Co(III) as oxidants.

The oxidation of americium(V) and other reductants by aqueous acidic Np(VII)

Abstract The oxidation of Am(V) by Np(VII) proceeds by the rate-law: −d[Np(VII)]/dt = βc[Np(VII)][Am(V)][H+]/1 + c[H+] where at 25°, μ = 1.00 M, β = (4.42 ± 0.10) × 105 M−1 s−1, c = 1.30 ± 0.12 M −1 ; ΔH β ∗ = 5.58 ± 0.76, ΔH c o = −1.8 ± 1.0 kcal / mole ; ΔS β ∗ = −14.1 ± 2.6, ΔS c o = −5.5 ± 3.3 e.u. Reactions between Np(VII) and H2C2O4, HN3, SCN−, H2TeO3, H2SO3, H3PO3, Fe(III), Ni(II), (NH3)5CoBr2+, Ce(III), Cr(III) and Pd(II) are also noted.

A kinetic study of the oxidation of ascorbic acid by Np(VI) in aqueous acidic perchlorate media

Abstract The empirical form of the rate law for the oxidation of ascorbic acid (AA) by Np(VI) in aqueous perchloric acid media is -d[Np(VI)]dt = k[Np(VI)] [AA]. The value of k at 25°C and in 1.0 M HClO4 = (1.23±0.02) × 105 M−1 sec−1 No hydrogen ion dependent path of kinetic significance exists over the range 0.05 ΔH ∗ and ΔS ∗ were 7.02±0.07 kcal/mole and −11.7 ± 0.3 e.u., respective The results of this study are compared with those obtained using other metal ion oxidants.

Oxidation of co-ordinated thiol to co-ordinated disulphide via induced electron transfer

The reaction of an excess of [(2-mercaptoethylamine)-N,S] bis (ethylenediamine)cobalt(III) with the one-equivalent oxidant NpVI(or [Coaq]3+) in aqueous HClO4 gives [(2-aminoethyl 2-ammonioethyl disulphide-N,S]-bis(ethylenediamine)cobalt(III)via induced electron transfer and a presumed radical ion dimer intermediate.