Promotion of the fenton reaction by Cu2+ ions: Evidence for intermediates

The promotion of the Fenton reaction by Cu²⁺ ions has been investigated using a wide range of [Cu²⁺]. Both the disappearance of Fe²⁺ and the evolution of O₂ were followed as a function of time by quenching the reaction mixture with o‐phenanthroline or with excess Fe^{2 +} ions, respectively. Two series of experiments were performed. In one series [H₂O₂] was 5 × 10⁻⁴ mol dm⁻³, and in the other [H₂O₂] was reduced to 5 × 10⁻⁵ mol dm ⁻³. By stopping the reaction with excess Fe²⁺ ions, significant differences in the measured absorbance in the two series were observed. In the higher [H₂O₂] range, the absorbance decreased monotonically in time, due to O₂ formation during the reaction. In the lower range, an initial transient rise of the absorbance was observed, indicating the formation of spectroscopically distinct intermediates in the system. A mechanism involving the intermediates FeOCu⁴⁺ and FeOCu⁵⁺ has been set up. Rate constants of the mechanism have been determined. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 725–736, 2006     

Some results on minimal sumset sizes in finite non-abelian groups

Let G be a group. We study the minimal sumset (or product set) size μG(r,s)=min{|A⋅B|}, where A,B range over all subsets of G with cardinality r,s respectively. The function μG has recently been fully determined in [S. Eliahou, M. Kervaire, A. Plagne, Optimally small sumsets in finite abelian groups, J. Number Theory 101 (2003) 338-348; S. Eliahou, M. Kervaire, Minimal sumsets in infinite abelian groups, J. Algebra 287 (2005) 449-457] for G abelian. Here we focus on the largely open case where G is finite non-abelian. We obtain results on μG(r,s) in certain ranges for r and s, for instance when r?3 or when r+s?|G|−1, and under some more technical conditions. (See Theorem 4.4.) We also compute μG for a few non-abelian groups of small order. These results extend the Cauchy-Davenport theorem, which determines μG(r,s) for G a cyclic group of prime order.     

Kinetics of aerobic and anaerobic oxidations of ethanol by Fenton's reagent

For the first time, the time dependence of [H₂O₂] and [Fe²⁺] was followed during the aerobic oxidation of ethanol by Fenton's reagent. It was found that part of the ethanol was oxidized by dissolved O₂ via the transient formation of H₂O₂. A model was set up based on FeO²⁺ as the key intermediate. Both one‐ and two‐equivalent oxidations of ethanol occur, the former producing radical species derived from ethanol. No free radicals derived from H₂O₂ play part in the system. The relevant rate constants or their ratios were determined. The mechanism accounted successfully also for the anaerobic oxidation of ethanol. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 541–553, 2008     

Crystallographic report: Dimethyl‐2‐phenylethan‐2‐olamine cyanoborane

The structure of the title compound reveals the geometry around the boron atom to be tetrahedral, and the B? C?N moiety has a bent geometry. Copyright © 2005 John Wiley & Sons, Ltd.     

Structure of 74Ge from the 72Ge(t,p) reaction

The reaction ⁷²Ge(t, p)⁷⁴Ge has been investigated with a 15 MeV triton beam. Fifty energy levels of ⁷⁴Ge were identified up to about 4.9 MeV excitation, eighteen of which were previously unreported. Angular distributions were measured and compared with DWBA calculations. Two low-lying states at 1.913 and 2.164 MeV have been assigned as J^π = 0⁺, corresponding to the 0₃⁺ and 0₄⁺ states in ⁷⁴Ge. The 4₂⁺ state has been located at 2.674 MeV, and the 2₄⁺ at 2.836 MeV. Many additional spin and parity assignments have been made. The ⁷⁴Ge nucleus shows a considerably different structure of 0⁺ states compared with the neighboring ⁷⁶Ge and ⁷⁸Ge nuclei, perhaps further evidence for the shape transition suggested recently for the Ge isotopes.