Alimet Sema Özen

A Computational Study of the Wallach Rearrangement

Treatment of azoxybenzene and its derivatives with acids is known to result in the Wallach rearrangement, which leads to 2- or4-hydroxyazobenzenes. Starting in the 1960s, experimental findings have lead to the proposal of several mechanisms for this rearrangement. In this work, molecular orbital theory employing the semiempirical AM1 method is used to locate and discuss the energetics of the intermediates and the transition states for this rearrangement. Based on the results of AM1 calculations in vacuum and in solution, the most plausible mechanistic pathways are proposed and discussed.

Chemical Reactivity Perspective into the Group 2B Metals Halides

Chemical reactivity descriptors within the conceptual density functional theory can be used to understand the nature of the interactions between two monomers of the Group 2B metal halides. This information might be valuable in the development of adequate force law parameters for simulations in the liquid state. In this study, MX2 monomers and dimers, where M = Zn, Cd, Hg and X = F, Cl, Br, I, were investigated in terms of chemical reactivity descriptors. Relativistic effects were taken into account using the effective core potential (ECP) approach. Correlations were produced between global and local reactivity descriptors and dimerization energies. Results presented in this work represent the first systematic investigation of Group 2B metal halides in the literature from a combined point of view of both relativistic effects and chemical reactivity descriptors. Steric effects were found to be responsible for the deviation from the chemical reactivity principles. They were introduced into the chemical reactivity descriptors such as local softness.