Easy experiments for detection of chromium intermediates

Abstract

Detection of reaction intermediates is an important matter when a kinetic experiment is carried out, to reinforce the mechanism derived from the rate law. However, this task may be difficult when the transient species are very short-lived, and under kinetic conditions they may not be observed. If this is so, conditions under which detection would be feasible will have to be found out, and students should be taught to do it.Herein oxidations of organic substrates by potassium dichromate in aqueous solution have been chosen as model systems, since both Crv and Crvl complexes involved in these reactions (1) may be detected easily. When CrVI is mixed with biologically related molecules in aqueous solution, growth and decay of CrVI and Crv intermediates are observed, with "stability" ascribed to complex formation with substrate (2). Besides, stable Crv compounds with ahydroxy-acids having a tertiary alcohol group have been isolated and characterized (3). Identification of Crv intermediates has led to the consideration that such species may be involved in the molecular processes leading to the onset of cancer formation, and they are likely candidates

An Undergraduate Experiment To Explore Cu(II) Coordination Environment in Multihistidine Compounds through Electron Spin Resonance Spectroscopy

“…Several ESR laboratory experiments designed for upper level undergraduate courses have been reported in this Journal . Some focus on kinetic studies, − others focus on coordinated compound structure, − and two show direct application to bioinorganic chemistry. , The experiment described here also has a direct application to biochemistry while providing learning opportunities on the correlation of electron density to changes in metal–ligand structure. In this designed laboratory experiment, ESR spectra are used to elucidate the coordination environment of Cu­(II) .…”