Oxidative Desulfurization using Functional Thiol Dioxygenase Models

The sulfur contaminants in diesel fuel are a major source of SO2, a greenhouse gas, and particulate matter emissions. Thiol deoxygenases use iron (an inexpensive, abundant and non-toxic metal) and oxygen to carry out the oxidation of thiols under ambient temperatures and pressures. For these reasons, we have developed iron complexes that mimic the chemical environment found inside the enzyme of cysteine dioxygenase (CDO). The air sensitive complexes were synthesized using standard Schlenk or glove box techniques under a dinitrogen atmosphere. The first coordination sphere is structurally similar to the enzyme and we are examining how closely the reactivity matches the enzymatic system. Once exposed to oxygen, the reactivity was monitored by UV-Vis spectroscopy. The products of this reactivity have been studied by UV-Vis spectroscopy, mass spectrometry, and NMR. The characterization of these products will be discussed. In addition to this, the mechanism of this reaction was probed using kinetic studies.