Design and study of catalytic activators of hydrogen peroxide promising rapid, efficient petroleum desulfurization and bleaching technologies.

摘要

The principles of green chemistry and the importance of replacing polluting oxidation technologies are introduced. A review of some recent inorganic catalytic systems that catalyze oxidations with hydrogen peroxide is presented. The systems that have potential for use in commercial oxidation technologies and industrial chemical synthesis are highlighted. Some applications that utilize hydrogen peroxide as an oxidant are discussed.; A new generation of oxidatively robust tetraamido macrocyclic ligands was synthesized. An iterative design process was employed, in which oxidatively sensitive ligand moieties were identified and replaced. One of the new ligands were prepared by a two step synthetic procedure previously used in the Collins group. A new synthesis was ultimately developed for the new ligand generation that provided significantly higher yields. Moreover, this new synthesis is more green since it has replaced the use of more toxic solvents.; The Fe(III)-H₂O complex of each ligand in the new generation was synthesized and characterized to provide a pure Fe(III)-tetaamido complex with a labile axial ligand. The Fe(III)-H₂O complexes were characterized by combustion elemental analysis along with UV/visible, IR, and ESI-MS spectroscopies.; The new Fe(III)-H₂O complexes, resulting from a subtle change in ligand design feature, have significantly increased lifetimes that are sufficient to usefully activate H₂O₂ for oxidation in water from neutral to basic pH. The increased longevity of these complexes in activating H₂O₂ has been demonstrated by their ability, at nanomolar concentrations, to oxidize various dyes in water. Pinacyanol chloride was the analytically pure dye that were particularly used to establish this increased lifetime. UV/visible spectroscopy was used to measure dye bleaching times, to monitor the disappearance of dye absorbance, and to measure the amount of dye that was bleached before the complex degraded. The new Fe(III)-H ₂O complexes also have applications as catalytic H₂O ₂ activators for green oxidation technologies. They activate H ₂O₂, at relatively low temperatures, for the selective and efficient oxidation.; Fe-TAML activator/hydrogen peroxide systems are used to bleach dyes in order to explore structure-reactivity relationship. The initial rates of dye bleaching by hydrogen peroxide were measured and compared by differently substituted Fe-TAML activators. Initial rates of dye bleaching were measured by UV/visible spectroscopy. The substituent effect on the catalytic activity was discussed.; U.S. EPA has mandated reduction of the maximum sulfur content in diesel to 15 ppm by 2006 and in gasoline to 30 ppm by 2004. The conventional method for reducing sulfur is hydrodesulfurization (HDS) under severe conditions. In order to reduce sulfur concentration in fuels, desulfurization of dibenzothiophene, 4-Methyl dibenzothiophene and 4,6-Dimethyl dibenzothiophene is required. Desulfruization of those compounds is very difficult by HDS due to their steric-hindrance. Micromolar concentrations of Fe-TAML activators reacting with hydrogen peroxide convert greater than 99% of dibenzothiophene derivatives to the corresponding sulfones under mild conditions. The identification of the products was performed by combustion elemental analysis along with UV/visible, IR, GC-MS, NMR and GC-AED spectroscopies. The initial rates of the oxidation reactions were measured by UV/visible spectroscopy.