TAML Oxidant Activators:  A New Approach to the Activation of Hydrogen Peroxide for Environmentally Significant Problems

Abstract

The removal of recalcitrant sulfur species, dibenzothiophene and its derivatives, from automotive fuels is an integral component in the development of cleaner burning and more efficient automobile engines. Oxidative desulfurization (ODS) wherein the dibenzothiophene derivative is converted to its corresponding sulfoxide and sulfone is an attractive approach to sulfur removal because the oxidized species are easily extracted or precipitated and filtered from the hydrocarbon phase. Fe-TAML ® activators of hydrogen peroxide (TAML is Tetra-Amido-Macrocyclic-Ligand) catalytically convert dibenzothiophene and its derivatives rapidly and effectively at moderate temperatures (50-60 °C) and ambient pressure to the corresponding sulfoxides and sulfones. The oxidation process can be performed in both aqueous systems containing alcohols such as methanol, ethanol, or t-butanol, and in a two-phase hydrocarbon/aqueous system containing tert-butanol or acetonitrile. In the biphasic system, essentially complete conversion of the DBT to its oxidized products can be achieved using slightly longer reaction times than in homogeneous solution. Among the key features of the technology are the mild reaction conditions, the very high selectivity where no over oxidation of the sulfur compounds occurs, the near stoichiometric use of hydrogen peroxide, the apparent lack of degradation of sensitive fuel components, and the ease of separation of oxidized products.

Photoassisted Oxidation of Sulfides Catalyzed by Artificial Metalloenzymes Using Water as an Oxygen Source

“…Current chemical processes take place in wasteful organic solvents at high temperature, in addition to lacking in efficiency and/or selectivity [2,3]. Although promising metal catalysts have been developed and show encouraging implementation potential [4], several aspects such as efficacy, regio-and stereoselectivity, compound stability, or environmental toxicity remain to be addressed. In addition, these reactions often resort to oxidant reactants that might have a direct or indirect impact on the environment [2,3].…”

“Green” Oxidation Catalysis for Rapid Deactivation of Bacterial Spores

“…Minute concentrations of the Fe-tetraamido macrocyclic ligand ([Fe(taml)]) activator [12,13] 7 -fold reduction in the viable bacterial spore population in 15 minutes-an important criterion in the pursuit of a superior spore decontamination technology. [8,14] The resistance of Bacillus spores to enzymatic and chemical treatments has been attributed partly to the presence of protein disulfide cross-linkages in the spore coat.…”

Synthetic iron-oxo “diamond core” mimics structure of key intermediate in methane monooxygenase catalytic cycle

“…Lastly, given the tremendous oxidation power of MMO-Q, which is Nature's only species known to date that is capable of converting methane to methanol, synthetic complexes possessing an [Fe IV 2 ( -O) 2 ] diamond core may also represent promising candidates for the advancement of green oxidation technology. Indeed, research carried out by Collins and coworkers (16)(17)(18) over the last two decades has revealed that high-valent ironoxo species are well suited for catalyzing a wide range of technologically important oxidations, such as the rapid bleaching of water-soluble dyes, the decolorization of pulp mill effluents, and the complete remediation of chlorophenol persistent pollutants.…”