Grantee Research Project Results

Biomimetic Oxidation of Hydrocarbons Related to Bioremediation Processes

EPA Grant Number: R823377
Title: Biomimetic Oxidation of Hydrocarbons Related to Bioremediation Processes
Investigators: Stavropoulos, Pericles
Institution: Boston University
EPA Project Officer: Aja, Hayley
Project Period: October 1, 1995 through September 30, 1998
Project Amount: $321,711
RFA: Exploratory Research - Engineering (1995) RFA Text | Recipients Lists
Research Category: Safer Chemicals , Land and Waste Management

Description:

The purpose of this project is to undertake a comprehensive study of the iron- and copper-based chemistry related to a remarkable hydrocarbon-oxidizing system. The so-called Gif systems are biomimetic Fe/Cu-containing catalysts that exhibit preferential selectivity for the ketonization/hydroxylation of secondary carbons, a trend that has been frequently encountered in oxidation of substrates by metal-containing hydroxylases. The present study is directed towards understanding the structural features and functional behavior of the metal sites involved in catalytic turnovers upon hydrocarbon oxidation. An ensemble of ferrous species along with their ferric counterparts have been isolated under Gif conditions and placed on a firm structural/functional basis. The following are the principal findings of this study: (a) Basic iron or iron/zinc acetates are involved in redox transformations with a host of Fe(II)/Zn(II)-containing species. These redox cycles, mediated by a variety of reducing agents and dioxygen, are essential components in sustaining the catalytic conversions of Gif chemistry; (b) The reduced Fe/Zn species are implicated in multiple equilibria involving well-defined oligonuclear and one-dimensional Fe(II)/Zn(II)- containing polymers that have been structurally characterized and studied with an arsenal of physicochemical probes. Remarkable similarities with structural elements of the diiron site in the hydroxylase component of soluble methane monooxygenase (sMMO) of methanotrophic bacteria have been uncovered; (c) Catalytic oxidation of hydrocarbons, mediated by any given member of the equilibria-related Fe/Zn species, affords typical Gif selectivity, featuring a preponderance for the ketonization/hydroxylation of secondary carbons. Only minor amounts of products resulting from activation of tertiary positions are observed, an indication that the system operates at least partially under a nonradical mode. The preference for ketonization versus hydroxylation can be modified by employing reducing co-substrates. Finally, the yield and selectivity of the Gif reaction has been substantially improved by employing hindered pyridines as solvents. Experimental details of this work have recently appeared as a communication in the JACS 1996, 118, 5824-5825. Future investigations are directed towards conducting an exhaustive study of the activation of dioxygen in the presence of isolated Fe(II) and Cu(I) species. Prime targets of this study are the isolation and characterization of the active oxidants involved as well as the determination of the kinetic competency of the isolated compounds with respect to hydrocarbon oxidation. Improvement of the catalyst's efficiency will also be sought for future application against pollutant hydrocarbons.

Publications and Presentations:

Publications have been submitted on this project: View all 4 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 4 journal articles for this project

Supplemental Keywords:

air, air pollution control, hydrocarbon oxidation, iron-based oxidizing system, copper-based oxidizing system., Scientific Discipline, Toxics, Waste, Environmental Chemistry, HAPS, Bioremediation, Environmental Engineering, iron based oxidizing system, air pollutants, hydrocarbon, copper based oxidizing, hydrocarbon oxidation, ecological consequences, redox transformations, hydrocarbon degrading, hydroxylation of secondary carbons

Progress and Final Reports:

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.