Commodity Utilization Research Site Logo
ARS Home About Us Helptop nav spacerContact Us En Espanoltop nav spacer
Printable VersionPrintable Version     E-mail this pageE-mail this page
Agricultural Research Service United States Department of Agriculture
Search
  Advanced Search
 
Programs and Projects
Subjects of Investigation
 

Research Project: THERMOCHEMICAL PROCESSING OF AGRICULTURAL WASTES TO VALUE-ADDED PRODUCTS AND BIOENERGY

Location: Commodity Utilization Research

Title: Reduction of substituted p-Benzoquinones by Fe II near neutral pH

Authors
item Uchimiya, Sophie
item Stone, Alan -

Submitted to: Aquatic Geochemistry Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 26, 2009
Publication Date: November 17, 2009
Repository URL: http://hdl.handle.net/10113/36719
Citation: Uchimiya, M., Stone, A.T. 2009. Reduction of substituted p-Benzoquinones by Fe II near neutral pH. Aquatic Geochemistry. 16(1):173-188.

Interpretive Summary: Quinones are important component of soil organic matter. Redox chemistry of quinones is known to influence a wide range of soil biogeochemical processes, such as respiratory electron shuttling by microorganisms. In this study, the impact of quinone structure and pH on the driving force for the reaction with Fe(II), and on the rate of reaction was investigated. Results showed that ring substituents that raise the potential of the p-benzoquinone/hydroquinone half reaction raise reaction rates. Electron transfer reactions between quinones and iron may be an important link in networks of electron transport taking place in suboxic and anoxic environments.

Technical Abstract: The oxidation of dihydroxyaromatics to benzoquinones by FeIII (hydr)oxides is important in respiratory electron shuttling by microorganisms and has been extensively studied. Prior publications have noted that the Gibbs Free Energy (DG) for the forward reaction is sensitive to dihydroxyaromatic structure, pH, and concentrations of reactants and products. Here, we address the back reaction, benzoquinone reduction by FeII. Rates markedly increase with increasing pH, in accord with increases in DG. Ring substituents that raise the potential of the p-benzoquinone and hydroquinone half reaction raise reaction rates:–OCH3\–CH3\–C6H5\–H\–Cl. p-Naphthoquinone, with a reduction potential lower than the five substituted p-benzoquinones just listed, yields the lowest reaction rates. The complexity of the reaction is reflected in lag periods and less-pronounced S-shaped time course curves. Benzoquinone reduction by FeII may be an important link in networks of electron transport taking place in suboxic and anoxic environments.

   

 
Project Team
Klasson, K Thomas
Lima, Isabel
Uchimiya, Sophie
 
Publications
   Publications
 
Related National Programs
  Bioenergy (213)
  Quality and Utilization of Agricultural Products (306)
 
Related Projects
   Evaluation of Activated Carbons from Animal Manure and Plant Residuals for Adsorption of Gaseous Ammonia
   NANOSCALE INTERACTIONS BETWEEN ENGINEERED NANOMATERIALS AND BIOCHAR
 
 
Last Modified: 05/23/2013
ARS Home | USDA.gov | Site Map | Policies and Links 
FOIA | Accessibility Statement | Privacy Policy | Nondiscrimination Statement | Information Quality | USA.gov | White House