Submitted to: Chemical Engineering Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2007
Publication Date: June 1, 2007
Citation: Stephenson, S.K., Offeman, R.D., Robertson, G.H., Orts, W.J. 2007. Hydrogen-bond networks in linear, branched and tertiary alcohols. Chemical Engineering Science. 62: 3019-3031. Interpretive Summary: More usable energy may be produced from a wider array of natural resources by improving energy efficiency in the processing steps, which convert and purify ethanol for use as a fuel. As part of research to develop liquid-liquid solvent extraction for ethanol separation and purification, this study adds to our understanding of intermolecular interactions allowing us to select the best solvents. Results of molecular dynamics simulations on 54 alcohol isomers containing from 6 to 20 carbon atoms show the effects of hydroxyl location on bulk hydrogen-bonded structures. Trends are seen between molecular dynamics calculations and experimentally observed extraction results. These findings improve the ability to rapidly optimize liquid-liquid extractions by focusing the selection process on a few candidate solvents, and therefore shorten the process development time.
Technical Abstract: Molecular dynamics simulations are used to determine the hydrogen bond networks formed by 54 linear and branched alcohols containing 5 to 20 carbon atoms, and results show systematic differences in their hydrogen-bonded structures, depending both on hydroxyl group position and the alcohol's molecular weight. The hydrogen-bonded networks within these pure solvents correspond with experimentally determined water capacities for solvents in 4 main structural classes. These categories are: primary alcohols, secondary alcohols, tertiary alcohols, and alcohols with the branching point removed from the hydroxyl group. Each of these structural classes exhibits unique behavior in the correlation between the extended hydrogen-bond networks and observed capacities for water.