HR: 0800h
AN: A51D-0737    [Abstracts]
TI: Atmospheric Chemistry of Fluorinated Ethers: Estimation of Radiative Forcing from Chemical Structure
AU: * Young, C J
EM: cyoung@chem.utoronto.ca
AF: Department of Chemistry, University of Toronto, 80 St George Street, Toronto, ON M5S 3H6, Canada
AU: Hurley, M D
EM: mhurley3@ford.com
AF: Ford Motor Company, Mail Drop SRL-3083, Dearborn, MI 48121, United States
AU: Wallington, T J
EM: twalling@ford.com
AF: Ford Motor Company, Mail Drop SRL-3083, Dearborn, MI 48121, United States
AU: Mabury, S A
EM: smabury@chem.utoronto.ca
AF: Department of Chemistry, University of Toronto, 80 St George Street, Toronto, ON M5S 3H6, Canada
AB: Fluorinated compounds absorb within the atmospheric window and contribute approximately 13% of the radiative forcing (RF) of climate change associated with long-lived greenhouse gases. Among the halocarbons with the highest RFs are fluorinated ethers, which are increasingly being used as replacements for ozone depleting substances. Radiative forcing by fluorinated ethers is not simply proportional to the number of C-F bonds contained in the molecule. It has been proposed that changes in the chemical environment of the C-F bond can change the radiative properties of the bond. For instance, increasing fluorination increases the bond strength, moving the absorption out of the atmospheric window. Density functional theory was employed to calculate the infrared spectra of a series of fluorinated ethers and to estimate the radiative forcing contribution of different substituent groups. Values and trends were consistent between theoretically and experimentally derived radiative forcing values. A structure-activity relationship was developed to estimate radiative forcing from chemical structure. This relationship avoids the time and expense associated with chemical synthesis and laboratory experiments and may be a useful screening tool to search for compounds with lower radiative forcing values.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting