Molecular structure and radiative efficiency of fluorinated ethers: A structure-activity relationship

Abstract

Fluorinated ethers are receiving attention as possible replacements for ozone-depleting substances. Accurate knowledge of their radiative forcing is required to assess the contribution of these compounds to climate change. Radiative efficiency is a metric used to determine the potential of long-lived greenhouse gases to impact climate. A structure-activity relationship (SAR) was derived that can estimate the majority of radiative efficiencies of fluorinated ether compounds within 25% of the published experimentally determined values. The SAR allows prediction of radiative efficiency solely from molecular structure, and was developed from 154 calculated and 11 experimentally measured infrared spectra for fluorinated ethers. Stretching vibrations for C-F bonds adjacent to an ether oxygen absorb at lower frequencies than those which are further removed from the ether moiety, which typically gives rise to a higher radiative efficiency. Molecular structure plays an important role in determining the radiative efficiency of fluorinated ethers. The SAR developed herein could be used in the design of new fluorinated ethers that have minimal climate impacts. Copyright 2008 by the American Geophysical Union.