ORGN 15 |
| The conversion of azulene to naphthalene at high temperatures has captured the attention of both experimentalists and theoreticians.[1] Its importance lies not only as the first documented thermal rearrangement of an aromatic hydrocarbon, but more specifically as the reorganization of an aromatic polar nonbenzenoid to an aromatic nonpolar benzenoid structure. Various experimental and computational approaches have been made over the years to determine the reaction pathways involved. It has been argued that two radical-promoted pathways play a role in the conversion process. Both of these reactions, the spiran mechanism and the methylene-walk mechanism, involve the attack of a hydrogen atom (H•) to the azulene molecule. In addition, both pathways require the unfavorable geometry of a hydrogen or methylene bonded to one of the two bridging carbon atoms. More recently, Stirling et. al. recognize the necessity for an experimental study of the radical products of H• addition to azulene. Using the light ‘isotope' of hydrogen, muonium (Mu = µ+e-), formed by the capture of an electron by a positively charged muon, we have been able to detect the radical products formed by Mu addition to azulene. We have also been able to identify each of the detected radicals, based on our measurements of the hyperfine coupling constants of the spin active atoms in the Mu-azulyl radicals. |
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Heterocycles and Aromatics
8:00 AM-12:00 PM, Sunday, 26 March 2006 Georgia World Congress Center -- C301, Oral
Division of Organic Chemistry |