Sølling, Theis I. and Hammerum, Steen (2001) The retro-ene reaction of gaseous immonium ions revisited. Journal of the Chemical Society-Perkin Transactions 2 (12). pp. 2324-2328. ISSN 1472-779X http://resolver.caltech.edu/CaltechAUTHORS:20111121-095541906
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The retro-ene reaction is a common reaction of metastable immonium ions, leading to the expulsion of an alkene molecule. The kinetic energy release that accompanies this reaction decreases with alkyl substitution on the γ-carbon of the immonium ion. A number of authors have taken this result to indicate that the retro-ene reaction proceeds in a non-concerted manner via a carbocation intermediate. Using ab initio calculations to test this hypothesis we find that the retro-ene reaction is a concerted process, in which the reactant immonium ion is connected to the products via a single six-membered cyclic transition state. The calculated energy barriers and the measured kinetic energy releases are highly sensitive to alkyl substitution at the γ-position, which indicates that a substantial fraction of the positive charge of the transition state resides at the γ-carbon, not that the retro-ene reaction is a stepwise process with a carbocation intermediate.
|Additional Information:||© 2001 Royal Society of Chemistry. Received 19 Jun 2001, Accepted 10 Oct 2001. First published on the web 09 Nov 2001. We gratefully acknowledge Statens Naturvidenskabelige Forskningsraad and the Australian National University Supercomputing Facility for generous grants of computer time|
|Official Citation:||The retro-ene reaction of gaseous immonium ions revisited Theis I. Sølling and Steen Hammerum J. Chem. Soc., Perkin Trans. 2, 2001, 2324-2328 DOI: 10.1039/B105386H|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||21 Nov 2011 19:05|
|Last Modified:||26 Dec 2012 14:26|
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