Photochemical intramolecular gamma-hydrogen abstraction in a ketone and an alkene and the role of tunneling of hydrogen

Rao, Sreedhara V and Chandra, AK (1996) Photochemical intramolecular gamma-hydrogen abstraction in a ketone and an alkene and the role of tunneling of hydrogen. In: Journal of Photochemistry and Photobiology A: Chemistry, 101 (2-3). pp. 189-196.

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Abstract

Intramolecular gamma-hydrogen abstraction reactions were examined in pentane-2-one and 2-methyl-1-pentene in their lowest triplet states using the AM1 semi-empirical molecular orbital method with the complete geometry optimization in the unrestricted Hartree-Fock frame. The results reveal that the oxygen atom of the carbonyl group and the end carbon atom of the olefinic bond acquire high free valence and spin density indices in their respective lowest triplet states, leading to abstraction of hydrogen from the gamma-position relative to the carbonyl and olefinic bonds. The theoretical energy profiles fit with a polynomial and the probability of tunneling of hydrogen was estimated by the WKB (Wentzel, Kramer and Brillouin) method. The results, after thermal averaging of the rate constants, reveal that tunneling of hydrogen is significant at room temperature.

Item Type:	Journal Article
Publication:	Journal of Photochemistry and Photobiology A: Chemistry
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Hydrogen abstraction;Hydrogen tunnelling;Alkene;Ketone
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	09 May 2011 10:50
Last Modified:	09 May 2011 11:09
URI:	http://eprints.iisc.ac.in/id/eprint/37468

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