Studies on the Norrish type II reactions of aliphatic \alpha-diketones and the accompanying cyclization and disproportionation of 1:4 biradicals

Sengupta, Debasis and Chandra, AK (1993) Studies on the Norrish type II reactions of aliphatic \alpha-diketones and the accompanying cyclization and disproportionation of 1:4 biradicals. In: Journal of Photochemistry and Photobiology A: Chemistry, 75 (2). pp. 151-162.

PDF 1993_JPP-A_V75_pp151-162.pdf Restricted to Registered users only Download (908kB) | Request a copy

Abstract

The Norrish type II process of several alkyl diketones was examined using the AM1 semi-empirical molecular orbital method with complete geometry optimization at the configuration interaction (CI) level in the restricted Hartree-Fock (RHF) frame. Unrestricted Hartree-Fock calculations of the triplet state of the diketone lead to a decrease in symmetry and strong localization of excitation on one carbonyl. The results of RHF+CI reveal that diketones have much lower reactivities than monoketones and the barriers to conformational change in diketones play an important role in the triplet reaction. The cyclization and disproportionation reactions of the resulting 1 : 4 biradicals were studied in the unrestricted Hartree-Fock frame and the results were compared with those derived from alkyl monoketones. In many respects, the reactions of 1 : 4 biradicals derived from alkyl monoketones parallel those derived from diketones. The free valence indices on the radical sites correlate qualitatively with the radical-like reactivities.

Item Type:	Journal Article
Publication:	Journal of Photochemistry and Photobiology A: Chemistry
Publisher:	Elsevier
Additional Information:	Copyright for this article belongs to the Elsevier.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	26 Jun 2008
Last Modified:	19 Sep 2010 04:46
URI:	http://eprints.iisc.ac.in/id/eprint/14655

Actions (login required)

View Item