Rao, Bantu Nageshwer ; Chandrasekhar, Jayaraman ; Ramamurthy, Vaidhyanathan (1988) Photochemical, photophysical, and theoretical studies on cyclobutanethiones. α-cleavage reactions Journal of Organic Chemistry, 53 (4). pp. 745-751. ISSN 0022-3263
Full text not available from this repository.
Official URL: http://pubs.acs.org/doi/abs/10.1021/jo00239a008
Related URL: http://dx.doi.org/10.1021/jo00239a008
Abstract
Photophysics and photochemistry of cyclobutanethiones 1-5 have been studied with the view to generalize the a-cleavage reactions of cyclobutanethiones. The above cyclobutanethiones possess a unit intersystem crossing efficiency from S1 to T1, a high self-quenching rate (-4 X lo9 M-' s-'), and a short triplet lifetime (<0.50 ws). Photolysis of 1-5 yields in benzene a product resulting from 1,3-transposition and in methanol two cyclic thioacetals.The origin of these products is traced to the triplet excited state. A mechanistic scheme involving a-cleavage as the primary photoprocess and diradicals and thiacarbenes as intermediates has been formulated to rationalize the formation of thioacetals and rearranged products. The proposed mechanistic scheme is supported by UHF MIND013 calculations performed on four model systems, cyclobutanethiones and 1,3-cyclobutanedithiones 18-21. These calculations indicate that formation of diradical is favored thermodynamically and kinetically for systems analogous to 19 and 21, while rearrangement to thiacarbene is likely only for those similar to 21.
Item Type: | Article |
---|---|
Source: | Copyright of this article belongs to American Chemical Society. |
ID Code: | 55526 |
Deposited On: | 18 Aug 2011 11:37 |
Last Modified: | 19 Aug 2011 06:08 |
Repository Staff Only: item control page