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Concerted Wolff rearrangement in two simple acyclic diazocarbonyl compounds.

Authors :
Burdzinski G
Zhang Y
Wang J
Platz MS
Source :
The journal of physical chemistry. A [J Phys Chem A] 2010 Dec 23; Vol. 114 (50), pp. 13065-8. Date of Electronic Publication: 2010 Nov 30.
Publication Year :
2010

Abstract

The photochemistry of two simple acyclic diazo carbonyl compounds, azibenzil and diazoacetone, were studied using the tools of ultrafast time-resolved spectroscopy. In the former case, UV-vis detection allows observation of an absorption band of singlet benzoylphenylcarbene, decaying with a 740 ± 150 ps time-constant in acetonitrile. IR detection shows that the ketene product of Wolff rearrangement (∼2100 cm(-1)) is formed by two parallel pathways: a stepwise mechanism with carbene intermediacy with a slow rise time-constant of 660 ± 100 ps, and directly in the diazo excited state as confirmed by the immediate formation of an IR band of a nascent hot ketene species. Photolysis (270 nm) of diazoacetone in chloroform leads mainly to the ketene species through a concerted process, consistent with the predominance of the syn conformation in the diazoacetone electronic ground state and a zero quantum yield of the internal conversion process.

Details

Language :
English
ISSN :
1520-5215
Volume :
114
Issue :
50
Database :
MEDLINE
Journal :
The journal of physical chemistry. A
Publication Type :
Academic Journal
Accession number :
21117638
Full Text :
https://doi.org/10.1021/jp108690n