Concerted Wolff Rearrangement in Two Simple Acyclic Diazocarbonyl Compounds
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- 作者：Gotard Burdzinski ; Yunlong Zhang ; Jin Wang ; Matthew S. Platz
- 刊名：Journal of Physical Chemistry A
- 出版年：2010
- 出版时间：December 23, 2010
- 年：2010
- 卷：114
- 期：50
- 页码：13065-13068
- 全文大小：232K
- 年卷期：v.114,no.50(December 23, 2010)
- ISSN：1520-5215
文摘
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.