Fragmentation of 2,2,2-triphenylethoxychlorocarbene: evidence for ultrafast fragmentation-rearrangement in excited diazirines.
[reaction: see text] Photolysis of 3-(2,2,2-triphenylethoxy)-3-chlorodiazirine gives 2,2,2-triphenylethoxychlorocarbene which fragments with 1,2-phenyl migration and loss of CO and Cl(-) to yield the 1,1,2-triphenylethyl cation and thence 1,1,2-triphenylethene by proton loss. However, ps and fs laser flash photolysis provides evidence that up to 25% of the alkene product stems from carbocation that arises directly from excited diazirine rather than from the carbene.
Ionic and radical fragmentations of alkoxyhalocarbenes – a perspective
Fragmentations of secondary or tertiary alkoxyhalocarbenes in polar solvents generate carbocations as components of ion pairs. A variety of carbocations can be produced including acyclic, alicyclic, benzyl, bridgehead, cyclopropyl, cyclopropylcarbinyl, and norbornyl examples. Laser flash photolysis (LFP) studies provide kinetics and activation parameters for the carbene fragmentations, which are orders of magnitude faster, and require considerably reduced activation energies, compared to analogous solvolytic carbocation-generative processes. In some cases, the time required for solvent and anion equilibration of the ion pairs can be estimated. In nonpolar solvents, the gas phase, or cryogenic matrices, homolytic carbene fragmentation may, in certain cases, supplant heterolytic fragmentation. Copyright © 2008 John Wiley & Sons, Ltd.
Capturing Crime in the Antipodes: Colonist Cultural Representation of Indigeneity
This chapter adopts a Southern criminological lens, which allows the authors to explore how colonialism has been constructed and depicted in museums within both regional and urban Australia. By studying spatial and historical silences in Australian museums, this chapter offers a consistent frame to chronologically chart Anglo-Australian depictions of Indigeneity, imperialism and violence wielded by the state. As this chapter will argue, museums can often reflect Westernized (white) conceptualizations about Indigeneity and the state violence involved in colonization, which actively re-enforces popular views and influences sociopolitical visions of identity, the state and justice.