5,318 research outputs found
Photoinitiated oxidative addition of CF3I to gold(I) and facile aryl-CF3 reductive elimination.
Herein we report the mechanism of oxidative addition of CF3I to Au(I), and remarkably fast Caryl-CF3 bond reductive elimination from Au(III) cations. CF3I undergoes a fast, formal oxidative addition to R3PAuR (R = Cy, R = 3,5-F2-C6H4, 4-F-C6H4, C6H5, 4-Me-C6H4, 4-MeO-C6H4, Me; R = Ph, R = 4-F-C6H4, 4-Me-C6H4). When R = aryl, complexes of the type R3PAu(aryl)(CF3)I can be isolated and characterized. Mechanistic studies suggest that near-ultraviolet light (Ī»max = 313 nm) photoinitiates a radical chain reaction by exciting CF3I. Complexes supported by PPh3 undergo reversible phosphine dissociation at 110 Ā°C to generate a three-coordinate intermediate that undergoes slow reductive elimination. These processes are quantitative and heavily favor Caryl-I reductive elimination over Caryl-CF3 reductive elimination. Silver-mediated halide abstraction from all complexes of the type R3PAu(aryl)(CF3)I results in quantitative formation of Ar-CF3 in less than 1 min at temperatures as low as -10 Ā°C
The Province of Conceptual Reason: Hegel\u27s Post-Kantian Rationalism
In this dissertation, I seek to explain G.W.F. Hegelās view that human accessible conceptual content can provide knowledge about the nature or essence of things. I call this view āConceptual Transparency.ā It finds its historical antecedent in the views of eighteenth century German rationalists, which were strongly criticized by Immanuel Kant. I argue that Hegel explains Conceptual Transparency in such a way that preserves many implications of German rationalism, but in a form that is largely compatible with Kantās criticisms of the original rationalist version. After providing background on Hegelās relationship to the traditional rationalist theory of concepts and Kantās challenge to it, I claim that Hegelās central task is to provide a theory of conceptual content that allows a relationship to the objective world without being dependent on the specifically sensory aspect of the world, which Kantās theory of concepts required. Since many interpreters deny that Hegelās use of the term āconceptā is comparable to other historical philosophers (or our own), I first show that Hegelās critique of standard conceptions of concepts presupposes an agreement of subject matter. I then show how Hegelās account of the āformal conceptā provides the skeleton for a view of conceptual content that relies on negative relations between terms, rather than a relation to sensibility, to provide content. Hegelās account of conceptual content is completed when he shows how a universal term is further specified so that it can determine singular objects. This occurs in its adequate form in a teleological process. I argue that Hegelās account of teleology in the Science of Logic is an attempt to explain how and where Conceptual Transparency obtains. A teleological process is one in which a concept constitutes an object, and this means that a concept is perfectly adequate to express that thingās nature and not merely to represent it. However, in the final chapter, I show that Hegelās concept of teleology is meant paradigmatically to illuminate how human purposive processes have constituted a social world that is conceptually accessible to us. In this way, the primary āprovinceā of Hegelās rationalism is the human constructed world
Economic Leapovers
This paper examines the phenomenon of economic leapovers in technology. Leapovers are defined and placed in historical context, with some examples from telecommunications and case settings from Russia and China. In particular, the socioeconomic factors behind leapovers are noted and analyzed in light of several classical economic doctrines of Adam Smith, David Ricardo, Thomas Malthus, and Karl Marx. The potential for other leapovers is also examined in an extension
- ā¦