Gas-phase reactions of anions with substituted silanes
| Autor: | Sally A. Sullivan, Joseph J. Grabowski, Veronica M. Bierbaum, Robert J. Schmitt, L. A. Flippin, Charles H. DePuy, Gary King |
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| Rok vydání: | 1980 |
| Předmět: | |
| Zdroj: | Journal of the American Chemical Society. 102:5012-5015 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja00535a031 |
| Popis: | The gas-phase reactions of fluoride, amide, hydroxide, and methoxide ions with a variety of substituted silanes have been studied by the flowing afterglow technique. Fluoride reacts readily with trimethylsilyl derivatives to displace benzyl, alkenyl, and alkynyl anions. These reactions have also been used to generate specific structural isomers (CH3C=C" and CH2=C=CH"). Anions more basic than phenide ion cannot be produced in this manner, and their parent trimethylsilanes interact with fluoride by more complex mechanisms. Amide, hydroxide, and methoxide ions react with substituted trimethylsilanes by both displacement and proton abstraction whenever an acidic hydrogen is present; in the absence of displaceable groups and acidic hydrogens, the reactions of amide, hydroxide, and methoxide parallel those of the fluoride ion. appeared. We have been using a flowing afterglow system for experiments of this kind.5,6 One immediate problem concerns methods for the formation of carbanions in the gas phase, since only a relatively few anions can be formed efficiently by electron capture. As a consequence most organic anions are generated by proton transfer from a neutral organic compound by a strong gas-phase base such as CH3O", OH", or NH2". In many cases this is an efficient and unambiguous method and, when applicable, is clearly the method of choice. As our studies have become more sophisticated, how ever, it has become apparent that proton transfer is not always a "simple" reaction and that the anions formed by such reactions do not always have the expected structure. We were therefore interested in developing a new method for the generation of gas-phase carbanions which would be more specific and which might overcome some of the problems of anion formation by proton transfer. |
| Databáze: | OpenAIRE |
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