**The presence of a negative partial charge on the benzylic carbon atom in the transition state** __(1)__ can be deduced from the experimentally determinable Hammett Ο± values. Alkyl radicals R^Λ^ are accordingly seen to develop nucleophilic properties during addition to olefins. equation image
Addition of methoxy radicals to olefins
β Scribed by E. A. Lissi; G. Massiff; A. Villa
- Publisher
- John Wiley and Sons
- Year
- 1975
- Tongue
- English
- Weight
- 321 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0538-8066
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β¦ Synopsis
Abstract
The addition of methoxy radicals to several olefins has been studied by a competitive method at 127Β°C in gas phase. The thermal decomposition of dimethyl peroxide was used as methoxy radical source. The rate of addition to the double bond was measured relative to the oxidation of carbon monoxide. For the addition to ethylene it was obtained that
This rate constant is similar to the one shown by methyl radicals under similar conditions. From the relative rate of addition to several chlorinated and fluorinated olefins it can be concluded that methoxy radicals show very little βelectrophilicβ character.
π SIMILAR VOLUMES
Diene complexes which are substituted in the 2-position, or do not bear electron-withdrawing substituents, react less specifically[31. For example, the complex ( 9 ) yields a mixture of the isomericenones ( l o ) , ( l l ) , and (12), with the 1,4-addition of hydrogen strongly predominating.
Regiochemical trends in the addition of free radicals to substituted olefins are investigated by different quantum chemical approaches with special reference to oxygen centered radicals. From a methodological point of view, density functional methods provide correct general trends but they do not re