In order to gather direct chemical evidence for the occurrence of protonated cyclopropanes as intermediates in a gas-phase reaction, gaseous cis- and trans-l,2-dimethylcyclopropane were allowed to react with a gaseous Brqnsted acid, the helium tritide ion formed from the decay of molecular tritium. The cis and trans isomers gave the corresponding tritiated compounds retaining the configuration of the original molecules. The lack of any measurable cis-trans isomerization lends strong support to the view that the formation of the tritiated cycloalkanes, following the transfer of a triton from He3H+ to the substrate, proceeds uia a cyclic intermediate, and does not involve the cleavage of the cyclopropane ring. These results corroborate the mechanistic interpretation of earlier experiments concerning the triton transfer from He3H+ to unsubstituted cycloalkanes, and provide unambiguous evidence for the intermediacy of protonated cyclopropanes in a gas-phase reaction.
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|Titolo:||Reactions of helium tritide ions with gaseous hydrocarbons. V. cis- and trans-1,2-Dimethylcyclopropane. Unambiguous evidence for gaseous protonated cyclopropanes|
|Data di pubblicazione:||1971|
|Appartiene alla tipologia:||01a Articolo in rivista|