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Updated: May 18, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Superacid-promoted ionization of alkanes without carbonium ion formation: a density functional theory study
1Department of Chemistry-BMC, Uppsala University, Box 576, S-751 23 Uppsala, Sweden. peter.diner@kemi.uu.se
Abstract:
The carbonium ion has been suggested to be the intermediate in superacid-promoted reactions (SbF(5)-HF) such as hydrogen-deuterium exchange and in the electrophilic C-H cleavage into hydrogen and the carbenium ion. In this study, the superacid-promoted C-H cleavage into hydrogen and the carbenium ion was studied using density functional theory (B3LYP and M062X) and ab initio methods (MP2 and CCSD). The calculations suggest that the superacid-promoted C-H cleavage proceeds via a concerted transition state leading to hydrogen (H(2)) and the carbenium ion without the formation of the elusive carbonium ion. The reactivity for the superacid-promoted C-H cleavage decreases upon going from isobutane (tertiary) > propane (secondary) > isobutane (primary) > propane (primary) > ethane >> methane.
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