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Published December 1, 1978 | public
Journal Article

Observation by Carbon-13 Nuclear Magnetic Resonance Spectroscopy of Hydride Shifts in C_4H_7^+ Derived from Cyclopropylcarbinol- 1-^(13)C in SbF_5-SO_2CIF-SO_2F_2 Solution

Abstract

The interconversion in carbocationic reactions of cyclobutyl, cyclopropylcarbinyl, and allylcarbinyl derivatives has been the subject of many investigations since its discovery in 1950. Although controversy continues to surround the precise nature of the "nonclassical" C_4H_7^+ cationic intermediate(s) involved in these transformations, the very rapid equilibration of the methylene carbons is well established. At present, opinion is divided as to whether the equilibration process involves rapidly interconverting bicyclobutonium ions (la-c) or "bisected" cyclopropylcarbinyl cations (2a-c). In contrast, no evidence has been reported to indicate that hydride migrations occur in these intermediates. We now report that the ^(13)C NMR spectrum of an isotopically labeled C_4H_7^+ under stable-ion conditions provides unequivocal evidence for slow occurrence of such hydride shifts.

Additional Information

© 1978 American Chemical Society. Supported by the National Science Foundation. We thank Professor G. A. Olah of the University of Southern California for the generous use of his facilities to obtain the FT 20-MHz ^(!3)C NMR spectra and Dr. D. J. Donovan and Mr. G. K. S. Prakash for their assistance in recording these spectra.

Additional details

Created:
August 19, 2023
Modified:
October 24, 2023