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Nuclear magnetic resonance spectra of carbanions—VI . Cumyl‐, α‐methylbenzyl‐ and benzyl carbanions
Author(s) -
Takahashi Kensuke,
Takaki Mikio,
Asami Ryuzo
Publication year - 1971
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270030507
Subject(s) - carbanion , chemistry , ionic bonding , proton , chemical shift , spectral line , resonance (particle physics) , ion , stereochemistry , organic chemistry , physics , nuclear physics , atomic physics , astronomy
The proton magnetic resonance spectra of the three title carbanions have been observed in THF with potassium as a counter ion. The ortho ‐protons in the α‐methylbenzyl carbanion are nonequivalent at room temperature. This shows that the α‐carbon in this carbanion is in the near‐sp 2 configuration. The aromatic proton chemical shifts of the benzylpotassium obtained here are at higher shielding than those of benzyllithium reported previously by Sandel and Freedman. This seems to arise from the different ionic nature of the bonds between carbon and metal in the carbanions.