Proton magnetic resonance of aromatic carbonium ions

Abstract
N.M.R. spectra of aromatic carbonium ions obtained by dissolving highly basic aromatic hydrocarbons in CF3COOH+H2O.BF3 or HF+BF3 were measured. The resonance of the protons in the CH2 group in the carbonium ion was detected. It was concluded that this configuration, formed by the addition of the proton to the most reactive carbon atom in the hydrocarbon, has an ‘aliphatic’ character. In most instances the N.M.R. spectra of the carbonium ions are blurred by exchange reactions. The character of these reactions is discussed.