Transferts Protoniques de Sels D'ammonium. Substitues—II: Vitesse D'inversion a L'azote Par la Methode de ‘Protonation Competitive’

Nitrogen in version rate of an amine may be brought to within the NMR time-scale by use of an acidic medium of variable pH, in which it is almost completely prevented through protonation. Rigorous equations are derived for computing this rate from the mean lifetime of the ammonium cation determined by NMR spectroscopy. The validity of Saunders and Yamada's approximate formula is discussed: the protonation rate of the amine must be far larger than its nitrogen inversion rate, while the rate at which the salt loses its acidic proton is immaterial. If in version occurs between two different isomers, the equilibrium ratio of the isomeric cations is also derived.