Nitrogen-15 Magnetic Resonance Spectroscopy. IV. The Degenerate Bimolecular Exchange of Protons in Ketimines.

摘要

The imine protons of nitrogen-15 labeled ketimines exhibit temperature-dependent nuclear magnetic resonances. Analysis of the effect of concentration of substrate on the mean lifetime indicates that the spectral changes result from a bimolecular exchange of protons between imines. The activation energy of this process in diphenylketimine-N15 was determined to be 13.8 = 2 kcal/mole, whereas in s-butylphenylketimine-N15, the activation energy was about 6 kcal/mole. In the latter case, separate resonances were observed for the distinct syn and anti isomers. (Author)