Article révisé par les pairs
Résumé : The NMR spectrum of caffein shows three NCH3 peaks. By study of solvent effect and pH effect on this spectrum, it was possible to make a correct attribution of the absorption peaks. A proof of this attribution was searched in the examination of NMR spectra of theophylline and theobromine. Two new chlorocaffeins were prepared during this work. © 1965.