31p Nuclear Magnetic Resonance Spectroscopy of Polyphenol-Containing Olive Oil Model Compounds

Phosphitylation of the free hydroxyl and carboxyl groups of a series of polyphenol-containing olive oil model compounds with 2-chloro-4,4,5,5-tetramethyl-dioxaphospholane allows their classification on the basis of 31P NMR chemical shifts. Unambiguous assignment of the 31P NMR chemical shifts of the dihydroxy- and polyhydroxy-phenols has been achieved by employing one and two-dimensional NMR techniques. Furthermore, integration of the appropriate signals of the hydroxyl derivatives in the corresponding 31P NMR spectra allows the quantification of these compounds. This study forms the basis for the development of a novel and sensitive method that can be used to obtain valuable information about polyphenols that are present in olive oils.