Substituent effects in the mass spectral fragmentation of some phenoxaphosphinic acids

Abstract

The mass spectra of eight phenoxaphosphinic acids exhibit marked influence of the substituents in the aromatic rings on the modes of the electron-impact induced fragmentations. Eliminations of PO₂H or OH· followed by PO· were generally observed, but only methyl substituted molecular ions lost H₂O, probably after a double rearrangement indicated by a very intense metastable transition. Ethyl substituted derivatives were dominated by loss of CH₃·.