Mass spectrometry of quinones. Part II. A study of the distinguishing features found in the mass spectra of 1,2- and 1,4-naphthaquinones

The mass spectra of 18 variously substituted 1,2-naphthaquinones are reported and discussed. It is shown that the majority of the ortho-naphthaquinones studied are reduced by water vapour present in the mass spectrometer and that this reaction provides a mass spectral method for distinguishing between 1,2- and 1,4-naphthaquinones. No simple relationship is found to exist between the solution redox potentials and the ease of reduction of the 1,2-naphthaquinones in the spectrometer. Finally, fragmentation patterns for the individual quinones studied are suggested and these are correlated with the type and position of the substituent in the quinone nucleus.