Abstract
The difference between the mass spectra of Ar-CH=N-N=CH-Ar derivatives and those of Ar (OH)-CH=N-N=CH-Ar (OH) derivatives was pointed out. Mass spectra of 24 kinds of ortho-hydroxyaromatic aldehyde para-substituted benzylidenehydrazones (Ar (OH)-CH=N-N=CH-Ar'-R) were determined. These compounds were shown to have several kinds of characteristic fragment ions ; [Ar (OH)-CH=N]+ (gion), [N=CH-Ar'-R]+ (g'ion), [Ar (OH)-CH=N+H]+·, [Ar (OH)-CH=N-H]+·, [N=CH-Ar'-R+H]+·, [N=CH-Ar'-R+2H]+ and [M-OH]+ (b ion). The relative ion intensities of g, g'and b ions were found to be strongly dependent on the substituent constant. And all of the values of log [g+] / [dM+·], log [g'+] / [dM+·], and log [b+] / [dM+] were shown to correlate linearly with σ+. The substituent effect on the value of either log [g'+] / [g+] or log [b+] / [g+] was found to be the reflection of the substituent effect on the difference of ionization potentials of either g· and g'· radicals or g· and b· radicals, respectively.
