Synthesis and 13C NMR Spectra of N-Substituted para-Quinone Imines: II. N-Arylthio- and N-Arylsulfonyl-1,4-benzoquinone Imines with Enhanced Electron-withdrawing Character of the Quinoid Ring

Introduction of chlorine substituents into quinone imine fragment results in virtually the same variations in the chemical shifts of the quinoid ring carbons both in N-arylthio and N-arylsulfonyl-1,4-benzoquinone imines as compared to the unsubstituted analogs. In both classes of chloro-substituted compounds the effect of substituents in the benzene ring on the character and the range of chemical shifts variations for the carbon signals from the quinoid ring also turned out to be identical. Any differences observed may be due to the change in the geometry of the molecules, in particular, to the increase in the bond angle C = N-S.