Extraction-photometric determination of trace amounts of vanadium with N-hydroxy-N-p-tolyl-N'-phenyl-benzamidine

N-hydroxy-N-p-tolyl-N'-phenylbenzamidine has been employed as a spectrophotometric reagent for vanadium(V) in presence of several metals. The influence of methyl and the resonance favouring methoxy substituents was studied, to determine their effect on complex formation. It was observed that a p-tolyl group at the hydroxylic nitrogen displayed both bathochromic and hyperchromic effects on vanadium complex whereas when present on azomethinenitrogen produced only bathochromic shift. The shift of absorption band to longer wavelengths is most pronounced when a p-anisyl group forms part of the conjugated system. (author)