The absorption spectra of water, methanolic, ethanolic and
propanolic solutions of jatrorubine in the VIS and UV spectral
range were recorded. The acidity and the alkalinity of the solutions
were changed in the wide range from pH = 2 to pH = 13 by
the addition of KOH and HCl in the solutions. From the influence
of pH on the shapes of the absorption curves, it was concluded
that jatrorubine exists as quaternary aminic cation in the acidic
medium and as the resonance dipole molecula in the basic media,
but no evidence for the existence of carbinolic form was found.
The results were compared with the literature data
