On the preparation and spectral properties of some hydroxy-substituted triphenylmethane dyes

Abstract Although the first hydroxy substituted triphenlymethane dyes were prepared at the beginning of the 19th century, they found, other than their amino-substituted derivatives, surprisingly less scientific and practical interest hitherto. Only triphenylmehane dyes derived from salicylic acid and some of its derivatives received practical importance as Mordant Dyes. To close this gap, we have prepared and characterized few hydroxy-substituted triphenlymethane dyes by starting from appropriate phenols and using different synthetic routes. The structure of the hydroxy-substituted triphenlymethane dyes prepared are confirmed by means of mass spectra and 1 H NMR spectra. Their colors vary with the acidity of the solutions and is originated by a stepwise protonation of the oxygen moieties at their triphenylmethane cores.