SPECTROPHOTOMETRIC DETERMINATION OF ACIDITY CONSTANTS OF SOME ANTHRAQUINONE DERIVATIVES IN BINARY METHANOL-WATER MIXTURES

A spectrophotometric method was used to determine the acidity constants of some synthetic derivatives of 1-hydroxy-9,10-anthraquinone in binary methanol-water mixtures at 25 degrees C. A linear inverse relationship is observed between pK(a) of all acids and the mole fraction of methanol in the solvent mixtures. The influence of the nature and position of substituents in the molecular structure of anthraquinone on the ionization constants is discussed. (C) 1995 Academic Press, Inc.