Solvent effect on ion-pair extraction of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion using alcohols and 1-octanol/octane mixed solvents

Extraction of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated h ydroxonium ion was carried out using 14 kinds of alcohols and 1-octanol/oct ane mixed solvents as a solvent at 25 degreesC. Alcohols are 1-pentanol, 1- hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-heptanol, 1-octanol, 2-octan ol, 3-octanol, 1-nonanol, 2-nonanol, 3-nonanol, 5-nonanol and 1-decanol. Am ong them, 1-octanol was found to be extremely high in extractability for 2- (2-pyridylazo)-1-naphthol-4-sulfonate anion with hydroxonium cation. The ex traction equilibrium for the systems using 1-octanol/octane mixed solvents was analyzed in detail in order to examine the extraction mechanism for the se extraction systems. 2-(2-Pyridylazo)-1-naphthol-4-sulfonate anion was fo und to be extracted with the hydroxonium ion solvated by three 1-octanol mo lecules as an ion-pair. The extraction and partition constants of the ion-p air of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxon ium ion were estimated in the 1-octanol/octane mixed solvent systems.