Paper Chromatography of the Pyrogallol Tannins

Abstract

BY one-dimensional paper partition chromatography, some of the phenolic substances allied to the pyrogallol tannins have been separated. When using the well-known solvent phases such as butanol/acetic acid and phenol, previous workers¹ have found that the simpler phenols tend to give long diffuse trails. The preparation of the more complex phenols, such as are found among the pyrogallol tannins, is complicated by their ready oxidation in the presence of bases. Tailing of the spots in neutral and acidic solvents is influenced by the acidity of the mobile phase (cf. organic acids²). Addition of strong organic acid to the eluting solvent causes separation into well-defined spots. Unfortunately, formic acid greatly increases the rate of run of the tannin, the spots coming too close to the solvent front for clear definition. Two new solvents have now been found which separate many mixtures of complex phenols into well-defined spots : (1) phenol/acetic acid/water, prepared by adding 30 ml. glacial acetic acid to approximately 500 ml. liquid phenol and just saturating with water at room temperature ; (2) phenol-trichloracetic acid/water, prepared by adding 35 gm. trichloracetic acid to approximately 500 ml. liquid phenol and just saturating with water at room temperature.