The absorption spectra of acid-base indicators in the mixed solvents

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  • KATOH Koichi
    Institute for Solid State Physics, The University of Tokyo

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Other Title
  • 混合溶媒中の酸-塩基指示薬の吸収スペクトル
  • コンゴウ ヨウバイ チュウ ノ サン-エンキ シジヤク ノ キュウシュウ スペクトル
  • The behaviour of acid-base indicators in mixed solvents. III
  • 混合溶媒中の酸-塩基指示薬の動向(第3報)

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Description

The absorption spectra of sulfophthaleins in mixed solvents were relatively independent of the organic solvent, but azoes showed larger dependence. In this experiment, alcohols and acetone were used as water-soluble solvents. The influences seemed to have some relation to basicity of the mixed solvents and the type acidic or basic of indicators. In acidic solution, absorption spectra of B.C.G. were independent of the composition of solvent.<BR>On the other hand, on the absorption spectrum of D. Y. in acidic solution, a valley appeared near the peak of the spectrum with increasing concentration of organic solvent. In basic solution, however, absorption at 450 mμ decreased and a shoulder at 410 mμ developed. Other azo indicators such as M.R., p-M.R. behaved similarly. Absorption spectra of D.Y. in 80% methanol, ethanol and iso-propanol indicated that the wavelengths of acidic peaks did not vary with the solvent, while the alkaline peaks shifted to shorter wavelengths as the alcohols became higher. Molecular structures of B.C.G. and D.Y. at their transformation ranges were also described.

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 15 (3), 241-246, 1966

    The Japan Society for Analytical Chemistry

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