Fundamental Studies on the Collection of Sulphide Minerals with Xanthic Acids. I : On the Dissociation and Decomposition of Xanthic Aicds

DOI 機関リポジトリ 機関リポジトリ (HANDLE)

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公開日
1961
資源種別
departmental bulletin paper
DOI
  • 10.50974/00042121
公開者
Tohoku University

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説明

The dissociation constants of xanthic acids and the rates of decomposition of xanthic ions in acidified aqueous solutions were determined by spectrophotometric measurements. It was found that xanthic ion and xanthic acid are virtually in equilibrium, and that the dissociation constants of methyl-, ethyl, propyl-, butyl-, amyl-, iso-propyl-, and iso-butylxanthic acids are respectively 3.4×10^<-2>, 2.9×10^<-2>, 2.5×10^<-2>, 2.3×10^<-2>, 1.9×10^<-2>, 2.0×10^<-2> and 1.4×10^<-2> at 25℃ and the ionic strength of 0. The instability of xanthic ion in acidic range is due to the bimoleucular decomposition of xanthic ion and hydrogen ion. The rate constants of decomposition of methyl-, ethyl-, propyl-, amyl-, isopropyl-, and iso-butylxanthic ions are respectively 233, 226, 214, 209, 211. 207, and 202 mole^<-1>min^<-1> at 25℃ and the ionic strength of 0. The dissociation constants of these xanthic acids and the rate constants of these xanthic ions decreased the increase in carbon numbers of these alkyl groups, and iso-isomer has smaller values of these constants than those of normal ones. Furthermore, it was shown that the peak of absorption spectrum of xanthic ion is at 301 mμ and that of xanthic acid at 270 mμ.

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