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1998 (1)
1997 (1)
1Author    A. Kondoh, T. OiRequires cookie*
 Title    Interaction of Alkaline Earth Metal Ions with Acetic and Lactic Acid in Aqueous Solutions Studied by 13 C NMR Spectroscopy  
 Abstract    Interaction of alkaline earth metal (magnesium, calcium, strontium and barium) ions with acetic and lactic acid in aqueous media was investigated by 13 C NMR spectroscopy. In the acetate systems, signals whose chemical shifts were the averages of those of the free and bound acetate ions were observed. Downfield shifts of the carboxylate carbon signals with increasing metal ion concentration indicated that the acetate ion acted as a monodentate ligand coordinating to the metal ion using the carboxylate group. The metal ion concentration dependence of the peak positions of the methine and carboxylate carbon signals of the lactate ion in the lactate systems suggested that the lactate ion coordinated to a metal ion using the carboxylate and hydroxyl groups. Unique upfield shifts upon complexation in the magnesium lactate systems suggested that the lactate ion coordinated to the magnesium ion from outside the primary hydration sphere. The present results were consistent with the isotope effects of the alkaline earth metals observed in cation exchange chromatography. 
  Reference    Z. Naturforsch. 52a, 351—357 (1997); received December 4 1996 
  Published    1997 
  Keywords    13 C NMR, Alkaline Earth Metals, Acetic Acid, Lactic Acid, Isotope Effects 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0351.pdf 
 Identifier    ZNA-1997-52a-0351 
 Volume    52 
2Author    Akiko Kondoh, Takao OiRequires cookie*
 Title    Interaction of Alkaline Earth Metal Ions with Carboxylic Acids in Aqueous Solutions studied by 13 C NMR Spectroscopy  
 Abstract    1? C NMR spectroscopic measurements of aqueous solutions containing alkaline earth metal chloride and a carboxylic acid have been carried out to acquire some insight into the coordination manners of various carboxylic acids to alkaline earth metal ions. The dependence of the l 3 C NMR signal positions of the carboxylate carbons on the magnesium ion concentration in a magnesium carboxylate system is a good index to understand the coordination manner of the carboxylate ion. The upfield shift of the car-boxylate carbon signal with increasing magnesium ion concentration indicates that the carboxylate ion acts as a bidentate ligand to form a ring structure. Only in the citrate systems, the existence of a rela-tively stable complex is evidenced in which the citrate ion is expected to act as a tridentate ligand. 
  Reference    Z. Naturforsch. 53a, 77—91 (1998); received December 30 1997 
  Published    1998 
  Keywords    13 C NMR Spectroscopy, Carboxylic Acids, Alkaline Earth Metals, Coordination, Chemical Shifts 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0077.pdf 
 Identifier    ZNA-1998-53a-0077 
 Volume    53