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Study of Equilibria in the Aluminium(III)‐Glycine and ‐Alanine Systems
Author(s) -
Djurdjević Predrag T.,
Jelić Ratomir
Publication year - 1989
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.19895750126
Subject(s) - chemistry , hydrolysis , trimer , glycine , stability constants of complexes , amino acid , dimer , medicinal chemistry , monomer , amine gas treating , alanine , aluminium , nuclear chemistry , stereochemistry , ion , organic chemistry , polymer , biochemistry
The formation of various hydrolytic and mixed hydrolytic complexes of the aluminium(III) ion in the presence of glycine and L‐alanine, has been studied in 0.5 mol dm −3 (Na)NO 3 medium at 25deg;C, by emf method. The concentration ratios of amine acids to aluminium(III) were varied from 1 : 1 to 10 : 1. The least‐squares treatment of the data obtained, in the absence of the amino acids, indicates the formation of the dimer, [Al 2 (OH) 2 ] 4+ , and monomer, [AlOH] 2+ , with the stability constants log β 22 = −7.03 ± 0.03 and log β 11 = −5.65 ± 0.09, respectively. At pH values higher then ∼4.0 formation of the trimer [Al 3 (OH) 4 ] 5+ (log β 34 = −12.60 ± 0.08) becomes significant. In the presence of amino acids the evidence has been found for the formation of [Al 2 (OH) 4 ] 2+ (log β 24 = −15.65 ± 0.09). Besides the formation of the pure hydrolytic complexes, equilibria in the title systems can be explained by assuming the main reaction products to have the compositions [Al(OH) 3 Gly] (log β 131 = −7.53 ± 0.04), [Al 2 (OH) 2 (Gly) 2 ] (log β 222 = 6.56 ± 0.09) and [Al(OH) 3 Ala] (log β 131 = −7.70 ± 0.03), [Al 2 (OH) 2 Ala 2 ] (log β 222 = 7.23 ± 0.07).