Determination of the acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoylmethyl)-2,3-dihydroxy-5-carbomethoxy benzylamine and the stability constants of its metal complexes

1989 ◽  
Vol 7 (2) ◽  
pp. 136-144
Author(s):  
Qing-Yu Yan ◽  
Ning Jiang ◽  
Chang-Sheng Ge ◽  
Yu-Yuan Xie
Keyword(s):  
Metal Complexes ◽  
Stability Constants ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Acid Dissociation Constants ◽  
The Stability

Thio derivatives of β-diketones and their metal chelates. V. Acid dissociation constants of some Monothio-β-diektones and stability constants of anickel(II) and a copper(II) chelate

1966 ◽  
Vol 19 (11) ◽  
pp. 2035 ◽  
Author(s):  
SHH Chaston ◽  
SE Livingstone
Keyword(s):  
Stability Constants ◽  
Mole Fraction ◽  
Dissociation Constants ◽  
Metal Chelates ◽  
Acid Dissociation ◽  
Acid Dissociation Constants ◽  
Water Solutions ◽  
Acetyl Acetone ◽  
The Stability ◽  
Derivatives Of

The acid dissociation constants (PKD) of the monothio derivatives of acetyl-acetone, dibenzoylmethane, and 3,3,3-trifluoro-1-(2- thenoyl)acetone, viz. 4-mercap-topent-3-en-2-one (I), 3-mercapto-1,3- diphenylprop-2-en-1-one (II), and 1,1,1-trifluoro-4-mercapto-4-(2- thienyl)but-3-en-2-one (III), were determined in dioxan/water solutions with varying mole fraction (n2) of dioxan. Over a range of n2 from 0.18 to 0.44 the values of pKD were found to vary linearly with n2 as given by the equations: (I) pKD = 5.7+12.0n2; (II) pKD = 7.0+10.9n2; (III) pKD = 3.55 + 9.2n2. The thio derivatives (I), (II), and (III) have pKD values 2.0-2.7 log units lower than their oxygen analogues. The logarithm of the stability constants (log β2) for the nickel(II) and copper(II) complexes of (II) were found to be 21.7 and 22.2, respectively. For both complexes K2 > K1. Comparison with the stability constants of the dibenzoylmethane complexes shows that for nickel(II) the complex of the monothio-β-diketone is more stable than that of the β-diketone while the converse is true for copper(II).

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