Formation Constants of Chromium(III), Scandium(III) and Yttrium(III) Complexes of Some Hydroxy Naphthoic Acids

Abstract

We continue our studies on the complex equilibria between Cr(III), Sc(III), Y(III) and 1-hydroxy-2-naphthoic acid (1,2-HNA: H 2 L) and 3-hydroxy-2-naphthoic acid (3,2-HNA: H 2 L). We have reported the stabilities of the complexes between these metal ions and the title ligands. [1][2][3][4][5][6][7][8][9][10][11] The structural formulas of the studied ligands are shown in Fig. 1. There have been some reports on the Sc(III) and Y(III) complexes of hydroxy naphthoic acids [12][13][14][15] ; but almost nothing is known about the complexes between Cr(III) and these two naphthoic acids. However, the stabilities and stoichiometries of the complexes formed with Cr(III), Sc(III), Y(III) and hydroxy benzoic acids were already determined by us. [4][5][6][7][8][9][10][11] It is well known that the derivatives of naphthoic acids are used as dyes and reagents for spectrophotometric measurements since they form chelates with several metal ions, whereas hydroxy carboxylic acids of the naphthalene series are far less common as ligands for complexometric studies than hydroxy benzoic acids. Some reports on binary complex formation abilities are available in the literature for various metal ions. [12][13][14][15][16][17][18][19][20][21] Currently our main aim is to investigate the binding abilities of 1,2-HNA and 3,2-HNA to Cr(III), Sc(III) and Y(III) and to determine the formation constants of their complexes.On the other hand, the humic substances are derivatives of hydroxy naphthoic and hydroxy benzoic acids and they are found in natural ligands. They can remove environmentally mobile ions like Cu(II), Fe(III) and Al(III) that originate from various industries since humic substances are easily coordinated from oxygen donor sites to these metal ions and form very stable chelates. [22][23][24][25][26][27] Cr(III), with Cr(VI), is one of the main pollutant during waste water treatment in our city, Bursa. 28) So, the removal of Cr(III) from waste water may be possible using 1,2-HNA and 3,2-HNA ligands. Therefore, our second aim is to determine the concentration of uncomplexed Cr(III) by means of the formation constants of its 1,2-HNA and 3,2-HNA complexes as a part of our research project.However, Bhatt et al. 12,13) were interested in the complex formation reactions of Sc(III) with 1,2-HNA and 3,2-HNA but they were mainly ternary complex forming systems. They obtained the stability constants of binary complexes of Sc(III) with 1,2-HNA and 3,2-HNA only at an ionic strength of 0.1 M KNO 3 in 50% (v/v) aqueous-ethanol medium by the average value method. 29,30) Y(III) and lanthanides formed with 2-hydroxy-3-naphthoic acid (2,3-HNA), 2-hydroxy-1-naphthoic acid (2,1-HNA) and 1,2-HNA were also investigated by Bhatt et al. 14) and Deshpande et al. 15) They applied only the Calvin-Bjerrum potentiometric titration technique at 25°C and 0.1 M NaClO 4 ionic strength in 75% dioxane-25% (v/v) water medium. Neither Bhatt et al. [12][13][14] nor Deshpande et al. 15) had taken into consideration the stoichiometries of Sc(III) and Y(III) complexe...

Study of the Interaction between Chromium(III) and Hydroxamic Acids

“…In previous studies, we demonstrated the coordination of Cr(III) to salicylic acid and its derivatives and to hydroxynaphthoic acids, and we also described the stabilities of various complex species of Cr(III). − …”

“…In previous studies, we demonstrated the coordination of Cr(III) to salicylic acid and its derivatives and to hydroxynaphthoic acids, and we also described the stabilities of various complex species of Cr(III). [22][23][24][25][26] The stoichiometric protonation constants of these two ligands and the stoichiometric stability constants of Cr(III)-hydroxamic acid complexes were calculated.…”

Complexes of Chromium(III) with 2,3-Dihydroxynaphthalene-6-sulfonic Acid and 4,5-Dihydroxynaphthalene-2,7-disulfonic Acid in Aqueous Solution

“…We performed our research project 12,[19][20][21] from 1996-1998 to define the total Cr, Cr(III) and Cr(VI) concentrations in the river. The total chromium concentrations measured were 0.970-0.090 mg/l range.…”

Removal of yttrium (III) ions from water solutions by alginate compounds

“…At present, there are no particular materials proposed for effective removal of yttrium ions from water disposals especially when their concentrations are very low. Up to date, there are just a few of published studies devoted to investigation of the properties of materials interacting with yttrium ions such as hydroxy-naphthoic acids (Aksoy et al 2005) and dihydroxybenzoic acids (Aydin and Ozer 2004). Application of these substances for removal of yttrium ions from water disposals is almost impossible due to their low molecular weight and complicated processes of separation from aqueous solutions.…”