• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.343-349
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• 1989

The dissociation constants of ${\beta}$-alanine and ${\gamma}$-aminobutyric acid were measured in the temperature range from 20 to $40^{\circ}C$ and pressure up to 2,500 bar by conductometric method. The both dissociation constants of respective amino acid increase with temperature increase but pressure effect is not same as the temperature. The $K_1$ increases as pressure increases but $K_2$ decreases. The properties of these amino acids were discussed in terms of the thermodynamic properties of the dissociation reaction. A relationship between the dissociation constants and the distance between substituted groups of amino acid was discussed. The substituted effects of the reaction were deduced from Hammett reaction and substituted constants which were calculated from the measured dissociation constants.

• YAKHAK HOEJI
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• v.9 no.1_2
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• pp.4-7
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• 1965

Acid dissociation constants of sulfamethoxypyridazine, sulfadimethoxine, sulfamerazine, sulfathiazole and sulfadiazine, and stability constants for formation of copper chelate were calculated from their titration curves in 80% dimethylformamide with ionic strength 0.1 at $25{\deg}$ It was found that the acid dissociation constants (pKa) of sulfa-drugs were in the range of 9.33 - 10.05, and the stability constants (log $k_{1}$, $k_{2})$ of their copper chelates were in the range of 9.33-9.71.

• Archives of Pharmacal Research
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• v.16 no.3
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• pp.180-185
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• 1993

The acid dissociation constants of certain Schiff bases derived from isatin with p-substituted benzoyl hydrazines and somee amino acids of glycine, $\beta$-and $\alpha$-alanine, valine, $\beta$-phenyl-$\alpha$-alanine and anthranilic acid have been detemined potentiometrically at different temperatures in different aquo-organic solvent mixtures (ethnol, dioxane, dimethyl formamide, methanol, acetone and tetrahydrofurance). The pKa values were demonstrated on the light of the different electornic and steric effects of the substituents and the sovlent characteristics. In all the mixed media used, ionization of the compounds decreased by increasing the mole fraction of the organic cosolvent. Theemodynamic parameters $(\Delta{H}^\circ,\;\Delta{G}^\circ,\;\Delta{S}^\circ)$ were evaluated. The structural effects of the investigated compounds on these parameters were reported and discussed.

• Journal of the Korean Chemical Society
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• v.12 no.1
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• pp.1-3
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• 1968

New chelating ligands, thiocatechol and p-chlorothiocatechol, have been synthesized and the acid dissociation constants were determined by potentiometric method in 50% dioxane-water; $pK_1 \;and\; pK_2$ were 7.28, 10.97 for thiocatechol and 6.37, 10.22 for p-chlorothiocatechol, respectively. Color reactions with various metal ions were studied. It was found that the above ligands are specific for Bi(III), Mo(VI) and W(VI) as an analytical reagent.

• Journal of the Korean Chemical Society
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• v.12 no.4
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• pp.150-154
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• 1968

2,3,4-Pentanetrionetrioxime was synthesized from 2,4-pentanedione(or acetylacetone) and its acid dissociation constants were determined in 50%(v/v) dioxane-water solvent mixture at $20{\pm}0.1^{\circ}C$. The color reactions of the ligand with divalent metal ions, Fe(II), Ni(II), Co(II), Cu(II), and Mn(II) were studied.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.3013-3016
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• 2010

• Journal of Environmental Science International
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• v.20 no.6
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• pp.687-700
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• 2011

A new $N_3-O_2$ pentadentate ligand, H-BHPT, was synthesized. Hydrochloric acid salts of Br-BHPT, Cl-BHPT, $CH_3O$-BHPT and $CH_3$-BHPT, having Br-, Cl-, $CH_{3-}$ and $CH_3O-$ substituents at the para position of the phenol hydroxyl group of H-BHPT were synthesized. Hydrochloric acid salts of 3OH-BHPT and 4OH-BHPT, having different position of the phenol hydroxyl group of H-BHPT were also synthesized. The synthesis of each ligand was confirmed by C. H. N. atomic analysis and $^1H$ NMR, $^{13}C$ NMR, UV-visible, and mass spectra. The calculated proton dissociation constants ($log{K_n}^H$) of the phenol hydroxyl group and secondary amine group of the synthesized $N_3-O_2$ ligands showed five steps of the proton dissociations. The order of the overall proton dissociation constants ($log{\beta}_p$) of the ligands was Br-BHPT < Cl-BHPT < H-BHPT < $CH_3O$-BHPT < $CH_3$-BHPT. The order agreed with that of Hammett substituent constants (${\delta}_p$). However, dissociation steps of 3OH-BHPT were four and that of 4OH-BHPT was three. The calculated stability constants ($logK_{ML}$) between the ligands and transition metal ions agreed with the order of $log{\beta}_p$ values of the ligands. The order of the stability constants between the transition metal ions with the synthesized ligands was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II). The order agreed well with that of the Iriving-Williams.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.400-405
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• 1987

The two dissociation constants of three amino acid, glycine, alanine, and tryptophan were measured by the conductometric method in the temperature from 15 to 35$^{\circ}$C and pressure up to 2,500bar in aqueous solution. The both dissociation constants were increased as the temperature increased but the pressure effect were not same as the temperature effect. The first constants were increased as the pressure increased but second constants were decreased except tryptophan. The characteristic properties of these amino acids were discussed from the thermodynamic properties of the dissociation reaction. The substituted effects of the reaction were deduced from Hammett reaction and substituted constants which were calculated from the dissociation constants.

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.67-74
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• 1981

The dissociation constants of benzoic acid, p-methoxybenzoic acid and p-nitrobenzoic acid have been determined at $25^{\circ}C$ in ethanol-water mixtures containing 0, 10, 20, 30, 40, 50, 65 and 80 weight % ethanol by the direct conductance measurements and the method involving titration of the acid sample with perchloric acid reagent. The results by the two methods have been discussed and compared with those by other methods.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.145-151
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• 1986

Using a new conductometric method, dissociation constants of 3-cyano, 4-cyano, 3-amino and 4-aminopyridine were measured in the temperature range 15 ∼ 40${\circ}C$ and pressure up to 2500bar in aqueous media. This method is convenient to apply to the low dissociative acid and base but have to do tedious extrapolating procedure for the ionic conductance in elaborated temperatures and pressures and have to know any reference dissociation constant. The measured dissociation constants were increased as the temperature increase but decreased as the pressure increase. From the constants, various thermodynamic properties were evaluated and discussed for the dissociation reactions.