Protonation Equilibria of L-Dopa and 1,10 Phenonthroline in Propylene Glycol-Water Mixtures

Raju, B. Rama; Devi, K.V. Santhee; Padmaja, Nimmagadda; Rao, G. Nageswara

doi:10.4067/s0717-97072011000400004

Cited by 4 publications

(4 citation statements)

References 29 publications

(38 reference statements)

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“…The approximate protonation constants of 5-Sulphosalicylic acid and 5-Hydroxysalicylic acid were calculated with the computer program SCPHD [14][15][16] . The best fit chemical model for each system investigated was arrived at using non-linear least-squares computer program, MINIQUAD75 17 , which exploit the advantage of constrained least-squares method in the initial refinement and reliable convergence of Marquardt algorithm.…”

Section: Modeling Strategymentioning

confidence: 99%

Effect of Cationic Micelles of Cetyltrimethylammonium Bromide on Protonation Equilibria of Salicylic Acid Derivatives

Ramanaiah

Sri

Balakrishna

et al. 2017

J. Chil. Chem. Soc.

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To gain more information about the effect of surfactant on salicylic acid derivatives, the stoichiometric protonation constants of 5-Sulphosalicylic acid and 5-Hydroxysalicylic acid in 0.0%-2.5% (w/v) cetyltrimethylammonium bromide (CTAB) -water mixtures were determined at an ionic strength of 0.16 mol dm -3 and at 303 K. A potentiometric method was used and the calculation of constants was carried out using the computer program MINIQUAD75. These protonation constants values have been found to shift in micellar media as compared to those in pure water. The differences in the values have been attributed to the solvent properties of the interfacial and bulk phases involving contribution from the micellar surface potential in the case of charged micelles. The trend of log values of step-wise protonation constants with mole fraction of the medium have been explained based on specific solute-solvent interactions. In this study Distributions of species, percentage of species composition, protonation equilibria and effect of influential parameters on the protonation were also discussed.

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Section: Modeling Strategymentioning

confidence: 99%

Effect of Cationic Micelles of Cetyltrimethylammonium Bromide on Protonation Equilibria of Salicylic Acid Derivatives

Ramanaiah

Sri

Balakrishna

et al. 2017

J. Chil. Chem. Soc.

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“…Titrations with different ratios 1:7.5, 1:8.5 and 1:10.0 in the case of Cd(II) and Pb(II) of metal-to-ligand were carried out with 0.4 mol L −1 sodium hydroxide. Other experimental details are as reported previously [24].…”

Section: Analytical Proceduresmentioning

confidence: 99%

Speciation of binary complexes of Pb(II) and Cd(II) with L-asparagine in dimethyl sulfoxide - water mixtures

Rao¹,

Ramanaiah²,

Sailaja³

2016

Bull. Chem. Soc. Eth.

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Chemical speciation of L-Asparagine complexes of Pb(II) and Cd(II) in presence of (0-50% v/v) dimethyl sulfoxide(DMSO)-water mixtures has been studied potentiometrically at 303.0 K and at an ionic strength of 0.16 mol L-1. The models containing different number of species were refined by using the computer program MINIQUAD75. The number of species in the models is chosen based on exhaustive modeling. The predominant species formed are of the type ML2, ML2H, and ML2H2. The best fit chemical models were chosen based on statistical parameters. The convenience of the models is ascertained by studying the effect of errors in concentrations of ingredients. The trend in variation of stability constants with change in the composition of medium is explained on the basis of predominant electrostatic and non-electrostatic forces. Chemical speciation was discussed based on the distribution diagrams.

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“…Titrations with different ratios (1:2.5, 1:3.75 and 1:5.0 in the case of Pb(II) and Cd(II) and 1:7.5, 1:8.5 and 1:10.0 in the case of Hg(II)) of metal-to-ligand were carried out with 0.4 M sodium hydroxide. Other experimental details are as reported previously [14,15].…”

Section: Analytical Proceduresmentioning

confidence: 99%

Stability of binary complexes of Pb(II), Cd(II) and Hg(II) with maleic acid in TX100-water mixtures

Ramanaiah¹,

Sri²,

Sailaja³

2014

Bull. Chem. Soc. Eth.

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ABSTRACT. Binary complexes of maleic acid with toxic metal ions such as Pb(II), Cd(II) and Hg(II) have been studied in 0.0-2.5% v/v tritonX-100 (TX100) -water media at 303 K at an ionic strength of 0.16 M. The active forms of the ligand are LH2, LH -and L 2-. The derived 'best fit' chemical speciation models are based on crystallographic R-factors, χ 2 and Skewness and Kurtosis factors. The predominant species formed are of the type ML2, ML2H and ML3. The trend in variation of complex stability constants with change in the mole fraction of the medium is explained on the basis of prevailing electrostatic and non-electrostatic forces. The species distribution as a function of pH at different compositions of TX100-water mixtures and plausible speciation equilibria are presented and discussed.

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Protonation Equilibria of L-Dopa and 1,10 Phenonthroline in Propylene Glycol-Water Mixtures

Cited by 4 publications

References 29 publications

Effect of Cationic Micelles of Cetyltrimethylammonium Bromide on Protonation Equilibria of Salicylic Acid Derivatives

Effect of Cationic Micelles of Cetyltrimethylammonium Bromide on Protonation Equilibria of Salicylic Acid Derivatives

Speciation of binary complexes of Pb(II) and Cd(II) with L-asparagine in dimethyl sulfoxide - water mixtures

Stability of binary complexes of Pb(II), Cd(II) and Hg(II) with maleic acid in TX100-water mixtures

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