Protolytic Equilibrium Constants of Nicotinic Acid Solutions in Water–Dimethylsulfoxide Mixtures

2020 ◽  
Vol 94 (10) ◽  
pp. 2030-2033
Author(s):  
N. N. Kuranova ◽  
N. A. Chesnokova ◽  
A. S. Gushchina ◽  
K. V. Grazhdan ◽  
V. A. Sharnin
Keyword(s):  
Nicotinic Acid ◽  
Equilibrium Constants ◽  
Acid Solutions ◽  
Protolytic Equilibrium

Infrared Study of Acetic Acid Solutions in CCl4

1995 ◽  
Vol 60 (7) ◽  
pp. 1094-1100 ◽  
Author(s):  
Ivona Malijevská ◽  
Martin Polášek
Keyword(s):  
Acetic Acid ◽  
Regression Analysis ◽  
Carbon Tetrachloride ◽  
Room Temperature ◽  
Equilibrium Constants ◽  
Acid Solutions ◽  
Standard State ◽  
Infrared Study ◽  
Mean Values ◽  
Linear Dimer

Spectra of acetic acid solutions in carbon tetrachloride were taken at room temperature over the concentration range 0.025-0.00125 mol dm-3. Solutions of acetic acid were modelled as an ideal mixture of monomers, and cyclic and linear dimers. Regression analysis effected separation of the experimental envelope into its component bands. Band shapes were approximated by a Lorenzian function with the resolved band peak frequencies 1 712 cm-1 for the cyclic dimer, 1 724 cm-1 for the linear dimer and 1 765 cm-1 for the acetic acid monomer. Mean values of equilibrium constants for the standard state of unit concentration are 2 700 for the cyclic and 393 for the linear dimer, respectively.

Tautomeric equilibria and pKa values for 'sulfurous acid' in aqueous solution: a thermodynamic analysis

1979 ◽  
Vol 57 (4) ◽  
pp. 454-457 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Aqueous Solutions ◽  
Equilibrium Constants ◽  
Acid Solutions ◽  
Sulfurous Acid ◽  
Free Energy Of Formation ◽  
Dilute Aqueous Solutions ◽  
Sulfite Ion ◽  
Energy Of Formation

The free energy of formation of dimethyl sulfite in aqueous solution can be calculated as −91.45 ± 0.79 kcal/mol; this calculation required measurement of the solubility of dimethyl sulfite. From this value and the pKa of SO(OH)2, using previously reported methods, the free energy of formation of SO(OH)2 can be calculated to be −129.26 ± 0.89 kcal/mol. Comparison of this value with the value obtained from the free energy of formation of 'sulfurous acid' solutions, calculated from the free energy of formation of sulfite ion and the apparent pKa, values, permits evaluation of the free energy of covalent hydration of SO2 as 1.6 + 1.0 kcal/mol, in agreement with earlier qualitative spectroscopic observations. From the apparent pKa and the anticipated pKa values for the tautomers (SO(OH)2, pK1 = 2.3; HSO2(OH), pK1 = −2.6) it is possible to calculate the free energy change for tautomerization of SO(OH)2 to H—SO2(OH) as +4.5 ± 1.2 kcal/mol. All equilibrium constants required for Scheme 1, describing the species present in dilute aqueous solutions of SO2, have been calculated. In agreement with previous Raman studies the major tautomer of 'bisulfite ion' is calculated to be H—SO3−.

scholarly journals ASSESSMENT OF BIOLOGY ACTIVITY OF THE PEELING SUBSTANCES BY THE PHYSICOCHEMICAL APPROACHES ON THE SPIROSTOMUM AMBIGUUM CELL MODEL

2021 ◽  
pp. 82-86
Author(s):  
USPENSKAYA E. V. ◽  
PLETENEVA T. V. ◽  
PHAM MY HANH ◽  
KAZIMOVA I. V.
Keyword(s):  
Activation Energy ◽  
Cell Death ◽  
Cell Model ◽  
Equilibrium Constants ◽  
Animal Experiments ◽  
Acid Solutions ◽  
Arrhenius Kinetics ◽  
Functional Changes ◽  
Dead State ◽  
Spirostomum Ambiguum

Objective: To evaluate the biological activity of chemical peeling substances based on enzymatic and Arrhenius kinetics using Spirostomum ambiguum as an alternative approach to animal experiments. Methods: The Spirotox method was used to analyze the mechanism of «xenobiotic-cell» interaction, similar to the Michaelis-Menten enzymatic kinetics. The Hill-Langmuir equation was used to determine the degree of cooperativity in the binding of xenobiotics to cellular receptors. Using the Arrhenius kinetics, the observed activation energy obsEa of cell death in the model solutions of glycolic and carbolic acids was determed, which will allow predicting the toxicity parameters of any peeling substances. Results: The relationship Spirostomum ambiguum lifetime tL-lgC concentration of peeling compound solution made it possible to characterize the moment of cellular transition from the intermediate state C•Ln to the dead state DC, characterized by irreversible structural and functional changes in the cell/death. The values were 5.3 mmol•l-1 for glycolic acid solutions and 2.8 mmol•l-1 for carbolic acid solutions. Equilibrium constants Keq of complexation, the rate of infusoria death fm, and the degree of ligand cooperativity n were calculated. The activation energy °bsEa of cell death was determined in Arrhenius coordinates, which were 210±0.39 kJ·mol-1 and 108±0.09 kJ·mol-1 for glycolic and carbolic acids respectively. The correlation between the values ​​of activation energy and DL50 of mammals (rats) was discovered. Conclusion: The obtained kinetic parameters made it possible, without animals and humans testing, to characterize the mechanisms of interaction of peeling substances with the living cell.

EQUILIBRIUM CONSTANTS OF ZINC(II) AND COPPER(II) WITH HEMATOPORPHYRIN IX

1966 ◽  
Vol 44 (18) ◽  
pp. 2157-2164 ◽  
Author(s):  
D. A. Brisbin ◽  
R. J. Balahura
Keyword(s):  
Acetic Acid ◽  
Glacial Acetic Acid ◽  
Equilibrium Constants ◽  
Acid Solutions ◽  
Displacement Reactions ◽  
Hematoporphyrin Ix

Equilibrium constants have been measured for the following displacement reactions between copper(II) and zinc(II) with hematoporphyrin IX.[Formula: see text]Preliminary measurements have also been made for the reactions of Mn(II) and Co(II) with hematoporphyrin IX in glacial acetic acid solutions.

Thermodynamics of protolytic equilibrium of nicotinic acid in water-ethanol solutions

2010 ◽  
Vol 84 (5) ◽  
pp. 792-795 ◽  
Author(s):  
N. N. Kuranova ◽  
S. V. Dushina ◽  
V. A. Sharnin
Keyword(s):  
Nicotinic Acid ◽  
Protolytic Equilibrium
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