O. N. Krutova

Thermodynamic characteristics of stepwise dissociation of glycyl-glycyl-glycine in aqueous solutions

The heats of interaction between glycyl-glycyl-glycine and solutions of nitric acid and potassium hydroxide are determined by calorimetry at 298.15 K and ionic strengths of 0.25, 0.50, and 0.75 in the presence of KNO3. The standard thermodynamic characteristics (ΔrH°, ΔrG°, and ΔrS°) of acid–base interaction in aqueous solutions of the peptide are calculated. The effect of background electrolyte concentration on the enthalpy of dissociation of glycyl-glycyl-glycine is discussed.

Thermochemical study of the reactions of acid–base interaction in an aqueous solution of α-aminobutyric acid

The heat effects of the interaction between a solution of α-aminobutyric acid and solutions of HNO3 and KОН are measured by means of calorimetry in different ranges of рН at 298.15 K and values of ionic strength of 0.25, 0.5, and 0.75 (KNO3). The heat effects of the stepwise dissociation of the amino acid are determined. Standard thermodynamic characteristics (ΔrH0, ΔrG0, and ΔrS0) of the reactions of acid–base interaction in aqueous solutions of α-aminobutyric acid are calculated. The connection between the thermodynamic characteristics of the dissociation of the amino acid and the structure of this compound is considered.

Thermodynamics of the dissolution of crystalline L-methionine in water

The enthalpies of dissolution of crystalline L-methionine in water and aqueous solutions of potasium hydroxide at 298.15 K are measured by means of direct calorimetry. The standard enthalpies of formation are calculated for L-methionine and products of its dissociation in aqueous solution.

Thermodynamic characteristics of acid-base equilibria of DL-α-alanyl-DL-norleucine in aqueous solutions at 298 K

Protolytic equilibria in aqueous solutions of DL-α-alanyl-DL-norleucine are studied via potentiometry and calorimetry. Measurements are made at 298.15 K and ionic strengths of 0.5, 1.0, and 1.5 (against a background of potassium nitrate). The thermodynamic characteristics (pK, ΔG, ΔH, ΔS) of the stepwise dissociation of the dipeptide both in aqueous-salt solutions and in standard solution are obtained for the first time.

Standard enthalpy of formation of L-glutamine and the products of its dissociation in aqueous solutions

Heat effects of the dissolution of crystalline L-glutamine in water and lithium hydroxide solutions were determined by direct calorimetry at 298.15 K. Standard enthalpies of formation of L-glutamine and the products of its dissociation in aqueous solution were calculated.

Enthalpies of Dissolution of Crystalline Naproxen Sodium in Water and Potassium Hydroxide Aqueous Solutions at 298 K

The enthalpies of dissolution of crystalline naproxen sodium in water and aqueous solutions of KOH at 298.15 K are measured by direct calorimetric means in a wide range of concentrations. The acid–base properties of naproxen sodium at ionic strength I ~ 0 and I = 0.1 (KNO3) and a temperature of 298.15 K are studied by spectrophotometric means. The concentration and thermodynamic dissociation constants are determined. The standard enthalpies of the formation of naproxen sodium and the products of its dissociation in aqueous solution are calculated.

Enthalpies of Dissolution of Diclofenac Sodium in Water and Aqueous Solutions of KOH at 298.15 K

Enthalpies of dissolution of crystalline diclofenac sodium are measured in water and in aqueous solutions of KOH at 298.15 K via direct calorimetry in a wide range of concentrations. The acid–base properties of diclofenac sodium are studied via spectrophotometry at ionic strengths of I ~ 0 and I = 0.1 (KNO3) and a temperature of 298.15 K. The concentration and thermodynamic dissociation constants are determined. The standard enthalpies of formation are calculated for diclofenac sodium, and for the products of its dissociation in an aqueous solution.

Standard Enthalpies of Formation of N-Methylglycine and Products of Its Dissociation in Aqueous Solutions

Enthalpies of dissolution of crystalline N-methylglycine in water and in aqueous potassium hydroxide solutions are determined at 298.15 K via direct calorimetry. Standard enthalpies of formation of the amino acid and products of its dissociation in aqueous solution are calculated.

Thermodynamics of Dissolution for Crystalline Racemic Tartaric and Glutaric Acids and Isatin in KOH Aqueous Solutions at 298.15 K

Enthalpies of dissolution are found for crystalline racemic tartaric and glutaric acids and isatin in water and in potassium hydroxide solutions at 298.15 K via direct calorimetry. The protolytic equilibria in isatin aqueous solutions are studied at 298.15 K and ionic strengths of 0.5 (relative to potassium nitrate) by potentiometric means. Standard enthalpies of formation are calculated for racemic tartaric and glutaric acids, isatin, and the products of their dissociation in aqueous solutions.

Standard Enthalpies of Formation of L-Ornithine and Products of Its Dissociation in Aqueous Solutions

The enthalpies of solution of crystalline L-ornithine in water and potassium hydroxide solutions are determined at 298.15 K by direct calorimetry. The standard enthalpies of formation of L-ornithine and products of its dissociation in aqueous solution are calculated.