Solubility of Gallic Acid, Vanillin, Syringic Acid, and Protocatechuic Acid in Aqueous Sulfate Solutions from (293.15 to 318.15) K

Abstract

International audienc

Solubility and solution thermodynamic properties of quercetin and quercetin dihydrate in subcritical water

“…The positive sign on the molar Gibbs free energy of solution for both phenolic compounds indicates that the dissolution process is endergonic and non-spontaneous (Queimada et al, 2009;Noubigh et al, 2008). A plot of the molar enthalpy of solution of anhydrous and dihydrate quercetin versus temperature, Fig.…”

“…Independent studies have indicated a 10% loss in weight of quercetin when heated to temperatures as high as 103-342°C (Noubigh et al, 2008). This loss in mass at temperatures greater than 100°C is mainly attributed to the loss of water molecules in quercetin (Vyaznikova et al, 1997).…”

Solubility of gallic acid in liquid mixtures of (ethanol+water) from (293.15 to 318.15)K

“…The solubility of gallic acid was measured in pure water, ethanol and (water + ethanol) mixtures, at different temperatures ranging from (293.15 to 318.15) K. This complementary study permits us to extend our solubility data basis of gallic acid [14][15][16][17].…”

“…However, in our knowledge no experimental or theoretical study concerning the solubility of gallic acid in binary solvents has been reported in the literature. As a continuation of our earlier studies concerning the phenolic compounds solubility [14][15][16][17], we report here on the effects of binary solvents composition and temperature on the solubility of gallic acid. The solubilities of gallic acid in (water + ethanol) mixed solvents with ethanol mole fractions of 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0, on a solute-free basis were determined at T = (293.…”

Solvent and temperature effects on the solubility of syringic, vanillic or veratric acids: Experimental, modeling and solid phase studies

“…In this work, the solubility of the selected acids was measured in water and organic solvents (methanol, ethanol, 1-propanol, 2-propanol, 2-butanone, ethyl acetate, acetonitrile, dimethylformamide -DMF, 1,2propanediol, 1,3-propanediol and 1,3-butanediol) at 298.2 K and 313.2 K. For many of the studied binary systems, no solubility data have been reported yet, but whenever possible, the new solubility data were critically compared to the data available in literature. Besides a few studies concerning veratric [16,17], vanillic [18][19][20][21], and syringic acids [22][23][24] solubility, other works focused on aromatic acids with similar structures, such as o-anisic acid (2-methoxybenzoic acid) [25], p-anisic acid (4-methoxybenzoic acid) [25], 2,4-dimethoxybenzoic acid [26], 3,5-dimethoxybenzoic acid [27] and 3,4,5-trimethoxybenzoic acid [28]. In order to obtain a more complete picture of the solid-liquid equilibrium (SLE), the melting properties of the solutes were measured by Differential Scanning Calorimetry (DSC) as well as solid phase studies were carried out by X-Ray Diffraction (XRD).…”