Solid-liquid phase equilibrium of trans-cinnamic acid, p-coumaric acid and ferulic acid in water and organic solvents: Experimental and modelling studies

Abstract

The solubility of the trans isomers of cinnamic acid, p-coumaric acid and ferulic acid was measured in water and seven organic solvents (methanol, ethanol, 1-propanol, 2-propanol, 2-butanone, ethyl acetate and acetonitrile), at 298.2 K and 313.2 K, using the analytical shake-flask technique. The melting temperatures and enthalpies of the solutes were studied by differential scanning calorimetry, while solute solid structures were identified by powder and single X-ray diffraction.The NRTL-SAC model was applied to calculate the solubility of trans-cinnamic acid and trans-ferulic acid in pure solvents. For trans-p-coumaric acid, the NRTL-SAC was combined with the Reference Solvent Approach, as the solute melting properties could not be determined. The global average relative deviations (ARD) were 32% and 41%, in the correlation and prediction stages, respectively. The Abraham solvation model was also applied. The global ARD were 20% for correlation and 29% for predictions, which can be considered very satisfactory results for these semi-predictive models.

Production of p-Coumaric Acid from Corn GVL-Lignin

“…For FA, the analogous values were surprisingly similar at 37.5 ± 0.1, 2.7 ± 0.1, 1.1 ± 0.3, and 1.1 ± 0.1 g/L at 100, 50, 22, and 5 °C. Our results are in good agreement with reported data for p CA. , …”

Comparison of two computational methods for solvent screening in countercurrent and centrifugal partition chromatography

“…The NRTL-SAC segment descriptors obtained in this work are considerably different from the values reported in previous works for ferulic acid [47] , hesperetin [37] and quercetin [49] , which were fitted using mostly solubility data in water and in pure organic polar solvents. From our experience [ 36 , 45 , 47 ], the robustness of the model descriptors is associated with the chemical diversity of solvent systems used in the correlation step, and differences in the fitted parameters were expected since partition coefficients in less polar biphasic solvent systems (e.g., heptane/methanol) were included in the data set.…”

“…Briefly, the model proposes four conceptual segment descriptors to describe each molecule: X (hydrophobicity), Y -(polar repulsive), Y + (polar attractive) and Z (hydrophilicity). These parameters have already been reported for all the solvents studied in this work, with the exception of limonene, [ 21 , 4 8 , 4 9 ] and the solutes ferulic acid [47] , quercetin [49] and hesperetin [37] .…”

Modeling the Solubility of Phenolic Acids in Aqueous Media at 37 °C

“…Analogous results were obtained for ferulic and p-coumaric acids, the latter showing the highest value for the H-bond acidity parameter, which is partially reduced in ferulic acid due to the intramolecular hydrogen bond between the hydroxyl group and the methoxy group in the meta position. In contrast, the H-bond basicity character decreases from ferulic acid to p-coumaric acid, according to the increase in the number of hydrogen acceptors in the molecules [47].…”

“…Thus, the presence of hydroxyl groups increases the H-bond acidity, i.e., the strength of the hydrogen bonds formed by the donor hydroxyl groups with water, whereas the H-bond basicity descriptor, related to the strength of the hydrogen bonds formed by the acceptor groups in the molecules with water, increases with the number of methoxy substituents on the ring. On the other hand, when the hydroxy and/or the methoxy groups are absent, the above solute descriptors significantly decrease in value, such as in the case of veratric and cinnamic acids [46,47].…”