Under ordinary atmospheric circumstances, the gravimetric technique was used to measure the solubility of L-cysteine (L-Cys) and L-alanine (L-Ala) in various solvents, including methyl alcohol, ethyl acetate, and mixtures of the two, in the range o 283.15 K to 323.15 K. Both individual solvents and their combinations showed a rise in the solubility of L-Cys and L-Ala with increasing temperature, according to the analyzed data but when analyzed at a constant temperature in the selected mixed solvents, the solubility declined with decreasing of initial mole fractions of methyl alcohol. To further assess, the relative utility of the four solubility models, we fitted the solubility data using the Jouyban-Acree (J-A), van’t Hoff-Jouyban-Acree (V-J-A), Apelblat-Jouyban-Acree (A-J-A), and Ma models followed by evaluation of the values of the RAD information criteria and the RMSD were. The dissolution was also found to be an entropy-driven spontaneous mixing process in the solvents since the thermodynamic parameters of the solvents were determined using the van't Hoff model. In order to support the industrial crystallization of L-cysteine and L-alanine and contribute to future theoretical research, we have determined the experimental solubility, correlation equations, and thermodynamic parameters of the selected amino acids during the dissolution process.

L-cysteine, L-alanine, Solubility, Mixed solvents, Thermodynamic modeling, Thermodynamic properties

1. Tseng, H. C., Lee, C. Y., Weng, W. L. and Shiah, I. M., “Solubilities
of Amino Acids in Water at Various pH Values Under 298.15
K,” Fluid Phase Equilib., 285, 90-95(2009).
2. Wang, Y., Lin, K., Jia, W. and Yu, Q., “Measurement, and Correlation of Solubility of L-Valine, L-Isoleucine, L-Methionine, and
L-Threonine in Water + tert-Butanol from 283.15 to 328.15 K,”
J. Chem. Eng. Data, 66, 677-683(2021).
3. Roy, S., Guin, P. S., Mahali, K., Houssain, A. and Dolui B. K.,
“Evaluation and Correlation of Solubility and Solvation Thermodynamics of Glycine, dl-alanine and dl-valine in Aqueous
Sodium Sulphate Solutions at Two Different Temperatures,” J.
Mol. Liq., 234, 124-128(2017).
4. Roy, S., Hossain, A. and Dolui, B. K., “Solubility and Chemical
Thermodynamics of d,l-Alanine and d,l-serine in Aqueous NaCl
and KCl Solutions,” J. Chem. Eng. Data, 61(1), 132-141(2016).
5. Lammens, T. M., Franssen, M. C. R., Scott, E. L. and Sanders, J.
P. M., “Availability of Protein-derived Amino Acids as Feedstock for the Production of Bio-based Chemicals,” Biomass Bioenergy, 44(9), 168-181(2012).
6. Thombre, S. M. and Sarwade, B. D., “Synthesis and Biodegradability of Polyaspartic Acid: A Critical Review,” J. Macromol.
Sci. A, 42(9), 1299-1315(2005).
7. Abualreish, M. J. and Noubigh, A., “Experimental Measurement
and Correlation of two α-Amino Acids Solubility in Aqueous
Salts Solutions from 298.15 to 323.15 K,” Korean Chem. Eng.
Res., 58, 98-105(2020).
8. Abualreish, M. J. and Noubigh, A., “Evaluation of Thermodynamic Properties and Correlation of L-glutamic Acid Solubility
in Some Aqueous Chloride Solutions from 298.15 to 323.15 K,”
Can. J. Chem., 97, 615-620(2019).
9. Romero, C. M. and Oviedo, C. D., “Effect of Temperature on the
Solubility of Alpha-amino Acids and Alpha, Omega - Amino Acids
in Water,” J. Solution Chem., 42(6), 1355-1362(2013).
10. Lu, J., Wang, X. J., Yang, X. and Ching, C. B., “Solubilities of
Glycine and Its Oligopeptides in Aqueous Solutions,” J. Chem.
Eng. Data, 51, 1593-1596(2006).
11. Pradhan, A. A. and Vera, J. H., “Effect of Acids and Bases on
the Solubility of Amino Acids,” Fluid Phase Equilib., 152(1),
121-132(1998).
12. Koseoglu, F., Kilic, E. and Dogan, A., “Studies on the Protonation
Constants and Solvation of Alpha-amino Acids in Dioxan-water
Mixtures,” Anal. Biochem., 277(2), 243-246(2000).
13. Lu, J., Wang, X. J., Yang, X. and Ching, C. B., “Solubilities of
Glycine and Its Oligopeptides in Aqueous Solutions,” J. Chem.
Eng. Data, 51, 1593-1596(2006).
14. Anfinsen, C. B. and Scheraga, H. A., “Experimental and Theoretical Aspects of Protein Folding,” Adv. Protein Chem., 29, 205-
300(1975).
15. Lapamje, S., “In Physico-chemical Aspects of Proteins Denaturation,” New York; Wiely Interscience(1978).
16. Han, J., Liu, H., Hu, S., Qiu, J., Yi, D., An, M., Guo, Y., Huang,
H., He, H. and Wang, P., “Determination and Correlation of the
Solubility of L-cysteine in Several Pure and Binary Solvent Systems,” J. Chem. Eng. Data, 65, 2649-2658(2020).
17. An, M., Qiu, J., Yi, D., Liu, H., Hu, S., Han, J., Huang, H., He,
H., Liu, C., Zhao, Z., Shi, Y. and Wang, P., “Measurement and
Correlation for Solubility of L-Alanine in Pure and Binary Solvents at Temperatures from 283.15 to 323.15 K,” J. Chem. Eng.
Data, 65, 549-560(2020).
18. Noubigh, A. and Akremi, A., “Experimental Measurements, Equilibrium Study and Model Correlation of Methyl Paraben in Ethanol and Methanol Aqueous Solutions from = (293.15 to 323.15)
K,” J. Mol. Liq., 293, 111505(2019).
19. Noubigh, A., “Stearic Acid Solubility in Mixed Solvents of (water
+ ethanol) and (ethanol + ethyl acetate): Experimental Data and
Comparison Among Different Thermodynamic Models,” J. Mol.
Liq., 296, 112101(2019).
20. Noubigh, A. and Abderrabba, M., “Thermodynamic Modeling
of the Solubility and Preferential Solvation of the Natural Product
Vanillic Acid in Some Aqueous Mixtures of Alcohols at Different Temperatures,” J. Chem. Eng. Data, 67, 2675-2686(2022).
21. Noubigh, A., Abualreish, M. J., Mogharbel, R. T., Alanazi, A. F.,
Alanazi, T. S. and Guetat A., “Solubility Measurement of Syringic
Acid, Trans-cinnamic Acid, p-coumaric Acid, and Vanillin Constituent of Deverra DC. Genus in (ethyl acetate + ethyl alcohol)
Mixtures: Thermodynamic Modeling and Preferential Solvation,” 387, 122710(2023).
22. Noubigh, A., Ben Tahar, L. and Eladeb, A.,“Solubility Modeling
and Preferential Solvation of Benzamide in Some Pure and
Binary Solvent Mixtures at Different Temperatures,” J. Chem.
Eng. Data, 68, 1018-1030(2023).
23. Jouyban-Gharamaleki, A., Valaee, L., Barzegar-Jalali, M., Clark,
B. J. and Acree, Jr W. E., “Comparison of Various Cosolvency
Models for Calculating Solute Solubility in Water–cosolvent
Mixtures,” Int. J. Pharm., 177, 93-101(1999).
24. Jouyban, A., “Review of the Cosolvency Models for Predicting
Solubility of Drugs in Water-cosolvent Mixtures,” J. Pharm. Pharm.
Sci., 11, 32(2007).
25. Zhou, C., Shi, X., Wang, H. and An, N., “Measurement and Correlation of Solubilities of Trans-ferulic Acid in Solvents,” J. Chem.
Ind. Eng., 58, 2705-2709(2007).
26. Jouyban, A., Fakhree, M. A. A. and Acree, Jr. W. E., “Comment
on Measurement and Correlation of Solubilities of (z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetic Acid in Different Pure Solvents and Binary Mixtures of Water + (ethanol, methanol, or glycol),”
J. Chem. Eng. Data, 57, 1344-1346(2012).
27. Vahdati, S., Shayanfar, A., Hanaee, J., Martínez, F., Acree, Jr. W.
E. and Jouyban, A., “Solubility of Carvedilol in Ethanol + propylene Glycol Mixtures at Various Temperatures,” Ind. Eng. Chem.
Res., 52, 16630-16636(2013).
28. Apelblat, A. and Manzurola, E., “Solubilities of L-aspartic, DLaspartic, DL-glutamic, p-hydroxybenzoic, o-anisic, p-anisic, and
Itaconic Acids in Water from T=278 K to T=345 K,” J. Chem.
Thermodyn., 29, 1527-1533(1997).
29. Sunsandee, N., Hronec, M., Štolcová, M., Leepipatpiboon, N.
and Pancharoen, U., “Thermodynamics of the Solubility of 4-
acetylbenzoic Acid in Different Solvents from 303.15 to 473.15
K,” J. Mol. Liq., 180, 252-259(2013).
30. Wang, K., Hu, Y., Yang, W., Guo, S. and Shi, Y., “Measurement
and Correlation of the Solubility of 2,3,4,5-tetrabromothiophene
in Different Solvents,” J. Chem. Thermodyn., 55, 50-55(2012).
31. Du, C. B., Xu, R. J., Han, S., Xu, J., Meng, L., Wang, J. and Zhao, H. K., “Solubility Determination and Correlation for 1,8-
dinitronaphthalene in (acetone + methanol), (toluene + methanol)
and (acetonitrile + methanol) Mixed Solvents,” J. Chem. Thermodyn., 94, 24-30(2016).
32. Ma, H., Qu, Y, Zhou, Z., Wang, S. and Li, L., “Solubility of
Thiotriazinone in Binary Solvent Mixtures of Water + methanol
and Water + ethanol from (283 to 330) K,” J. Chem. Eng. Data,
57, 2121-2127(2012).
33. Ruidiaz, M. A., Delgado, D. R., Martínez, F. and Marcus, Y.,
“Solubility and Preferential Solvation of Indomethacin in 1,4-
dioxane + water Solvent Mixtures,” Fluid Phase Equilib., 299,
259-265(2010).
34. Kalam, M. A., Khan, A. A. and Alshamsan, A., “Solubility of a
Poorly Soluble Immunosuppressant in Different Pure Solvents:
Measurement, Correlation, Thermodynamics and Molecular Interactions,” J. Mol. Liq., 249, 53-60(2018).
35. Noubigh, A. and Akrmi, A., “ Temperature Dependent Solubility
of Vanillic Acid in Aqueous Methanol Mixtures: Measurements
and Thermodynamic Modeling,” J. Mol. Liq., 220, 277-282(2016).
36. Delgado, D. R., Holguin, A. R., Almanza, O. A., Martinez, F.
and Marcus, Y., “Solubility and Preferential Solvation of Meloxicam
in Ethanol + water Solvent Mixtures,” Fluid Phase Equilib., 305,
80-85(2011).