Comment/Reply Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX
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Comment on “Solid-Liquid Phase Equilibrium and Thermodynamic Properties of Olaparib in Selected Organic Solvents and (Tetrahydrofuran + MTBE, Acetonitrile + Isopropyl Alcohol) Binary Solvent Mixtures” William E. Acree, Jr.* Department of Chemistry, 1155 Union Circle Drive #305070, University of North Texas, Denton, Texas 76203, United States ABSTRACT: Several mathematical errors in the published paper by Zhao and co-workers are identified. The errors pertain to the calculated equation coefficients for the polynomial version of the combined nearly ideal binary solvent (CNIBS)/RedichKister and for the Combined Jouyban−Acree−van’t Hoff equation. In the case of the CNIBS/Redlich−Kister equation the authors’ tabulated equation coefficients give 100 times the mole fraction solubility of olaparib, and not the mole fraction solubility as the authors’ equation implies. n a recent paper published in the Journal of Chemical & Engineering Data Zhao and co-workers1 reported the solubility of olaparib in binary tetrahydrofuran + methyl tertbutyl ether (MTBE) and acetonitrile + 2-propanol solvent mixtures in the temperature range of 280.35−319.35 K. Solubilities were measured at six mixture compositions and in both monosolvents for each binary solvent system. The authors correlated their measured mole fraction solubility data, x1, using a polynomial equation:
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ln x1 = B0 + B1x 2 + B2 x 22 + B3x 23 + B4 x 24
ln x1 = 2.493 − 0.107x 2 + 1.566x 22 − 2.323x 23 + 1.222x 24 (3)
calculated mole fraction solubilities of olaparib of x1 = 12.098 in 2-propanol (at x2 = 0.00) and of x1 = 17.305 in acetonitrile (at x2 = 1.00). Mole fraction solubilities cannot exceed unity. The authors’ tabulated experimental fraction solubilities are 100x1 = 12.051 and 100x1 = 17.354 for the solubility of olaparib in 2propanol and acetonitrile at T/K = 319.35, respectively. What I suspect is that the authors have regressed ln 100x1, and not ln x1. If this is the case, then the calculated values are 100x1, and not x1, as eq 1 implies. Second, there are serious problems with the curve-fit equation coefficients that the authors give in Table 9 of their published paper for eq 2 above. The tabulated equation coefficients for the binary tetrahydrofuran + MTBE solvent system are A0 = −5538.61; A1 = 14.93; A2 = 1.83; A3 = −326.29; J0 = 88.70; J1 = −240.50; and J2 = 236.85, which when substituted into eq 2 give
(1)
derived from the combined nearly ideal binary solvent (NIBS)/ Redlich−Kister model, and a second mathematical representation: ⎛ A ⎞ ⎛ A⎞ ln x1 = x 2⎜A 0 + 1 ⎟ + x3⎜A 2 + 3 ⎟ ⎝ ⎝ T⎠ T⎠ 2 ⎡x x ⎤ + ⎢ 2 3 ∑ Ji (x 2 − x3)i ⎥ ⎢⎣ T i = 0 ⎥⎦
(2)
⎛ ⎛ 14.93 ⎞⎟ − 326.29 ⎟⎞ ln x1 = x 2⎜− 5538.61 + + x3⎜1.83 + ⎝ ⎝ ⎠ T ⎠ T ⎡ 88.70 − 240.50(x 2 − x3) 236.85(x 2 − x3)2 ⎤ ⎥ + x 2x3⎢ + + T T ⎦ ⎣ T
based on the Combined Jouyban-Acree and van’t Hoff models. In eqs 1 and 2 x2 and x3 are the initial mole fraction compositions of the two monosolvents that comprise the binary solvent mixture, T is the system temperature, and Bi, Ai and Ji represent the curve-fit equation coefficients of the two models used in describing how the measured solubility of olaparib varies with solvent composition and/or temperature. The purpose of the present communication is to identify for journal readers several shortcomings in the authors’ mathematical representations. First, the authors’ calculated curve-fit equation coefficients that are tabulated in Table 7 do not correctly back-calculate the mole fraction solubility when substituted into eq 1 above. For example, the tabulated curve-fit equation coefficients for the binary acetonitrile + 2propanol solvent system at T/K = 319.35 are B0 = 2.493; B1 = −0.107; B2 = 1.566; B3 = −2.323; and B4 = 1.222. These equation coefficients when substituted into eq 1 give: © XXXX American Chemical Society
(4)
an extremely small mole fraction solubility of x1 = e−5538.5 for olaparib at x2 = 1.0 and T/K = 319.35. Similarly, one would calculate a mole fraction solubility of x1 = 2.244 at x3 = 1.00. There are clearly problems with the curve-fit equation coefficients that the authors give in Table 9 of their published paper. Received: November 2, 2017 Accepted: February 8, 2018
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DOI: 10.1021/acs.jced.7b00955 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
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Comment/Reply
AUTHOR INFORMATION
Corresponding Author
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[email protected]. Fax: 940-565-4318. ORCID
William E. Acree Jr.: 0000-0002-1177-7419 Notes
The author declares no competing financial interest.
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REFERENCES
(1) Zhao, Z.; Yang, W.; Zhang, J.; Sheng, H.; Zhao, X.; Hu, Y. SolidLiquid Phase Equilibrium and Thermodynamic Properties of Olaparib in Selected Organic Solvents and (Tetrahydrofuran + MTBE, Acetonitrile + Isopropyl Alcohol) Binary Solvent Mixtures. J. Chem. Eng. Data 2017, 62, 3744−3752.
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DOI: 10.1021/acs.jced.7b00955 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
