Article Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX
pubs.acs.org/jced
Solubility Modeling and Solvent Effect of 2‑Amino-6-chloropurine in Twelve Neat Solvents Wentian Li,† Yanqing Zhu,† Xincheng Wang,† Min Zheng,‡ Xinbao Li,† and Hongkun Zhao*,‡ †
J. Chem. Eng. Data Downloaded from pubs.acs.org by UNIV DE BARCELONA on 02/02/19. For personal use only.
School of Environmental & Municipal Engineering, North China University of Water Resources and Electric Power, ZhengZhou, Henan 450046, People’s Republic of China ‡ College of Chemistry & Chemical Engineering, YangZhou University, YangZhou, Jiangsu 225002, People’s Republic of China ABSTRACT: The determination of 2-amino-6-chloropurine solubility in water and 11 organic solvents including dimethyl sulfoxide (DMSO), N,Ndimethylformamide (DMF), 2-butanone, ethylene glycol (EG), n-butanol, npropanol, isobutanol, isopropanol, 1,4-dioxane, ethanol, and methanol was performed by using the shake flask technique. The experiments were conducted covering the temperatures from 278.15 to 333.15 K at ambient pressure p = 101.2 kPa. The values of solubility for 2-amino-6-chloropurine in selected solvents increased as the temperature rised. The maximum solubility value of 2-amino-6-chloropurine was recorded in DMSO, and the minimum, in water. They ranked as DMSO > DMF > 2-butanone > EG > n-butanol > npropanol > isobutanol > isopropanol >1,4-dioxane > ethanol > methanol > water. The solubility data obtained were mathematically described through the Apelblat equation. The largest percentage of average relative deviation was 1.75 × 10−2, and the maximum value of root-mean-square deviation, 1.14 × 10−4. Moreover, using the Kamlet and Taft linear solvation energy relationship analysis of the solvent effect, the type and degree of solvent, solute, and solvent−solvent interactions were recognized.
■
INTRODUCTION In the late years, investigation on the solubility of drugs and their intermediates has been a common topic in pharmaceutical fields. The study of the solubility of a drug and its intermediates is a key action for drug development. Solubility data may be employed to predict the dissolution of active pharmaceutical ingredients in solvents and optimize the purification procedure in pharmaceutical industry.1−3 Some thermodynamic properties of dissolution such as change of Gibbs energy, entropy, and enthalpy can be obtained through the solubility data as a function of temperature.4,5 Additionally, aqueous solubility is also a significant property that plays an important role in various biological and physical processes.6 Lower aqueous solubility may cause low formulation difficulty or bioavailability in medical development.7,8 For these reasons mentioned above, solubility evaluation at initial stages of candidate selection and lead optimization is required in a drug discovery procedure.9−11 The compound 2-amino-6-chloropurine (CAS Reg. No. 10310-21-1, structure shown in Figure 1) is a useful intermediate in the preparation of nucleoside analogue antiviral agents such as penciclovir and famciclovir. 12−14 This intermediate is 9-substituted with an appropriate side chain precursor, followed by conversion of the 6-chloro moiety to a hydroxyl (a guanine) or hydrogen (a 2-aminopurine).152Amino-6-chloropurine is the most widespread nitrogencontaining heterocycle compound in the natural world. However, 2-amino-6-chloropurine shows slight solubility in © XXXX American Chemical Society
Figure 1. Chemical structure of 2-amino-6-chloropurine.
water,12,16 which is the main drawback in subsequent reaction processes. Despite the usefulness of the intermediate, it is completely devoid of information on the physicochemical properties such as solubility of this substance in different solvents and solvent mixtures. A comprehensive publication search illustrates that only the 6-chloropurine solubility in several aqueous cosolvent mixtures17 and bis-Boc-2-amino-6chloropurine in water12,18,19 and different neat organic solvents12 has been determined. Nevertheless, to the best of our current knowledge, no solubility data of 2-amino-6chloropurine are available in the present publications. With the purpose of studying the physicochemical properties of 2amino-6-chloropurine in neat solvents, it is necessary to determine systematically the 2-amino-6-chloropurine solubility for pharmaceutical systems. Received: November 1, 2018 Accepted: January 18, 2019
A
DOI: 10.1021/acs.jced.8b01014 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
Article
Table 1. Detailed Information on the Materials Used in the Work chemicals
molar mass (g·mol−1)
2-amino-6-chloropurine methanol
169.57 32.04
ethanol isopropanol isobutanol n-propanol n-butanol DMF 2-butanone 1,4-dioxane DMSO EG water
46.07 60.10 74.12 60.10 74.12 73.09 72.11 88.11 78.13 62.07 18.02
initial mass fraction purity
source Sigma Chemical Co., Ltd. Sinopharm Chemical Reagent Co., Ltd.
final mass fraction purity
purification method
analytical method
0.982 0.997
0.996 0.997
recrystallization none
HPLCa GCb
0.994 0.995 0.994 0.995 0.994 0.995 0.994 0.995 0.994 0.995
0.994 0.995 0.994 0.995 0.994 0.995 0.994 0.995 0.994 0.995 conductivity DMF > 2-butanone > EG > nbutanol > n-propanol > isobutanol > isopropanol >1,4-dioxane > ethanol > methanol > water. At 298.15 K, the solubility values in DMSO are approximately 872 times of that in water C
DOI: 10.1021/acs.jced.8b01014 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
Article
Table 2. Experimental Mole Fraction Solubility (x) of 2-Amino-6-chloropurine in Different Solvents in the Temperature Range from T = 278.15 to 333.15 K under 101.2 kPaa 104x T (K)
methanol
ethanol
n-propanol
n-butanol
isopropanol
isobutanol
278.15 283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15 333.15 T (K)
0.3086 0.3960 0.4936 0.6136 0.7533 0.9430 1.118 1.374 1.684 1.979 2.326 2.791 DMSO
0.4386 0.5421 0.6873 0.8557 1.052 1.251 1.528 1.843 2.178 2.579 3.027 3.569 DMF
1.030 1.221 1.493 1.744 2.016 2.339 2.737 3.144 3.620 4.201 4.720 5.394 2-butanone
1.353 1.592 1.853 2.102 2.419 2.756 3.155 3.584 4.093 4.609 5.149 5.857 EG
0.5988 0.7430 0.9383 1.137 1.367 1.650 1.950 2.304 2.660 3.141 3.629 4.313 1,4-dioxane
0.8803 1.061 1.312 1.553 1.804 2.107 2.439 2.796 3.253 3.728 4.326 4.986 water
108.1 126.9 150.1 171.8 203.5 240.0 284.2 331.3
22.59 26.62 31.27 36.61 42.74 49.74 57.73 66.83 77.15 88.84 100.1 120.7
1.783 2.135 2.563 3.033 3.520 4.079 4.760 5.470 6.259 7.233 8.405 10.02
5.488 6.340 7.193 8.231 9.235 10.42 11.68 12.99 14.49 16.04 17.71 19.77
0.7484 0.9156 1.124 1.349 1.621 1.949 2.359 2.768 3.253 3.960
0.03283 0.04657 0.06526 0.09040 0.1239 0.1680 0.2256 0.3001 0.3956 0.5171 0.6704 0.8625
278.15 283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15 333.15 a
Standard uncertainties u are u(T) = 0.02 K and u(p) = 0.45 kPa; the relative standard uncertainty ur is ur(x) = 0.0224.
Figure 3. Mole fraction solubility of 2-amino-6-chloropurine in different solvents: (a) ●, DMSO; ■, DMF; ▼, 2-butanone; ▲, EG. (b) ★, nbutanol; ▼, n-propanol; ▶, isobutanol; ◀, isopropanol; ●, 1,4-dioxane; ■, ethanol; ◆, methanol; ▲, water. , calculated curves with the Apelblat equation.
and those in DMF are approximately 345 times of that in water, respectively. For the 2-amino-6-chloropurine + water and alcohol systems, the solubility magnitude is in agreement with the changing tendency of polarity of the solvents with exception of isobutanol and isopropanol. This case illustrates that the polarities of solvents appear to be a significant factor to influence the 2-amino-6-chloropurine solubility in the alcohols and water. 2-Amino-6-chloropurine shows approximate symmetrical structure, so it has a relatively small polarity. The water polarity is larger than those of the alcohols,29 so the solubility of 2-amino-6-chloropurine in water is lower than that in these alcohols. The lower aqueous solubility may be due to its largest molecular polarity among the studied solvents. Nevertheless, for the other pure solvents, the solubility order is
not in rigorous agreement with this property. Alternatively, 2amino-6-chloropurine has high dipole moments. Therefore, it may offer strong dipole−dipole interactions with the solvents due to the >HH group.17,30 The formed H-bonds have a direct influence on the 2-amino-6-chloropurine solubility. The mole fraction solubility of 2-amino-6-chloropurine is greater in DMSO and DMF than in the other selected solvents. Obviously, the case results from the formation of H-bonds between the >HH and >NH 2 groups of 2-amino-6chloropurine and the free electron pairs of the oxygen atom of DMSO and DMF. In general, it is very difficult to clarify the 2-amino-6-chloropurine solubility behavior tabulated in Table 2 through a single reason. Actually, many factors may affect the solute solubility in solvents, e.g., molecular geometry and size D
DOI: 10.1021/acs.jced.8b01014 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
Article
Table 3. Parameters in the Apelblat Equation for 2-Amino-6-chloropurine in Different Solvents Apelblat equation solvent
A
B
C
100RAD
106RMSD
methanol ethanol n-propanol n-butanol isopropanol isobutanol DMF water DMSO 1,4-dioxane EG 2-butanone
13.5601 21.0826 −4.9718 −33.5514 −5.6808 −37.1002 −93.6731 6.88700 −141.394 −56.876 −8.2745 −110.614
−4180.29 −4357.53 −2513.19 −932.473 −2894.99 −1122.68 1649.05 −5493.62 3688.74 −798.246 −1751.71 2273.04
−1.5839 −2.7448 0.85904 4.9762 1.1383 5.6574 14.5114 0.04212 21.8498 8.8539 1.25699 16.6773
0.71 0.57 0.71 0.45 1.38 1.34 0.96 0.01 0.59 1.06 0.36 1.75
1.34 0.87 1.93 1.71 2.57 2.48 102 0.001 114 2.42 5.25 8.09
(i.e., structural and steric effects), molecule polarity, solute− solvent interactions, and solvent−solvent interactions.31 Solubility Modeling. According to the determined solubility data in the present work, the equation parameters in the Apelblat equation are attained by Mathcad software. The acquired values of equation parameters are presented in Table 3, along with the values of the RMSD and the RAD. The 2amino-6-chloropurine solubility in the 12 pure solvents is evaluated according to the parameters’ values and shown graphically in Figure 3. As is seen from Table 3, the maximum relative average deviation (RAD) is 1.75%, which is found for the (2-butanone + water) system. The maximum RMSD value is 1.02 × 10−4, which is obtained for the DMF solvent. As a result, the Apelblat equation provides acceptable correlation results. Solvent Effect. With the purpose of acquiring the details upon the solvent effect, the KAT-LSER model is used to describe the solubility of 2-amino-6-chloropurine in 12 pure solvents at 298.15 K. The parameters, α, β, π*, and δH, presented in Table 4 are taken from the literature.29,32−37 The molar volume of 2-amino-6-chloropurine, 77.4 cm3·mol−1, is evaluated through the Fedors method (Table 5).38 The cavity term is expressed as VsδH2/(100RT) in order to get a dimensionless parameter with a similar range as the other properties α, β, and π*. This treatment may make a reliable estimation of the relative significance among different terms in
Table 5. Application of the Fedors Method to Estimate the Hildebrand Solubility Parameter of 2-Amino-6chloropurine group Cl >NH >NH2 N C< CH ring closure five or more atoms conjugation in ring for each double bond
α
β
π*
VsδH2/(100RT)
methanol ethanol isopropanol n-propanol n-butanol isobutanol 1,4-dioxane DMF water DMSO 2-butanone EG
0.98 0.86 0.76 0.84 0.84 0.79 0 0.00 1.17 0.00 0.06 0.90
0.66 0.75 0.84 0.90 0.84 0.84 0.37 0.69 0.47 0.76 0.48 0.52
0.60 0.54 0.48 0.52 0.47 0.40 0.55 0.88 1.09 1.00 0.67 0.92
0.274 0.220 0.174 0.189 0.168 0.160 0.131 0.193 0.714 0.222 0.114 0.342
1 1 1 3 4 1 2 4 total solubility parameter
V (cm3·mol−1)
U (kJ·mol−1)
24.0 4.50 19.2 5.0 −5.5 13.5 16 −2.2
11.54 8.36 12.54 11.70 4.31 4.31 1.05 1.67
77.4 97.87 (97870/77.4)1/2 = 35.56MPa1/2
eq 3 so as to explain the solvent effect upon solubility. The experimental 2-amino-6-chloropurine solubility is described by using the solvent parameters with the multiple linear regression analysis. The obtained results at 298.15 K are expressed through eq 7 for the selected pure solvents ln(x) = −14.606(0.912) + 0.8198(0.7349)α + 3.3169(1.0217)β + 11.001(1.386)π * ij V δ 2 yz − 15.585(2.645)jjj s H zzz j 100RT z k {
Table 4. Hildebrand Solubility Parameter (δH) and Solvatochromic Parameters α, β, and π* at 298.15 K for Neat Solventsa solvent
group number
(7)
2
n = 12, R = 0.94, RSS = 1.38, F = 44.44
where R2 is the squared correlation coefficient, F denotes the F-test, and RSS signifies residual sum of squares. The numbers in parentheses are standard deviations for the equation coefficient. Equation 7 shows that the KAT-LSER model comprising all variables may present a satisfactory description for the 2-amino-6-chloropurine solubility over the 12 pure solvents. The coefficient magnitudes demonstrate that the contributions to 2-amino-6-chloropurine solubility are, respectively, 2.67, 10.80, 35.81, and 50.73% for the hydrogen bond acidity, hydrogen bond basicity, dipolarity/polarizability, and Hildebrand solubility parameter. Hence, the Hildebrand solubility parameter, expressed as c4, plays a significant role in 2-amino-6-chloropurine solubility, which specifies a negative contribution of the solvent cohesive energy and solvent−
a
Taken from refs 29 and 32−37. E
DOI: 10.1021/acs.jced.8b01014 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
Article
(5) Sengupta, A.; Pai, G. K.; Tippavajhala, V. K. A Review on the Physico-chemical Properties of Solvent Influencing the Solubility of Drugs. J. Global Pharma Technol. 2017, 8, 22−31. (6) Hanna, M.; Shan, N.; Cheney, M. L.; Weyna, R. D.; Houck, R. Crystallization Method for Improvement of Oral Bioavailability of Drugs Including Bisphosphonates. US Patent 20,130,035,315, Feb 07, 2013. (7) Yalkowsky, S. H. Solubility and Solubilization in Aqueous Media; American Chemical Society and Oxford University Press: New York, 1999; pp 180−235. (8) Aulton, M. E. Pharmaceutics. The Science of Dosage Forms Design, 2nd ed.; Churchill Livingstone: London, 2002. (9) Kolár,̌ P.; Shen, J. W.; Tsuboi, A.; Ishikawa, T. Solvent Selection for Pharmaceuticals. Fluid Phase Equilib. 2002, 194−197, 771−782. (10) Jouyban, A. Handbook of Solubility Data for Pharmaceuticals; CRC Press: Boca Raton, FL, 2010. (11) Rubino, J. T. Cosolvents and Cosolvency. In Encyclopedia of Pharmaceutical Technology; Swarbrick, J., Boylan, J. C., Eds.; Marcel Dekker: New York, 1988. (12) Dai, L. Y.; Shi, Q. L.; Zhang, J.; Wang, X. Z.; Chen, Y. Q. Accelerated Effect on Mitsunobu Reaction via Bis-N-tert-butoxycarbonylation Protection of 2-Amino-6-chloropurine and Its Application in a Novel Synthesis of Penciclovir. J. Zhejiang Univ., Sci., A 2013, 14, 760−766. (13) Jin, X.; Ji, L.; Chen, W. X.; Qian, W.; Shen, D. D. An Improved Synthetic Process of Famciclovir and Penciclovir. Chin. J. Pharm. 2016, 47, 1352−1356. (14) Harnden, M. R.; Jarvest, R. L. Process for the Preparation of 2Amimo-6-chloro-purine. WO Patent 940,789,214, April 14, 1994. (15) Balachandran, V.; Parimala, K. Tautomeric Purine Forms of 2Amino-6-chloropurine (N9H10 and N7H10): Structures, Vibrational Assignments, NBO Analysis, Hyperpolarizability, HOMO−LUMO Study using B3 Based Density Functional Calculations. Spectrochim. Acta, Part A 2012, 96, 340−351. (16) Fletcher, S.; Shahani, V. M.; Lough, A. J.; Gunning, P. T. Concise Sccess to N9-mono-, N2-mono- and N2,N9-di-Substituted Guanines via Efficient Mitsunobu Reactions. Tetrahedron 2010, 66, 4621−4632. (17) Li, X. B.; Feng, S.; Farajtabar, A.; Zhang, N.; Chen, G. Q.; Zhao, H. K. Solubility Modelling, Solvent Effect and Preferential Solvation of 6-Chloropurine in Several Aqueous Co-Solvent Mixtures between 283.15 K and 328.15 K. J. Chem. Thermodyn. 2018, 127, 106−116. (18) Bendich, A.; Russell, P. J., Jr.; Fox, J. J. The Synthesis and Properties of 6-Chloropurine and Purine. J. Am. Chem. Soc. 1954, 76, 6073−6077. (19) Albert, A.; Brown, D. J. Purine Studies. Part I. Stability to Acid and Alkali. Solubility. Ionization. Comparison with pteridines. J. Chem. Soc. 1954, 29, 2060−2071. (20) Jouyban, A.; Fakhree, M. A. A. Experimental, Computational Methods Pertaining to Drug Solubility. In Toxicity and Drug Testing; Acree, W. E., Jr., Ed.; InTech: Rijeka, Croatia, 2012; pp 187−218. (21) Apelblat, A.; Manzurola, E. Solubilities of L-Aspartic, DLAspartic, DL-Glutamic, Phydroxybenzoic, o-Anistic, p-Anisic, and Itaconic Acids in Water from T = 278 K to T = 345 K. J. Chem. Thermodyn. 1997, 29, 1527−1533. (22) Taft, R. W.; Abboud, J. L. M.; Kamlet, M. I.; Abraham, M. H. Linear Solvation Energy Relations. J. Solution Chem. 1985, 14, 153− 186. (23) Carr, P. W. Solvatochromism, Linear Solvation Energy Relationships, and Chromatography. Microchem. J. 1993, 48, 4−28. (24) Kamlet, M. J.; Abboud, J. L. M.; Taft, R. W. An Examination of Linear Solvation Energy Relationships. Prog. Phys. Org. Chem. 2007, 13, 485−630. (25) Marcus, Y. Solubility and Solvation in Mixed Solvent Systems. Pure Appl. Chem. 1990, 62, 2069−2076. (26) Jouyban, A.; Martinez, F.; Panahi-Azar, V. Solubility of Fluphenazine Decanoate in Aqueous Mixtures of Polyethylene
solvent interaction to the solvent effect. The contribution of nonspecific polarizability/dipolarity interactions to the solubility is a little lower than that of the cavity term. Specific interactions explained by α and β of solvent have less contribution to the 2-amino-6-chloropurine solubility. The positive sign of coefficients of α, β, and π* demonstrates that the solubility of 2-amino-6-chloropurine increases with the rise in hydrogen bond acidity, hydrogen bond basicity, and dipolarity/polarizability of solvent. On the contrary, the 2amino-6-chloropurine solubility decreases as the Hildebrand solubility parameter of the solvents increases.
■
CONCLUSION The equilibrium solubilities of 2-amino-6-chloropurine in water and 11 organic solvents, including DMSO, DMF, 2butanone, EG, n-butanol, n-propanol, isobutanol, isopropanol, 1,4-dioxane, ethanol, and methanol, were determined through the saturation shake-flask method at temperatures from 278.15 to 323.15 K under local atmospheric pressure (101.2 kPa). The obtained mole fraction solubility obeyed the following order in different pure solvents: DMSO > DMF > 2-butanone > EG > n-butanol > n-propanol > isobutanol > isopropanol >1,4-dioxane > ethanol > methanol > water. The solvent effect upon the 2-amino-6-chloropurine solubility was investigated by the linear solvation energy relationship to obtain the type and significance of different intermolecular interactions. The polarizability/dipolarity and Hildebrand solubility parameter played a significant role on the 2-amino-6-chloropurine solubility. Additionally, the mole fraction solubility was described by the Apelblat equation obtaining average relative deviations smaller than 1.75% for correlative investigations.
■
AUTHOR INFORMATION
Corresponding Author
*Phone: +86 514 87975568. Fax: +86 514 87975244. E-mail:
[email protected]. ORCID
Xinbao Li: 0000-0001-9598-3027 Hongkun Zhao: 0000-0001-5972-8352 Funding
This work was supported by Henan Province Programs for Science and Technology Development (Grant No. 172102310625). Notes
The authors declare no competing financial interest.
■
REFERENCES
(1) Domańska, U. Modelling, Solubility and pK(a) of Five Sparingly Soluble Drugs. Int. J. Pharm. 2011, 403, 115−122. (2) Nti-Gyabaah, J.; Chmielowski, R.; Chan, V. Solubility of Lovastatin in a Family of Six Alcohols: Ethanol, 1-Propanol, 1Butanol, 1-Pentanol, 1-Hexanol, and 1-Octanol. Int. J. Pharm. 2008, 359, 111−117. (3) Cisneros, J. A.; Robertson, M. J.; Mercado, B. Q.; Jorgensen, W. L. Systematic Study of Effects of Structural Modifications on the Aqueous Solubility of Drug-like Molecules. ACS Med. Chem. Lett. 2017, 8, 124−127. (4) Mota, F. L.; Carneiro, A. P.; Queimada, A. J.; Pinho, S. P.; Macedoa, E. A. Temperature and Solvent Effects in the Solubility of Some Pharmaceutical Compounds: Measurements and Modeling. Eur. J. Pharm. Sci. 2009, 37, 499−507. F
DOI: 10.1021/acs.jced.8b01014 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
Article
Glycols 400 and 600 at Various Temperatures. Fluid Phase Equilib. 2014, 368, 58−64. (27) Shakeel, F.; Haq, N.; Siddiqui, N. A. Solubility and Thermodynamics Function of Vanillin in Ten Different Environmentally Benign Solvents. Food Chem. 2015, 180, 244−248. (28) Chen, G. Q.; Liang, J. H.; Han, J. C.; Zhao, H. K. Solubility Modeling, Solute-Solvent Interactions and Thermodynamic Dissolution Properties of P-Nitrophenylacetonitrile in Sixteen Mono-Solvents at Temperatures Ranging from 278.15 to 333.15 K. J. Chem. Eng. Data 2019, 64, 315. (29) Smallwood, I. M. Handbook of Organic Solvent Properties; Amold: London, 1996. (30) Huyskens, F.; Morissen, H.; Huyskens, P. Solubilities of pNitroanilines in Various Classes of Solvents. Specific Solute-Solvent Interactions. J. Mol. Struct. 1998, 441, 17−25. (31) Wang, H. R.; Cao, Y.; Feng, S.; Chen, G. Q.; Farajtabar, A.; Zhao, H. K.; Li, X. B. Solubility and Molecular Interactions of Trimetazidine Hydrochloride in 12 Monosolvents and Solvent Mixtures of Methanol + (Ethanol, NN-Dimethylformamide or Ethyl Acetate). J. Chem. Eng. Data 2018, 63, 3704−3714. (32) Marcus, Y. The Properties of Organic Liquids that are Relevant to Their Use as Solvating Solvents. Chem. Soc. Rev. 1993, 22, 409− 416. (33) Hansen, C. M. Hansen Solubility Parameters: a User’s Handbook, 2nd ed.; Taylor and Francis: Boca Raton, FL, 2012. (34) Kamlet, M. J.; Abboud, J. L. M.; Abraham, M. H.; Taft, R. W. Linear Solvation Energy Relationships. 23. A Comprehensive Collection of the Solvatochromic Parameters, π*, α and β and Some Methods for Simplifying the Generalized Solvatochromic Equation. J. Org. Chem. 1983, 48, 2877−2887. (35) Zahid, M.; Rosspeintner, A.; Angulo, G.; Grampp, G.; Jacques, P.; Mansha, A. Synthesis and Photophysical Properties of 2,6Dicyano-p-Phenylenediamine. J. Photochem. Photobiol., A 2011, 220, 54−63. (36) Kamlet, M. J.; Taft, R. W. The Solvatochromic Comparison MethoD. I. The Beta-scale of Solvent Hydrogen-bond Acceptor (HBA) Basicities. J. Am. Chem. Soc. 1976, 98, 377−383. (37) Taft, R. W.; Kamlet, M. J. The solvatochromic Comparison Method. 2. The. Alpha.-Scale of solvent Hydrogen-bond Donor (HBD) Acidities. J. Am. Chem. Soc. 1976, 98, 2886−2894. (38) Fedors, R. F. A Method for Estimating Both the Solubility Parameters and Molar Volumes of Liquids. Polym. Eng. Sci. 1974, 14, 147−154.
G
DOI: 10.1021/acs.jced.8b01014 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
