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Article Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Solubility Measurement, Modeling, and Thermodynamic Functions for para-Methoxyphenylacetic Acid in Pure and Mixed Organic and Aqueous Systems Ramesh Tangirala,†,‡ Debiparna De,† Vineet Aniya,† Bankupalli Satyavathi,*,† Prathap Kumar Thella,† Madapusi P. Srinivasan,*,‡ and Rajarathinam Parthasarathy‡

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†

Process Engineering & Technology Transfer Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, Telangana 500007, India ‡ The School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne 3000, Australia

ABSTRACT: The solubility of para-methoxyphenylacetic acid in different solvents is of critical significance for the design and optimization of its purification process via crystallization. The present study illustrates new solid−liquid phase equilibrium data of para-methoxy phenyl acetic acid in water, acetonitrile, propan-2-ol, morpholine, toluene, anisole, and binary (propan-2-ol + water, propan-2-ol + toluene) mixed solvents using a static analytical method from 283.15 to 323.15 K at atmospheric pressure. The highest solubility of para-methoxyphenylacetic acid was observed in propan-2-ol and lowest in water, with the maximum solubility effect for propan-2-ol + toluene binary system obtained at 0.5001 solute-free mole fraction of propan-2-ol. The modified Apelblat equation, λh (Buchowski) equation, and nonrandom two-liquid (NRTL) activity coefficient model were used to correlate the experimental solubility data in pure solvents, whereas the binary solvent systems were modeled using the van’t Hoff−Jouyban−Acree, Apelblat−Jouyban−Acree, and NRTL models, among which the NRTL model exhibited better goodness of fit. Also, for insight into the molecular interactions in the solvent systems, the enthalpy of dissolution has been being evaluated.

1. INTRODUCTION para-Methoxyphenylacetic acid is one of the aryl alkanoic acids (molecular formula, C9H10O3; CAS no. 104-01-8) that finds a versatile role as an intermediate and is used extensively in synthetic organic chemistry. It is also used predominantly as a building block material for the production of essential drugs such as dextromethorphan, an anticough medicine. The other applications include its use as an additive in the manufacture of unsubstituted indigo dyes and a corrosion inhibitor for aluminum in acidic and alkaline solutions.1 The process synthesis of para-methoxy phenyl acetic acid from ethyl para-methoxyphenyl acetate has been reported by Giordano et al. with sodium hydroxide in methanol.2 Alternatively, the carbonylation of para-methoxybenzyl chloride with butan-1-ol at 353 K under pressurized condition followed by adjusting the pH yields a 93.6% para-methoxyphenylacetic acid with 99.6% purity.3 Certain other literature also suggests that substituted phenylacetic acid derivatives can be synthesized © XXXX American Chemical Society

by a two-step mechanism that includes a sulfonylation reaction on substituted phenyl-glycine and sulfuryl chloride under the action of an alkali to obtain an intermediate, followed by a deamination reaction on the intermediate under the action of an organic acid and a reducing agent and product purification.4 However, in all of the production routes the method of isolation and purification of the crude product is predominated by crystallization or recrystallization from aqueous, organic, or mixed solvents. A crystallization is the most energy-intensive and economical purification procedure, the appropriate design and optimization of the process are vital. In this purview, the solid−liquid equilibrium (SLE) data of the solute in different solvents become a prerequisite to mark the process more convenient, thereby yielding high-purity product.5,6 SLE is an Received: April 2, 2018 Accepted: July 25, 2018

A

DOI: 10.1021/acs.jced.8b00271 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

important physicochemical property that dictates the thermodynamic studies and design of a crystallization process for suitable scale-up from bench scale to commercial operations. Therefore, with the aim to purify the para-methoxyphenylacetic acid crystals from the crude product, its solubility in various pure solvents and binary mixtures was experimentally evaluated at different temperatures from 283.15 to 323.15 K using a static equilibrium method at local atmospheric pressure. Amidst the commonly utilized industrial solvents, a set of six neat solvents, including water, acetonitrile, propan-2-ol, morpholine, toluene, and anisole, and two binary solvent systems of propan-2-ol + water and propan-2-ol + toluene were selected for investigating the solubility of para-methoxyphenylacetic acid, which play a key role in its subsequent processing and derivatives production. The recrystallized para-methoxyphenylacetic acid from toluene and water individually were in the purest form with utmost whiteness index. However, the solubility of the solute in toluene and water was much lower for scale-up operations in crystallization. Thus to obtain the purest form of the solute matching the USP standards, toluene and water were proposed to be used as antisolvent and cosolvent, respectively, with propan-2-ol that portrayed high-solubility limits. The experimental SLE data of para-methoxyphenylacetic acid in these solvents were suitably correlated using different thermodynamic models; neat solvent: modified Apelblat equation, λh equation, and nonrandom two-liquid (NRTL) model; binary solvent systems: van’t Hoff−Jouyban−Acree, Apelblat−Jouyban−Acree, and NRTL. The powder X-ray diffraction (PXRD) analysis of the dissolved solute was also conducted to verify the nonexistence of polymorphism. Furthermore, the thermodynamic functions for the dissolution (dissolution enthalpy, entropy, and Gibbs free energy) of paramethoxyphenylacetic acid in the selected solvent systems with the inclusion of the extent of nonideality of the solutions in the process were estimated.7

Table 1. Properties and Sources of Materials Used chemical (IUPAC name)

CAS registry number

source

molar mass (g·mol−1)

mass purity

para-methoxy phenyl acetic acid propan-2-ol toluene morpholine acetonitrile anisole water methanol

104-01-8

Sigma-Aldrich, India

166.17

0.99

67-63-0 108-88-3 110-91-8 75-05-8 100-66-3 7732-18-5 67-56-1

Finar, India Finar, India Finar, India S D Fine, India Finar, India Finar, India S D Fine, India

60.10 92.14 87.12 41.05 108.14 18.02 32.04

0.998 0.998 0.99 0.995 0.99 >0.99 0.995

specific temperatures to make sure the equilibrium was achieved. The undissolved para-methoxyphenylacetic acid crystals were further allowed to settle for another 10 h under the same conditions for clean separation. The equilibrium time of 8 h was predetermined through preliminary kinetic dissolution studies of para-methoxyphenylacetic acid in each solvent system. It was observed that no system portrayed a higher equilibrium time than 8 h, after which the concentration of the solute remained constant. The clear supernatant after settling was withdrawn using a preheated glass syringe mounted with a micron filter at the tip. Micropipettes were used to accurately dilute the samples in methanol that was used as an internal standard for the analysis of equilibrium concentrations of para-methoxyphenyl acetic acid. Each experiment was conducted in triplicate, and the mean value was considered for evaluating the mole fraction solubility for higher precision and reliability. 2.2. Analysis. The equilibrium saturation compositions of para-methoxyphenyl acetic acid in neat organic solvents and the mixed organic binary solvent were analyzed by a gas chromatograph (GC-2010, Shimadzu) equipped with a flame ionization detector (FID). A ZB-5 column (30 m × 0.53 mm × 1.5 μm) was used with a temperature-programmed analysis. The conditions maintained were column temperature: 353 K ramped at the rate of 10 K·min−1 heating for 12 min, 473 K maintain 0 min, 10 K min−1 heating for 8 min, 553 K maintain 2 min; injection mode, split ratio 50/1; injector temperature: 493 K; and detector temperature: 523 K. Alternatively, the samples containing aqueous media were analyzed through Shimadzu high-performance liquid-phase chromatograph. A reverse-phase column with of Luna 5 μ-C18 (2) 100A (250 mm × 4.6 mm) was employed. The wavelength of the UV detector was 215 nm, attained using a single-wavelength prominence diode array detector. The mobile phase was a mixture of buffered acetonitrile (20 mM phosphoric acid + acetonitrile) and methanol in the volume ratio 3:1 with a flow rate of 1 mL min−1. Under the mentioned conditions, para-methoxyphenylacetic acid was detected after a retention time of 5.2 min. The experimental analysis was conducted as instantly as possible, with each determination recorded thrice to minimize errors. In this work, the relative standard uncertainty of the mole fraction solubility determination was evaluated to be 0.1% for all systems except pure water that showed an uncertainty of 0.3, on consideration of the standard uncertainty in mole fraction with respect to each system investigated. 2.3. Thermal Measurement of Solute. A differential scanning calorimeter (DSC) of PerkinElmer (Pyris-Diamond) make was used to measure the melting temperature and fusion enthalpy of para-methoxyphenylacetic acid for the correlation of the experimental solubility data. The instrument was

2. EXPERIMENTAL SECTION 2.1. Materials and Measurement. para-Methoxyphenylacetic acid was provided by Sigma-Aldrich, India with a mass fraction purity being 0.99 and analyzed using high-performance liquid chromatography (HPLC). The neat solvents (acetonitrile, propan-2-ol, morpholine, toluene, and anisole) of analytical reagent grade were all procured from reputed suppliers and used directly in solubility determinations without any further treatment. HPLC-grade water was used for the experimentation, and all of the remaining solvents were stored in desiccators loaded with silica gel. The properties and sources of the different solvents used in this study together with that of para-methoxyphenylacetic acid are reported in Table 1. The experimental solubility of para-methoxyphenylacetic acid in neat water, acetonitrile, propan-2-ol, morpholine, toluene, and anisole and the binary systems containing propan-2-ol + water and propan-2-ol + toluene from 283.15 to 323.15 K were investigated as reported in our previous publication8,9 using the static equilibrium method. Shaking incubator (LSI-4018R, Daihan LabTech, India) with a temperature accuracy within ±0.1 K was utilized to conduct the experimental investigations. The experiments were started by gravimetrically weighing the known quantity of solvents in a Teflon-coated glass-stoppered conical flask using a Shimadzu balance (AUX 220), capable of recording weights with an accuracy of ±0.0001 g to which an excess of para-methoxyphenylacetic acid was added. The solutions were agitated in the shaker continuously for 8 h at B



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propan-2-ol, morpholine, toluene, and anisole, within the temperature range of 283.15−323.15 K have been reported in Table 2 and are shown in Figure 2a,b. Each pure solvent exhibited a significant trend of increase in solubility of paramethoxyphenyl acetic acid with respect to variation in temperature. The mole fraction solubility of para-methoxyphenylacetic acid was observed to be highest in propan-2-ol (35.09%) and lowest in water (1.05%) at 323.15 K. Moreover, the sequential order of solubility in the pure solvents followed the order propan-2-ol > acetonitrile > anisole > toluene > morpholine and water under all investigated conditions. This order of solubility also well aligns with the molecular structures and interactions of these neat solvents.12 The solubility of para-methoxy phenyl acetic acid in the mixed-solvent system of propan-2-ol + water and propan-2-ol + toluene for changing the mole fraction (solute-free basis) at different temperatures is summarized in Tables 3 and 4, respectively. The experimental mole fraction solubility data of para-methoxy phenyl acetic acid increased as a function of temperature for each solute-free mole fraction of the mixedsolvent system, as a particular mole fraction was found to increase with increasing temperature, and are presented in Figures 3 and 4a,b for the two binary mixtures propan-2-ol + water and propan-2-ol + toluene, respectively. Furthermore, Figures 5 and 6 explicitly display the interdependency of temperature and the solubility of para-methoxyphenylacetic acid in mixed solvents at different solute-free mole fractions of propan-2-ol. It can be clearly visible that the solubility of paramethoxyphenylacetic acid in propan-2-ol + water binary mixture constantly increases as the solute-free mole fraction of propan-2-ol varies from 0 to 0.3995. However, in the case of the propan-2-ol + toluene mixed-solvent system, the solubility of para-methoxy phenyl acetic acid displayed a prominent increase in the propan-2-ol varies from 0 to 0.5001 and thereafter decreased. This phenomenon is often referred to as the maximum solubility effect, which can be attributed to the Scatchard−Hildebrand theory, which suggests that when a solute (solid) is solubilized in a mixed solvent, the curve plotted between solubility and solvent composition (solutefree) passes through a maximum.8 Furthermore, it is evident from Figures 5 and 6 that equilibrium saturation was achieved for para-methoxyphenylacetic acid at the corresponding temperatures investigated up to 0.3995 and 0.5001 solutefree mole fraction of propan-2-ol for the binary system of propan-2-ol + water and propan-2-ol + toluene solvent mixtures, respectively. 3.3. Recrystallization of para-Methoxyphenylacetic Acid. A crucial parameter in the SLE studies includes the behavior of the solute after dissolution in any solvent owing to the critical control of polymorph formation on interaction of the solute and the solvent. This can be well analyzed through the well-known analytical technique PXRD. The PXRD analysis was performed using (Bruker D8 Advanced) with Cu Kα radiation at 40 kV and 130 mA to confirm the crystalline structure of the sample during the solubility measurements. The samples were scanned in the range of 2θ = 5−70° at the scanning speed of 1°/min. The para-methoxyphenylacetic acid investigated in the present study was analyzed by PXRD together with the solid phase obtained after recrystallization from each neat solvent and mixed-solvent system used in the present study. The consistent crystal patterns explained that there was no polymorphism

standardized using indium as a reference material prior to the experimentation. The calibration was carried out using 4.2 mg of sample and a heating rate of 5 K min−1. The melting properties of para-methoxyphenylacetic acid were measured within the temperature range 303−573 K under an inert atmosphere (nitrogen) atmosphere with 3.65 mg of sample and a constant heating rate of 10 K min−1. The standard uncertainties for temperature and fusion enthalpy were estimated to be 0.5 K and 200 J·mol−1, respectively.

3. RESULTS AND DISCUSSION 3.1. Solute Fusion Properties. The DSC thermogram of para-methoxyphenyl acetic acid is exhibited in Figure 1. It is

Figure 1. DSC thermogram of para-methoxyphenylacetic acid.

evident from the Figure that the fusion temperature (Tfus) and the fusion enthalpy (ΔfusH) of para-methoxyphenylacetic acid are 358.05 K and 21.8 kJ mol−1 respectively. The fusion temperature considered in the present study was the onset point of the DSC curve, which is the intersection of the extension of the baseline with the tangent at the point of greatest slope, also known as the inflection point of the DSC curve. Literature reports the Tfus value (358.15 to 359.15 K)10,11 to be in the same range or slightly higher, although that evaluated in the present study was within the range of experimental limits. However, no data have been reported yet for the fusion enthalpy (ΔfusH) of para-methoxyphenylacetic acid. This difference can be owed to the method of synthesis, analysis, and experimental conditions maintained. Also, the high crystallinity of the solute is indicated by the strong and sharp peak in the thermogram. The fusion entropy (Sfus) for para-methoxyphenylacetic acid has been further determined using eq 1. ΔSfus =

ΔfusH Tm

(1) −1

−1

which was calculated as 60.88 J·mol ·K . The obtained fusion properties were further utilized to correlate the experimental solubility data using various thermodynamic models as well as used to estimate the dissolution functions of solutions. 3.2. Experimental SLE Data. The experimentally evaluated mole fraction solubility of para-methoxyphenylacetic acid in different neat solvents, namely, water, acetonitrile, C



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Table 2. Experimental (xexp) and Predicted (xcal) Mole Fraction Solubility of para-Methoxyphenylacetic Acid in Different Pure Solvents in the Temperature Range from T = (283.15 to 323.15) K at 94.9 kPaa xcal T/K

xexp

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 RMSD × 102

0.1140 0.1416 0.1691 0.1982 0.2275 0.2581 0.2886 0.3227 0.3509

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 RMSD × 102

0.0166 0.0209 0.0264 0.0337 0.0415 0.0522 0.0641 0.0784 0.0941

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 RMSD × 102

0.0094 0.0139 0.0185 0.0239 0.0293 0.0348 0.0404 0.0459 0.0503

modified Apelbat equation Propan-2-ol 0.1246 0.1454 0.1685 0.1940 0.2219 0.2524 0.2854 0.3210 0.3593 0.5713 Toluene 0.0172 0.0216 0.0270 0.0336 0.0416 0.0514 0.0633 0.0778 0.0952 0.0638 Morpholine 0.0133 0.0160 0.0192 0.0229 0.0273 0.0324 0.0384 0.0453 0.0534 0.2244

λ equation

xcal NRTL

T/K

xexp

0.1288 0.1473 0.1681 0.1916 0.2182 0.2483 0.2826 0.3217 0.3666 0.9195

0.1317 0.1513 0.1731 0.1969 0.2231 0.2516 0.2829 0.3164 0.3541 0.7940

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 RMSD × 102

0.0423 0.0499 0.0587 0.0687 0.0803 0.0941 0.1115 0.1347 0.1658

0.0178 0.0221 0.0272 0.0335 0.0412 0.0507 0.0625 0.0774 0.0963 0.1240

0.0188 0.0228 0.0276 0.0337 0.0410 0.0505 0.0623 0.0773 0.0961 0.1530

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 RMSD × 102

0.0323 0.0425 0.0519 0.0626 0.0737 0.0858 0.0999 0.1178 0.1388

0.0139 0.0164 0.0192 0.0226 0.0266 0.0315 0.0375 0.0450 0.0547 0.2890

0.0129 0.0156 0.0188 0.0227 0.0271 0.0324 0.0384 0.0453 0.0530 0.2080x x c

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 RMSD × 102

0.0011 0.0020 0.0031 0.0043 0.0057 0.0069 0.0079 0.0092 0.0105

modified Apelbat equation Acetonitrile 0.0394 0.0475 0.0571 0.0683 0.0816 0.0971 0.1153 0.1365 0.1611 0.2711 Anisole 0.0331 0.0416 0.0514 0.0625 0.0748 0.0884 0.1031 0.1189 0.1354 0.1478 Water 0.0021 0.0027 0.0033 0.0041 0.0050 0.0062 0.0075 0.0092 0.0111 0.0594

λ equation

NRTL

0.0412 0.0489 0.0578 0.0684 0.0809 0.0958 0.1138 0.1358 0.1628 0.1550

0.0426 0.0505 0.0598 0.0704 0.0828 0.0970 0.1138 0.1339 0.1583 0.2999

0.0373 0.0438 0.0514 0.0604 0.0711 0.0838 0.0991 0.1179 0.1412 0.2326

0.0354 0.0426 0.0509 0.0606 0.0718 0.0848 0.1001 0.1185 0.1404 0.1591

0.0011 0.0018 0.0027 0.0039 0.0052 0.0066 0.0080 0.0093 0.0103 0.0295

0.0018 0.0023 0.0029 0.0038 0.0048 0.0061 0.0075 0.0094 0.0118 0.0685

a

Standard uncertainties u are u(T) = 0.05 K, u(P) = 0.20 kPa, and relative standard uncertainty ur(x) = 0.1 (for all solvents), ur(x) = 0.3 (for water)

ÄÅ N É ÅÅ ∑ (ZM − Z )2 ÑÑÑ0.5 ÅÅ i = 1 i i Ñ ÑÑ RMSD = ÅÅÅ ÑÑ ÅÅ ÑÑ k ÅÇ ÑÖ

or phase transition observed during the dissolution processes. The diffractogram of the para-methoxyphenylacetic acid used in this study as well as that recrystallized from toluene, which portrayed the best purity after recrystallization, is shown in Figure 7, which further makes it evident. 3.4. Thermodynamic Modeling of SLE Data. The thermodynamic modeling of SLE data enables the appropriate representation of the mathematical aspects of solubility that can be used to predict the saturation limit under different conditions accurately.13,14 The modeling of experimental solubility data in this work is described by modified Apelblat equation,15−18 λh equation,19−21 NRTL model,22,23 and van’t Hoff−Jouyban− Acree and Apelblat−Jouyban−Acree equations.24−26 These equations are used to evaluate the regressed parameters between the mole fraction solubility of para-methoxyphenylacetic acid with respect to each equilibrium temperature for the different investigated pure and mixed solvents. Moreover, to foresee the quality of the regressed parameters, the statistical analysis was conducted by evaluating the deviations between the experimental and that predicted by the models conveyed in terms of their root-mean-square deviation (RMSD).27

(2)

where Zi is a regressed property value (mole fraction solubility) based on different models, ZMi is the corresponding experimental solubility value of the data set, and N is the number of data points. 3.4.1. Modified Apelbat Equation. The modified Apelbat equation,15,16 as represented by eq 3, was used to correlate the experimental mole fraction solubility of para-methoxyphenylacetic acid at different temperatures in the investigated solvents. ln x = A +

B + C ln(T /K ) T /K

(3)

where x (mole fraction) is the solubility of para-methoxyphenylacetic acid in the organic solvents at experimental temperature T in Kelvin and A, B, and C are adjustable parameters. The variation in the solution activity coefficient is reflected by A and B values, whereas the value of C responses to the effect of temperature on the fusion enthalpy. The values of parameters are obtained by correlating the experimental solubility data of D



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are reported in Table 5 for the pure solvents. The computed solubilities of para-methoxyphenylacetic acid in different neat solvents on the basis of the regressed parameters, along with their RMSDs, are listed in Table 2. It is evident that the deviations are, however, higher than those of the other models for most of the pure solvent systems; a very minimal RMSD of (1.55 and 0.29) × 10−3 was observed for the acetonitrile and water systems, respectively. Thereby, it could be concluded that the λh equation is also a suitable model to represent the SLE for para-methoxy phenylacetic acid. 3.4.3. NRTL Model. The NRTL model is an activitycoefficient-based thermodynamic equation used widely to correlate and predict the vapor−liquid phase equilibrium and SLE of mixtures. It is based on the concept of molecular local composition as proposed by Renon and coworkers.22,28 Equations 5 and 6 describe the NRTL model for a component i. 3

ln γi =

∑ j = 1 τjiGjiXj 3 ∑k = 1 Gkixk

3

+

XjGij 3 j = 1 ∑k = 1 Gkjxk

∑

3 ij ∑k = 1 XK τkjGkj yzz j zz × jjjτij − z 3 jj ∑k = 1 Gkjxk zz k {

Gij = exp( −α ijτij), τij = aij +

(5)

bij T

, τij ≠ τji , αij = αji = 0.3 (6)

where Gij is the model parameter obtained from τij and αij relating to the intermolecular energy interaction and the nonrandomness of the solution, respectively, while T is the absolute temperature and γi is the activity coefficient of component i. Moreover, to correlate the experimental SLE data without solid−solid phase transition, the following equilibrium equation can be deployed Figure 2. Mole fraction solubility of para-methoxyphenylacetic acid in pure solvents. Experimental solubility: (a) propan-2-ol (▲), toluene (■), and acetonitrile (●); (b) morpholine (◆), anisole (▼), and water (◀). Solid lines () are calculated data by the NRTL model.

ln γ1x = −

ΔfusH ijj 1 1 yzz jjj − z R kT Tm zz{

(7)

where x, ΔfusH, Tm, R, and T are the mole fraction solubility of the solute, molar fusion enthalpy, the melting point of the solute, the universal gas constant, and the absolute temperature of the solution, respectively. The melting temperature and the fusion enthalpy were considered from the thermal analysis of the pure solute through the DSC thermogram. The binary interaction parameters of the NRTL model are assumed to have a linear relation with the temperature.29 The activity coefficient that depends on the mole fraction solubility and temperature of solution (eq 5) is used to solve eq 7 iteratively using the generalized reduced gradient nonlinear regression model to evaluate the predicted solubility results by minimizing the RMSD between experimental and predicted mole fraction solubility as the objective function.30 The modeled values of solubility using the NRTL equation together with the overall RMSD values for each system are reported in Table 2 for pure solvents and Tables 3 and 4 for binary mixed solvents, respectively. Furthermore, the binary interaction parameters for the NRTL model for the pure and binary mixed solvents have been enlisted in Tables 5 and 6, respectively. Among the pure solvents, the highest RMSD of 7.93 × 10−3 was obtained for the pure solvent propan-2-ol, whereas the lowest deviation was observed for the pure aqueous system with an RMSD of 0.68 × 10−3 for the mole fraction solubility of para-methoxyphenylacetic acid. In the case of the binary solvent mixture systems, the largest RMSD

para-methoxyphenylacetic acid at the different temperatures and are reported in Table 5 for the pure solvents. The computed solubilities of para-methoxyphenylacetic acid in different solvents on the basis of the regressed parameters, along with the RMSDs, are listed in Table 2. It was observed that the Apelbat equation exhibited low RMSD values for most of the neat solvent systems except that of morpholine and acetonitrile, with the maximum deviation observed to be 5.71 × 10−3 for the propan-2-ol system. 3.4.2. λh Equation. Equation 4 represents the λh equation proposed by Buchowski et al.,19 which is a nonactivity coefficient two-parameter model widely used to correlate the solubility data. É ÅÄÅ ij 1 (1 − x) ÑÑÑÑ 1 yzz Å lnÅÅÅ1 + λ ÑÑ = λhjjj − z j ÅÅÇ Ñ x ÑÖ Tm zz{ (4) kT where Tm is melting point of para-methoxyphenylacetic acid and λ and h are two model parameters. The value of h indicates the excess dissolution enthalpy of the solution, whereas the parameter λ represents the extent of nonideality of the solution by accounting for the number of solute molecules associated with the solvent system. These solubility parameters are obtained by correlating the experimental solubility data of para-methoxyphenylacetic acid at the different equilibrium temperatures and E



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Table 3. Experimental (xexp) and Predicted (xcal) Mole Fraction Solubility of para-Methoxyphenylacetic Acid in the Binary Mixture of Propan-2-ol + Water in the Temperature Range of 283.15 to 323.15 K at 94.9 kPaa xcal T/K

xexp

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0038 0.0048 0.0057 0.0069 0.0082 0.0098 0.0118 0.0141 0.0170

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0084 0.0102 0.0124 0.0149 0.0180 0.0216 0.0259 0.0310 0.0369

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0239 0.0287 0.0350 0.0425 0.0514 0.0619 0.0744 0.0890 0.1061

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0513 0.0614 0.0736 0.0877 0.1047 0.1242 0.1462 0.1731 0.2011

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 overall RMSD × 102

0.0950 0.1199 0.1526 0.1931 0.2413 0.2974 0.3613 0.4329 0.5124

van’t Hoff−Jouyban−Acree x′ 0.0035 0.0043 0.0052 0.0064 0.0077 0.0092 0.0110 0.0131 0.0154 x′ 0.0078 0.0096 0.0116 0.0141 0.0169 0.0202 0.0240 0.0283 0.0333 x′ 0.0235 0.0289 0.0351 0.0425 0.0511 0.0610 0.0725 0.0857 0.1008 x′ 0.0456 0.0565 0.0696 0.0852 0.1035 0.1249 0.1499 0.1789 0.2123 x′ 0.1001 0.1259 0.1572 0.1948 0.2397 0.2929 0.3557 0.4293 0.5151 0.3306

Apelblat−Jouyban−Acree

NRTL

0.0040 0.0049 0.0059 0.0070 0.0083 0.0098 0.0114 0.0133 0.0153

0.0042 0.0051 0.0060 0.0071 0.0084 0.0099 0.0118 0.0139 0.0166

0.0088 0.0107 0.0129 0.0154 0.0182 0.0214 0.0249 0.0288 0.0331

0.0089 0.0106 0.0127 0.0151 0.0180 0.0215 0.0257 0.0307 0.0369

0.0255 0.0312 0.0377 0.0452 0.0538 0.0635 0.0745 0.0867 0.1003

0.0236 0.0284 0.0343 0.0413 0.0499 0.0603 0.0733 0.0893 0.1095

0.0459 0.0570 0.0701 0.0855 0.1035 0.1244 0.1483 0.1757 0.2068

0.0524 0.0624 0.0742 0.0880 0.1042 0.1232 0.1454 0.1719 0.2025

0.0985 0.1245 0.1561 0.1941 0.2395 0.2932 0.3565 0.4305 0.5166 0.2660

0.1030 0.1263 0.1555 0.1919 0.2367 0.2911 0.3558 0.4315 0.5178 0.2434

= 0.0501

= 0.0999

= 0.1996

= 0.3001

= 0.3995

a

Standard uncertainties u are u(T) = 0.05 K, u(P) = 0.20 kPa, and relative standard uncertainty ur(x) = 0.1. x′: solute-free mole fraction of propan2-ol; u(x′) = 0.00045

for the propan-2-ol + water binary solvent system was 5.13 × 10−3, whereas that for the propan-2-ol + toluene binary solvent system was 0.68 × 10−3 at a solute-free mole fraction of 0.3995 and 0.097 of propan-2-ol, respectively.

3.4.4. Jouyban−Acree Model. The present study explores the effect of temperature as well as the solute-free mole fraction of the solvent in a mixture using two different hybrid models that correspond to a combination of the basic Jouyban−Acree F



Article

Table 4. Experimental (xexp) and Predicted (xcal) Mole Fraction Solubility of para-Methoxy Phenylacetic Acid in the Binary Mixture of Propan-2-ol + Toluene in the Temperature Range of 283.15 to 323.15 K at 94.9 kPaa xcal T/K

xexp

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0302 0.0385 0.0482 0.0588 0.0709 0.0904 0.1111 0.1385 0.1752

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0322 0.0428 0.0528 0.0635 0.0788 0.0986 0.1253 0.1595 0.2068

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0485 0.0533 0.0615 0.0734 0.0896 0.1106 0.1371 0.1694 0.2183

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0664 0.0780 0.0924 0.1100 0.1316 0.1584 0.1914 0.2322 0.2828

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0898 0.1058 0.1247 0.1473 0.1742 0.2061 0.2441 0.2893 0.3431

283.15 288.15 293.15 298.15 303.15 308.15 313.15

0.0844 0.0978 0.1167 0.1364 0.1625 0.1932 0.2280

van’t Hoff−Jouyban−Acree x′ 0.0283 0.0367 0.0471 0.0599 0.0756 0.0947 0.1177 0.1454 0.1785 x′ 0.0325 0.0414 0.0524 0.0658 0.0820 0.1015 0.1247 0.1522 0.1847 x′ 0.0410 0.0516 0.0644 0.0798 0.0981 0.1199 0.1456 0.1757 0.2109 x′ 0.0579 0.0717 0.0882 0.1078 0.1308 0.1577 0.1890 0.2252 0.2670 x′ 0.0778 0.0951 0.1154 0.1391 0.1667 0.1986 0.2352 0.2772 0.3250 x′ 0.0800 0.0969 0.1166 0.1395 0.1659 0.1962 0.2308


NRTL

0.0308 0.0376 0.0463 0.0573 0.0715 0.0898 0.1133 0.1437 0.1830

0.0346 0.0422 0.0513 0.0621 0.0751 0.0923 0.1126 0.1380 0.1699

0.0354 0.0429 0.0522 0.0640 0.0788 0.0975 0.1213 0.1514 0.1898

0.0339 0.0422 0.0519 0.0635 0.0788 0.0986 0.1250 0.1597 0.2067

0.0449 0.0538 0.0648 0.0784 0.0953 0.1165 0.1428 0.1758 0.2170

0.0439 0.0523 0.0626 0.0753 0.0912 0.1111 0.1363 0.1682 0.2133

0.0633 0.0750 0.0892 0.1066 0.1279 0.1540 0.1861 0.2255 0.2741

0.0638 0.0766 0.0920 0.1103 0.1325 0.1594 0.1922 0.2325 0.2820

0.0845 0.0990 0.1166 0.1377 0.1632 0.1941 0.2313 0.2765 0.3312

0.0871 0.1041 0.1241 0.1475 0.1750 0.2073 0.2452 0.2897 0.3420

0.0858 0.1001 0.1171 0.1375 0.1618 0.1908 0.2255

0.0821 0.0977 0.1162 0.1377 0.1631 0.1931 0.2282

= 0.0976

= 0.2029

= 0.3001

= 0.3993

= 0.5001

= 0.6012

G



Article

Table 4. continued xcal T/K

xexp

318.15 323.15

0.2682 0.3197

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

0.0761 0.0895 0.1057 0.1255 0.1494 0.1786 0.2141 0.2574 0.3051

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 overall RMSD × 102

0.0682 0.0815 0.0973 0.1160 0.1383 0.1649 0.1968 0.2350 0.2781

van’t Hoff−Jouyban−Acree x′ = 0.6012 0.2701 0.3146 x′ = 0.6995 0.0658 0.0810 0.0991 0.1204 0.1454 0.1745 0.2082 0.2470 0.2915 x′ = 0.8002 0.0725 0.0890 0.1084 0.1311 0.1577 0.1884 0.2239 0.2647 0.3112 1.0173


NRTL

0.2671 0.3169

0.2693 0.3189

0.0718 0.0846 0.1003 0.1193 0.1424 0.1706 0.2050 0.2471 0.2986

0.0746 0.0891 0.1062 0.1264 0.1503 0.1790 0.2136 0.2558 0.3060

0.0790 0.0929 0.1096 0.1299 0.1545 0.1843 0.2205 0.2645 0.3181 0.9573

0.0678 0.0813 0.0973 0.1162 0.1386 0.1652 0.1968 0.2344 0.2784 0.1840

a Standard uncertainties u are u(T) = 0.05 K, u(P) = 0.20 kPa, and relative standard uncertainty ur(x) = 0.1. x′: solute-free mole fraction of propan2-ol; u(x′) = 0.00045

where ji (i = 0−2) are the Jouyban−Acree model parameters, w1 and w2 are the solute-free mass fraction of the investigated solvent system, with the subscript 1 denoting propane-2-ol and 2 denoting water and toluene, respectively; xw,T is the mole fraction solubility of para-methoxyphenylacetic acid at temperature T (K), while x1,T and x2,T are the mole fraction solute solubilities in the individual pure solvents. The amalgamation of the van’t Hoff equation and eq 8, the van’t−Hoff Jouyban−Acree model,25,26 can be derived and expressed as eq 9 as follows i i B1 zy B2 zy zz + w2jjjA 2 + zz ln xw , T = w1jjjjA1 + z j T T /K /K z{ k { k 2 ww + 1 2 ∑ ji (w1 − w2)i T /K i = 0

where Ai, Bi, and ji are the model parameters obtained in the van’t Hoff−Jouyban−Acree model. Correspondingly, combining the modified Apelblat equation and the Jouyban−Acree model (eq 8), the Apelblat−Jouyban−Acree model25,26 is obtained as shown in eq 10.

Figure 3. Mole fraction solubility of para-methoxyphenylacetic acid in propane-2-ol + water binary mixed-solvent system. Experimental solubility: solute-free mole fraction of propane-2-ol (x′): 0.0501 (■), 0.0999 (●), 0.1996 (▲), 0.3001 (▼), and 0.3995 (◆). Solid lines () are calculated data by the NRTL model.

i y B1 ln xw , T = w1jjjjA1 + + C1 ln(T /K)zzzz T /K k { i y B2 + w2jjjjA 2 + + C2 ln(T /K)zzzz T /K k { 2 w1w2 + ∑ j (w1 − w2)i T /K i = 0 i

model with the van’t Hoff equation and the modified Apelblat equation, respectively, for the two binary solvent mixtures under consideration.24 The skeletal equation of the Jouyban−Acree model, which is relatively a universal model for describing the interactions in multicomponent mixtures, is described as eq 8.31 ln xw , T = w1 ln x1, T + w2 ln x 2, T +

w1w2 T /K

(9)

2

∑ ji (w1 − w2)i

(10)

where Ai, Bi, and Ci (i = 1, 2) and ji (i = 0, 1, 2) are the constants from the Apelblat−Jouyban−Acree model.

i=0

(8) H



Article

Figure 6. Mole fraction solubility of para-methoxyphenylacetic acid in propan-2-ol + toluene binary mixed-solvent system against mole fraction of propan-2-ol (x′) on solute-free basis at different temperatures: 283.15 (■), 288.15 (●), 293.15 (▲), 298.15 (▼), 303.15 (◆), 308.15 K (■), 313.15 (●), 318.15 (▲), and 323.15 K (▼).

Figure 4. Mole fraction solubility of para-methoxyphenylacetic acid in propane-2-ol + toluene binary mixed-solvent system. Experimental solubility: solute-free mole fraction of propane-2-ol (x′): (a) 0.0976 (■), 0.3001 (▲), and 0.3993 (▼); (b) 0.2029 (■), 0.5001 (◆), 0.6012 (▼), 0.6995(▲), and 0.8002 (●). Solid lines () are calculated data by the NRTL model.

Figure 7. PXRD analysis of para-methoxyphenylacetic acid (a) used in the present study and (b) recrystallized from toluene.

Figure 5. Mole fraction solubility of para-methoxyphenylacetic acid in propan-2-ol + water binary mixed-solvent system against mole fraction of propan-2-ol (x′) on solute-free basis at different temperatures: 283.15 (■), 288.15 (●), 293.15 (▲), 298.15 (▼), 303.15 (◆), 308.15 (■), 313.15 (●), 318.15 (▲), and 323.15 K (▼).

The values of the parameters derived by correlating the experimental solubility data of para-methoxyphenylacetic acid at the different temperatures using the van’t Hoff−Jouyban− Acree and the Apelblat−Jouyban−Acree models are enlisted in Table 7 for the two binary mixed-solvent systems. The predicted solubility of para-methoxyphenylacetic acid in the binary mixtures of propan-2-ol + water and propan-2-ol + toluene on the basis of these regressed parameters, along with the average RMSD, are also listed in Tables 3 and 4, respectively. It was evident from the RMSD values that for both the organic as well as the aqueous mixed-solvent systems a higher deviation was observed for the van’t Hoff−Jouyban− Acree mode than its Apelblat counterpart, with the highest RMSD being 10.17 × 10−3 for the propan-2-ol and toluene binary system. Thus among the three models investigated for pure solvents, the predicted solubility results based on NRTL model gave better fit to the experimental ones as compared with the modified Apelblat equation and λh equation. Likewise, for the mixed-solvent systems, the calculated solubility based on the NRTL model gave improved correlation results as compared with Apelblat−Jouban−Acree and van’t Hoff−Jouyban−Acree I



Article

Table 5. Parameters of the Different Models Used To Correlate Solubility Data of para-Methoxyphenylacetic Acid in Different Pure Solvents λh equation

modified Apelbat equation

NRTL equation

neat solvent

A

B

C

λ

H

τ12

τ21

propan-2-ol toluene morpholine acetonitrile anisole water

45.05 −77.13 −63.65 −63.34 −61.18 −76.47

−4159.23 −1.40 −0.94 −1.18 −1.22 −1.04

−5.75 12.94 10.51 10.65 10.25 12.46

0.43 0.17 0.05 0.20 0.15 1.98

4275.14 18593.12 41743.99 11724.42 14372.60 8210.97

6.04 2.03 4.09 6.73 7.76 86.50

−0.82 1.59 1.57 0.52 0.82 4.46

Table 6. Parameters of the NRTL Model Used To Correlate Solubility Data of para-Methoxy Phenylacetic Acid in Propan-2-ol + Water and Propan-2-ol + Toluene Binary System x′

τ12

τ21

0.0501 0.0999 0.1996 0.3001 0.3995

1.122 1.123 0.910 0.168 −1.901

−0.002 −0.002 −0.012 0.755 −0.354

0.0976 0.2029 0.3001 0.3993 0.5001 0.6000 0.6995 0.8002

0.906 1.254 1.122 0.538 0.196 −0.329 −0.175 0.426

1.021 0.565 −0.002 0.266 0.051 0.056 −0.174 0.370

τ13

τ31

Propan-2-ol + Water 1.847 2.130 1.845 2.125 1.109 2.019 0.443 2.016 0.827 −0.232 Propan-2-ol + Toluene 2.865 2.706 1.290 3.189 1.847 2.130 0.441 1.457 2.770 0.372 1.063 1.140 1.083 1.032 0.290 1.429

τ32

Α

−0.596 −0.561 −0.413 −0.222 −0.469

−0.712 −0.719 −0.561 −0.125 0.107

−0.585 −0.414 −0.414 −0.414 −0.585

18.603 18.595 −0.596 −0.335 0.161 0.182 0.177 −0.196

−2.802 −2.807 −0.712 −0.152 −0.014 0.124 0.070 −0.128

0.300 0.300 0.300 0.300 0.300 0.300 0.300 0.300

Also, on accounting for the ideal conditions for the solute, ΔmixHid is considered zero.33,34 Furthermore, the excess thermodynamic dissolution enthalpy of the solute was evaluated using the following equations using the excess Gibbs free energy that considers the nonideality of the system.35

equations. Also, Figures 2−4 illustrate that the computed solubility values with the NRTL model show an excellent goodness of fit with the experimental data. Thereby, it can be concluded that the NRTL model is much more reliable to be used to correlate the solubility of para-methoxy phenyl acid, the six pure solvents, and the two binary solvent systems investigated presently, probably owing to the prominent inclusion of the nonideality factor. 3.5. Dissolution Thermodynamic Functions of Solutions. The thermodynamic properties of the solute based on its dissolution in solutions provide vital information for designing the processes involving such components. Hence, to gain more powerful insight into the mechanism of dissolution of paramethoxyphenylacetic acid in different pure solvents and mixedsolvent systems, the thermodynamic functions of the solutions were evaluated. The dissolution enthalpy (ΔdH) conventionally varies according to the different intermolecular and intramolecular interactions.8,32 The enthalpy of dissolution(ΔdH) in the present study has been estimated using the following equation33 Δd M = Δmix M id + ΔfusM + ME + (ΔMA + ΔMB)

τ23

ÅÄÅ G E ÑÉÑ ÅÅ ∂ ÑÑ Ñ H = − T ÅÅ T ÑÑÑÑ ÅÅ ∂T ÑÑ ÅÅ ÑÑ ÅÇ ÑÖ E

ÅÅ 2Å

n ji zy GE = RT jjjj∏ xi ln γizzzz j z k i=1 {

(12)

(13)

Tables 8−10 sequentially report the values of dissolution enthalpy change for the dissolution process of para-methoxyphenylacetic acid in the six selected neat solvents and the two binary mixtures, respectively. Because all of the values of the dissolution enthalpies were non-negative, it clearly indicated that each solvation process was endothermic. Interestingly, the enthalpy values for the neat solvent systems were higher compared with the mixed-solvent systems of propan-2-ol + water but lower in certain cases for the propan-2-ol + toluene primarily attributed to the excess energy required to break the cohesive bonds between the solute and the particular solvent, indicating a strong temperature effect on dissolution of para-methoxyphenylacetic acid in the pure solvents and the binary mixture of propan-2-ol + toluene.

(11)

where M represents the desired enthalpy of dissolution. ΔmixMid is the mixing property of an ideal solution, ME is the excess property, and ΔfusM is the thermodynamic property of fusion of solute, ΔMA is the change of thermodynamic property of the heating process, and ΔMB is the change of thermodynamic property of the cooling process. The values of thermodynamic functions of fusion of solute are much greater than the sum (ΔMA + ΔMB) and thereby can be considered negligible.

4. CONCLUSIONS In this work, the SLE of para-methoxyphenylacetic acid was measured in six neat solvents: water, acetonitrile, propan-2-ol, J



Article

Table 7. Parameters of the Different Jouyban−Acree Models Used To Correlate Solubility Data of para-Methoxy Phenylacetic Acid in Propan-2-ol + Water and Propan-2-ol + Toluene Binary System propan-2-ol + water van’t Hoff−Jouyban−Acree

propan-2-ol + toluene


van’t Hoff−Jouyban−Acree


parameter

value

parameter

value

parameter

value

parameter

value

A1 B1 A2 B2 J0 J1 J2

36.23 −270644.53 5.89 −3554.82 530343.48 448443.78 197395.54

A1 B1 C1 A2 B2 C2 J0 J1 J2

−211.77 −1426.68 37.92 74.73 −6338.07 −10.42 57581.53 149906.15 111664.92

A1 B1 A2 B2 J0 J1 J2

7.028 −4358.13 12.01 −4537.28 3761.76 4396.77 3625.76

A1 B1 C1 A2 B2 C2 J0 J1 J2

−109.75 1008.88 17.32 −353.59 12035.83 54.40 3822.01 4433.00 3608.41

Table 8. Dissolution Properties of para-Methoxyphenyl Acetic Acid in Different Pure Solventsa ΔdH (kJ·mol−1) T/K

propan-2-ol

toluene

morpholine

acetonitrile

anisole

water

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

28.93 29.18 29.44 29.71 29.97 30.25 30.52 30.80 31.09

22.52 22.54 22.57 22.60 22.62 22.65 22.68 22.71 22.73

22.14 22.15 22.16 22.17 22.18 22.20 22.21 22.22 22.24

23.24 23.29 23.35 23.40 23.45 23.51 2356 23.62 23.68

22.28 22.29 22.31 22.33 22.35 22.37 22.39 22.41 22.43

22.28 22.88 22.92 22.95 22.99 23.03 23.07 23.11 23.16

a

Combined standard uncertainties u are uc(ΔdH) = 0.065ΔdH.

Table 9. Dissolution Properties of para-Methoxyphenyl Acetic Acid in the Binary Mixture of Propan-2-ol + Watera ΔdH (kJ·mol−1) T/K

x′ = 0.0501

x′ = 0.0999

x′ = 0.1996

x′ = 0.3001

x′ = 0.3995

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

22.75 22.79 22.83 22.86 22.89 22.94 22.97 23.01 23.05

22.95 22.99 23.02 23.07 23.11 23.15 23.20 23.25 23.29

22.64 22.67 22.70 22.73 22.76 22.79 22.83 22.86 22.89

20.09 20.03 19.97 19.91 19.84 19.78 19.71 19.64 19.57

19.75 19.67 19.60 19.52 19.45 19.37 19.29 19.21 19.13

a


Table 10. Dissolution Properties of para-Methoxyphenyl Acetic Acid in the Binary Mixture of Propan-2-ol + Toluenea ΔdH (kJ·mol−1) T/K

x′ = 0.0976

x′ = 0.2029

x′ = 0.3001

x′ = 0.3993

x′ = 0.5001

x′ = 0.6012

x′ = 0.6995

x′ = 0.8002

283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15

40.62 41.29 41.98 42.67 43.78 44.09 44.82 45.56 46.32

31.27 31.60 31.95 32.29 32.65 33.01 33.38 33.75 34.13

24.46 24.56 24.66 24.76 24.86 24.96 25.06 25.17 25.27

20.87 20.84 20.80 20.77 20.73 20.69 20.66 20.62 20.58

31.81 32.17 32.53 32.90 33.28 33.66 34.04 34.44 34.84

23.64 23.70 23.78 23.84 23.91 23.98 24.05 24.12 24.20

21.01 20.99 20.96 20.93 20.89 20.87 20.84 20.81 20.78

21.62 21.62 21.61 21.60 21.59 21.59 21.58 21.58 21.57

a


morpholine, toluene, and anisole and two binary mixture systems of propan-2-ol + water/toluene from 283.15 to 323.15

K. The thermal analysis of the pure solute was conducted using a differential scanning calorimeter to estimate the fusion K



Article

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temperature and enthalpy that supplemented the modeling of the SLE data. Although the solubility of para-methoxyphenylacetic acid increased with the increase in temperature for all of the investigated cases, it decreased with the solute-free mole fraction of propan-2-ol from 0.5001 for the propan-2-ol + toluene mixed-solvent system. The models applied to correlate the experimental solubility data (modified Apelblat equation, the λh (Buchowski) equation, hybrid Jouyban−Acree models, and NRTL) were all suitable, although the NRTL model could predict the SLE most accurately. Furthermore, the thermodynamic dissolution property was investigated that revealed the dissolution process to be endothermic. Thereby, the newly reported solubility data for para-methoxyphenylacetic acid would aid the design of its purification operation in industries.

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AUTHOR INFORMATION

Corresponding Authors

*Tel: +91 040 27191399/3141. Fax: +91 04027193626 1. E-mail: [email protected] (B.S.). *Tel: +61 3 9925 0956. Fax: +61 3 9925 0956 2. E-mail: [email protected] (M.P.S.). ORCID

Vineet Aniya: 0000-0003-2446-2894 Bankupalli Satyavathi: 0000-0002-8495-317X Notes

The authors declare no competing financial interest.

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