Kirkwood–Buff Integrals, Excess Volume, and Preferential Solvation in

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

Kirkwood−Buff Integrals, Excess Volume, and Preferential Solvation in Pentanoic Acid/(C5−C10) 1‑Alkanol Binary Mixtures Mohammad Almasi* Department of Applied Chemistry, Faculty of Science, Malayer University, Malayer 65174, Iran

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S Supporting Information *

ABSTRACT: In order to study the nature, type, and magnitude of interactions in the binary mixtures of pentanoic acid and a series of 1-alkanol from 1pentanol up to 1-decanol, Kirkwood integrals along with the experimental methods have been used and reported at T = 298.15 K. Negative values of VEm, Gii, Gij, Δnii, Δnij, and δii and positive values of Gij, Δnij, and δij indicate the fact that in the mixtures the tendency of the unlike molecular components to form the new interactions and stay together is much higher than the pure state. Investigating the changes in the calculated quantities for different mixtures shows that with the increase in the length of the alcoholic chain the tendency of the heterogeneous molecules to interact with each other decreases. Variations in the VEm values are in the same direction as the Kirkwood integrals, and mentioned data for binary systems are reported for the first time.

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on the alcohol binary mixtures,4,5and as far as we know no study on the volumetric behavior or Kirkwood−Buff formalism for these binary mixtures has been reported yet.

INTRODUCTION In recent years, the study of the thermodynamic properties of liquid mixtures and linking them to the microscopic structure, particularly with local deviations from the bulk composition, has become very popular and interesting. Usually these studies that are known as fluctuations in the composition are common subjects in statistical mechanics. There are two pathways to test these fluctuations in the binary mixtures: (1) investigate the fluctuations in the number of molecules N1 and N2 and the cross fluctuations and (2) consider the fluctuations in the molecule number, regardless of the components and cross fluctuations. The first method is the subject of the Kirkwood− Buff integral.1,2 In this theory, there is an important quantity called pair correlation functions gij which measure the extent of correlation and direction of the pair of molecules i and j. This parameter that connects the microscopic structures to the macroscopic behavior of the mixtures can be derived from experimental measurements, and by combining with the values of activity coefficients, compressibility data, and density, preferential solvation δ for liquid mixtures is obtained. In the Kirkwood−Buff theory, the main focus is on the Gij integrals, and by calculating this parameter, values of excess or deficit number of molecules around a central molecule Δnij are determined. In this article, with the aim of discovering the favorite interactions between pentanoic acid and 1-alkanol binary mixtures, values of VEm, Gij, Δnij, and δij have been calculated. The considered alcohols are 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, and 1-decanol. Necessary information for calculation of the mentioned parameters such as isothermal compressibility and density was obtained experimentally, and the modified UNIFAC (Dortmund) model3 was applied to estimate the activity coefficients of mixtures. This paper is the continuation of our earlier studies © XXXX American Chemical Society

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EXPERIMENTAL SECTION Pentanoic acid and all 1-alkanols from 1-pentanol up to 1decanol (>99%, mass fraction) were supplied by Merck and used from an unopened bottle without further purification. A sample description of pure materials is reported in Table 1. A Table 1. Sample Description of Pure Materials chemical name pentanoic acid 1-pentanol 1-hexanol 1-heptanol 1-octanol 1-nonanol 1-decanol

source

CAS number

initial mass fraction purity (as stated by the supplier)

purification method

Merck

109-52-4

0.995

-

Merck Merck Merck Merck Merck Merck

71-41-0 111-27-3 111-70-6 111-87-5 143-08-8 112-30-1

0.995 0.995 0.995 0.996 0.997 0.995

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fully automatic apparatus, namely, an SVM 3000 Anton-Paar Stabinger viscometer, has been used to measure the density. The device, which operates by the modified Couette principle, contains a rapid rotating outer tube and an inner measuring bob which rotates more slowly. Because the density values are very sensitive to temperature, they are controlled by a built-in Received: December 11, 2018 Accepted: February 4, 2019

A

DOI: 10.1021/acs.jced.8b01189 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

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dependence of κT on composition is not known for investigated binary mixtures, and values of RTκT have a small contribution to the KB integrals. So, the dependence of κT on the composition is approximately calculated by the linear relation from the pure components

thermoelectric thermostat. Every day and before each series of measurements, the apparatus is calibrated using doubly distilled water and dry air. For measuring the density, the mixtures are provided precisely before use by mass on an analytical balance (Mettler AE 163, Switzerland) with the precision of ±0.01 mg. At first, the liquid with low volatility is prepared, and the maximum of cautions are taken to prevent evaporation of the samples. To provide each mixture, ten compositions were prepared, and their physical properties in the range of mole fraction were measured. For density measurements, the expanded uncertainty was 1 × 10−3 g· cm−3. The uncertainty in the mole fraction is estimated to be ±1 × 10−3. In Table 2, values of measured densities for pure materials are reported alongside the scientific literature.6−12

κT = κT0,1φ1 + κT0,2φ2

(5)

where ϕi is the volume fraction and κ0T,i is the isothermal compressibility for the pure state and were obtained from the literature. Parameter D is defined as ij ∂ 2GE yz ij ∂ ln γi yz zz D = RT + xixjjjj 2 zzz = 1 + xijjj j ∂x z j ∂xi zz k {T , P k l {T , P

(6)

To calculate D, we also need G or γi. In this paper, the γ values and its derivations were evaluated by the modified UNIFAC model. Details of this method are explained elsewhere3 and in the absence of experimental data are a useful technique. KBIs are very sensitive to experimental uncertainties, and the main sources are mathematical differentiation to derive the D (eq 6) and calculation of the partial molar volumes. The uncertainty in the activity coefficients has a pronounced effect on the D and KBI values. In summary, accurate and thermodynamically consistent activity coefficients should be applied. For example, the thermodynamic stability condition inflicts that the D function must be always positive, and the negative D values may arise when the low-precision VLE data are available. When the D values are close to zero, the systems are in the boundary of the phase separation. In short, obtaining the accurate KBIs depends on the proper choice of the VLE and molar excess volumes, and when the experimental data of VLE are not available, the UNIFAC13 method for calculation of activity coefficients is proposed. Also, by linking the KB integrals to the parameter Δnij, named the excess (or deficit) number of i and j molecules around a central molecule i, useful information about the structure of liquid at the microscopic level is obtained. E

Table 2. Densities, ρ, of Pure Components at T = 298.15 K and Pressure p = 0.1 MPaa ρ (g·cm−3) chemical name

exptl.

lit.

pentanoic acid 1-pentanol 1-hexanol 1-heptanol 1-octanol 1-nonanol 1-decanol

0.9351 0.8108 0.8151 0.8187 0.8214 0.8240 0.8261

0.93485b 0.81073c 0.8148d 0.81879e 0.82181f 0.82448g 0.8265h

a

Standard uncertainties are u(T) = 0.02 K, u(x) = 0.001, and u(p) = 10 kPa, and the expanded uncertainty for density is U(ρ) = 0.001 g· cm−3. bRef 6. cRef 7. dRef 8. eRef 9. fRef 10. gRef 11. hRef 12.

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THEORY In the Kirkwood−Buff (KB) theory, the thermodynamic behavior of mixtures over the whole range of concentrations is described by the radial distribution function gij. This parameter expresses the probability of finding the molecule i at a distance r from the center of j species and provides the microscopic information of mixtures to describe their macroscopic behavior. Gij =

∫0

∞

[gij(r ) − 1]4πr 2dr

Δn12 = c1ΔG12 = − Δn21 = c 2ΔG21 = −

(1)

Positive values of Gij (Gij > 0) mean the attractive interactions between i and j species, while the negative values Gij suggest the interactions of i−i and j−j types are preferred.13 The mentioned integrals may be derived from experimental data such as isothermal compressibility, density, and activity coefficient. The final equations are G12 = G21 = RTκT −

V1̅ V2̅ VD

Δnii = ciiΔGii = −

x 2 V2̅ 2 V − x1 VD x1

(3)

G22 = RTκT +

x1 V1̅ 2 V − x 2 VD x2

(4)

(7)

c 2V1V2 ij 1 − D yz jj zz V k D {

cixjV j2 i 1 − D y jj zz j z xiV k D {

(8)

i≠j

(9)

Furthermore, for consideration of enlargement of solute size and deviation of solvents from the ideal behavior, values of preferential solvation parameter δij were calculated as

(2)

G11 = RTκT +

c1V1V2 ji 1 − D zy jj zz V k D {

δij = xixj(Gij − Gjj)

(10)

δii = xixj(Gii − Gij)

(11)

The quantity (Gij − Gjj) measures the difference between the affinities of the component j toward itself and i species; therefore, δij gives the sign of the real preferential solvation, and the main advantage is that it avoids the correlation volume. In fact, this parameter indicates the changes of local mole fractions of i species around the central j molecule and depends on the two main factors: the differences in the molecular sizes and the energy of intermolecular interactions. The δij values satisfy13 the obvious relation ∑δij = 0.

where xi is the molar fraction of component i; v̅i is the partial molar volume of the i component; R is the gas constant; κT is the isothermal compressibility; ci is the molar concentration of species i in the mixture; and T is the absolute temperature. The B

DOI: 10.1021/acs.jced.8b01189 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Table 3. Densities ρ for Binary Mixtures of Pentanoic Acid with 1-Alkanol at T = 298.15 K and Pressure p = 0.1 MPaa pentanoic acid (1) + 1-pentanol (2) ρ (g·cm−3)

x1 0 0.0807 0.1596 0.2398 0.3501 0.4401 0.5604 0.6498 0.7399 0.8498 0.9396 1

pentanoic acid (1) + 1-hexanol (2) x1

pentanoic acid (1) + 1-heptanol (2)

ρ (g·cm−3)

x1

0.8151 0.8254 0.8352 0.8451 0.8586 0.8695 0.8839 0.8945 0.9050 0.9178 0.9282 0.9351

0 0.0812 0.1601 0.2400 0.3506 0.4398 0.5605 0.6496 0.7405 0.8501 0.9405 1

0.8108 0 0.8214 0.0924 0.8319 0.1783 0.8424 0.2640 0.8567 0.3796 0.8682 0.4718 0.8831 0.5914 0.8940 0.6785 0.9047 0.7639 0.9176 0.8656 0.9281 0.9468 0.9351 1 pentanoic acid (1) + 1-nonanol (2)

ρ (g·cm−3)

pentanoic acid A (1) + 1-octanol (2) ρ (g·cm−3)

x1

0.8187 0 0.8265 0.0809 0.8343 0.1604 0.8425 0.2392 0.8542 0.3496 0.8640 0.4399 0.8778 0.5605 0.8885 0.6497 0.8997 0.7401 0.9141 0.8504 0.9265 0.9403 0.9351 1 pentanoic acid (1) + 1-decanol (2)

x1

ρ (g·cm−3)

x1

ρ (g·cm−3)

0 0.0802 0.1604 0.2394 0.3496 0.4397 0.5605 0.6497 0.7401 0.8502 0.9403 1

0.8240 0.8300 0.8361 0.8428 0.8525 0.8612 0.8739 0.8843 0.8956 0.9110 0.9250 0.9351

0 0.0809 0.1598 0.2406 0.3493 0.4405 0.5601 0.6502 0.7406 0.8504 0.9411 1

0.8261 0.8314 0.8370 0.8430 0.8520 0.8602 0.8723 0.8825 0.8939 0.9096 0.9242 0.9351

0.8214 0.8282 0.8351 0.8424 0.8530 0.8623 0.8755 0.8861 0.8974 0.9124 0.9257 0.9351

Standard uncertainties are u(T) = 0.02 K, u(x) = 0.001, and u(p) = 10 kPa. Expanded uncertainty for density is U(ρ) = 0.001 g·cm−3

a

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RESULTS AND DISCUSSION The required parameters of pure chemicals for calculation of the KB integrals such as isobaric thermal expansion coefficient, isothermal compressibility, and molar volume at T = 298.15 K are gathered in the SI, Table S1.5,14,15 In Table 3, values of densities for the binary systems are presented. Calculated values for Gij, Gii, Gjj, Δnii, Δnjj, and Δnij as a function of mole fraction for pentanoic acid + 1-alkanol mixtures are shown in Table S2, and in Table S3, linear coefficients of preferential solvation, δij, and excess molar volumes, VEm, are depicted. It is noteworthy that four local compositions in a binary mixture composed of spices 1 and 2 should be considered: x11 and x21 are the local mole fractions of components 1 and 2 near a central molecule 1, and x12 and x22 are the local mole fractions of components 1 and 2 near a central molecule 2.16 Values of Gij for all six studied binary mixtures in the whole range of composition are positive, while Gii and Gjj are negative. Positive values of Gij show the tendency of species 1 to remain or react to the species 2, and the dominant forces are of attraction type in the mixtures. Negative values of Gii and Gjj are indicative of this fact that the molecules 1 and 2 in the mixture tend not to stay alongside the similar molecules. In other words, the strong interactions between i and j molecules (unlike molecules) in the mixtures occur comparing the interactions in the pure states. The Gij values for the binary mixtures show the algebraic relation

The relation shows that at a given pentanoic acid, replacement of the 1-pentanol molecule with the greater size alcohol (1hexanol up to 1-decanol) leads to a decrease of G12 due to the formation of weaker acid−alcohol interactions, and the strongest interactions occur in the pentanoic acid + 1-pentanol mixture. Figures 1 to 3 graphically present the G12, G11, and G22 calculations for all binary mixtures at T = 298.15 K. Values of excess or deficit alcohol molecules around the pentanoic acid molecule Δn21 depict that this quantity is positive for mixtures, and there are unlike molecules around the central acid molecules in the mixtures. Comparison of peaks of Δn21 display this relation Δn21PA + 1‐pentanol > Δn21PA + 1‐hexanol > Δn21PA + 1‐heptanol > Δn21PA + 1‐octanol > Δn21PA + 1‐nonanol > Δn21PA + 1‐decanol

The above relation shows that around the central molecule of pentanoic acid the highest number of alcohol molecules is 1pentanol, and by increasing the chain length of 1-alkanol, the number of alcohol molecules around the central acid decreases, so that the smallest amount of alcohol is 1-decanol. An increase in the length of the alkyl group of 1-alkanol from 1pentanol to 1-decanol reduces the Δn21 values and interactions between the unlike molecules in the mixtures. In the binary mixtures, pentanoic acid molecules are most commonly rounded by 1-pentanol molecules and less commonly with 1decanol. Also we calculated the excess or deficit pentanoic acid molecules around the central alcohol Δn21, and for all binary

G12 PA + 1‐pentanol > G12 PA + 1‐hexanol > G12 PA + 1‐heptanol > G12 PA + 1‐octanol > G12 PA + 1‐nonanol > G12 PA + 1‐decanol C

DOI: 10.1021/acs.jced.8b01189 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Figure 1. Comparisons of G12 values as a function of mole fraction for pentanoic acid + 1-alkanol at T = 298.15 K.

Figure 3. G22 for the pentanoic acid (1) + 1-alkanol (2) mixtures as a function of mole fraction at T = 298.15 K.

Furthermore, the calculation of Δn22 and Δn11 for all mentioned mixtures indicates that these parameters are negative, and their maximum belongs to the pentanoic acid + 1-decanol and the minimum to the pentanoic acid + 1pentanol binary system. The process of changing these parameters shows that the highest interaction of pentanoic acid in the mixtures is with 1-pentanol molecules, and an increase in the number of carbons of the alcohol chain weakens the interactions. In other words, around the 1-pentanol central molecule, the minimum number of similar molecules exists and is more closely surrounded by the pentanoic acid. By increasing the length of alcohol, similar molecules around the central alcohol increase, and the unlike interactions decrease. Values of Δn12 and Δn11 for binary mixtures are shown in Figures 4 and 5. In order to confirm the above views on the occurred interactions, and to study more deeply about the mentioned liquid systems, values of linear coefficients of preferential solvation, δij, were also calculated. δ21 and δ12 are positive for the whole binary mixtures and show that both pentanoic acid and alcohol molecules tend to dissolve in each other’s atmosphere. Comparison of δ21 for binary systems indicates the relation

Figure 2. G11 for the pentanoic acid (1) + 1-alkanol (2) mixtures as a function of mole fraction at T = 298.15 K.

δ21PA + 1‐pentanol > δ21PA + 1‐hexanol

mixtures, positive values similar to Δn21 were obtained as follows

> δ21PA + 1‐heptanol > δ21PA + 1‐octanol > δ21PA + 1‐nonanol > δ21PA + 1‐decanol

Δn12 PA + 1‐pentanol > Δn12 PA + 1‐hexanol

The above relation along with the obtained values for δ12, δ11, and δ22 propose that the preferential solubility of pentanoic acid molecules is in the 1-pentanol atmosphere, and the increase in the alkyl chain of alcohols reduces the amount of

> Δn12 PA + 1‐heptanol > Δn12 PA + 1‐octanol > Δn12 PA + 1‐nonanol > Δn12 PA + 1‐decanol D

DOI: 10.1021/acs.jced.8b01189 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Figure 4. Δn21 for pentanoic acid (1) + 1-alkanol (2) mixtures in the vicinity of pentanoic acid molecules at T = 298.15 K.

Figure 6. δ12 for pentanoic acid (1) + 1-alkanol (2) mixtures in the vicinity of alcohol molecules at T = 298.15 K.

less than the pure state. The mixture volume is smaller than the pure form. This behavior is shown graphically in Figure 7. The

Figure 7. Excess molar volume, VEm, versus the mole fraction x1 of pentanoic acid with (□) 1-pentanol, (●) 1-hexanol, (■) 1-heptanol, (▲) 1-octanol, (Δ) 1-nonanol, and (○) 1-decanol at T = 298.15 K. Solid lines (−) are Redlich−Kister equation.

Figure 5. Δn11 for pentanoic acid (1) + 1-alkanol (2) mixtures in the vicinity of pentanoic acid molecules at T = 298.15 K.

negative values of VEm fall in the order: 1-pentanol > 1-hexanol > 1-heptanol > 1-octanol > 1-nonanol > 1-decanol. The negative VEm values confirm the idea that specific interactions through the hydrogen bond formation among the mixture components are stronger than the interactions of both alcohol and pentanoic acid in the pure state. When the chain length of the alcohol increases, the hydrophobic character of the 1alkanol amplifies, and the interactions between unlike molecules weaken, resulting in the increase of VEm. In alcohols

dissolution. Figure 6 indicates the δ12 values for pentanoic acid + 1-alkanol at T = 298.15 K. On the other hand, the excess molar volumes, VEm, for binary mixtures were calculated and fitted by the Redlich−Kister17 polynomial, and the values of adjustable parameters along with the standard deviations are reported in SI, Table S4. VEm for pentanoic acid + 1-alkanol is negative, and the molecular distances in the liquid solutions are E

DOI: 10.1021/acs.jced.8b01189 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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nitrate ionic liquid and alcohols at 298.15 K. J. Mol. Liq. 2019, 275, 122−125. (5) Almasi, M.; Daneshi, R. Investigation of Molecular Interactions in Binary Mixtures of n-Butyl Acetate and (C6 − C10) 1-Alkanol: PCSAFT Model. J. Chem. Eng. Data 2018, 63, 3881−3888. (6) Bahadur, I.; Singh, S.; Deenadayalu, N.; Naidoo, P.; Ramjugernath, D. Influence of alkyl group and temperature on thermophysical properties of carboxylic acid and their binary mixture. Thermochim. Acta 2014, 590, 151−159. (7) Yang, C.; Lai; Liu; Ma, P. Density and Viscosity of Binary Mixtures of Diethyl Carbonate with Alcohols at (293.15 to 363.15) K and Predictive Results by UNIFAC-VISCO Group Contribution Method. J. Chem. Eng. Data 2006, 51, 1345−1351. (8) Baltazar, A.; Bravo-Sanchez, M.; Iglesias-Silva, G.; Javier Alvarado, J.; Castrejon-Gonzalez, E.; Ramos-Estrada, M. Densities and viscosities of binary mixtures of n-decane + 1-pentanol, + 1hexanol, + 1-heptanol at temperatures from 293.15 to 363.15 K and atmospheric pressure. Chin. J. Chem. Eng. 2015, 23, 559−571. (9) Cao, X.; Qin, X.; Wu, X.; Guo, Y.; Xu, L.; Fang, W. Density, Viscosity, Refractive Index, and Surface Tension for Six Binary Systems of Adamantane Derivatives with 1-Heptanol and Cyclohexylmethanol. J. Chem. Eng. Data 2014, 59, 2602−2613. (10) Coquelet, C.; Valtz, A.; Richon, D.; de la Fuente, J. Volumetric properties of the boldine + alcohol mixtures at atmospheric pressure from 283.15 to 333.15K. A new method for the determination of the density of pure boldine. Fluid Phase Equilib. 2007, 259, 33−38. (11) Zorebski, E.; Lubowiecka-Kostka, B. Thermodynamic and transport properties of (1,2-ethanediol + 1-nonanol) at temperatures from (298.15 to 313.15) K. J. Chem. Thermodyn. 2009, 41, 197−204. (12) Faria, M.; deSa, C.; Lima, G.; Filho, J.; Martins, R.; Cardoso, M.; Barcia, O. Measurement of Density and Viscosity of Binary 1Alkanol Systems (C8-C11) at 101 kPa and Temperatures from (283.15 to 313.15) K. J. Chem. Eng. Data 2005, 50, 1938−1943. (13) Gonzalez, J. A.; de la Fuente, I. G.; Mozo, I.; Cobos, J. C.; Riesco, N. Thermodynamics of Organic Mixtures Containing Amines. VII. Study of Systems Containing Pyridines in Terms of the Kirkwood Buff Formalism. Ind. Eng. Chem. Res. 2008, 47, 1729−1737. (14) Vong, W.; Tsai, F. Densities, Molar Volumes, Thermal Expansion Coefficients, and Isothermal Compressibilities of Organic Acids from 293.15 to 323.15 K and at Pressures up to 25 MPa. J. Chem. Eng. Data 1997, 42, 1116−1120. (15) Diaz Pena, M.; Tardajos, G. Isothermal compressibilities of n-lalcohols from methanol to I-dodecanol at 298.15, 308.15, 318.15, and 333.15 K. J. Chem. Thermodyn. 1979, 11, 441−445. (16) Ruckenstein, E.; Shulgin, I. Hydrophobic self-assembling in dilute aqueous solutions of alcohols and hydrocarbons. Chem. Eng. Sci. 2001, 56, 5675−5680. (17) Redlich, O. J.; Kister, A. T. Thermodynamic of nonelectrolyte solutions: algebraic representation of thermodynamic properties and the classification of solutions. Ind. Eng. Chem. 1948, 40, 345−348. (18) Chandraiah, T.; Karlapudi, S.; Govinda, V.; Sreedhar, N. Y.; Bahadur, I. Effect of alkyl group of 1-alkanol on molecular interactions of ethanoic acid mixtures: FT-IR spectroscopic and volumetric studies. J. Mol. Liq. 2018, 255, 354−363.

with higher chain length, the relative volume contributions of the polar OH versus the nonpolar alkyl chain for the alcohols decrease, and the excess molar volumes increase. A similar study18 was performed on the interactions between the ethanoic acid and different chain length 1-alkanol. The results in this paper demonstrate that an increase of carbon chain of alcohols causes a decrease of molecular interactions in binary mixtures and increase in the excess molar volumes. In general, from the calculation of KB integrals as well as the preferential solvation and excess molar volumes for all systems, we conclude that at a given pentanoic acid molecule increasing the number of CH2 in alcohols decreases the Gij, Δnij, and δ12 which means that the affinity between the two components and preferential solvation drops when the alkanol chain length increases.

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CONCLUSIONS With the aim of gaining new insights into the nature and type of molecular interactions that occur in the binary mixtures pentanoic acid + 1-alkanol, excess molar volume, Kirkwood− Buff integrals, and preferential solvation were calculated. Implementation of KB theory to the binary systems shows that the mixture structure is governed by the strong interactions, especially in the pentanoic acid + 1-pentanol mixture. G12 is positive for all mixtures and decreases with an increase in the methylene group of alcohols by the following sequence: G12 PA + 1-decanol < G12 PA + 1-nonanol < G12 PA + 1-octanol < G12 PA + 1-heptanol < G12 PA + 1-hexanol < G12 PA + 1-pentanol. Also for VEm values and preferential solvation, the same results were investigated. In the mixtures, at a given pentanoic acid, replacement of a long chain alcohol by a short chain leads to the strengthening of the hydrogen bonds formed.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.8b01189. Pure parameters required for KB integrals, linear coefficients of preferential solvation, and excess molar volumes (PDF)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel.: + 98-813-2355381. ORCID

Mohammad Almasi: 0000-0001-9771-8702 Notes

The author declares no competing financial interest.

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REFERENCES

(1) Almasy, L.; Jancso, G. Small-angle neutron scattering and Kirkwood−Buff integral study of aqueous solutions of pyridine. J. Mol. Liq. 2004, 113, 61−66. (2) Marcus, Y. Preferential solvation in mixed solvents. Completely miscible aqueous co-solvent binary mixtures at 298.15 K. Monatsh. Chem. 2001, 132, 1387−1411. (3) Gmehling, J.; Lohmann, J.; Jakob, A.; Li, J.; Joh, R. A modified UNIFAC (Dortmund) model. 3. Revision and Extension. Ind. Eng. Chem. Res. 1998, 37, 4876−4882. (4) Heydarian, S.; Almasi, B.; Saadati, Z. Calculation of KirkwoodBuff integrals for binary mixtures of 1-butyl-3-methylimidazolium F

DOI: 10.1021/acs.jced.8b01189 J. Chem. Eng. Data XXXX, XXX, XXX−XXX