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

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Densities and Volumetric Properties of Aqueous Solutions of {Water (1) + N‑Methylurea (2)} Mixtures at Temperatures of 274.15−333.15 K and at Pressures up to 100 MPa Gennadiy I. Egorov* and Dmitriy M. Makarov G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo, 153045, Russia S Supporting Information *

ABSTRACT: Densities of the mixture {water (1) + N- methylurea (2)} in the concentration range to mole fraction x2 = 0.07071 (or to the solution molality concentration m2 = 4.22335 mol·kg−1) at atmospheric pressure in the temperature range from 274.15 to 333.15 K and compression k = ΔV/V0 at pressures to 100 MPa (10, 25, 50, 75, and 100) in the temperature range from 278.15 to 323.15 K (278.15, 288.15, 288.15, 308.15, 323.15) in the same concentration range were calculated in this study. The apparent molar volumes of N-methylurea Vϕ,2 and the partial molar volumes of both components V̅ 1 and V̅ 2 in the mixture, molar isothermal compressibilities KT,m, molar isobaric thermal expansions EP,m, and isochoric coefficients of thermal pressure β of the mixture were calculated. Moreover, volumetric measures for the infinitely dilute solution of N-methylurea solution were calculated: limiting partial molar volumes V̅ ∞ 2 , the limiting partial molar isothermal compres∞ sibilities K̅ ∞ T,2, and the limiting partial molar isobaric thermal expansions E̅ P,2. The results obtained are discussed from the point of view of solute−solvent and solute−solute interactions.

1. INTRODUCTION Urea has been known for many years as a protein-denaturizing substance, and the mechanism of its impact on protein hydration is still not understood completely. Even hydration of separate urea in water remains unexplained so far despite the large number of theoretical1−18 and experimental studies.9−43 It was supposed that either the interaction between urea and the protein molecule occurs directly in a solution, or this impact on the macromolecule stability is performed through its hydration shell, that is, through changing the structure of water which surrounds protein. So, the comprehensive study of solutions of alkyl derivatives of urea will contribute to clarifying this issue. If it confirms that the influence of urea on protein occurs through its hydration shell, in this case, the urea alkyl derivatives at refolding the denaturized proteins may be more efficient under some conditions. The implication is that changes of the solvent structural properties in the presence of urea and its derivatives1,14,15,20−28,32,38,43 represent the fundamental importance in understanding the protein denaturation process.3,7,13−15,44 The previous results of the studies of water and urea interaction are contradictory so far; some of them are interpreted to suppose that urea may be included into the water structure without disturbing it, as a “water-like” molecule.45,46 Meanwhile, the conclusions of the other studies consider the impact of urea on water as a “structure breaker”,47−49 or, on the contrary, “structure maker”.11,50 The third of them suppose that urea has zero impact on the nature of water hydrogen bonds.51,52 Studying the bulk properties of its alkyl derivatives will help to clarify the features of intermolecular interaction in urea aqueous solution. © XXXX American Chemical Society

Volume properties are frequently used for understanding the system packaging and intermolecular interaction in liquid solutions due to their sensitivity to the entire spectrum of solvent− solvent, solvent−solute, and solute−solute interactions.53−56 Volume properties of urea aqueous solutions and its alkyl derivatives were studied earlier20−28,32,38,43,57−62 and for single atmospheric pressure only. All these studies were conducted in conditions, where concentration, temperature, alkyl group length, and the number of these groups were the variables. Water + N-methylurea (MU) mixtures were studied only in the papers,19,24,25,57,61 they represented densities in the interval of MU very low concentrations with the purpose to calculate the limiting partial molar volumes. Herskovits and Kelly19 Ogawa et al.,57 and Akers and Gabler61 have carried out the measurements only at the sole temperature of 298.15 K, and they have presented only standard (at infinite dilution) molar volumes. Singh and Kumar25 measured the density at three temperatures (293.15, 298.15, and 303.15 K) whereas Krakowiak et al.24 measured at five temperatures (288.15, 293.15, 298.15, 303.15, and 308.15 K). This study focuses on the examination of the bulk properties of the water + N-methylurea mixture. Unlike studies carried out earlier, this study includes a wider range of temperatures and measurements at high pressures. Results obtained in a wide range of pressures and temperatures make it possible to estimate the change in the bulk properties under isothermal, isobaric, and Received: August 23, 2017 Accepted: November 3, 2017

A

DOI: 10.1021/acs.jced.7b00750 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. Specification of Samples chemical name

CASRN

formula

source

purity (supplier) mass fraction

purification

N-methylurea water

598-50-5 7732-18-5

C2H6N2O H2O

Sigma-Aldrich

≥0.97

none double distillation (≈ 2 × 10−4 S·m−1)

Table 2. Densities (ρo/g·cm−3) of {Water (1) + N-Methylurea (2)} Mixtures from T = (274.15 to 333.15) K and at ρo = (0.101 ± 0.003 MPa) (x2, MU Mole Fraction)a ρo

x2 274.15 K 0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421

0.999899 1.00177 1.00212 1.00358 1.00411 1.00596 1.00621 1.00805 1.01056 275.15 K

0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421

0.999940 1.00180 1.00215 1.00360 1.00413 1.00598 1.00623 1.00807 1.01058 276.15 K

0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421

0.999964 1.00182 1.00217 1.00362 1.00414 1.00598 1.00624 1.00806 1.01058 277.15 K

0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421 278.15 K 0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421

0.999972 1.00182 1.00217 1.00361 1.00413 1.00597 1.00623 1.00805 1.01054 0.999964 1.00180 1.00215 1.00358 1.00410 1.00592 1.00618 1.00799 1.01045

x2

ρo

x2

ρo

x2

ρo

0.01662 0.01900 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

1.01218 1.01389 1.01684 1.02270 1.02947 1.03547 1.04078 1.04657

0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421

1.00147 1.00181 1.00320 1.00371 1.00548 1.00572 1.00748 1.00988

0.999940 1.00176 1.00211 1.00353 1.00405 1.00586 1.00611 1.00792 1.01037

0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421 0.01662 0.01900 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.00799 0.00834 0.01081 0.01421 0.01662 0.01900 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.99919 0.99941 1.00097 1.00310 1.00461 1.00607 1.00861 1.01365 1.01945 1.02466 1.02926 1.03427

279.15 K 0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421

288.15 K

280.15 K 0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421 281.15 K 0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421 282.15 K 0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421 283.15 K 0.00000

0.999901 1.00171 1.00205 1.00347 1.00398 1.00578 1.00603 1.00783 1.01026

0.999090 1.00082 1.00115 1.00251 1.00300 1.00472 1.00496 1.00667 1.00902 1.01063 1.01222 1.01500 1.02053 1.02690 1.03259 1.03758 1.04301 298.15 K

0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421 0.01662 0.01900 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071 308.15 K 0.00000 0.00244 0.00291 0.00483 0.00553

0.999848 1.00165 1.00199 1.00339 1.00390 1.00570 1.00595 1.00772 1.01015 0.999781 1.00157 1.00191 1.00331 1.00381 1.00559 1.00584 1.00761 1.01002 0.999699

0.997043 0.99869 0.99900 1.00030 1.00076 1.00241 1.00263 1.00426 1.00648 1.00805 1.00957 1.01220 1.01745 1.02352 1.02896 1.03374 1.03896 0.994029 0.99562 0.99592 0.99716 0.99761

323.15 K 0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421 0.01662 0.01900 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.988030 0.98955 0.98984 0.99102 0.99145 0.99295 0.99316 0.99463 0.99666 0.99809 0.99947 1.00187 1.00667 1.01219 1.01713 1.02148 1.02624 333.15 K

0.00000 0.00244 0.00291 0.00483 0.00553 0.00799 0.00834 0.01081 0.01421 0.01662 0.01900 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.983191 0.98467 0.98495 0.98609 0.98651 0.98796 0.98816 0.98960 0.99156 0.99296 0.99426 0.99660 1.00130 1.00670 1.01149 1.01572 1.02032

Standard uncertainties, u, are u(T) = 3 × 10−2 K, and u(x2) = 5 × 10−5, and the combined expanded uncertainty, Uc, is Uc(ρ) = 1 × 10−4 g·cm−3 (0.95 level of confidence). a

B



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Table 3. Compressions k of {Water (1) + N-Methylurea (2)} Mixture at Pressures to 100 MPa and at T = (278.15 to 323.15 K) (x2, MU Mole Fraction)a k × 102 x2

p = 10.0 MPa

p = 25.0 MPa

p = 50.0 MPa

p = 75.0 MPa

p = 100.0 MPa

2.2711 2.208 2.176 2.142 2.104 2.062 2.022 1.986 1.945

3.2844 3.188 3.138 3.085 3.022 2.950 2.884 2.826 2.762

4.2256 4.098 4.033 3.961 3.874 3.775 3.685 3.607 3.518

2.1661 2.105 2.072 2.038 1.998 1.951 1.915 1.880 1.843

3.1390 3.048 3.000 2.948 2.888 2.818 2.759 2.707 2.646

4.0470 3.927 3.863 3.794 3.710 3.615 3.534 3.463 3.383

2.1005 2.038 2.004 1.969 1.927 1.884 1.844 1.814 1.781

3.0470 2.959 2.913 2.864 2.804 2.739 2.681 2.639 2.591

3.9329 3.822 3.763 3.700 3.624 3.540 3.468 3.408 3.348

2.0632 2.002 1.970 1.936 1.896 1.853 1.816 1.786 1.756

2.9940 2.909 2.865 2.817 2.761 2.701 2.650 2.611 2.570

3.8664 3.758 3.703 3.643 3.572 3.497 3.434 3.384 3.334

2.0471 1.987 1.956 1.924 1.886 1.842 1.808 1.781 1.760

2.9696 2.882 2.836 2.792 2.737 2.681 2.635 2.599 2.570

3.8339 3.719 3.660 3.602 3.534 3.465 3.404 3.358 3.306

T/K = 278.15 0.00000 0.01081 0.01662 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.4792 0.468 0.464 0.458 0.454 0.448 0.443 0.438 0.433

1.1775 1.148 1.133 1.118 1.104 1.085 1.069 1.054 1.036

0.00000 0.01081 0.01662 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.4557 0.443 0.437 0.430 0.425 0.415 0.407 0.400 0.392

1.1209 1.090 1.073 1.056 1.038 1.015 0.996 0.980 0.962

0.00000 0.01081 0.01662 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.4415 0.428 0.420 0.412 0.403 0.395 0.386 0.378 0.371

1.0860 1.052 1.034 1.015 0.994 0.970 0.949 0.933 0.915

0.00000 0.01081 0.01662 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.4335 0.420 0.412 0.405 0.396 0.387 0.378 0.370 0.362

1.0665 1.034 1.016 0.997 0.977 0.952 0.932 0.915 0.898

0.00000 0.01081 0.01662 0.02321 0.03185 0.04218 0.05184 0.06068 0.07071

0.4306 0.418 0.411 0.404 0.396 0.384 0.377 0.373 0.368

1.0590 1.028 1.011 0.994 0.973 0.948 0.929 0.915 0.905

T/K = 288.15

T/K = 298.15

T/K = 308.15

T/K = 323.15

Standard uncertainties, u, are u(T) = 2 × 10−2 K and u(x2) = 5 × 10−5, and relative uncertainty, ur is ur(p) = 2 × 10−2; the combined expanded uncertainty, Uc, is Uc(k) = 1 × 10−4 (0.95 level of confidence).

a

2. EXPERIMENTAL SECTION Table 1 lists the specification of the samples being used in this work. In this study, N-methylurea was used without additional purification and it was dried at ≈335 K under vacuum for 24 h.

isochoric conditions. In addition, the experimental data on the aqueous mixture with N-methylurea are very poor in the literature, and therefore, the present study will substantially increase our knowledge of the behavior of this system. C



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Table 4. Limiting Partial Molar Volumes V̅ ∞ 2 of N-Methylurea in Water at Various Temperatures T and Pressures p

The MU aqueous mixtures were prepared by gravimetric method, with the use of an analytical balance (model LLB200, Russia) with an accuracy of 5 × 10−5 g. The maximum uncertainty at the mixture composition preparation did not exceed 1 × 10−4 mole fraction. The maximum concentration of N-methylurea solutions was limited with the mole fraction x2 = 0.07071 (or to the solution molality m2 = 4.22335 mol·kg−1) which is close to saturation concentration at 278.15 K and 100 MPa. The loading of the studied mixtures at density and compression measurements were carried out without any contact with atmospheric air. The studies were conducted only with the freshly prepared solutions. Molar values were calculated with the use of atomic masses recommended by IUPAC.63 Measurements of densities ρ at atmospheric pressure were conducted with the use of an “Anton Paar” DMA-4500 vibration density meter with U-shaped vibrating tube. The temperature reproducibility was 0.01 K. The density reproducibility was 1 × 10−5 g·cm−3. Density measurements were conducted in the temperature range from 274.15 to 333.15 K. The maximum temperature uncertainty at the density measurements did not exceed 0.03 K. Total uncertainty at density measurement did not exceed 5 × 10−5 g·cm−3. The work procedure was described in detail earlier.64−66 The measurement results are given in Table 2. The compression k (the relative volume change) is presented as k = (νo − ν)/νo = (ρ − ρo )/ρ

3 −1 V̅ ∞ 2 /cm ·mol

60.23 60.32 60.33 60.39 60.47 60.40a 60.59 60.70 60.75 60.83 60.99 61.31 61.19a 61.58b 62.05 61.90a 62.66c 62.25b 62.40d 62.69e 62.23f 62.60 62.53a 62.85b 63.42 63.42a 63.98

(1) 308.15

323.15 333.15

(3)

V2̅ = Vm − x1(∂Vm/∂x1)

(4)

p = 25 MPa

p = 50 MPa

p = 75 MPa

p = 100 MPa

60.31

60.24

60.15

60.11

60.07

61.15

61.07

60.93

60.85

60.79

61.87

61.81

61.70

61.55

61.39

62.50

62.43

62.31

62.15

62.01

63.38

63.31

63.21

63.12

63.07

When calculations at ambient pressures were carried out, the number of points was similar to those at higher pressures. bKrakowiak et al.24 c Singh and Kumar.25 dOgawa et al.57 eAkers and Gabler.61 fHerskovits and Kelly.19

Extrapolations of the apparent molar volumes measured at the atmospheric pressure were conducted in the concentration range of m2 = 0.13577−0.44731 (by five points), and extrapolations of the apparent molar volumes calculated at increased pressures were conducted in the concentration range of m2 = 0.60632−1.82605 (by four points). The average uncertainty in determining V̅ ∞ values at atmospheric pressure was about i 0.05 cm3·mol−1, at increased pressures −0.08 cm3·mol−1. The comparison of the calculated V̅ ∞ 2 values with literature data at 298.15 K19,24,25,57,61 showed that our results are a little lowered. The observed difference in values obtained by all researchers should be explained by the purity of the applied N-methylurea. Molar isothermal compressibility KT,m is given by

(2)

V1̅ = Vm − x 2(∂Vm/∂x 2)

p = 10 MPa

a

The partial molar volumes of components V̅ 1 and V̅ 2 for each pressure and temperature value were calculated by eqs 3 and 4.

KT , m = −(∂Vm/∂p)T , x = κTVm = (M /ρ2 )(∂ρ /∂p)T , x

(6)

where κT is the coefficient of isothermal compressibilities, Vm is the molar volume, ρ is the density, M is the molar mass of x composition pressure calculated by processing the dependence of the mixture densities from pressure at each composition and temperature by the second order polynomial with further differentiation. The results are given in SI (Table S1). The molar isobaric thermal expansion EP,m was calculated by the expression:

The mixture molar volumes were described with the third order equation and differentiated further. The average uncertainty in determining V̅ i values did not exceed 0.05 cm3·mol−1. Limiting partial molar volumes of MU V̅ ∞ 2 , given in Table 4, were obtained by linear extrapolation by molality of the apparent molar volume of Vϕ2 by eq 5. Extrapolation of Vϕ2 to m2 → 0 ∞ leads to the value V∞ ϕ2 = V̅ 2 . Vϕ2 = V ϕ∞2 + b2m2

274.15 275.15 276.15 277.15 278.15

298.15

3. RESULTS The apparent molar volumes of N-methylurea Vϕ2 were obtained directly from experimental data by the formula. (ρ − ρ)x1M1 (Vm − x1V1o) M = 1 + 2 ρ x2 x 2ρρ1

p0 = 0.10 MPa

279.15 280.15 281.15 282.15 283.15 288.15

where vo, ρo, and v, ρ are specific volumes and densities of water + N-methylurea mixture, respectively, at atmospheric pressure (po = 0.10 MPa) and pressure p. The compression k measurements were conducted on an installation, with the use of piezometers with a volume of 40 mL. Reproducibility of water compression k at 100 MPa in a line of four measurements was within the limits of 5 × 10−5. The uncertainty of pressure measurements was 0.02%; the uncertainty of temperature maintaining at compression measurements was 0.02 K. The maximum total uncertainty in determining the mixture k value did not exceed 1 × 10−4. The work procedure was described in detail earlier.66,67 The measured compressions for the mixture {water (1) + N-methylurea (2)} are given in Table 3.

Vϕ2 =

T, K

EP , m = (∂Vm/∂T )p , x = αpVm = −(M /ρ2 )(∂ρ /∂T )p , x

(5) D

(7)



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where αp is the coefficient of thermal expansion. EP,m values were also calculated by description with the second order polynomial with further differentiation of ρ = f(T)p,x dependence of each composition mixture. The results are given in SI (Table S2). Thermal pressure coefficient, β, was calculated as β = (∂p /∂T )V = (EP , m /KT , m)T , p , x

(8)

The relative uncertainty of molar isothermal compressibilities was within the range of 1% < ΔKT,m/KT,m < 2%, of molar isobaric thermal expansions 1% < ΔEP,m/EP,m < 3%, isochoric coefficients of thermal pressure 2% < Δβ/β < 4%. Lower uncertainty values are typical for values at atmospheric pressure which are higher, respectively, at 100 MPa. The method of the mixture relative uncertainty calculation was conducted by water, in the assumption that the relative deviation of calculation values in the mixture in the entire concentration range is the same as for water. The shift of the temperature of maximal density (TMD) was calculated as ΔT = Tmix − Twater

Figure 1. Comparison of the densities ρ of a mixture of water + N-methylurea with literature data at low concentrations of N-methylurea at T = (288.15 K, red; 298.15 K, green; 308.15 K, blue): ●, this work; ☆, ref 24; □, ref 25.

showing such behavior have the hydrophilic nature and fall into the group of structure breakers. On the other hand, ΔT positive changes are connected with water structure stabilization, and respectively, such molecules have the hydrophobic nature and fall into the group of structure makers. As it is seen from Figure 2, the

(9)

where Tmix is the temperature of maximal density of the mixture, and Twater is the temperature of maximal density of water.

4. DISCUSSION The N-methylurea molecule is amphiphilic intrinsically, showing the hydrophilic and hydrophobic nature at the interaction with water molecules. The displacement of one hydrogen atom of one −NH2 group in the urea molecule with the −CH3 alkyl group gives hydrophobic property to the solute which on the whole changes the nature of interactions with water molecules, although the second −NH2 group remains fully available for hydrophilic interactions. Such replacement assumes that the alkyl group of the nitrogen atom does not fully screen the other nonreplaced proton, remaining in the same atom, from the surrounding water molecules, and does not deprive it of the possibility of participation in forming hydrogen bonds. Although, it is more than probable that the hydrophobic shell being formed around the alkyl group somewhat neutralizes the remaining proton, so it becomes less active in interactions with water molecules.24 4.1. Density and Partial Molar Volume at 0.10 MPa. Figure 1 shows a comparison of the measured densities of the water + N-methylurea mixture in this paper with the data in the literature24,25 in the range of low concentrations at 288.15, 298.15, and 308.15 K. In the figure, we can see a satisfactory fit of our data with the data of Krakowiak et al.24 The results of Singh and Kumar25 show an increasing discrepancy with the increase of concentrations of MU. Table 1 and Figure S1 (Supporting Information) show the dependences of (N-methylurea + water) mixture densities at atmospheric pressure. As seen from the presented data, the mixture density increases monotonously with increasing mole fraction x2. When the temperature is rising, the curve slope becomes increasingly negative. Moreover, temperature growth leads to the shift of the temperature of maximal density of the mixture. As it is known, this shift is used for classification of the nonelectrolyte molecules impact on liquid water structure.68−70 The value of the TMD shift depends on the solute concentration and its nature,68−73 and the phenomenon of the TMD shift is explained by the result of the temperature impact on balances between the two types of water structures.74 The negative shift, ΔT, according to refs 68−70 is connected with the destruction of liquid water structure, and nonelectrolytes

Figure 2. Shift of temperature of maximal density, ΔT, at 0.10 MPa in the following mixtures: black ■, {water (1) + N-methylurea (2)}; red ●, {water (1) + urea (2)}. The points were calculated from experimental data, whereas the lines are the result of approximation by the secondorder equation. The ΔT inaccuracy does not exceed 0.02 K.

addition of N-methylurea leads to the TMD shift to the mixture negative area in this narrow interval of compositions, although with the growth of MU mole fraction, the trend to the decrease of ΔT dependence on x2 is observed. The comparison with the similar dependence of water + urea mixture shows that the hydrogen atom replacement with the − CH3 group, leads to the TMD value decrease at the same compositions. Concentration dependencies of the partial molar volumes of water and N-methylurea, as it is seen from Figure 3, show the presence of poorly expressed extremes (the maximum on the dependence V̅ 1 = f(x2) and the minimum on the dependence V̅ 2 = f(x2) in the interval x2 ≈ 0.03−0.04, which are more expressed at temperature decrease. In connection with the low mixture concentration range, the extreme value is comparable to the uncertainty value and depends on the polynomial equation for molar volume differentiation. With the purpose of more detailed fixation of the extreme, the consideration of the concentration dependencies of the apparent molar volumes (Figure 4) does not clarify the situation as well. The point is that the value, as defined, includes the uncertainty. E



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Figure 3. Dependences of the partial molar volume of water V̅ 1 (a) and N-methylurea V̅ 2 (b) vs. mole fraction x2 of {water (1) + N-methylurea (2)} mixture at atmospheric pressure po and different temperatures T: black ■, 278.15 K; red ●, 288.15 K; green ▲, 298.15 K; blue ▼, 308.15 K; cyan ⧫, 323.15 K; magenta ◀, 333.15 K.

the range of higher temperatures is observed (Figure 5a). At 100 MPa (Figure 5b), values of molar isothermal compressibility become lower in comparison with the respective values at 0.10 MPa, and temperature growth leads to the change of ∂KT,m/∂x2 sign which leads to the formation of a temperature inversion area at x2 ≈ 0.03−0.04. Pressure growth at 278.15 K (Figure 5c) also leads to the change of the ∂KT,m/∂x2 sign. KT,m = f(x2) dependencies at 323.15 K (Figure 5d), in distinction from the respective dependencies at 278.15 K (Figure 5c), are symbasic. The decrease of the KT,m value with pressure growth (Figure 5c and 5d) is connected with the dynamics of the process of water molecules not connected with strong hydrogen bonds and situated in its structure cavities, that is, pressure growth stimulates the increase of number of H2O molecules situated there. Both temperature growth and the increase of N-methylurea concentration contribute to this as well. But such action is observed only in limited temperature and concentration ranges. The molar isobaric thermal expansions EP,m, as shown on Figure 6, increase with MU concentration growth, and this increase is also connected with the dynamics of water molecules. The temperature growth stimulates the increase of the intensity of thermal movement of the mixture molecules and the increase of the oscillation amplitude leading to the displacement of H2O molecules from water structure cavities. As it is seen from the figure, the growth of N-methylurea temperature and concentration impact the EP,m value in one direction. Low dispersion of EP,m = f(x2) curves from the pressure change at 323.15 K (Figure 6d) confirms that the thermal changes of the mixture in the interval of MU studied concentrations are determined by water properties (at ≈ 319 K, baric dependencies of molar isobaric thermal expansion are characterized by temperature inversion).78,79 The thermal pressure coefficient β is a sensitive value to changing intermolecular associative equilibriums in liquid. Thermal pressure of the liquid mixture in isochoric conditions is determined both by thermal vibrations of molecules and the system ability to transform its structure for external conditions. The β value in the liquid mixture depends on intermolecular interaction forces from its packaging and may change considerably depending on the external parameters. If large structural transformations occur inside the liquid as, for example, in water in the temperature range from 273.15 to 277.13 K at atmospheric pressure, the β value may be negative as well. As it is seen from Figure 7, the growth of N-methylurea concentration, temperature, and pressure act in one direction and lead to the increase of the thermal pressure coefficient.

Namely, it is always an argument of two functions simultaneously, one of which is taken to be constant. As it is seen from Figure 4, the Vϕ2 concentration dependence also contains the

Figure 4. Apparent molar volumes Vϕ2 of N-methylurea vs mole fraction x2 for {water (1) + N-methylurea (2)} mixtures at atmospheric pressure and different temperatures: black ■, 278.15 K; green ▲, 298.15 K; magenta ◀, 333.15 K; black ☆, data by Krakowiak et al. at 298.15 K.24

minimum at x2 ≈ 0.03−0.04. Moreover, Vϕ2 = f(x2) dependencies at 278.15 and 298.15 K are characterized by the negative coefficient b2 of the eq 5, which proves, according to ref 75, that at lowered temperatures MU is a moderate structure maker. Krakowiak et al.24 noted also that at temperature decrease (in their paper, at 288.15 K), b2 < 0 is observed. However, the adoption of hydrophobic (hydrophilic) properties under the b2 coefficient sign contradicts the provision based on TMD shift in the mixture. We mentioned such contradiction earlier in water + ethylenediamine76 and water + 1,2-propanediol systems.77 4.2. Thermal Molar Properties. Low MU concentrations deliberately suppose that the thermal properties of the mixture in the studied concentration range will be determined, first of all, by water thermal properties. For better perception of changes of the properties considered, the dependencies are shown in one scale and at two extreme temperatures (278.15 and 323.15 K), and pressures (0.10 and 100 MPa) from x2 mole fraction. As it is seen from Figure 5, concentration dependencies of molar isothermal compressibility of the mixture at atmospheric pressure are characterized by the weak minimum which shifts to the region of higher MU concentrations with the temperature growth. In addition, the higher temperature dependence of KT,m value within the range of 278.15 to 298.15 K, then within F



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Figure 5. Molar isothermal compressibility KT,m vs mole fraction x2 of {water (1) + N-methylurea (2)} mixture (a) at 0.10 MPa and (b) at 100 MPa and various temperatures T: black ■, 278.15 K; red ●, 288.15 K; green ▲, 298.15 K; blue ▼, 308.15 K; cyan ⧫, 323.15 K. Also, (c) at 278.15 K, (d) at 323.15 K and various pressures p: black ■, 0.10 MPa; red ●, 10 MPa; green ▲, 25 MPa; blue ▼, 50 MPa; cyan ⧫, 75 MPa; magenta ◀, 100 MPa.

Figure 6. Molar isobaric expansion, EP,m, vs mole fraction, x2, of {water (1) + N-methylurea (2)} mixture (a) at 0.10 MPa and (b) 100 MPa and various temperatures T: black ■, 278.15 K; red ●, 288.15 K; green ▲, 298.15 K; blue ▼, 308.15 K; cyan ⧫, 323.15 K; black ☆, data by Krakowiak et al.24 at 298.15 K. Also (c) at 278.15 K and (d) 323.15 K and various pressures p: black ■, 0.10 MPa; red ●, 10 MPa; green ▲, 25 MPa; blue ▼, 50 MPa; cyan ⧫, 75 MPa; magenta ◀, 100 MPa. G



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Figure 7. Coefficients of thermal pressure β vs mole fraction x2 of {water (1) + N-methylurea (2)} mixture (a) at 0.10 MPa, (b) at 100 MPa and various temperatures T: black ■, 278.15 K; red ●, 288.15 K; green ▲, 298.15 K; blue ▼, 308.15 K; cyan ⧫, 323.15 K. Also (c) at 278.15 K, (d) at 323.15 K, and various pressures p: black ■, 0.10 MPa; red ●, 10 MPa; green ▲, 25 MPa; blue ▼, 50 MPa; cyan ⧫, 75 MPa; magenta ◀, 100 MPa.

Figure 8. Dependences of limiting partial molar volumes of N-methylurea in water, V̅ ∞ 2 (a) on pressure at different temperatures T: black ■, 278.15 K; red ●, 288.15 K; green ▲, 298.15 K; blue ▼, 308.15 K; cyan ⧫, 323.15 K. Also (b) on temperature at different pressures p: black ■, 0.10 MPa; red ●, 10 MPa; green ▲, 25 MPa; blue ▼, 50 MPa; cyan ⧫, 75 MPa; magenta ◀, 100 MPa; black □, our data at 0.10 MPa, being calculated within the extended temperature range; black ☆, data by Krakowiak et al.24 at 0.10 MPa.

The low β coefficient of mixtures at low MU concentration is explained, as it was stated earlier, with water properties, and is connected with the openness of the hydrogen-bond networks and the availability of free spaces in its structure.80−85 The addition of the first nonelectrolyte portions to water always leads to the thermal pressure coefficient growth. In aqueous mixtures of nonelectrolytes the molecules of which have hydrophobic groups, like in acetone, 2-propanol, tert-butyl alcohol, such processes lead to the appearance of a spike extreme on β = f(x2) dependence,67,85,86 and this maximum is formed at nonelectrolyte concentrations considerably exceeding the maximum fraction of N-methylurea in the mixture. In nonaqueous mixtures, β = f(x2) dependencies have no extreme.66,87 Thermal pressure

coefficient increase is connected with the intensive displacement of H2O molecules from water structure cavities. These so-called “free” H2O molecules are not connected with strong hydrogen bonds with the other neighboring water molecules, and are absent in the tetraedrical frame of hydrogen bonds. Hydrophobic groups of nonaqueous components led to the displacement of “free” H2O molecules from water structure cavities with their repelling actions on water molecules, and this displacement occurs already at low concentrations of hydrophobic electrolyte. Hydrophilic (as a rule, always amphiphilic) molecules also lead to displacement of H2O molecules from water structure cavities. But the extreme in the process with the participation of hydrophilic nonelectrolytes is visible at much higher nonaqueous H



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Figure 9. Dependences of the limiting partial molar isothermal compressibility K̅ ∞ T,2 of N-methylurea in water (a) on pressure at different temperatures T: black ■, 278.15 K; red ●, 288.15 K; green ▲, 298.15 K; blue ▼, 308.15 K; cyan ⧫, 323.15 K. Also (b) on temperature at different pressures p: black ■, 0.10 MPa; red ●, 10 MPa; green ▲, 25 MPa; blue ▼, 50 MPa; cyan ⧫, 75 MPa; magenta ◀, 100 MPa.

Figure 10. Dependences of the limiting partial molar isobaric expansion, E̅∞ P,2, of N-methylurea in water (a) on pressure at different temperatures T: black ■, 278.15 K; red ●, 288.15 K; green ▲, 298.15 K; blue ▼, 308.15 K; cyan ⧫, 323.15 K. Also (b) on temperature at different pressures p: black ■, 0.10 MPa; red ●, 10 MPa; green ▲, 25 MPa; blue ▼, 50 MPa; cyan ⧫, 75 MPa; magenta ◀, 100 MPa; black □, our data at 0.10 MPa being calculated within the extended temperature range; black ☆, data by Krakowiak et al.24 at 0.10 MPa.

As shown on Figure 9, limiting partial isothermal compressibilities K̅ ∞ T,2 are positive and decrease both with pressure and temperature growth. If we accept the partial molar volume at the infinite dilution as the sum of two contributions88−90

component concentrations because the present hydrophilic groups either form hydrogen bonds with such H2O molecules in water cavities directly, or affect them by affecting the tetraedrical frame. The presence of both hydrophobic and hydrophilic groups in the MU molecule inevitably leads to competition between these two mechanisms. And the presence (or the absence) of such an extreme on β = f(x2) dependence in the mixture which, due to low N-methylurea solubility, is regretfully unachievable, would give an answer on a question about the possible prevalence of one of these two mechanisms. 4.3. Partial Molar Properties at Infinite Dilution. The partial molar values at the infinite dilution are of fundamental importance, they include the contact interaction between the dissolved particles. Only the long-range interactions which may be transferred through the solvent are allowed for in this value. All changes of these values (except very high pressures) are also not connected with the changes of the solute molecule intrinsic volume but are determined with the solvent packaging transformation (the solute influence on this packaging) to a great extent. Figure 8 shows the dependencies of limiting partial molar volumes of V̅ ∞ 2 N-methylurea in water on pressure and temperature. As could be expected, the V̅ ∞ 2 value decreases with pressure growth and increases with temperature growth. Figure 8b also shows the comparison of our results with those of Krakowiak et al. at 0.10 MPa.24 And, as is evident, the accordance between these data (see also Table 4) is satisfactory.

V2̅ ∞ = Vint + ΔV = Vint + nh(Vh̅ − Vs̅ )

(10)

where Vint is an intrinsic molar volume of the solute, ΔV is a molar volume change due to solute−solvent interaction (includes hydrogen bonds, electrostriction, hydrophobic hydration, the impact of long-range interaction on water structure), nh is a hydration number, V̅ h is the partial molar volume of water in the hydration shell, V̅ s is the partial molar volume of the bulk water, and assume that the nh value does not change at pressure increase to 100 MPa, that is, is constant, then the equation for isothermal compressibility for the infinitely dilute solution will have the following form: KT̅ ∞,2 = K int + nh(KT̅ ,h − KT̅ ,s)

(11)

where Kint is the intrinsic isothermal compressibility of the solute, K̅ T,h is partial molar isothermal compressibility of water in hydration shell, and K̅ T,s is the partial molar isothermal compressibility of water within the hydration shell. Intrinsic isothermal compressibility of the solute (the totality of dissolved molecules), Kint, is a very small value, and it can be neglected.91 As the limiting partial isothermal compressibility of MU in water is positive, then the item in eq 11 (K̅ T,h − K̅ T,s) > 0, that is, K̅ T,h > K̅ T,s at all condition parameters. Consequently, more I



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compressible medium from water molecules in comparison with water in volume is formed around the MU molecule. However, further pressure growth, considerably exceeding 100 MPa, (Figure 9a), will, obviously, lead to K̅ ∞ T,2 negative values. As it is known, the negative values of isothermal compressibility, observed in wide temperature ranges and pressures, are typical for aqueous solutions of electrolytes92 and zwitterionic compounds,93,94 where the main reason for such transformation is the electrostriction. And, as it follows from this, further pressure increase leads to decrease of compressibility of water around the MU molecules. Changes of molar isobaric thermal expansion at the infinite dilution, E̅∞ P,2, of N-methylurea in water at different pressures and temperatures are shown on Figure 10. As it is seen from the figures shown, the values E̅∞ P,2 are positive, and practically do not depend on pressure (changes within the uncertainty) and decrease with the temperature growth. We may judge about the MU hydration change from the Hepler’s equation95 (∂CP̅ ∞,2/∂T 2)T

= − T (∂

V2̅ ∞/∂T 2)p

2

=

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel.: +7 4932 336259. Fax: +7 4932 336265. ORCID

Gennadiy I. Egorov: 0000-0003-0032-4251 Funding

The authors are grateful for the financial support from the Russian Foundation for Basic Research (projects 15-43-03092-r_center_a and 17-03-00309-a). The density measurements were made at the center for joint use of scientific equipment (the Upper Volga Regional Center for Physico-Chemical Research). Notes

The authors declare no competing financial interest.

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−T (∂EP̅ ∞,2 /∂T )p (12)

value (∂E̅∞ P,2/∂T)p

According to this approach, where the positive characterizes water structure making with the solute molecules, and the negative value, respectively, water structure breaking, the hydrogen atom replacement with a methyl group weakens the N-methylurea molecule hydrophility only to a small extent.

REFERENCES

(1) Toth, K.; Bopp, P.; Jancso, G. Ab initio studies on the interactions of water with tetramethylurea and tetramethylthiourea. J. Mol. Struct. 1996, 381, 181−187. (2) Ikeguchi, M.; Nakamura, S.; Shimizu, K. Molecular Dynamics Study on Hydrophobic Effects in Aqueous Urea Solutions. J. Am. Chem. Soc. 2001, 123, 677−682. (3) Nandel, F. S.; Verma, R.; Singh, B.; Jain, D. V. S. Mechanism of hydration of urea and guanidium ion: A model study of denaturation of proteins. Pure Appl. Chem. 1998, 70, 659−664. (4) Sokolic, F.; Idrissi, A.; Perera, A. A molecular dynamic study of the structural properties of aqueous urea solutions. J. Mol. Liq. 2002, 101, 81−87. (5) Chitra, R.; Smith, P. E. Molecular Association in Solution: A Kirkwood-Buff Analysis of Sodium Chloride, Ammonium Sulfate, Guanidinium Chloride, Urea, and 2,2,2-Trifluoroethanol in Water. J. Phys. Chem. B 2002, 106, 1491−1500. (6) Weerasinghe, S.; Smith, P. E. A Kirkwood-Buff Derived Force Field for Mixtures of Urea and Water. J. Phys. Chem. B 2003, 107, 3891−3898. (7) Smith, L. J.; Berendsen, H. J. C.; van Gunsteren, W. F. Computer Simulation of Urea−Water Mixtures: A Test of Force Field Parameters for Use in Biomolecular Simulation. J. Phys. Chem. B 2004, 108, 1065− 1071. (8) Ishida, T.; Rossky, P. J.; Castner, E. W., Jr A Theoretical Investigation of the Shape and Hydration Properties of Aqueous Urea: Evidence for Nonplanar Urea Geometry. J. Phys. Chem. B 2004, 108, 17583−17590. (9) Idrissi, A.; Cinar, E.; Longelin, S.; Damay, P. The effect of temperature on urea−urea interactions in water: a molecular dynamics simulation. J. Mol. Liq. 2004, 110, 201−208. (10) Caballero-Herrera, A.; Nilsson, L. Urea parametrization for molecular dynamics simulations. J. Mol. Struct.: THEOCHEM 2006, 758, 139−148. (11) Stumpe, M. C.; Grubmuller, H. Aqueous Urea Solutions: Structure, Energetics, and Urea Aggregation. J. Phys. Chem. B 2007, 111, 6220−6228. (12) Hermida-Ramon, J. M.; Ohrn, A.; Karlstrom, G. Planar or Nonplanar: What Is the Structure of Urea in Aqueous Solution. J. Phys. Chem. B 2007, 111, 11511−11515. (13) Idrissi, A.; Gerard, M.; Damay, P.; Kiselev, M.; Puhovsky, Y.; Cinar, E.; Lagant, P.; Vergoten, G. The Effect of Urea on the Structure of Water: A Molecular Dynamics Simulation. J. Phys. Chem. B 2010, 114, 4731−4738. (14) Wei, H.; Fan, Y.; Gao, Y. Q. Effects of Urea, Tetramethyl Urea, and Trimethylamine N-Oxide on Aqueous Solution Structure and Solvation of Protein Backbones: A Molecular Dynamics Simulation Study. J. Phys. Chem. B 2010, 114, 557−568.

5. CONCLUSIONS Changes in isothermal compressibility, isobaric thermal expansion, and thermal pressure coefficient for the mixture {water (1) + N-methylurea (2)} witness that processes occurring in this mixture are determined, in the first turn, by domination of the network of water hydrogen bonds. Although the hydrogen atom replacement with a methyl group in the urea molecule weakens its hydrophilic properties, the N-methylurea molecule in the studied parameters interval shows strong hydrophilic properties and is the water structure breaker, in the whole. Adding MU to water leads to the shift of the temperature of maximal density (TMD) to the temperature negative area. Comparison with similar dependence of the water + urea mixture shows that the hydrogen atom replacement with a −CH3 group leads to the TMD value decrease at similar compositions. It was explained that temperature and baric dependencies of all three molar thermal properties of the mixture, namely, molar isothermal compressibility, molar isobaric thermal expansions, and isochoric coefficients of thermal pressure are connected, in the first turn, with the dynamics of H2O molecules in water structure cavities. At infinite dilution, more compressed medium from water molecules in comparison with water in bulk is formed around the MU molecule which at a pressure increase may demonstrate negative compressibility, witnessing that at high pressures exceeding 100 MPa, the N-methylurea molecule is able to show the domination of hydrophobic properties.

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(278.15 between 323.15) K and at pressures from (0.10 to 100) MPa for the {water (1) + methylurea (2)} mixture (PDF)

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.7b00750. Plots of experimental and literature densities at atmospheric pressure; molar isothermal compressibility KT,m and molar isobaric expansions EP,m in the temperature range J



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(35) Korolev, V. P. Volume properties and structure of aqueous solutions of urea at 263−348 K. J. Struct. Chem. 2008, 49, 660−667. (36) Burton, R. C.; Ferrari, E. S.; Davey, R. J.; Hopwood, J.; Quayle, M. J.; Finney, J. L.; Bowron, D. T. The Structure of a Supersaturated Solution: A Neutron Scattering Study of Aqueous Urea. Cryst. Growth Des. 2008, 8, 1559−1565. (37) Yamazaki, T.; Kovalenko, A.; Murashov, V. V.; Patey, G. N. Ion Solvation in a Water-Urea Mixture. J. Phys. Chem. B 2010, 114, 613− 619. (38) Kumar, A.; Singh, M.; Gupta, K. C. An estimation of hydrophilic and hydrophobic interaction of aqueous urea, methylurea, dimethylurea and tetramethylurea from density and apparent molal volume at 30.0°C. Phys. Chem. Liq. 2010, 48, 1−6. (39) Funkner, S.; Havenith, M.; Schwaab, G. Urea, a Structure Breaker? Answers from THz Absorption Spectroscopy. J. Phys. Chem. B 2012, 116, 13374−13380. (40) Sahle, C. J.; Schroer, M. A.; Juurinen, I.; Niskanen, J. Influence of TMAO and urea on the structure of water studied by inelastic X-ray scattering. Phys. Chem. Chem. Phys. 2016, 18, 16518−16526. (41) Liu, J.-Ch; Jia, G.-Zh. Reconsideration of Dielectric Relaxation of Aqueous Urea Solutions at Different Temperatures. J. Solution Chem. 2016, 45, 485−496. (42) Mandal, T.; Larson, R. G. Nucleation of urea from aqueous solution: Structure, critical size, and rate. J. Chem. Phys. 2017, 146, 134501−7. (43) Philip, P. R.; Perron, G.; Desnoyers, J. Apparent Molal Volumes and Heat Capacities of Urea and Methyl-Substituted Ureas in H20 and D20 at 25°C. Can. J. Chem. 1974, 52, 1709−1713. (44) Barone, G.; Rizzo, E.; Vitagliano, V. Opposite effect of urea and some of its derivatives on water structure. J. Phys. Chem. 1970, 74, 2230− 2232. (45) Astrand, P. O.; Wallqvist, A.; Karlstrom, G.; Linse, P. Properties of urea−water solvation calculated from a new abinitio polarizable intermolecular potential. J. Chem. Phys. 1991, 95, 8419−8429. (46) Kallies, B. Coupling of solvent and solute dynamicsmolecular dynamics simulations of aqueous urea solutions with different intramolecular potentials. Phys. Chem. Chem. Phys. 2002, 4, 86−95. (47) Rupley, J. A. The Effect of Urea and Amides upon Water Structure. J. Phys. Chem. 1964, 68, 2002−2003. (48) Finer, E. G.; Franks, F.; Tait, M. J. Nuclear magnetic resonance studies of aqueous urea solutions. J. Am. Chem. Soc. 1972, 94, 4424− 4429. (49) De Xammar Oro, J. R. Role of Co-Solute in Biomolecular Stability: Glucose, Urea and the Water Structure. J. Biol. Phys. 2001, 27, 73−79. (50) Vanzi, F.; Madan, B.; Sharp, K. Effect of the Protein Denaturants Urea and Guanidinium on Water Structure: A Structural and Thermodynamic Study. J. Am. Chem. Soc. 1998, 120, 10748−10753. (51) Walrafen, G. E. Raman Spectral Studies of the Effects of Urea and Sucrose on Water Structure. J. Chem. Phys. 1966, 44, 3726−3727. (52) Panuszko, A.; Bruzdziak, P.; Zielkiewicz, J.; Wyrzykowski, D.; Stangret, J. Effects of Urea and Trimethylamine-N-oxide on the Properties of Water and the Secondary Structure of Hen Egg White Lysozyme. J. Phys. Chem. B 2009, 113, 14797−14809. (53) Chalikian, T. V. Volumetric measurements in binary solvents: Theory to experiment. Biophys. Chem. 2011, 156, 3−12. (54) Egorov, G. I.; Makarov, D. M. Densities and volume properties of (water + tert-butanol) over the temperature range of (274.15 − 348.15) K at pressure of 0.1 MPa. J. Chem. Thermodyn. 2011, 43, 430−441. (55) Lee, S.; Tikhomirova, A.; Shalvardjian, N.; Chalikian, T. V. Partial molar volumes and adiabatic compressibilities of unfolded protein states. Biophys. Chem. 2008, 134, 185−199. (56) Chalikian, T. V.; Breslauer, K. J. Thermodynamic analysis of biomolecules: a volumetric approach. Curr. Opin. Struct. Biol. 1998, 8, 657−664. (57) Ogawa, T.; Mizutani, K.; Ando, Y.; Yasuda, M. Apparent molal volumes of urea and its derivatives in aqueous alkali chloride solutions. Bull. Chem. Soc. Jpn. 1991, 64, 2869−2871.

(15) Kuffel, A.; Zielkiewicz, J. The hydrogen bond network structure within the hydration shell around simple osmolytes: Urea, tetramethylurea, and trimethylamine-N-oxide, investigated using both a fixed charge and a polarizable water model. J. Chem. Phys. 2010, 133, 035102− 8. (16) Carr, J. K.; Buchanan, L. E.; Schmidt, J. R.; Zanni, M. T.; Skinner, J. L. Structure and Dynamics of Urea/Water Mixtures Investigated by Vibrational Spectroscopy and Molecular Dynamics Simulation. J. Phys. Chem. B 2013, 117, 13291−13300. (17) Salvalaglio, M.; Perego, C.; Giberti, F.; Mazzotti, M.; Parrinello, M. Molecular-dynamics simulations of urea nucleation from aqueous solution. Proc. Natl. Acad. Sci. U. S. A. 2015, 112, E6−E14. (18) Bandyopadhyay, D.; Mohan, S.; Ghosh, S. K.; Choudhury, N. Molecular Dynamics Simulation of Aqueous Urea Solution: Is Urea a Structure Breaker? J. Phys. Chem. B 2014, 118, 11757−11768. (19) Herskovits, T. T.; Kelly, T. M. Viscosity Studies of Aqueous Solutions of Alcohols, Ureas and Amides. J. Phys. Chem. 1973, 77, 381− 388. (20) Spencer, J. N.; Hovick, J. W. Solvation of urea and methylsubstituted ureas by water and DMF. Can. J. Chem. 1988, 66, 562−565. (21) Bezzabotnov, V. Y.; Cser, L.; Grosz, T.; Jancso, G.; Ostanevich, Y. M. Small-angle neutron scattering in aqueous solutions of tetramethylurea. J. Phys. Chem. 1992, 96, 976−982. (22) Della Gatta, G.; Badea, E.; Jozwiak, M.; Del Vecchio, P. Thermodynamics of Solvation of Urea and Some Monosubstituted NAlkylureas in Water at 298.15 K. J. Chem. Eng. Data 2007, 52, 419−425. (23) Kustov, A. V.; Smirnova, N. L. Standard Enthalpies and Heat Capacities of Solution of Urea and Tetramethylurea in Water. J. Chem. Eng. Data 2010, 55, 3055−3058. (24) Krakowiak, J.; Wawer, J.; Panuszko, A. Densimetric and ultrasonic characterization of urea and its derivatives in water. J. Chem. Thermodyn. 2013, 58, 211−220. (25) Singh, M.; Kumar, A. Hydrophobic Interactions of Methylureas in Aqueous Solutions Estimated with Density, Molal Volume, Viscosity and Surface Tension from 293.15 to 303.15 K. J. Solution Chem. 2006, 35, 567−582. (26) Krakowiak, J.; Wawer, J. Hydration of urea and its derivatives − Volumetric and compressibility studies. J. Chem. Thermodyn. 2014, 79, 109−117. (27) Behbehani, G. R.; Dillon, M.; Smyth, J.; Waghorne, W. E. Infrared Spectroscopic Study of the Solvation of Tetramethylurea in Protic C Aprotic Mixed Solvents. J. Solution Chem. 2002, 31, 811−822. (28) Kushare, S. K.; Dagade, D. H.; Patil, K. J. Volumetric and compressibility properties of liquid water as a solute in glycolic, propylene carbonate, and tetramethylurea solutions at T = 298.15K. J. Chem. Thermodyn. 2008, 40, 78−83. (29) Motin, M. A.; Biswas, T. K.; Huque, E. M. Volumetric and Viscometric Studies on an Aqueous Urea Solution. Phys. Chem. Liq. 2002, 40, 593−605. (30) Abrosimov, V. K.; Ivanov, E. V.; Efremova, L. S.; Pankratov, Yu.P. Thermodynamics of H/D Isotope Effects in Urea Hydration and Structural Features of Urea Aqueous Solutions at Various Temperatures: III.1 Solubility of Argon and Krypton at 101 325 Pa in the Systems H2O−CO(NH2)2 and D2O−CO(ND2)2. Russ. J. Gen. Chem. 2002, 72, 667−674. (31) van der Vegt, N. F. A.; Lee, M.-E.; Trzesniak, D.; van Gunsteren, W. F. Enthalpy-Entropy Compensation in the Effects of Urea on Hydrophobic Interactions. J. Phys. Chem. B 2006, 110, 12852−12855. (32) Brown, B. R.; Gould, M. E.; Ziemer, S. P.; Niederhauser, T. L.; Woolley, E. M. Apparent molar volumes and apparent molar heat capacities of aqueous urea, 1,1-dimethylurea, and N,N′-dimethylurea at temperatures from (278.15 to 348.15) K and at the pressure 0.35 MPa. J. Chem. Thermodyn. 2006, 38, 1025−1035. (33) Hayashi, Y.; Katsumoto, Y.; Omori, S.; Kishii, N.; Yasuda, A. Liquid Structure of the Urea-Water System Studied by Dielectric Spectroscopy. J. Phys. Chem. B 2007, 111, 1076−1080. (34) Koga, Y.; Miyazaki, Y.; Nagano, Y.; Inaba, A. Mixing Schemes in a Urea-H2O System: A Differential Approach in Solution Thermodynamics. J. Phys. Chem. B 2008, 112, 11341−11346. K



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(80) Mallamace, F.; Corsaro, C.; Stanley, H. E. A singular thermodynamically consistent temperature at the origin of the anomalous behavior of liquid water. Sci. Rep. 2012, 2, 993−998. (81) Santra, B.; DiStasio, R. A., Jr; Martelli, F.; Car, R. Local structure analysis in ab initio liquid water. Mol. Phys. 2015, 113, 2829−2841. (82) Malenkov, G. Liquid water and ices: understanding the structure and physical properties. J. Phys.: Condens. Matter 2009, 21, 283101−35. (83) Clark, G. N. I.; Cappa, C. D.; Smith, J. D.; Saykally, R. J.; HeadGordon, T. The structure of ambient water. Mol. Phys. 2010, 108, 1415− 1433. (84) Egorov, G. I.; Makarov, D. M. Effect of high pressure and temperature on volumetric properties of {water (1) + ethylenediamine (2)} mixtures. J. Mol. Liq. 2017, 239, 68−73. (85) Egorov, G. I.; Makarov, D. M.; Kolker, A. M. Liquid phase PVTx properties of (water + tert-butanol) binary mixtures at temperatures from 278.15 to 323.15 K and pressures from 0.1 to 100 MPa. II. Molar isothermal compressions, molar isobaric expansions, molar thermal pressure coefficients, and internal pressure. J. Chem. Thermodyn. 2013, 61, 169−179. (86) Egorov, G. I.; Gruznov, E. L.; Kolker, A. M. The p-Vm-T-x properties of water-acetone mixtures over the temperature range 298− 323 K and pressures from 1 to 1000 bar. II. Isothermal compressions, isobaric expansions and internal. Russ. J. Phys. Chem. A 1996, 70, 197− 203. (87) Egorov, G. I.; Makarov, D. M. Bulk properties of a liquid phase mixture {ethylene glycol+tert-butanol} in the temperature range 278.15−348.15 K and pressures of 0.1−100 MPa. II. Molar isothermal compressibility, molar isobaric expansibility, thermal pressure coefficient, and internal pressure. J. Struct. Chem. 2013, 54, S320−S335. (88) Shiio, H.; Ogawa, T.; Yoshihashi, H. Measurement of the Amount of Bound Water by Ultrasonic Interferometer. J. Am. Chem. Soc. 1955, 77, 4980−4982. (89) Chalikian, T. V.; Sarvazyan, A. P.; Breslauer, K. J. Hydration and Partial Molar Compressibility of Biological Compounds. Biophys. Chem. 1994, 51, 89−109. (90) Hedwig, G. R.; Høgseth, E.; Høiland, H. Volumetric Properties of the Nucleosides Adenosine, Cytidine, and Uridine in Aqueous Solution at T = 298.15 K and p = (10 to 120) MPa. J. Chem. Thermodyn. 2013, 61, 117−125. (91) Chalikian, T. V.; Sarvazyan, A. P.; Funck, T.; Cain, C. A.; Breslauer, K. J. Partial Molar Characteristics of Glycine and Alanine in Aqueous Solutions at High Pressures Calculated from Ultrasonic Velocity Data. J. Phys. Chem. 1994, 98, 321−328. (92) Pitzer, K. S.; Peiper, J. C.; Busey, R. N. Thermodynamic Properties of Aqueous Sodium Chloride Solutions. J. Phys. Chem. Ref. Data 1984, 13, 1−102. (93) Chalikian, T. V.; Sarvazyan, A. P.; Funck, T.; Cain, C. A.; Breslauer, K. J. Partial Molar Characteristics of Glycine and Alanine in Aqueous Solutions at High Pressures Calculated from Ultrasonic Velocity Data. J. Phys. Chem. 1994, 98, 321−328. (94) Makarov, D. M.; Egorov, G. I.; Fadeeva, Y. A.; Kolker, A. M. Characterization of the Volumetric Properties of Betaine in Aqueous Solutions: Compositional, Pressure, and Temperature Dependence. Thermochim. Acta 2014, 585, 36−44. (95) Hepler, L. Thermal Expansion and Structure in Water and Aqueous Solutions. Can. J. Chem. 1969, 47, 4613−4617.

(58) Korolev, V. P. Properties and structure of aqueous urea up to the singular temperature of overcooled water: Isotopy effects. J. Struct. Chem. 2008, 49, 668−678. (59) Jakli, G. Thermal Expansion and Structure of 1,3-Dimethylurea, Tetramethylurea, and Tetrabutylammonium Bromide Aqueous Solutions Derived from Density Measurements. J. Chem. Eng. Data 2009, 54, 2656−2665. (60) Jakli, G.; van Hook, W. A. H2O− D2O Solvent isotope effects on apparent and partial molar volumes of 1,3-dimethylurea and tetramethylurea solutions. J. Chem. Eng. Data 1996, 41, 249−253. (61) Akers, H. A.; Gabler, D. G. The molar volume of solutes in water. Naturwissenschaften 1991, 78, 417−419. (62) Lapanje, S.; Vlachy, V.; Kranjc, Z.; Zerovnik, E. Effect of temperature on the apparent molal volume of ethylurea in aqueous solutions. J. Chem. Eng. Data 1985, 30, 29−32. (63) Wieser, M. E.; Holden, N.; Coplen, T. B.; Böhlke, J. K.; Berglund, M.; Brand, W. A.; De Bievre, P.; Gröning, M.; Loss, R. D.; Meija, J.; et al. Atomic weights of the elements 2011 (IUPAC Technical Report). Pure Appl. Chem. 2013, 85, 1047−1078. (64) Egorov, G. I.; Makarov, D. M. Densities and volume properties of (water + tert-butanol) over the temperature range of (274.15 to 348.15) K at pressure of 0.1 MPa. J. Chem. Thermodyn. 2011, 43, 430−441. (65) Egorov, G. I.; Makarov, D. M.; Kolker, A. M. Volume properties of liquid mixture of water + glycerol over thetemperature range from 278.15 to 348.15 K at atmospheric pressure. Thermochim. Acta 2013, 570, 16−26. (66) Egorov, G. I.; Makarov, D. M.; Kolker, A. M. Densities and Volumetric Properties of Ethylene Glycol + Dimethylsulfoxide Mixtures at Temperatures of (278.15 to 323.15) K and Pressures of (0.1 to 100) MPa. J. Chem. Eng. Data 2010, 55, 3481−3488. (67) Egorov, G. I.; Makarov, D. M. Compressibility Coefficients of Water−2-Propanol Mixtures over the Temperature and Pressure Ranges 278−323.15 K and 1−1000 bar. Russ. J. Phys. Chem. A 2008, 82, 1037−1041. (68) Wada, G.; Umeda, S. Effects of Nonelectrolytes on the Temperature of the Maximum Density of Water. I. Alcohols. Bull. Chem. Soc. Jpn. 1962, 35, 646−652. (69) Wada, G.; Umeda, S. Effects of Nonelectrolytes on the Temperature of the Maximum Density of Water. II. Organic Compounds with Polar Groups. Bull. Chem. Soc. Jpn. 1962, 35, 1797− 1801. (70) Franks, F.; Watson, B. Maximum Density Effects in Dilute Aqueous Solutions of Alcohols and Amines. Trans. Faraday Soc. 1967, 63, 329−334. (71) Macdonald, D. D.; McLean, A.; Hyne, J. B. The Influence of Aliphatic Diols on the Temperature of Maximum Density of Water. J. Solution Chem. 1978, 7, 63−71. (72) Kaulgud, M. V.; Pokale, W. K. Measurement of the Temperature of Maximum Density of Aqueous Solutions of Some Salts and Acids. J. Chem. Soc., Faraday Trans. 1995, 91, 999−1004. (73) Darnell, A. J.; Greyson, J. The Effect of Structure-Making and -Breaking Solutes on the Temperature of Maximum Density of Water. J. Phys. Chem. 1968, 72, 3021−3025. (74) Franks, F. Ed. Water: A Comprehensive Treatise; Plenum Press: New York, 1978; Vol. I−IV. (75) Marcus, Y. Ion Solvation; John Wiley: New York, 1985. (76) Egorov, G. I.; Makarov, D. M.; Kolker, A. M. Volume properties of liquid mixture of {water (1) + ethylenediamine(2)} over the temperature range from 274.15 to 333.15 K at atmospheric pressure. Thermochim. Acta 2016, 639, 148−159. (77) Makarov, D. M.; Egorov, G. I.; Kolker, A. M. Temperature and composition dependences of volumetric properties of (water + 1,2propanediol) binary system. J. Mol. Liq. 2016, 222, 656−662. (78) Kell, G. S.; Whalley, E. Reanalysis of the density of liquid water in the range 0°−150°C and 0−1 kbar. J. Chem. Phys. 1975, 62, 3496−3503. (79) Chen, Ch-T.; Fine, R. A.; Millero, F. J. The equation of state of pure water determined from sound speeds. J. Chem. Phys. 1977, 66, 2142−2144. L


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