Density and Viscosity of N‑Methylacetamide−Calcium Chloride

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Density and Viscosity of N‑Methylacetamide−Calcium Chloride Mixtures over the Temperature Range from 308.15 to 328.15 K at Atmospheric Pressure Alexey A. Dyshin,* Olga V. Eliseeva, and Michael G. Kiselev Laboratory of NMR-Spectroscopy and Computer Simulations, G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, 1 Akademicheskaya Street, Ivanovo, 153045, Russia ABSTRACT: The values of densities in N-methylacetamide solutions of calcium chloride have been measured at atmospheric pressure using an Anton Paar digital vibrating U-tube densimeter at temperatures ranging from 308.15 to 328.15 K, ΔT = 5 K and in the concentration range from 0 to 0.355 mol·kg−1. The kinematic viscosity for these mixtures has been measured at the same thermodynamic conditions using an Ubbelohde viscometer. Partial molar volumes of N-methylacetamide; partial molar volumes and apparent molar volumes of calcium chloride, and thermal expansion coefficients of solutions have been calculated using the experimental values. Dependences of these properties on the electrolyte concentrations have been discussed.

The initial N-methylacetamide was dried. At the first stage, calcium oxide was annealed for 8 h at 1373 K and added to NMA. The mixture was boiled for 3 h and then distilled under reduced pressure, which was followed by fractional crystallizations, with the selection of the middle fraction having a vapor temperature of 358 K. The initial calcium chloride was dried under vacuum. The moisture content of the used reagents after purification was determined by Karl Fisher titration, and the water content was found to be 0.001% for NMA and 0.005% for CaCl2. A summary of the materials used is presented in Table 1. The mixtures were prepared gravimetrically using an analytical balance Sartorius Genius ME235S with a precision of ±1 × 10−5 g. The solutions were prepared from degassed solvents. 2.2. Experimental Apparatus. 2.2.1. Density Measurement. A vibrating U-tube densimeter from Anton Paar GmbH (model DMA 5000M) was used to measure the density of the binary system and net solvent. The standard experimental error bar provided by the manufacturer for the density is ±1 × 10−6 g·cm−3. The temperature was determined with an integrated platinum resistor thermometer (Pt 100) together with Peltier elements which provided a high precision thermostat. The temperature setting accuracy reached in the cell was ±0.001 K. The densimeter was calibrated by water (liquid density standard, ultrapure water, Reinstwasser, Dichte-Kalibrierflussigkeit) and dry air before each measurement. 2.2.2. Kinematic Viscosity Measurement. The kinematic viscosity was measured using an Ubbelohde viscometer with a

1. INTRODUCTION Information on physicochemical properties of solutions of various salts of sodium, magnesium, potassium, and calcium in amides is of special interest because these systems are widely used as a mimetic of the protein backbone. It is well-known that sodium, magnesium, potassium, and calcium cations are crucial for live organisms: sodium is one of the main constituents of saline solution; magnesium is necessary for heart activity; calcium is a part of a bone skeleton, etc. N-Methylacetamide (NMA) is a good model compound for studying hydrogen bonds between peptide groups. The temperature and concentration dependences of properties such as density and viscosity can be analyzed from the standpoint of possible intermolecular interactions in solutions. Being a mimetic of the structure of amino acids, the NMA attracts the attention of many researchers.1−4 This solvent has a high polarity and therefore, the solubility of salts in NMA is relatively high. The study of the solubility of various salts in amide solvents is widely represented in the literature.5,6 However, these data have been obtained with a high experimental error bar in different studies. This is due to different degrees and methods of solvent and salts purification. In this project, the physical and chemical characteristics of calcium chloride solution in NMA have been studied.

2. EXPERIMENTAL SECTION 2.1. Chemicals and Preparation of Solutions. All the chemicals used were received from Acros Organics and SigmaAldrich. All the reagents were previously dehydrated. The initial solvents were purified by the standard procedure described in ref 7. © XXXX American Chemical Society

Received: June 1, 2017 Accepted: October 30, 2017

A

DOI: 10.1021/acs.jced.7b00494 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Table 1. Purity of Chemicals Used in This Study

a

abbreviated name

IUPAC name

NMA

N-methylacetamide

79-16-3

CaCl2

calcium chloride

10043-52-4

CASRN

initial purity, %

source Acros Organics Sigma-Aldrich

99+ ≥99

purification method fractional crystallizations and distillation vacuum drying

final water content, %

analysis method

0.001

KFa

0.005

KFa

Iodometric titration by Karl Fischer method.

suspended level and optical detection of the liquid flow time. The measurement error was ±2 × 10−6 m2·s−1. The precision of temperature maintenance while measuring viscosity was ±0.02 K. The viscometer was calibrated by bidistilled and degassed water.

The apparent molar volumes of calcium chloride were computed by applying the following equation:16

3. RESULTS AND DISCUSSION The density values of the net solvent over temperatures range from 308.15 to 328.15 K and the comparison of these values with literature data is reported in Table 2.

where ρ is the mixture density, kg·m−3; ρ0 is the density of NMA, kg·m−3; M2 is the molecular weight of CaCl2, kg·mol−1; m is the molality of CaCl2, mol·kg−1; and Vφ is the apparent molar volume of CaCl2, m3·mol−1. The partial molar volumes of the i-component of the mixture were calculated using the following equation:17

Vϕ =

Table 2. Comparison of Measured Net Solvent Properties with Literature Values at Temperatures Ranging from 308.15 to 328.15 K ρ·10−3/kg·m−3

Vi =

η·103/Pa·s

mρρ0

+

M2 ρ

(3)

Mi (1000 + mMi) ∂ρ − · ∂m ρ ρ2

(4) −3

solvent

T/K

this work

lit.

this work

lit.

NMA

308.15

0.94585

3.5807

3.31249 3.6712

313.15

0.94163

3.1544

2.90419 3.01214

318.15

0.93744

2.8009

2.60729

323.15 328.15

0.93324 0.92907

0.94598,9 0.9459110 0.9462411 0.958912 0.941313 0.941514 0.94178 0.9422411 0.94369 0.93768 0.9387211 0.93999 0.933515

where ρ is the mixture density, kg·m ; Mi is the molecular weight of i-component, kg·mol−1; m is the molality of CaCl2, mol·kg−1; and Vi is the partial molar volume of i-component, m3·mol−1. The calculated values for N-methylacetamide−calcium chloride system are reported in Table 3. The obtained experimental data show that the density grows with an increase in the salt concentration and goes down if the temperature increases. Since NMA can form hydrogen bonds through hydrogen-bonding with nitrogen and through the oxygen of the carbonyl group, it tends to form branchy hydrogen-bonded clusters. Some authors suggest that NMA, like water, forms a hydrogen-bonded network.3,18 The result shows that a temperature increase destroys the hydrogen-bonded network and, as a result, reduces the solution density and viscosity (Figure 1) and increases the thermal expansion coefficient (Figure 2). On the other hand, because of the high dipole moment of NMA (4.12 D), the hydrogen-bonded network destruction may reduce the partial molar volume of the electrolyte, in accordance with the electrostriction effect (Figure 3). As the authors of work ref 19 have shown, the binding energy of the calcium ion with NMA is noticeably higher than that of the calcium ion with water and acetone, which may explain the anomalous behavior of the calcium chloride solution in NMA. In fact, in the case of calcium chloride aqueous solution (the dipole moment of the water molecule in gas phase is 1.8 D), the partial molar volume of the calcium chloride increases as a function of temperature.20

2.4972 2.2482

The experimental values for the N-methylacetamide−calcium chloride system at the temperatures ranging from 308.15 to 328.15 K, ΔT = 5 K, are reported in Table 3. The experimental data of densities and kinematic viscosity were used to calculate dynamic viscosity from the following equation: η = ρν (1) where η is the solution dynamic viscosity, Pa·s; ρ is the solution densities, kg·m−3; ν is the solution kinematic viscosity, m2·s−1. The experimental data of densities were used to calculate the partial and apparent molar volumes of calcium chloride and the thermal expansion coefficients of the mixtures. The thermal expansion coefficients were calculated from experimental data by the following equation:

1 ⎛ ∂ρ ⎞ αp = − ·⎜ ⎟ ρ ⎝ ∂T ⎠ p

1000·(ρ0 − ρ)

4. CONCLUSION The viscosity and volumetric characteristics of calcium chloride solution in N-methylacetamide was measured in the current project, and it has been found that the partial molar volume of calcium chloride decreases with increasing the temperature. We explain this anomalous behavior taking into account two factors. First, the temperature increase destroys the hydrogen bonded network in the solvent. Second, the average distance between the calcium ion and NMA in the first solvation shell of

(2)

where ρ is the mixture density; T is the temperature, K; αp is the thermal expansion coefficient, K−1. B

DOI: 10.1021/acs.jced.7b00494 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Table 3. Densities ρ, Kinematic ν and Dynamic η Viscosities, Partial Molar Volumes of NMA V1, Partial Molar Volumes of CaCl2 V2, Apparent Molar Volumes of CaCl2 Vφ, and Thermal Expansion Coefficients αp for the N-Methylacetamide−Calcium Chloride System at Temperatures Ranging from 308.15 to 328.15 K, ΔT = 5 K and Pressure (99.6 ± 0.8) kPaa ρ × 10−3

m −1

−3

ν × 106 2 −1

η × 103

kg·m

m ·s

0 0.00398 0.01042 0.04232 0.05605 0.08536 0.10221 0.13142 0.15392 0.16135 0.17193 0.19978 0.22189 0.25782 0.35462

0.94585 0.94610 0.94661 0.94877 0.94967 0.95177 0.95301 0.95497 0.95657 0.95709 0.95784 0.95980 0.96127 0.96400 0.97082

3.7857 3.8126 3.8299 4.0371 4.1300 4.3364 4.4687 4.7010 4.8875 4.9507 5.0340 5.2625 5.4596 5.7919 6.9209

3.5807 3.6071 3.6254 3.8303 3.9222 4.1273 4.2587 4.4893 4.6752 4.7383 4.8218 5.0510 5.2482 5.5834 6.7189

0 0.00398 0.01042 0.04232 0.05605 0.08536 0.10221 0.13142 0.15392 0.16135 0.17193 0.19978 0.22189 0.25782 0.35462

0.94163 0.94191 0.94238 0.94456 0.94549 0.94759 0.94887 0.95079 0.95241 0.95296 0.95369 0.95568 0.95726 0.95975 0.96661

3.3499 3.3754 3.4125 3.5886 3.6683 3.8271 3.9469 4.1486 4.3052 4.3492 4.4241 4.6334 4.7985 5.0979 6.0086

3.1544 3.1793 3.2159 3.3897 3.4683 3.6265 3.7451 3.9444 4.1003 4.1446 4.2192 4.4280 4.5934 4.8927 5.8080

0 0.00398 0.01042 0.04232 0.05605 0.08536 0.10221 0.13142 0.15392 0.16135 0.17193 0.19978 0.22189 0.25782 0.35462

0.93744 0.93773 0.93820 0.94039 0.94134 0.94345 0.94470 0.94662 0.94818 0.94873 0.94944 0.95158 0.95304 0.95568 0.96240

2.9878 3.0208 3.0431 3.1895 3.2491 3.3991 3.4941 3.6661 3.8012 3.8512 3.9010 4.0814 4.2417 4.4961 5.3201

2.8009 2.8327 2.8550 2.9994 3.0585 3.2069 3.3009 3.4704 3.6042 3.6537 3.7038 3.8838 4.0425 4.2968

0 0.00398 0.01042 0.04232 0.05605 0.08536 0.10221 0.13142 0.15392 0.16135

0.93324 0.93354 0.93397 0.93624 0.93718 0.93913 0.94052 0.94251 0.94399 0.94454

2.6758 2.6914 2.7239 2.8603 2.9178 3.0476 3.1274 3.2763 3.3921 3.4323

2.4972 2.5125 2.5440 2.6779 2.7345 2.8621 2.9414 3.0879 3.2021 3.2419

mol·kg

V1 × 106 −1

m ·mol 3

Pa·s

V2 × 106 m ·mol 3

−1

Vφ × 106 −1

αp × 104

m ·mol

K−1

3

T = 308.15 K 77.28 77.28 77.28 77.28 77.28 77.28 77.29 77.29 77.29 77.29 77.29 77.29 77.29 77.30 77.31

38.69 38.67 38.63 38.45 38.37 38.21 38.11 37.95 37.82 37.78 37.72 37.57 37.45 37.25 36.73

38.6810 38.6625 38.5711 38.5319 38.4485 38.4007 38.3182 38.2548 38.2340 38.2043 38.1264 38.0647 37.9650 37.6989

8.85 8.84 8.84 8.82 8.81 8.79 8.78 8.76 8.75 8.74 8.74 8.72 8.70 8.68 8.62

77.63 77.63 77.63 77.63 77.63 77.63 77.63 77.63 77.63 77.63 77.63 77.64 77.64 77.64 77.65

38.35 38.33 38.29 38.11 38.03 37.87 37.77 37.61 37.48 37.44 37.38 37.23 37.11 36.91 36.39

38.3396 38.3211 38.2300 38.1909 38.1077 38.0600 37.9777 37.9145 37.8937 37.8641 37.7864 37.7249 37.6254 37.3601

8.89 8.88 8.88 8.86 8.85 8.83 8.82 8.80 8.79 8.78 8.77 8.76 8.74 8.72 8.66

77.97 77.97 77.97 77.97 77.97 77.98 77.98 77.98 77.98 77.98 77.98 77.98 77.98 77.99 78.00

38.16 38.14 38.10 37.92 37.84 37.67 37.58 37.42 37.29 37.25 37.19 37.04 36.92 36.72 36.20

38.1475 38.1291 38.0380 37.9989 37.9157 37.8681 37.7858 37.7227 37.7018 37.6723 37.5946 37.5332 37.4338 37.1686

8.93 8.92 8.92 8.90 8.89 8.87 8.86 8.84 8.83 8.82 8.81 8.80 8.78 8.76 8.70

78.32 78.32 78.32 78.32 78.32 78.32 78.32 78.33 78.33 78.33

38.06 38.04 38.00 37.82 37.74 37.57 37.48 37.32 37.19 37.15

38.0474 38.0290 37.9378 37.8987 37.8155 37.7678 37.6855 37.6223 37.6015

8.97 8.96 8.96 8.94 8.93 8.91 8.90 8.88 8.86 8.86

T = 313.15 K

T = 318.15 K

T = 323.15 K

C

DOI: 10.1021/acs.jced.7b00494 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Table 3. continued m

ρ × 10−3

ν × 106

η × 103

mol·kg−1

kg·m−3

m2·s−1

Pa·s

V1 × 106

V2 × 106

Vφ × 106

αp × 104

m3·mol−1

m3·mol−1

m3·mol−1

K−1

78.33 78.33 78.33 78.34 78.35

37.09 36.94 36.82 36.62 36.10

37.5719 37.4942 37.4327 37.3332 37.0679

8.85 8.83 8.82 8.80 8.74

78.67 78.67 78.67 78.67 78.68 78.68 78.68 78.68 78.68 78.68 78.68 78.68 78.68 78.69 78.70

37.92 37.90 37.86 37.68 37.60 37.44 37.34 37.18 37.06 37.02 36.96 36.80 36.68 36.49 35.97

37.9131 37.8946 37.8034 37.7643 37.6811 37.6334 37.5511 37.4879 37.4670 37.4374 37.3597 37.2982 37.1988 36.9334

9.01 9.00 9.00 8.98 8.97 8.95 8.94 8.92 8.90 8.90 8.89 8.87 8.86 8.84 8.77

T = 323.15 K 0.17193 0.19978 0.22189 0.25782 0.35462

0.94540 0.94731 0.94877 0.95140 0.95822

3.4841 3.6423 3.7730 3.9968 4.7097

3.2939 3.4504 3.5797 3.8025 4.5129

0 0.00398 0.01042 0.04232 0.05605 0.08536 0.10221 0.13142 0.15392 0.16135 0.17193 0.19978 0.22189 0.25782 0.35462

0.92907 0.92934 0.92979 0.93207 0.93303 0.93499 0.93621 0.93824 0.93985 0.94037 0.94117 0.94319 0.94471 0.94713 0.95399

2.4199 2.4355 2.4611 2.5777 2.6340 2.7416 2.8107 2.9509 3.0522 3.0877 3.1290 3.2736 3.3852 3.5846 4.2039

2.2482 2.2634 2.2883 2.4026 2.4576 2.5634 2.6314 2.7687 2.8686 2.9036 2.9449 3.0876 3.1980 3.3951 4.0105

T = 328.15 K

a

m is the molality of CaCl2 in the (CaCl2 + NMA) solutions. Standard uncertainties u are u(T) = 0.01 and 0.02 K for density and viscosity measurements, respectively, and the expanded uncertainties U are U(m) = 2 × 10−5 mol·kg−1, Ur(ρ) = 0.002, and Ur(ν) = 0.01 for 0.95 level of confidence.

Figure 3. Partial molar volumes of CaCl2: black ■, 308.15 K; red ●, 313.15 K; green ▲, 318.15 K; blue ▼, 323.15 K; aqua ⧫, 328.15 K.

Figure 1. Kinematic viscosities for the N-methylacetamide−calcium chloride system at different temperatures: black ■, 308.15 K; red ●, 313.15 K; green ▲, 318.15 K; blue ▼, 323.15 K; aqua ⧫, 328.15 K.

the calcium ions decreases as a result of their strong charge− dipole interaction. Therefore, the partial molar volume also becomes smaller. Such an electrostriction effect follows from the competition between the calcium ion−NMA interactions and the energy of the hydrogen bonds of the solvent molecules.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel.: +7 4932 351869. Fax: +7 4932 336237. ORCID

Alexey A. Dyshin: 0000-0002-0263-642X Funding

This research was supported by the Russian Foundation for Basic Research (Grant RFBR No. 17-03-00309 A).

Figure 2. Thermal expansion coefficient for the N-methylacetamide− calcium chloride system: black ■, 308.15 K; red ●, 313.15 K; green ▲, 318.15 K; blue ▼, 323.15 K; aqua ⧫, 328.15 K.

Notes

The authors declare no competing financial interest. D

DOI: 10.1021/acs.jced.7b00494 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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11. Tetraalkylamrnonium Halides and Some Alkali Metal Formates, Acetates, and Propionates. J. Phys. Chem. 1971, 75, 2319−2325. (19) Peschke, M.; Blades, A. T.; Kebarle, P. Binding Energies for Doubly-Charged Ions M2+ = Mg2+, Ca2+ and Zn2+ with the Ligands L = H2O, Acetone and N-methylacetamide in Complexes MLn2+ for n = 1 to 7 from Gas Phase Equilibria Determinations and Theoretical Calculations. J. Am. Chem. Soc. 2000, 122, 10440−10449. (20) Kumar, A.; Atkinson, G. Thermodynamics of concentrated electrolyte mixtures. 3. Apparent molal volumes, compressibilities, and expansibilities of sodium chloride-calcium chloride mixtures from 5 to 35°C. J. Phys. Chem. 1983, 87, 5504−5507.

ACKNOWLEDGMENTS The density measurements were made with the vibrating tube densimeter Anton Paar DMA 5000M at the center for joint use of scientific equipment “The Upper Volga Region Center for Physico-Chemical Research”.

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REFERENCES

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DOI: 10.1021/acs.jced.7b00494 J. Chem. Eng. Data XXXX, XXX, XXX−XXX