Thermal and Volumetric Properties of Some C5 ... - ACS Publications

Article pubs.acs.org/jced

Thermal and Volumetric Properties of Some C5 and C6 Alkanones at Infinite Dilution in Water Vladimír Dohnal,* Karel Ř ehák, and Pavel Morávek Department of Physical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic S Supporting Information *

ABSTRACT: Precise measurements of excess enthalpies and densities of highly dilute aqueous solutions of five C5−C6 alkanones (namely 2-pentanone, 3-pentanone, 3-methyl-2-butanone, 2-hexanone, and 4-methyl-2-pentanone) were carried out using tandem flow mixing calorimetry and vibrating-tube densimetry. The experimental data obtained in the temperature range from 288.15 to 318.15 K were utilized for the evaluation of limiting partial molar excess enthalpies, partial molar volumes, and partial molar excess volumes of the alkanones in water. Within the temperature range studied, these infinite dilution properties were found to exhibit linear trends. As inferred from respective linear fits, partial molar excess heat capacities, partial molar expansions, and excess partial molar expansions were obtained with a good accuracy. Moreover, hydration enthalpies and heat capacities of the alkanones studied were evaluated, too. The thermodynamic behavior of the alkanone solutes was discussed in terms of molecular interactions and shown to be closely correlated with that for equi-structured alkanol solutes.

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INTRODUCTION

EXPERIMENTAL SECTION Materials. The chemical samples used in this study are specified in Table 1. The ketones used as solutes were all

Reliable experimental data on thermodynamic properties of volatile organic compounds (VOCs) at infinite dilution in water, such as limiting activity coefficient γ∞ 1 , Henry’s law constant KH, limiting partial molar excess enthalpy H̅ E,∞ 1 , E,∞ (C ), and limiting partial molar (excess) heat capacity C̅ ∞ ̅ p,1 p,1 E,∞ limiting partial molar (excess) volume V̅ ∞ 1 (V̅ 1 ), are of vital importance for numerous industrial and theoretical applications, in particular for design and control of thermal separation processes, for understanding the transport and fate of these substances in the environment, and for development of prediction methods and testing of solution theories. Over two past decades we have been greatly engaged in systematic measurements of these properties providing thus a bulk of data for various classes of VOCs, including aromatic and/or halogenated hydrocarbons,1−4 alkanols,5−10 phenols,11 ethers,12 esters,13,14 nitrocompounds,15 nitriles,16−18 amides,19 amines,20 nitrogen heterocyclic compounds,21,22 and others. Continuing our long-term effort, this work focuses on ketones. The infinite dilution thermodynamic properties have been determined for 2-butanone, cyclopentanone, and cyclohexanone in our previous works.16−18 Here, we report precise heat-of-mixing and density measurements for highly dilute aqueous solutions of five C5 and C6 alkanones, namely 2-pentanone, 3-pentanone, 3-methyl-2-butanone, 2-hexanone, and 2-methyl-4-pentanone, carried out at four temperatures T = 288.15, 298.15, 308.15, and 318.15 K. Based on this primary experimental data various thermal and volumetric properties of these alkanones at infinite dilution in water are evaluated and correlated with those for equi-structured alkanols obtained previously. © XXXX American Chemical Society

Table 1. Specification of the Chemicals Used in This Work compound

source, initial purity

2-pentanone

Sigma-Aldrich, Chromasolv, 0.997a Sigma-Aldrich, ReagentPlus, 0.997a Sigma-Aldrich, puriss, 0.985a Sigma-Aldrich, reagent grade, 0.982a Sigma-Aldrich, Chromasolv, 0.998a tap water

3-pentanone 3-methyl-2butanone 2-hexanone 4-methyl-2pentanone water a

purification method

final purity indication

dried with molecular sieves dried with molecular sieves dried with molecular sieves dried with molecular sieves dried with molecular sieves distillation, MilliQ purification

water contenta by KF titration: 320·10−6 water contenta by KF titration: 210·10−6 water contenta by KF titration: 390·10−6 water contenta by KF titration: 340·10−6 water contenta by KF titration: 170·10−6 electrical resistivity: 184 kΩ·m

Mass fraction.

obtained from Sigma-Aldrich at the highest purity available. The purities claimed by the supplier in respective certificates of analysis were verified by our own gas chromatography assay using a DB-WAX capillary column. The samples were not further purified except for drying with molecular sieves. Water contents, as determined by coulometric Fischer titration using a special reagent Hydranal Coulomat AK applicable to ketones, Received: January 13, 2017 Accepted: April 20, 2017

A

DOI: 10.1021/acs.jced.7b00035 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 2. Experimental Densities of Pure Solutes ρ,a Comparison with Selected Literature Values, and Parameters a, b of Equation ρ/(g · cm−3) = a + b·(T/K) Along With Standard Deviation of Fit s

did not exceed 0.0004 mass fraction. Water used as solvent was distilled and subsequently treated by a Milli-Q Water Purification System (Millipore, USA). Before measurements, all liquids were partially degassed by vacuum filtration and sonification. Apparatus and Procedure. The excess enthalpies and densities of highly dilute aqueous solutions were measured simultaneously by means of our experimental assembly called “calo/densimeter”. Detailed information on this tandem flow instrument consisting of a mixing microcalorimeter and a vibrating tube densimeter, as well as on the experimental procedure applied, can be found in our earlier publication.22 As in all previous measurement campaigns, the calorimeter was duly calibrated with a Joule effect produced by a built-in calibration heater. The calibration of the densimeter was established on water and dodecane density standards whose densities were taken from the literature.23,24 It is also important to note that an additional refreshing single-fluid calibration of the densimeter was repeated at each experimental run using baseline signal corresponding to the pure solvent (water).

ρ/(g · cm−3)

T/K this work 288.15 298.15 308.15 318.15 a = 1.091893 288.15 298.15 308.15 318.15 a = 1.102192

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288.15 298.15 308.15 318.15 a = 1.093436

RESULTS AND DISCUSSION Densities of the pure ketones at 288.15, 298.15, 308.15, and 318.15 K were measured first to provide reliable data for determination of the mass flows of pumped streams and evaluation of excess volumes. The expanded uncertainty (k = 2) of pure solute densities determined in this work is estimated to U(ρ) = 6 × 10−4 g·cm−3. This value of U(ρ) accounts for all sources of possible errors including the effects of sample impurities. The measured densities of pure solutes and their comparison to selected literature values are given in Table 2. Deviation plots (Figures S1−S5) allowing a more comprehensive and convenient comparison are shown in the Supporting Information to this article. As seen, the agreement of the present measurements with the literature data is generally very good, the differences being in the majority of cases within 3 × 10−4 g·cm−3. For 3-methyl-2-butanone the situation is however less clear-cut; though our measurements agree to the values given in the TRC database to 3 × 10−4 g·cm−3, they differ about 1 × 10−3 g·cm−3 from other fragmentary data available in the open literature. From Figures S1−S5 it is interesting to note that in most cases the literature densities are more or less higher than those determined in this work. One can suppose that the reason for this is the content of water: in contrast to this work, not all the samples used in the literature studies were dried and their water content was checked only very rarely. The excess enthalpy and density data measured for dilute aqueous solutions of the alkanones are listed in Table 3. At each temperature the data were typically collected from two experimental runs. The expanded uncertainties (k = 2) for density determinations and excess enthalpy determinations were estimated to be U(ρ) = 1 × 10−5 g·cm−3 and U(HE)/HE = 0.01, respectively, for C5 alkanones, and U(ρ) = 2 × 10−5 g·cm−3 and U(HE)/HE = 0.02, respectively, for C6 alkanones. The values of infinite dilution partial molar excess enthalpy H̅ E,∞ and 1 were determined by linear extrapolation of the volume V̅ E,∞ 1 quantity HE/(x1x2) and VE/(x1x2), respectively, as functions of x1 to infinite dilution. To evaluate the excess volumes, pure solute densities determined in this work (Table 2) and recommended water density values23 were used. For illustration, Figures 1 and 2 display the primary HE and VE data measured for 3-methyl-2-butanone and their extrapolation to obtain H̅ E,∞ 1

288.15 298.15 308.15 318.15 a = 1.077663 288.15 298.15 308.15 318.15 a = 1.070845

literature

2-pentanone 0.81106 0.81107 0.80141 0.80142 0.79166 0.78183 b = −9.7445 × 10−4 3-pentanone 0.81890 0.80916 0.80935 0.79932 0.7996 0.78941 b = −9.8299 × 10−4 3-methyl-2-butanone 0.80830 0.8094 0.79851 0.7982 0.78860 0.77862 b = −9.8938 × 10−4 2-hexanone 0.81572 0.81588 0.80670 0.8067 0.79760 0.78845 b = −9.0895 × 10−4 4-methyl-2-pentanone 0.80512 0.80536 0.79598 0.79615 0.78675 0.7868 0.77746 b = −9.2204 × 10−4

ref 25 26

s = 6 × 10−5 g·cm−3

27 28 s = 6 × 10−5 g·cm−3 29 30

s = 7 × 10−5 g·cm−3 25 30

s = 5 × 10−5 g·cm−3 25 31 32 s = 5 × 10−5 g·cm−3

a

At ambient pressure p = 100 kPa. Standard uncertainties are u(P) = 5 kPa, u(T) = 10 mK. Expanded uncertainty (0.95 level of confidence) for ρ is U(ρ) = 6 × 10−4 g·cm−3.

and V̅ E,∞ 1 , respectively. The infinite dilution partial molar volume • V̅ ∞ 1 was in turn obtained by adding the molar volume V̅ 1 to E,∞ E,∞ E,∞ V̅ 1 . The values H̅ 1 and V̅ 1 for studied alkanones in water, along with their standard uncertainties estimated using the error propagation law, are given in Table 4. As seen from Table 4, some of our results can be compared to data reported in the literature; the literature data being however limited almost exclusively to C5 alkanones and 298.15 K only. The difference of our H̅ E,∞ values and those 1 existing in the literature does not exceed their combined uncertainty, the closest agreement (within 2%) being observed with batch dissolution calorimetric experiments of Della Gatta et al.33 Regarding the infinite dilution partial molar volumes our values for 3-pentanone are seen to agree very well with those of Roux et al.37 and Cibulka et al.,36 but for 2-pentanone and especially for 3-methyl-2-butanone they are in a great disparity with older data of Edward et al.34 Within the temperature range studied, these infinite dilution properties exhibit effectively linear trends. Parameters of respec∞ tive linear fits are given in Table 5. The H̅ E,∞ 1 (T), V̅ 1 (T), and E,∞ V̅ 1 (T) data appear precise enough to allow reliable evaluation of infinite dilution partial molar excess heat capacities B



Article

Table 3. Experimental Excess Enthalpy HE and Density ρ for Highly Dilute Aqueous Solutions of Five Alkanones as a Function of Solute Mole Fraction x1 at Several Temperaturesa HE

ρ

x1

J·mol−1

g·cm−3

T = 288.15 0.005032 0.005035 0.004197 0.004198 0.003360 0.003361 0.002522 0.002522 0.001683 0.001683 0.000842 0.000842 T = 298.15 0.005028 0.005029 0.004193 0.004193 0.003358 0.003357 0.002521 0.002520 0.001682 0.001681 0.000842 0.000841

K −61.21 −61.27 −51.11 −51.49 −41.30 −41.46 −31.50 −31.41 −21.16 −21.18 −10.62 −10.66 K −49.65 −49.68 −41.81 −41.64 −33.46 −33.83 −25.81 −25.66 −17.24 −17.21 −8.67 −8.67

T = 288.15 0.005071 0.005069 0.004229 0.004227 0.003386 0.003385 0.002542 0.002540 0.001696 0.001695 0.000849 0.000848 T = 298.15 0.005066 0.005064 0.004225 0.004222 0.003383 0.003380 0.002539 0.002537 0.001694 0.001693 0.000847 0.000847

K −62.86 −62.73 −52.72 −52.95 −42.68 −42.57 −32.16 −32.25 −21.76 −21.50 −11.04 −10.92 K −51.57 −51.26 −43.14 −43.12 −34.74 −34.43 −26.35 −26.21 −17.83 −17.97 −8.97 −8.95

T = 288.18 K 0.004998 −60.47

x1

2-pentanone T = 308.15 0.996016 0.005034 0.996015 0.005031 0.996522 0.004197 0.996499 0.004194 0.997021 0.003360 0.997002 0.003358 0.997512 0.002522 0.997513 0.002520 0.998027 0.001683 0.998026 0.001681 0.998562 0.000842 0.998560 0.000841 T = 318.15 0.993716 0.005024 0.993707 0.004189 0.994250 0.003354 0.994260 0.002517 0.994811 0.001679 0.994797 0.000840 0.995334 0.995346 0.995902 0.995903 0.996472 0.996472 3-pentanone T = 308.15 0.996221 0.005074 0.996228 0.005069 0.996682 0.004231 0.996667 0.004226 0.997139 0.003387 0.997144 0.003384 0.997616 0.002543 0.997609 0.002540 0.998104 0.001696 0.998107 0.001695 0.998589 0.000849 0.998595 0.000848 T = 318.15 0.993902 0.005073 0.993924 0.005076 0.994423 0.004231 0.994420 0.004233 0.994931 0.003388 0.994944 0.003390 0.995442 0.002543 0.995458 0.002544 0.995958 0.001697 0.995960 0.001698 0.996504 0.000849 0.996504 0.000850 3-methyl-2-butanone T = 308.15 0.995988 0.005001

HE

ρ

J·mol−1

g·cm−3

K −38.34 −38.39 −32.43 −32.36 −26.07 −26.21 −19.81 −19.93 −13.49 −13.48 −6.85 −6.81 K −27.19 −23.12 −18.83 −14.27 −9.71 −4.92

Table 3. continued

0.990474 0.990475 0.991045 0.991052 0.991643 0.991617 0.992228 0.992226 0.992818 0.992814 0.993420

0.986447 0.987058 0.987666 0.988307 0.988929 0.989570

K −40.05 −39.95 −33.38 −33.33 −26.81 −27.03 −20.78 −20.63 −13.88 −13.87 −7.09 −6.97 K −28.35 −28.55 −24.11 −23.98 −19.31 −19.56 −14.87 −14.95 −10.08 −10.10 −5.06 −5.12

0.986636 0.986636 0.987229 0.987234 0.987821 0.987820 0.988399 0.988396 0.989005 0.988992 0.989610 0.989603

K −38.75

0.990494

ρ

HE

0.990660 0.990666 0.991216 0.991241 0.991774 0.991770 0.992311 0.992322 0.992873 0.992887 0.993449 0.993460

C

−1

x1

J·mol

g·cm

0.005001 0.004168 0.004171 0.003337 0.003339 0.002505 0.002506 0.001672 0.001672 0.000837 0.000837 T = 298.15 0.004998 0.004994 0.004168 0.004166 0.003337 0.003337 0.002505 0.002505 0.001671 0.001672 0.000836 0.000836

−60.25 −50.55 −50.67 −40.75 −40.85 −30.91 −30.97 −20.73 −20.80 −10.46 −10.48 K −49.48 −49.20 −41.57 −41.40 −33.56 −33.41 −25.59 −25.34 −17.20 −17.20 −8.67 −8.66

0.996000 0.996494 0.996488 0.996996 0.996993 0.997502 0.997502 0.998026 0.998025 0.998559 0.998558

T = 288.15 0.001739 0.001739 0.001450 0.001450 0.001160 0.001160 0.000870 0.000870 T = 298.15 0.001740 0.001737 0.001450 0.001448 0.001160 0.001159 0.000870 0.000869

K −21.05 −21.09 −17.70 −17.61 −14.35 −14.20 −10.72 −10.61 K −16.32 −16.48 −13.76 −13.43 −10.96 −11.03 −8.28 −8.25

T = 288.15 0.002006 0.002004 0.001720 0.001718 0.001434 0.001432 0.001147 0.001146 0.000860 0.000860 0.000574

K −24.73 −24.71 −21.25 −21.43 −17.78 −17.95 −14.40 −14.25

−7.27

ρ

HE −3

x1

−1

g·cm−3

−32.75 −32.68 −26.44 −26.53 −19.99 −20.16 −13.47 −13.53 −6.85 −6.83

0.991064 0.991067 0.991647 0.991646 0.992235 0.992224 0.992827 0.992824 0.993424 0.993426

K −28.33 −28.33 −23.99 −23.88 −19.47 −19.44 −14.78 −13.81 −9.98 −9.98 −5.06 −5.05

0.986481 0.986477 0.987083 0.987091 0.987696 0.987702 0.988318 0.988447 0.988945 0.988947 0.989576 0.989578

J·mol

0.004167 0.004171 0.003336 0.003340 0.002504 0.002506 0.001672 0.001672 0.000836 0.000837

T = 318.15 0.993722 0.004998 0.993729 0.004997 0.994254 0.004168 0.994261 0.004167 0.994799 0.003337 0.994805 0.003336 0.995337 0.002505 0.995348 0.002338 0.995897 0.001671 0.995899 0.001670 0.996470 0.000836 0.996470 0.000836 2-hexanone T = 308.15 0.997852 0.001735 0.997853 0.001737 0.998054 0.001447 0.998054 0.001448 0.998248 0.001158 0.998255 0.001159 0.998466 0.000869 0.998439 0.000869 T = 318.15 0.995681 0.001737 0.995664 0.001737 0.995903 0.001736 0.995926 0.001448 0.996137 0.001448 0.996128 0.001447 0.996364 0.001159 0.996347 0.001159 0.001158 0.000869 0.000870 0.000868 4-methyl-2-pentanone T = 308.15 0.997567 0.002002 0.997592 0.002003 0.997788 0.001716 0.997779 0.001717 0.998001 0.001431 0.997995 0.001431 0.998210 0.001145 0.998224 0.001145 0.998405 0.000859 0.998422 0.000859 0.998655 0.000573

K −11.42 −11.44 −9.46 −9.38 −7.54 −7.59 −5.79 −5.79 K −6.79 −6.92 −6.72 −5.64 −5.52 −5.55 −4.66 −4.54 −4.60 −3.42 −3.40 −3.45

0.988651 0.988636 0.988678 0.988931 0.988956 0.988934 0.989168 0.989197 0.989173 0.989446 0.989455 0.989450

K −13.82 −13.82 −11.93 −12.04 −10.00 −9.97 −8.09 −8.02 −6.15 −6.16 −4.05

0.992300 0.992285 0.992542 0.992525 0.992791 0.992795 0.993030 0.993053 0.993283 0.993282 0.993534

0.992573 0.992571 0.992840 0.992834 0.993074 0.993080 0.993309 0.993320



Article

Table 3. continued ρ

HE −1

x1

J·mol

0.000573 T = 298.15 0.002004 0.002007 0.001718 0.001721 0.001433 0.001435 0.001146 0.001148 0.000860 0.000861 0.000574 0.000574

−7.24 K −19.21 −19.05 −16.49 −16.59 −13.82 −14.00 −11.27 −11.33 −8.36 −8.51 −5.65 −5.60

g·cm

ρ

HE −3

0.998669 0.995417 0.995402 0.995624 0.995640 0.995875 0.995871 0.996114 0.996078 0.996345 0.996319 0.996572 0.996580

−1

x1

J·mol

g·cm−3

0.000573 T = 318.15 0.002004 0.002003 0.001718 0.001717 0.001432 0.001431 0.001146 0.001145 0.000859 0.000859 0.000573

−4.11 K −8.44 −8.55 −7.43 −7.48 −6.18 −6.24 −5.10 −5.10 −3.89 −3.84 −2.65

0.993533 0.988379 0.988402 0.988636 0.988633 0.988910 0.988905 0.989147 0.989156 0.989411 0.989421

a

At ambient pressure p = 100 kPa. Standard uncertainties are as follows: u(P) = 5 kPa, u(T) = 10 mK, u(x1)/x1 = 0.005. Expanded uncertainties (0.95 level of confidence) for ρ and HE are U(ρ) = 1 × 10−5 g·cm−3 and U(HE)/HE = 0.01, respectively, for 2-pentanone, 3-pentanone, and 3-methyl-2-butanone, and U(ρ) = 2 × 10−5 g·cm−3 and U(HE)/HE = 0.02, respectively, for 2-hexanone and 4-methyl-2pentanone. Densities of solutions refer to pure water densities23 used to calibrate the densimeter.

Figure 1. Excess enthalpy HE for 3-methyl-2-butanone (1) + water (2) as a function of mole fraction x1: experimental points ■, 288.15 K ; ●, 298.15 K; ▲, 308.15 K; ▼, 318.15 K, lines correspond to the linear HE/(x1x2) vs x1 fit; a) HE vs x1 plot, b) HE/(x1x2) vs x1 plot.

E,∞ ∞ ∞ C̅ E,∞ p,1 = (∂H̅ 1 /∂T)p, partial molar expansions E̅ 1 = (∂V̅ 1 / E,∞ E,∞ ∂T)p, and excess partial molar expansions E̅ 1 = (∂V̅ 1 /∂T)p as the slopes of the corresponding linear temperature dependences. These and additional infinite dilution thermodynamic properties of the alkanone solutes at T = 298.15 K derived from the present measurements, are given in Table 6. The hydration enthalpies ΔhydH1 were obtained from the present H̅ E,∞ data 1 and the values of standard vaporization enthalpies ΔvapH1° of pure solutes from the literature according to

Δhyd H = H1̅ E, ∞ − Δ vapH1◦

(1)

The hydration heat capacities ΔhydCp,1 were evaluated combining the present C̅ E,∞ p,1 values with the pure solute heat G, capacities in the liquid CL,• p,1 and the ideal gas state C̅ p,1°, respectively E, ∞ L, • G,◦ Δhyd Cp,1 = Cp,1 + Cp,1 − Cp,1 ̅

(2)

As seen from Table 4, the dissolution of all studied alkanones in water is strongly exothermic and accompanied by considerable volume contraction. This observation convincingly indicates an appreciable effect of solute−solvent complex formation. The complexes are formed by hydrogen bonding of the solvent water proton to the electron lone pairs of the solute oxygen atoms. Among isomers the values of dissolution properties differ very slightly exhibiting no apparent trends except perhaps for V̅ E,∞ values being more negative for more 1 compact branched structures (3-methyl-2-butanone, 4-methyl2-pentanone). Comparing C5 and C6 alkanones, one can see that the addition of CH2 shifts V̅ E,∞ also to more negative 1 values for both C5 and C6 alkanones values. Interestingly, H̅ E,∞ 1 appear however effectively the same at lower temperatures (at 288.15 K and below); their difference becomes apparent only as temperature increases where the dissolution of hexanones gets less exothermic than for pentanones. The increase of the hydrophobicity when going from pentanones to hexanones is well reflected by the increase of C̅ E,∞ p,1 and ΔhydCp,1 values, the

Figure 2. Excess volume VE for 3-methyl-2-butanone (1) + water (2) as a function of mole fraction x1: experimental points ■, 288.15 K ; ●, 298.15 K; ▲, 308.15 K; ▼, 318.15 K, lines correspond to the linear VE/(x1x2) vs x1 fit; a) VE vs x1 plot, b) VE/(x1x2) vs x1 plot.

enhanced heat capacity values for hexanones indicating mainly an enhanced structuring of solvent water around their larger hydrophobic moiety. Data on limiting partial molar expansivities are quite rare in the literature and their interpretation in D



Article

∞ Table 4. Experimental Limiting Partial Molar Excess Enthalpies H̅ E,∞ 1 , Limiting Partial Molar Volumes V̅ 1 , and Limiting Partial E,∞ Molar Excess Volumes V̅ 1 of Five Alkanones at Infinite Dilution in Water along with Their Standard Uncertainties and Comparison with Literature Data (in Parentheses)

solute 2-pentanone

H̅ E,∞ 1

u(H̅ E,∞ 1 )

V̅ ∞ 1

V̅ E,∞ 1

u(V̅ )

T/K

kJ·mol−1

kJ·mol−1

cm3·mol−1

cm3·mol−1

cm3·mol−1

288.15 298.15

−12.76 −10.42 (−10.21)a (−11.51)c −8.20 −5.95 −13.01 −10.68 (−10.90)a (−10.58)c −8.37 −6.09

0.05 0.05 (0.15)a (1.0) 0.03 0.02 0.08 0.06 (0.08)a (1.0) 0.06 0.05

97.93 98.87 (98.0)b

−8.26 −8.61

0.04 0.04 (0.1)b

−8.83 −9.05 −8.05 −8.32

−12.61 −10.47 (−10.63)a −8.25 −6.13 −12.23 −9.46 (−9.46)a −6.58 −3.92 −12.77 −9.97 (−9.0)f −7.25 −4.73

0.05 0.04 (0.12)a 0.03 0.03 0.10 0.08 (0.09)a 0.06 0.05 0.08 0.08 (1.0)f 0.05 0.04

99.98 101.11 97.13 98.13 (98.23)d (98.08)e 99.16 100.17 (100.32)d 98.04 99.01 (95.0)b 99.96 101.01 113.50 114.84

−9.27 −9.61 −9.28 −9.32

0.05 0.05 0.05 0.07 (0.06)d (0.05)e 0.08 0.07 (0.06)d 0.03 0.03 (0.3)b 0.03 0.03 0.25 0.20

115.98 117.53 114.28 115.47

−9.60 −9.50 −10.12 −10.37

0.20 0.25 0.25 0.25

116.71 118.14

−10.60 −10.68

0.10 0.15

308.15 318.15 288.15 298.15

3-pentanone

308.15 318.15 3-methyl-2-butanone

288.15 298.15 308.15 318.15 288.15 298.15

2-hexanone

308.15 318.15 288.15 298.15

4-methyl-2-pentanone

308.15 318.15 a

−8.60 −8.93 −8.51 −8.86

Reference 33. bReference 34. cReference 35. dReference 36. eReference 37. fReference 38.

Table 5. Parameters a, b of Linear Temperature Dependence Fits Y = a + b(T/K) of Experimental Infinite Dilution Partial ∞ E,∞ Molar Properties H̅ E,∞ Together with 1 , V̅ 1 , and V̅ 1 Respective Standard Deviations s of Fits and Coefficients of Determination r2 property Y −1 H̅ E,∞ 1 /(kJ·mol ) 3 −1 V̅ ∞ 1 /(cm ·mol ) 3 E,∞ V̅ 1 /(cm ·mol−1) −1 H̅ E,∞ 1 /(kJ·mol ) 3 ∞ V̅ 1 /(cm ·mol−1) 3 −1 V̅ E,∞ 1 /(cm ·mol ) −1 H̅ E,∞ 1 /(kJ·mol ) 3 −1 /(cm ·mol ) V̅ ∞ 1 3 −1 V̅ E,∞ 1 /(cm ·mol ) −1 H̅ E,∞ 1 /(kJ·mol ) 3 ∞ V̅ 1 /(cm ·mol−1) 3 −1 V̅ E,∞ 1 /(cm ·mol ) −1 H̅ E,∞ 1 /(kJ·mol ) 3 −1 /(cm ·mol ) V̅ ∞ 1 3 −1 /(cm ·mol ) V̅ E,∞ 1

a

ba

2-pentanone −78.00 0.2265 67.20 0.1064 −0.84 −0.0259 3-pentanone −79.47 0.2307 67.80 0.1018 0.38 −0.0292 3-methyl-2-butanone −75.03 0.2166 69.71 0.0983 2.18 −0.0371 2-hexanone −92.35 0.2781 75.41 0.1321 −6.58 −0.0094 4-methyl-2-pentanone −90.05 0.2684 77.22 0.1284 −4.65 −0.0191

s

r2

0.04 0.07 0.05

0.9999 0.9982 0.9851

0.02 0.01 0.02

0.9999 0.9999 0.9977

0.03 0.03 0.02

0.9999 0.9995 0.9987

0.07 0.12 0.11

0.9998 0.9966 0.6469

0.10 0.08 0.06

0.9994 0.9982 0.9576

terms of solute−solvent interactions is problematic. For all alkanones studied, the E̅∞ 1 values are (as expected) positive, are negative. Analogous but the respective excess values E̅E,∞ 1 behavior has been observed also for aqueous alkanols.42 In contrast to the limiting dissolution properties, the hydration properties are free of solute−solute interactions being thus more convenient for theoretical treatments and structure− property correlations. Having obtained respective data for alkanols in our previous studies, we can now compare hydration properties of alkanones to those of equi-structured alkanols. The comparison for ΔhydH1, ΔhydCp,1, and V̅ ∞ 1 (= ΔhydV1) at T = 298.15 K is shown in Figures 3, 4, and 5, respectively. Note that while the 4-methyl-2-pentanone/4-methyl-2-pentanol pair is missing in the comparison because the respective alkanol has not been studied yet, an additional C4 pair 2-butanone/ 2-butanol was included. Note also that all data underlying these figures, except for V̅ ∞ 1 for 2-hexanol, come from this laboratory. Figures 3−5 demonstrate that for each of the hydration properties, there is a linear interrelation between their values for equi-structured alkanones and alkanols having the unity slope. The corresponding fits are as follows Δhyd H1(alkanone)/(kJ·mol−1) = Δhyd H1(alkanol)/(kJ ·mol−1) + bH

∞ −1 −1 3 −1 −1 Parameter b equal to C̅ E,∞ p,1 /(kJ·K ·mol ), E̅ 1 /(cm ·K ·mol , and E,∞ ∞ E,∞ 3 −1 −1 /(cm ·K ·mol for H , V , and V , respectively. E̅ E,∞ ̅1 ̅1 ̅1 1

a

(3)

bH = 17.28( ±0.16), r 2 = 0.987, SD = 0.4 kJ ·mol−1 E



Article

Table 6. Additional Infinite Dilution Thermodynamic Propertiesa of Five Alkanones in Water at T = 298.15 K: Partial Molar Excess Heat Capacity C̅ E,∞ p,1 , Hydration Enthalpy ΔhydH1,b Hydration Heat Capacity ΔhydCp,1,c Partial Molar Expansion E̅∞ 1 , and Excess Partial Molar Expansion E̅ E,∞ 1 C̅ E,∞ p,1 solute 2-pentanone 3-pentanone 3-methyl-2butanone 2-hexanone 4-methyl-2pentanone

ΔhydH1

ΔhydCp,1

E̅ ∞ 1

E̅ E,∞ 1

J·K−1·mol−1 kJ·mol−1 J·K−1·mol−1 cm3·mol−1·K−1 cm3·mol−1·K−1 227 231 217

−48.88 −49.36 −47.34

290 292d 273d

0.106 0.102 0.098

−0.026 −0.029 −0.037

278 268

−52.61 −50.62

348 337

0.132 0.128

−0.009 −0.019

a −1 −1 Estimated uncertainties are as follows: u(C̅ E,∞ p,1 ) = 5 J·K ·mol , ) = u(ΔhydH1) = 0.4 kJ·mol−1, u(ΔhydCp,1) = 10 J·K−1·mol−1, u(E̅ E,∞ 1 c L,• 3 −1 −1 b u(E̅ E,∞ 1 ) = 0.005 cm ·mol ·K . ΔvapH1° taken from ref 39. Cp,1 and 40 d G, Cp,1° taken from ref 41. CG, p,1° taken from CDATA database.

Figure 4. Hydration heat capacity of equi-structured alkanones and alkanols: points are experimental data for ■, 2-butanone18/ 2-butanol;9 ●, 2-pentanone/2-pentanol;10 ▲, 3-pentanone/3-pentanol;10 ▼, 3-methyl-2-butanone/3-methyl-2-butanol;10 ⧫, 2-hexanone/2-hexanol;8 the line is ΔhydCp,1 (alkanones)/(J·K−1·mol−1) = ΔhydCp,1 (alkanols) /(J·K−1·mol−1) − 113.

Figure 3. Hydration enthalpy of equi-structured alkanones and alkanols: points are experimental data for ■, 2-butanone17/2-butanol;9 ●, 2-pentanone/2-pentanol;10 ▲, 3-pentanone/3-pentanol;10 ▼, 3-methyl2-butanone/3-methyl-2-butanol;10 ⧫, 2-hexanone/2-hexanol;8 the line is ΔhydH1 (alkanones)/(kJ·mol−1) = ΔhydH1 (alkanols) /(kJ·mol−1) + 17.3.

Figure 5. Limiting partial molar volume of equi-structured alkanones and alkanols: points are experimental data for ■, 2-butanone18/ 2-butanol;5 ●, 2-pentanone/2-pentanol;5 ▲, 3-pentanone/3-pentanol;5 ▼, 3-methyl-2-butanone/3-methyl-2-butanol;5 ⧫, 2-hexanone/ 3 ∞ −1 2-hexanol;43 the line is V̅ ∞ 1 (alkanones)/(cm ·mol ) = V̅ 1 (alkanols)/ 3 −1 (cm ·mol ) − 3.3.

Δhyd Cp ,1(alkanone)/(J·K−1·mol−1) = Δhyd Cp ,1(alkanol)/(J ·K−1·mol−1) + bC p

(4)

effectively the same for alkanones and alkanols, and (iii) the intercepts in eqs 3−5 express the difference between the contributions of the oxygen of the alkanone carbonyl and the alkanol hydroxyl to each of the hydration properties. Considering the significance of the intercepts in eqs 3−5, their values might be estimated using the existing group contribution method of Plyasunov et al.44 Combining their contributions for CO, CH, and OH according to the following scheme

bCp = −113( ±7), r 2 = 0.973, SD = 7 J ·K−1·mol−1 V1̅ ∞(alkanone)/(cm 3· mol−1) = V1̅ ∞(alkanol)/(cm 3·mol−1) + bV

(5)

bV = −3.29( ±0.28), r 2 = 0.997, SD = 0.6 cm 3·mol−1

where the intercept bY (Y = H, Cp, V) is the only parameter adjusted and its uncertainty given in parentheses corresponds to standard deviation. As seen the correlation for all three properties is excellent, fitting the data at level of experimental uncertainty. The significance of this result is 3-fold: (i) all experimental data involved in the correlations are mutually consistent, which further supports their credibility, (ii) the quantitative relationship between the molecular structure and the hydration property for the compounds is very tight and

bY = Δhyd Y (C = O) − Δhyd Y (CH) − Δhyd Y (OH) (Y = H , Cp , V )

(6)

we obtained values bH = 17.31 (±1.1), bCp = −103 (±9), and bV = −4.0 (±1.1). Although the bY values calculated in this way are less accurate (in part due to less data Plyasunov et al.44 had at disposal at that time), they agree very well with those fitted here to our newer and more extensive data. F



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(9) Fenclová, D.; Dohnal, V.; Vrbka, P.; Laštovka, V. Temperature Dependences of Limiting Activity Coefficients, Henry’s Law Constants, and Related Infinite Dilution Properties of Branched (C3 and C4) Alkanols in Water. Measurement, Critical Compilation, Correlation and Recommended Data. J. Chem. Eng. Data 2007, 52, 989−1002. (10) Fenclová, D.; Dohnal, V.; Vrbka, P.; Ř ehák, K. Temperature Dependence of Limiting Activity Coefficients, Henry’s Law Constants, and Related Infinite Dilution Properties of Branched Pentanols in Water. Measurement, Critical Compilation, Correlation, and Recommended Data. J. Chem. Eng. Data 2010, 55, 3032−3043. (11) Dohnal, V.; Fenclová, D. Air-Water Partitioning and Aqueous Solubility of Phenols. J. Chem. Eng. Data 1995, 40, 478−483. (12) Ondo, D.; Dohnal, V. Temperature dependence of limiting activity coefficients and Henry’s law constants of cyclic and open-chan ethers in water. Fluid Phase Equilib. 2007, 262, 121−136. (13) Dohnal, V.; Vrbka, P.; Ř ehák, K.; Böhme, A.; Paschke, A. Activity coefficients and partial molar excess enthalpies at infinite dilution for four esters in water. Fluid Phase Equilib. 2010, 295, 194− 200. (14) Fenclová, D.; Blahut, A.; Vrbka, P.; Dohnal, V.; Böhme, A. Temperature dependence of limiting activity coefficients, Henry’s law constants, and related infinite dilution properties of C4-C6 isomeric nalkyl ethanoates/ethyl n-alkanoates in water. Measurement, critical compilation, correlation, and recommended data. Fluid Phase Equilib. 2014, 375, 347−359. (15) Beneš, M.; Dohnal, V. Limiting Activity Coefficients of Some Aromatic and Aliphatic Nitro Compounds in Water. J. Chem. Eng. Data 1999, 44, 1097−1102. (16) Hovorka, Š.; Dohnal, V.; Roux, A. H.; Roux-Desgranges, G. Determination of temperature dependence of limiting activity coefficients for a group of moderately hydrophobic organic solutes in water. Fluid Phase Equilib. 2002, 201, 135−164. (17) Hovorka, Š.; Roux, A. H.; Roux-Desgranges, G.; Dohnal, V. Limiting Partial Molar Excess Enthalpies of Selected Organic Compounds in Water at 298.15 K. J. Chem. Eng. Data 2002, 47, 954−959. (18) Hovorka, Š.; Roux, A. H.; Roux-Desgranges, G.; Dohnal, V. Limiting partial molar excess heat capacities and volumes of selected organic compounds in water at 25 C. J. Solution Chem. 1999, 28, 1289−1305. (19) Bernauer, M.; Dohnal, V. Temperature Dependence of AirWater Partitioniong of N-Methylated (C1 and C2) Fatty Acid Amides. J. Chem. Eng. Data 2008, 53, 2622−2631. (20) Bernauer, M.; Dohnal, V.; Roux, A. H.; Roux-Desgranges, G.; Majer, V. Temperature Dependences of Limiting Activity Coefficients and Henry’s Law Constants for Nitrobenzene, Aniline, and Cyclohexylamine in Water. J. Chem. Eng. Data 2006, 51, 1678−1685. (21) Bernauer, M.; Dohnal, V. Temperature dependences of limiting activity coefficients and Henry’s law constants for N-methylpyrrolidone, pyridine, and piperidine in water. Fluid Phase Equilib. 2009, 282, 100−107. (22) Dohnal, V.; Ř ehák, K. Determination of Infinite Dilution Partial Molar Excess Enthalpies and Volumes for Some Ionic Liquid Precursors in Water and Methanol Using Tandem Flow Mixing Calorimetry and Vibrating-Tube Densimetry. J. Chem. Eng. Data 2011, 56, 3047−3052. (23) Wagner, W.; Pruss, A. The IAPWS Formulation 1995 for the thermodynamic properties of ordinary water substance for general and scientific use. J. Phys. Chem. Ref. Data 2002, 31, 387−535. (24) Decane density standard. Certificate of calibration No.12254; H&D Fitzgerald Ltd.: UK, 2011. (25) Malhotra, R.; Woolf, L. A. Volumetric measurements of liquid pentan-2-one, hexan-2-one, and 4-methylpentan-2-one at temperatures from 278.15 to 338.13 K and pressures in the range from 0.1 to 386 MPa. J. Chem. Thermodyn. 1996, 28, 1411−1421. (26) Gonzalez, B.; Dominguez, A.; Tojo, J. Dynamic Viscosities of the Binary Systems Cyclohexane and Cyclopentane with Acetone,

CONCLUSION In this work, precise measurements of excess enthalpy and density were carried out for highly dilute aqueous solutions of five alkanones. Reliable limiting values of several thermal and volumetric properties at infinite dilution were inferred from the data obtained. The reported standard changes of enthalpy, heat capacity, volume, and expansion associated with the dissolution and hydration of the alkanones present information which is of interest for both practice and theory. These accurate thermodynamic data can be helpful for instance to improve predictive schemes in chemical engineering and environmental protection or parametrize solution models in molecular simulations. To complete the thermodynamic description of the behavior of aqueous alkanones, we are about to present a methodical follow-up study on air/water partitioning of these solutes soon.

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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.7b00035. Comparison of density of ketones measured as a function of temperature in this work with literature values (PDF)

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AUTHOR INFORMATION

Corresponding Author

*Tel: +420 2 2044 4297; E-mail: [email protected]. ORCID

Vladimír Dohnal: 0000-0001-8934-4667 Notes

The authors declare no competing financial interest.

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REFERENCES

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H


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