1049J. Chern. Eng. Data 2009, 54, 1049-1051

Short Articles

Vapor Pressures for the Acetonitrile + Tetrabutylammonium Bromide, Water + Tetrabutylammonium Bromide, and Acetonitrile + Water + Tetrabutylammonium Bromide Systems

Alexander V. Kurzin,* Andrey N. Evdokimov, Victorija B. Antipina, and Olesja S. Pavlova

Organic Chemis try Department, Faculty of Chemical Technology , Saint-Petersburg State Technological Uni versity of Plant Polymers (SPST UPP-SPbGT URP ); 4 , Ivana Chemykh, Sa int-Petersburg 198095 , Russia

The va por pressures of the aceto ni trile + tetrabutylammonium bromide, w ater + tetrabutylammonium bromide, and aceto nitri le + w ater + tetrabutylammooium bromide systems have been measured at five constant salt molalities [(0.200,00400, 0.600, 0 .800, and 1.000) mol, kg-I] . These sys tems hav e been stud ied at (29 8 . 15 and 323 .15) K with a modified Othmer s till.

Introduction

Organic salts are important and are usually used as intermedi­ate chemicals, rea ction ca ta lys ts, inhibitors to und esired reac­tions, supporting electrolytes, and surfac tants. The e lec tro lyte systems containing salt s with large organic ion s (fatty acid anions, amm onium, phosphonium, sulfonium, arsonium, hy­drazinium, pyr idinium, borate s, and others ), beta ines, and ionic liquids continue to represent an import ant area of theoreti cal interest as well.

Recently, the vapor pressures of the aqueous and non aqueous solutions of several alkylarnmoniurn salt s have been reported .Y" In this study , the va por pressures of the acetonitrile + tetrabu­tylamrnonium bromide (TE AS ), water + TSAS, and ace to ni­trile+water + TSAS systems were measured at different sa lt molalities [(0.200, 0 .400, 0.600, 0 .800, and 1.000) mol' kg- J]

at (298.15 and 323 .15 ) K with an Othmer-type equilibrium cell. The vapor pre ssure data for the ace tonitrile + TSAS system at 298.15 K were found in the literature.P'"

Experimental Section

Jfaterials. Th e acetonitrile (w 2: 99 .9 %, Merck) was stored above 3 A molecular s iev es . Double-di stilled and deionized water wa s used. Tetrabutylammonium bromide (w 2: 99 .0 %, Fluka) wa s pre viou sl y dri ed at 75 °C in a vacuum oven until a constant mass was reached.

Procedure. Mixtures consisting of ace to nitri le, water, and TBAB were prepared gravimetrically using an analytical balance (Ohaus Explorer Pro Balance) with an unc ert ainty of ± 0.1 mg . Known masse s of salt were dis solved in 0.5 drn! of solvent (or mixed so lvent), and the so lution was placed in the still. Then the system was closed , and the s till was heated until constant pressure and temp erature were attained. The average uncertainty of the mole fract ion was 0.005. For a fixed liquid-phase composition, at least three data points were taken of the total pressure at the target temperature of (298.15 and 323 . 15) K. The uncertainty of measured temperature was ± 0.1 K.

' To whom correspondence should be add ressed . E-mail: zakora@mail.ru.

Tabl e 1. Vapor Pressure p and Osmotic Coefficients ... , of Acetonitrile in the Acetonitrile (1) + Tetrabutylarnmonium Bromide (2) System at T = 323.15 K as a Function of Salt Molality m;

0.000 0.200 0.400 0.600 0.800 1.000

33.860 33.008 32.504 32.020 31.487 31.022

0.812 0.767 0.738 0.716 0.695

Table 2. Vapor Pressure p of the Water (1) + Tetrabutylamrnoniurn Bromide (2) System from T = (298.15 to 323.15) K as a Function of Salt Molality m2

TlK = 298.15 TlK = 323.15

plkPa plkPa

0.000 3.166 12.348 0.200 3.055 12.006 0.400 2.959 11.704 0 600 2.864 11.358 0.800 2.779 10.907 1.000 2.701 10.532

Apparatus. A modified sta tic Othmer-type condensed vapor recirculating still used for the present study is the same as the one presented earlier. 1.8 The temperature was measured with a mercury-in-gl ass thermometer. A device co nsis ting of a 2200 typ e pre ssure sensor and PDRC-ICI2C type display supplied by the MKS Corp or ation (A ndover MA, USA) was used to me asure the pressure directly. The uncertainty of measured pre ssure was 0.0 13 kPa. The experimental setup and apparatus testing are described in detail in our previous work .'

Results and Discussion

The vap or pressures of the binary sys tems acetonitrile + TBAB and wat er + TBAB were me asured at (298. 15 and 323.15) K. In the se sys tems for each temperature, si x vapor pressure measurements at different salt molalities were studied. The vapor pressures of the acetonitrile + wat er + TBAB system were also me asured at (298. 15 and 323.15) K. All the

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1050 Journal of Chemical & Engineering Data, Vol. 54, No.3, 2009

Table 3. Total Va por Pressure p of th e Acetonitrile (1) + Water (2) + Tetrabutylammonium Bromide (3) System fr om T = (298.15 to 323.15) K as a Function of Liquid Mole Fract ion of Acetonitrile X' , 0 0 a Salt -Free Basis and Salt Molality ms

PlkP a

m 3/ (mol ' kg- l ) TIK. = 298.15 TlK = 323.15

0000 0.200 0.400 0.600 0.800 1.000

X', = 0.020 5.488 4.023 3.720 3.546 3.336 3.260

18.622 14.134 12.935 12.164 11.163 10.461

0.000 0.200 0.400 0.600 0.800 1.000

X', = 0.050 8.398 6.236 5.425 4.9 16 4.6 11 4.273

27.002 17.920 15.9 16 14.927 14. 196 13.636

0.000 0.200 0.400 0.600 0.800 1.000

X' , = 0.100 11.127 7.923 7.188 6.336 5.767 5.182

32.267 21.07 J 18.304 16.841 15.410 14.707

0.000 0.200 0.400 0.600 0.800 1.000

X' , = 0.200 12.441 10.867 9.839 8.742 7.657 6.933

35.890 27.844 24.554 21 .855 20.062 18.037

0.000 0.200 0.400 0.600 0.800 1.000

X' , = 0.300 12.663 11.124 10.280 9.528 8.763 8.099

36.79 1 29.985 26.243 24.054 22.019 20 .670

0.000 0.200 0.400 0.600 0.800 1.000

X', = 0.400 12.702 11.798 11.119 10.42 8 9.744 8.976

37.457 31.550 29.44 7 27.572 26.057 25.083

0.000 0.200 0.400 0.600 0.800 1.000

X', = 0.500 12.749 12.121 11.620 11.141 10.664 10. 176

37.60 1 34. 189 3 1.573 30.090 28.623 27.289

0.000 0.200 0.400 0.600 0.800 1.000

X', = 0.650 12.793 12.267 11.795 11.299 10.862 10.330

37.99 1 36.043 35.564 32.977 3 1.379 30.08 1

0.000 0.200 0.400 0.600 0.800 1.000

X', = 0.750 12.899 12.456 11.995 11.483 11.042 10.607

38.124 36.725 35.294 34.2 16 33.242 32.2 1J

0.000 0.200 0.400 0.600 0.800 1.000

X', = 0.850 12.797 12.330 11.886 11.427 11.019 10.648

37.629 36.288 35.002 33.593 32.320 31.009

0.000 0.200 0.400 0.600 0.800 1.000

x', = 0.950 12.264 11.865 11.53 1 11.188 10.859 10.577

35.340 34.229 33.225 32.069 31. 165 30.063

1.6

~ 1 2

<,

';} 0.8

0.4

Figure 1. Vapor pressure lowering I'>.p of water as a function of salt molality m-. in the water (I) + tetrabutylarnmonium bromide (2) system: 1'>.,298.15 K; 0 , 323.15 K.

experim ental data are give n in Tables I to 3 and in Figure 1. Vapor pressures of acetonitrile and water decrease with an increase of salt molalities in the binary sys tems. Tot al vapor pressures decrease wi th an increase of salt concentration and liquid mol e fraction of acetonitrile in the ternary system.

Calculation of Activities and Osmotic Coefficients of Acetonitrile in the Acetonitrile + TBAB System. Osmotic coe fficients (<1>,) as a function of sal t mol ality were calculated from vapor pressure lowerin g as described by Barthel and Kunz'

In as <I> =--­

S vmlvl , (I)

_ P (B -In a, ­ In ---: +

V;)(P ­RT

P*) (2)

P

M, is the molecul ar weight of ace toni trile; m is the salt molality: B is the second virial coefficient; and Vs is the molar volume of acetonitrile. The satura tion vapor pressure of pure acetonitrile (p*) was calc ulated with the publi shed Antoine constants.

The calculated data are presented in Table I. T he activi ty coefficients of solvents in the ternary system

acetonitrile + water + TBAB were ear lier" calculated by using the electrolyte NRTL model of Mo ck et al.10 which is used for the ternary mixed- solvent electro lyte sys tems.

Conclusion

The vapor pressures of the acetonitrile + tetrabutylarnmonium bromide , water + tetrabutylammonium brom ide, and acetonitrile + wa ter + tetrabutylarnm onium bromide systems have been measured at di fferent salt mo lalities at (29 8.15 and 323. 15) K with a modi fied Othmer-type equilibrium cell.

Literature Cited

(I ) Kurzin, A. V.; Evdokirnov , A. N.; Antipina, V. B.; Pavlova, O. S.; Gusev, V. E. Vapor Pressures for lA -Dioxane + Tetrabutylarnmonium Nitrate, Wa ter + Tetrabutylammo nium Nitrate. and IA-Dioxane + Water + Tetrabutylammoni um Nitrate. J. Chem. Eng. Dara 2008, 53. 207-210.

(2) Lee, L.-S.; Lee , Ci-C. Vapor Pressures and Enthalpies of Vaporization of Aqueous So lutions of Benzyl trimethylammonium Chloride, Ben ­zyltriethylammonium Chloride, and Benzyltributylamrnonium Chlo­ride. J. Chem. Eng. Dara 1998. 43, 17- 20.

(3) Lee, L.-S.; Lee, Ci-C, Vapor Pressures and Enthalpies of Vaporization of Aqueou s Solutions of Triethylammo nium Chloride, 2-Hydroxy· ethylarnmonium Chloride, and Tristhydroxyrnethyljarninomethane Hydroc hloride . J. Chem. Eng. Data 1998, 43, 469--472 .

(4) Lee, L.-S.; Huang , M.-Y.; Hsu, H..L. Vapor Press ure of Ethanol + Benzyltribut ylamm onium Chloride So lution and Vapor-Liquid Equi­

librium of Ethanol + Water + Benzylt ributylamm oni um Chloride Mixture at Atmos pheric Pressu re. J. Chern. Eng. Data 1999 , 44, 528­53 t.

(5) Barthe l, J.; Kunz, W. Vapo r Pressure Data for Non-aqueous Electrolyte So lutions . Part 5. Tetraa lkylarnmonium Sa lts in Acetonit rile. 1. Solution Chern. 1988, 17, 399-41 5.

(6) Barthel. J.; Klein, L. ; Kunz, W.; Calrnettes, P.; Turq , P. Te traalkylam­monium Bromides in Methanol: Small Angle Neutron Scattering and Vapor Pressure Measurements. 1. Solution. Chern. 1994, 23, 955-971.

(7) Treiner, C.; Tzias , P.; Chem la, M.; Poltoratskii, G. M. Solvation of Te trabutylammonium Bromide in Water + Aceton itri le Mixtures at 298.15 K from Va por Pressure Measu remen ts of Dilute So lutions. J. Chem. Soc.. Faraday Trans. 1 1976. 72. 2007- 2015.

tmolal ity ~. 298. J5

igure 1. •vith an J vapor ion and m. ints of lsmotic cu]ated Kunz''

(1)

(2)

ilality ; me of nitrile ~ .

' stem using :0 for

iiurn itrile )een i) K

. S.; ium e+ 53,

~on

en­tlo­

ion (y­me

+ Ji-

Journal of Chemical & Engineering Data, Vol. 54, No.3, 2009 1051

(8) Yang, S.-O.; Lee, Ci-S. Vapor-Liquid EquiLibria of Water + Methanol in the Presence of Mixed Salts. J. Olein. Eng. Data 1998, 43, 558- 56 1.

(9) Kurzin, A V.; Evdokimov, A N.; Poltoratskiy, G. M.; Platonov, A Yu.; Gusev, v. E.; Golubeva, Yu. M.1. Chem. Eng. Data 2004, 49, 208-21t.

( 10) Mock, B.; Evans, L. B.; Chen, Ci-C. Thermody namic Rep resentation of Phase Equilibria o f Mixed -Sol vent Electro lyte Systems. AlChE 1. 1986 , 32, 1655-1664.

Received for review Jul y 17, 2008 . Accepted November 23, 2008 . A N.E. thanks the Gove rnme nt of Sai nt-Petersburg for the financial SUppOI1 [Gran t for youn g PhD (Reg . No MKN-39!19 1-08)].

JE 80 0557H