Journal of Molecular Liquids 141 (2008) 35–38

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Journal of Molecular Liquids

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Volumetric properties of sec- and tert-butyl chloride with benzene, toluene andxylenes at 308.15 K

Naveen Verma a, Sanjeev Maken b,c,⁎, Krishan Chander Singh a

a Department of Chemistry, Maharshi Dayanand University, Rohtak-124 001, Indiab Department of Chemical Engineering, Yonsei University, 134, Shinchon-dong, Seodaemun-ku, Seoul, 120-749, Republic of Koreac Department of Chemistry, Deenbandhu Chhotu Ram University of Science and Technology, Murthal-131 039, Haryana, India

⁎ Corresponding author. Department of Chemical EngiShinchon-dong, Seodaemun-ku, Seoul, 120-749, Republicfax: +82 2 312 6401.

E-mail address: sanjeevmakin@gmail.com (S. Maken

0167-7322/$ – see front matter © 2008 Elsevier B.V. Aldoi:10.1016/j.molliq.2008.02.008

A B S T R A C T

A R T I C L E I N F O

Article history:

Molar excess volume (VE) o Received 1 June 2007Received in revised form 30 January 2008Accepted 27 February 2008Available online 7 March 2008

Keywords:Butyl chlorideAromatic hydrocarbonMolar excess volumeElectron donor–acceptor interactions

f sec-butyl chloride or tert-butyl chloride (A)+benzene or toluene or o- or m- orp-xylene (B) was measured using V-shaped dilatometer over the entire composition range at 308.15 K. TheVE values for all the binary (A+B) systems were found to be negative. While the VE values for an equimolarmixture of sec-butyl chloride+aromatics vary in the order: benzeneNm-xyleneN tolueneNp-xyleneNo-xylene, foran equimolar mixture of tert-butyl chloride+aromatics, it follows the sequence: benzeneNm-xyleneNp-xyleneNtolueneNo-xylene. Thedatawere interpreted qualitatively in termsof electron acceptor–donor type of interactions.

© 2008 Elsevier B.V. All rights reserved.

1. Introduction

Table 1Densities (ρ) and refractive indices (nD) of the pure components at 308.15 K

Material ρ/kg m−3 nD

Exptl. Lit. Exptl. Lit.

sec-Butyl chloride 867.62a 867.67 [15] 1.3941a 1.3942 [15]tert-Butyl chloride 836.14a 836.1 [15] 1.3830a 1.3828[15]

The excess thermodynamic properties are themeasure of non idealbehavior and of great importance to chemist to understand the natureof molecular interactions. Since a binary mixture is formed by thereplacement of like contacts in the pure components by unlikecontacts in themixture, it may trigger inter or intra molecular changesin either one or both the components or this must be reflected in theexcess molar volume.

The additions of inert solvents like alkane generally break theorientation order of pure alkyl halide to give the positive value ofexcess thermodynamic functions like excessmolar volume (VE), excessmolar enthalpy (HE), and excess molar Gibb's free energy (GE) [1–6].However, when alkane is replaced by aromatic hydrocarbons whichare potential electron donors,weak specific interactions of the electrondonor–acceptor type were reported between the components in alkylhalide-aromatic hydrocarbon mixtures along with disruption in theorientational order of the pure components [7–13]. In our previouspaper excess volume and excess enthalpy of n-butyl chloride witharomatic hydrocarbon were reported [14]. In order to study the effectof branching of the carbon chain in alkyl group, we have selected thebinary systems of sec- and tert-butyl chloride (A)+benzene, toluene,

neering, Yonsei University,134,of Korea. Tel.: +82 2 364 1807;

).

l rights reserved.

o-, m-, and p-xylene (B) and measured their excess volumes at308.15 K over the entire range of composition.

2. Experimental section

Butyl chloride, benzene, toluene, and xylenes (Merck) were puri-fied by standard procedure [15,16]. The purities of the purified sam-ples were checked by measuring their densities and refractive indicesat 308.15 K as described earlier [17] and these compared well with theliterature values [15,18,19] as shown in Table 1.

Molar excess volumes were measured using 2-limb speciallydesigned dilatometer shown in Fig. 1. It consisted of two limbs (shownas A and B in Fig. 1) having a vacuum tested B-7 standard joint at twoof the two limbs of capacity ∼4 ml each. The two limbs were

Benzene 862.93 862.95 [18] 1.4916 1.4917 [19]Toluene 852.80 852.85 [18] 1.4888 1.4887 [19]o-Xylene 867.42 867.38 [18] 1.5030a 1.50295 [15]m-Xylene 851.55 851.57 [18] 1.4946a 1.49464 [15]p-Xylene 847.83 847.87 [18] 1.4880 1.4881 [19]

a At 298.15 K.

Fig. 1. Schematics of two limb dilatometer.

36 N. Verma et al. / Journal of Molecular Liquids 141 (2008) 35–38

interconnected by small bent tubing which was further connected to athin uniform bored capillary having a referencemark R on it. A columnofmercury (3–5ml) was placed in the dilatometer and the dilatometerwas weighed. One of the liquids was added to the first limb Awith thehelp of a hypodermic syringe in such a way that no air bubbles wereentrapped in this bulb. The dilatometer was weighed again. Then thesecond liquid was added to the second limb B in similar fashion andthe dilatometer was weighed again. Both the liquids were degassed

Table 2Excess molar volume for binary mixtures of butyl chloride (BC)(A)+aromatics hydrocarbon

xA VE xA VE xA

cm3 mol−1 cm3 mol−1

sec-BC+Benzene sec-BC+Toluene sec-BC+o-Xylene

0.0851 −0.007 0.0901 −0.066 0.04210.1244 −0.012 0.1514 −0.110 0.10220.1789 −0.017 0.2216 −0.150 0.16690.2753 −0.026 0.3664 −0.205 0.22400.3508 −0.037 0.4642 −0.216 0.33880.3884 −0.042 0.5430 −0.214 0.49510.4129 −0.044 0.5960 −0.205 0.55190.4474 −0.048 0.6504 −0.186 0.59620.5040 −0.054 0.6962 −0.172 0.65170.5444 −0.056 0.7602 −0.142 0.72760.6509 −0.060 0.8505 −0.093 0.82760.7510 −0.055 0.8971 −0.064 0.84730.8306 −0.046 0.9370 −0.040 0.87540.9152 −0.028 0.9120

tert-BC+Benzene tert-BC+Toluene tert-BC+o-Xylen

0.0942 −0.076 0.1062 −0.136 0.05110.1344 −0.106 0.1575 −0.198 0.11210.1712 −0.132 0.2244 −0.268 0.18750.2109 −0.154 0.3032 −0.329 0.25230.3521 −0.228 0.4589 −0.394 0.32070.3834 −0.239 0.4851 −0.392 0.41540.5412 −0.266 0.5220 −0.394 0.49690.5961 −0.266 0.5412 −0.390 0.55180.6260 −0.256 0.6030 −0.378 0.62360.7796 −0.199 0.6329 −0.362 0.68800.8011 −0.184 0.7350 −0.298 0.77030.8573 −0.147 0.7661 −0.274 0.85170.9210 −0.088 0.8854 −0.154 0.9005

0.9244 −0.106 0.9551

before filling into the limbs. The dilatometer was then immersed in awater thermostat. The temperature of water thermostat was con-trolled to ±0.01 K by a mercury-in-toluene regulator. After thermalequilibrium, the reference mark R and the position of the liquid in thecapillary were noted with a cathetometer (OSAW, Ambala) that couldread to ±0.001 cm. Both liquids of the dilatometer were thenmixed bygently tilting it sideways several times. In order to ensure that theliquid in the capillary stem had the same composition as that of thebulk solution on mixing, the dilatometer (after mixing the compo-nents) was placed in a cold bath so that there was minimum liquid inthe capillary and then again immersed in the water thermostat. Thisprocess was repeated thrice. Once the thermal equilibrium wasachieved, the position of the reference mark R and that of the level ofthe liquid in the capillary was again recorded. The dilatometer wasthen taken out, cleaned and dried. The composition of mixture waschanged by varying the amount of mercury, liquids components andposition of mercury in the dilatometer. Molar excess volume of thebinary mixture was calculated from the following equation:

VE=cm3mol�1 ¼ Dh=cmð Þ� Capillary coeff : =cm2� �

= nA þ nBð Þ=molð Þ ð1Þ

where Δh is the change in height of liquid level in capillary before andafter mixing and nA and nB are the number of moles of liquid A and B,respectively. The capillary coefficient was the cross-sectional area of thecapillary. The radiusof the capillary tubewasdetermined fromtheweightof a length of mercury column in the capillary. The length of themercurycolumn at various positions in the capillary was read by a travellingmicroscope (OSAW, Ambala) that could read to ±0.001 cm. The density ofmercury was taken from the literature [20]. The cross-sectional area ofthe capillary was calculated from the average length of the mercurycolumn in the capillary and the volume of this mercury column. Theperformance of dilatometer was checked bymeasuring the molar excess

(B) at 308.15 K

VE xA VE xA VE

cm3 mol−1 Cm3 mol−1 cm3 mol−1

sec-BC+m-Xylene sec-BC+p-Xylene

−0.038 0.0804 −0.056 0.0790 −0.064−0.094 0.1371 −0.096 0.1511 −0.112−0.154 0.2123 −0.137 0.2122 −0.148−0.202 0.2761 −0.167 0.2993 −0.186−0.283 0.3669 −0.197 0.3352 −0.204−0.334 0.3890 −0.204 0.3897 −0.216−0.335 0.4620 −0.212 0.4739 −0.230−0.326 0.5440 −0.204 0.5634 −0.234−0.308 0.6508 −0.182 0.6138 −0.226−0.263 0.6918 −0.165 0.6988 −0.204−0.184 0.7619 −0.136 0.7164 −0.196−0.166 0.8591 −0.082 0.7785 −0.170−0.134 0.8918 −0.062 0.8583 −0.124−0.096 0.9378 −0.036 0.9179 −0.072

e tert-BC+m-Xylene tert-BC+p-Xylene

−0.076 0.0782 −0.092 0.0622 −0.094−0.164 0.1023 −0.122 0.0987 −0.144−0.256 0.1954 −0.212 0.1523 −0.214−0.332 0.2484 −0.256 0.2187 −0.278−0.39 0.2839 −0.278 0.2911 −0.336−0.456 0.3217 −0.302 0.3894 −0.382−0.482 0.3502 −0.312 0.4727 −0.392−0.484 0.4512 −0.342 0.4927 −0.386−0.472 0.5372 −0.336 0.5866 −0.361−0.436 0.6020 −0.322 0.6911 −0.298−0.372 0.6730 −0.286 0.7223 −0.272−0.268 0.7580 −0.226 0.8856 −0.118−0.194 0.8412 −0.156 0.9102 −0.094−0.092 0.9081 −0.092 0.9615 −0.038

Fig. 2. Excess molar volume for sec-butyl chloride (BC) (A)+aromatic hydrocarbon (B) at 308.15 K; symbols represent experimental values and lines represent values calculated fromEq. (1).

37N. Verma et al. / Journal of Molecular Liquids 141 (2008) 35–38

volume of the benzene+cyclohexane mixture at 298.15 K and theseagreed within the experimental limits with corresponding literaturevalues [21]. The uncertainty in the measured VE values was ±1%.

3. Results and discussion

Themeasuredmolar excess volume of sec- or tert-butyl chloride (A)+benzene or toluene or o- or m- or p-xylene (B) as a function of molefraction, xA, at 298.15 K are reported in Table 2 and also shown in Figs. 2and 3. The results were expressed by the Redlick–Kister equation

VE=cm3mol�1 ¼ xAxB V0 þ V1 xA � xBð Þ þ V2 xA � xBð Þ2þV3 xA � xBð Þ3h i

ð2Þ

where Vn (n=0 to 3) are the adjustable parameters and xA and xBare the mole fraction of butyl chloride and second component of

Fig. 3. Excess molar volume for tert-butyl chloride (BC) (A)+aromatic hydrocarbon (B) at 308Eq. (1).

the binary mixture, respectively. These parameters were evalu-ated by fitting VE/xAxB data to Eq. (2) by the method of leastsquares and are given along with standard deviations, σ(VE), of(VE) in Table 3.

r VE� �=cm3mol�1 ¼

XVEexpt: � VE

calcd Eq: 2ð Þ

� �� �= m� nð Þ

� 0:5

ð3Þ

where m is the number of experimental values, and n is the numberof adjustable parameters in Eq. (2). The number of parameters (n)was dictated by the consideration that the maximum deviation, σm,satisfied the relation: σm(VE)≤2σ(VE).

We are unaware of any previously published VE data with whichto compare our results. The VE values for all the binary (A+B)systems were found to be negative. While the VE values for an

.15 K; symbols represent experimental values and lines represent values calculated from

Table 3Adjustable parameters of Eq. (1) and standard deviation (σ)

System A0 A1 A2 A3 σ d 103

sec-BC+Benzene −0.2113 −0.1721 −0.0166 0.0230 0.8sec-BC+Toluene −0.8706 0.1027 0.1683 −0.0412 1.3sec-BC+o-Xylene −1.3441 −0.1393 0.346 0.0301 1.3sec-BC+m-Xylene −0.8431 0.0908 0.2029 −0.0175 1.3sec-BC+p-Xylene −0.9314 −0.0968 −0.0031 0.0332 1.5tert-BC+Benzene −1.0561 −0.1874 0.0180 −0.0110 1.4tert-BC+Toluene −1.5790 0.0594 0.1575 −0.1956 1.6tert-BC+o-Xylene −1.9302 −0.3274 0.0707 −0.0101 1.7tert-BC+m-Xylene −1.3682 0.1095 0.2467 0.0390 1.3tert-BC+p-Xylene −1.5474 0.3092 0.2543 −0.0188 1.4

38 N. Verma et al. / Journal of Molecular Liquids 141 (2008) 35–38

equimolar mixture of sec-butyl chloride+aromatics vary in theorder:

benzene N mQxylene N toluene N pQxylene N oQxylene;

for an equimolar mixture of tert-butyl chloride+aromatics, itfollows the sequence:

benzene N mQxylene N pQxylene N toluene N oQxylene:

At the simplest qualitative level, the observed VE values may beattributed to the resultant of two opposing effects. The positivecontribution to VE values arises from the disruption of orientationorder of pure component and negative contribution arises due to theformation of specific interactions of electron donor–acceptor typebetween chloride atom and π-electrons of aromatic hydrocarbons.When a methyl group is introduced in benzene (as in toluene), theelectron density of π-electron cloud increases and these interactionsbecome stronger and this leads to higher negative contribution andconsequently the more negative values of VE than benzene+butylchloride mixture. The introduction of two methyl groups in benzene(as in xylenes), should cause further enhancement of these attractiveinteractions and it should further yield more negative values of VE.However, it is not observed experimentally in all xylenes. It may bedue to the presence of steric hindrance between the two methylgroups of xylene and the alkyl groups of butyl chloride, which mighthave restricted the proper orientation of these molecules and obstructthe chlorine atom toward the ring thus making interactions weaker aswell as also making the packing less effective arrangement in thesemixtures. Among three xylenes, o-xylene seems to offer minimumsteric hindrance thus increasing electron donor–acceptor interactionto the maximum and hence making the VE minimum.

As for as the effect of branching of butyl group is concerned, it hasbeen found that branching decreases the VE and VE of the systemcontaining tert-butyl chloride, which is always less than that of therespective system having sec-butyl chloride at the samemole fraction.As VE is a packing effect, this indicates that placement of three methylgroups in tertiary butyl chloride reduces the size of the molecule ascompared to that of sec-butyl chloride where the chlorine atom isattached at the secondary carbon atom. This is also supported by thevalues of molar volume of tert-butyl chloride (82.28 cm3/mol) andsec-butyl chloride (88.50 cm3/mol). Thus a small size of tert-butylchloride offers better packing with aromatics.

Acknowledgement

Naveen Verma thanks University Grant Commission, New Delhi,India for the award of Junior Research Fellowship. Sanjeev Makenthanks Mr H. S. Chahal, Vice Chancellor, Deenbandhu Chhotu RamUniversity of Science & Technology, Murthal for moral support.

References

[1] J. Valero, M.C. Lopez, M. Gracia, C.G. Losa, J. Chem. Thermodyn. 12 (1980) 627–633.[2] J. Valero, M. Gracia, C.G. Losa, Excess enthalpies of some (chloroalkane+n-alkane)

mixtures, J. Chem. Thermodyn. 12 (1980) 621–625.[3] J. Muiioz Embid, S. Otin, I. Velasco, C.G. Losa, Fluid Phase Equilib. 38 (1987) 1–17.[4] M.C. Lopez, F.M. Royo, M. Gracia, C.G. Losa, J. Chem. Thermodyn. 15 (1983) 517–521

15.[5] K.C. Kalra, K.C. Singh, D.C. Spah, J. Chem. Eng. Data 39 (1994) 372–374.[6] K.C. Kalra, K.C. Singh, D.C. Spah, J. Chem. Thermodyn. 22 (1990) 321–326.[7] K.C. Singh, K.C. Kalra, P. Kumar, J. Chem. Soc. Faraday Trans. I 86 (1990) 2203–2207.[8] K.C. Singh, K.C. Kalra, P. Kumar, J. Soln. Chem. 20 (1991) 531–538.[9] K.C. Kalra, K.C. Singh, D.C. Spah, Thermochim. Acta 181 (1991) 227–235.[10] P. Kumar, K.C. Kalra, K.C. Singh, Thermochim. Acta 188 (1991) 151–156.[11] K.C. Kalra, K.C. Singh, D.C. Spah, Fluid Phase Equilib. 66 (1991) 211–220.[12] N. Verma, S. Maken, B.R. Deshwal, K.C. Singh, J.W. Park. J. Chem. Eng. Data 52 (2007)

2083–2085.[13] K.C. Singh, K.C. Kalra, P. Kumar, Thermochimica Acta 164 (1990) 329–337.[14] K.C. Singh, K.C. Kalra, P. Kumar, M. Soni, Thermochim. Acta 182 (1991) 57–66.[15] J.A. Riddick, W.B. Bunger, T.K. Sakano, Organic Solvents—Physical Properties and

Methods of Purification, fourth ed.Wiley-Interscience, New York, 1986.[16] A.I. Vogel, A Text Book of Practical Organic Chemistry, fourth ed.ELBS, Longman,

London, 1978.[17] S. Maken, B.R. Deshwal Anu, K.C. Singh, S.J. Park, J.W. Park, Phys. Chem. Liqs.

43 (2005) 149–156.[18] J. George, N.V. Sastry, J. Chem. Eng. Data 48 (2003) 977–989.[19] V. Mutalik, L.S. Manjeshwar, M. Sairam, T.M. Aminabhavi, J. Chem. Thermodyn.

38 (2006) 1062–1071.[20] D.R. Lide, Handbook of Chemistry and Physics, seventy sixth ed.CRC Press, Inc.,

Boca Raton, FL, 1995/96.[21] M.K. Kumaran, M.L. McGlashan, J. Chem. Thermodyn. 9 (1977) 259–267.