IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 Excess Molar Volumes and Viscosities of Mixtures Containing Dimethylformamide (DMF) with benzene, o- xylene, 1, 4- Dioxane and Tetrahydrofuran at 298.15 K. A.A. Kadhem Departme nt of Chemistry, Collage of Education, Unive rsity of of Al- Qadisiya Abstract M easurements of excess molar volumes V E , viscosities η , excess viscosities Δ ln η and excess molar activation energies of viscous flow ΔG E , are reported for binary mixtures of dimethy lformamide (DM F) with , benzene , o-xy lene , 1,4- dioxane and tetrahy drofuran are reported from density and viscosity measurements at 298.15 k and at atmosp heric p ressure over the entire comp osition range . The excess values are p ositive for the mixture (DM F+ p olar solvent) and negative deviation from ideality for the mixture (DM F + non-p olar solvent) over the whole comp osition range and discussed in the light of molecular interaction in the mixture. Introduction Obviously , the st arting materials of many chemical p roducts are aromatic comp ounds therefore the p etroleum industry is interested in finding way s and means of extracting and recovering these aromatic comp ounds in p ure form from oil. Consequently , wide research was carried out to find a solvent that is highly selective as well as maintaing sufficient solvent p ower to p revent the sep aration of p hases during the extractive distillation p rocess. Solvents that are highly p olar with high boiling p oints p ossess such prop erties[1]. Dimethy lformamide as p ure solvent is certainly to some extent associated by means of nonsp ecific dipole-dipole interaction , and is of p articular interest because any significant st ructural effects are absent due to the lack of hy drogen bonds ; therefore it may work as an aprotic p rotop hilic solvent of large dipole moment and high dielectric constant ( μ=3.24 D and ε=36.70 at 298.15 K) .It has been used in the sep aration of saturated and unsaturated hy drocarbons and serves as a solvent for many p olymers [2-5]. The p hy sical and thermody namic p rop erties of binary mixtures containing DM F as a common solvent with different organic liquids have been st udied by many authors [6-11] . Although a large number of invest igations are carried in liquid mixtures having DM F as one of the comp onents , It is found that no work has been made so for to the description of the thermody namic p rop erties of ( DM F + p olar solvents ) and ( DM F + nonp olar solvents ) . In general, excess volume depends mainly on two effects: a) the variation of the intermolecular forces when two comp onents come in to contact, and b) the variation of the molecular p acking as a consequence of the differences in the size and shap e of the molecules of the components [12-14]. Theoretical and exp erimental interest has increased in recent y ears in the thermody namic p rop erties of liquid mixtures containing associated comp ounds. The majority of the theoretical models, generally based on a rigid lattice concept, are not suitable for the p rediction of volumetric prop erties such as V E .Thus, t he model of Nitta [15] permits the IHJPAS IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 p rediction of several prop erties of p ure compounds and mixtures, simultaneously , including V E [16] . An ideal solution may be defined as one in which no sp ecific forces of att ractions exist between the comp onents of solution and no change occur in the p rop erties of the comp onents when mixed. Thus in an ideal solution , the total solution volume equal to the sum of volumes of the components and the other phy sical prop erties such as refractive index , fluidity and vapor p ressure can be calculated by taking the molal average of the comp onents p rop erties [17] . Thermody namic and transp ort p rop erties of binary and ternary mixtures with different organic liquids have been st udied by many authors [18-20]. In this p aper the exp erimental values of excess molar volumes , excess viscosities and excess molar activation energies for DM F + benzene ,+ o-xy lene , + 1-4 dioxane and tetrahy drofuran at 298.15 K and at atmosp heric p ressure which are calculated from the density and viscosity measurements of binary liquid mixtures over the entire comp osition range are reported and has been used to obtain a comp lete p icture of the volumetric and viscometric behaviour of dimethy lformamide in polar and nonpolar solvents Experimental All the organic liquids used were of analar grade and obtained from BDH Chemicals .The density measurements for the pure comp onents are summarized and comp ared with the corresp onding literature values in Table I. Since the agreement is good, further p urification of the employed compounds was not p erformed. The invest igation of sources of errors in V E by Lep ory et.al., [21], showed namely , that p urity of substances was not a crucial factor in V E measurements. The comp ositions of the binary mixtures were determined by weighing the app rop riate amounts of the p ure comp onents with a M ett ler mass balance with an accuracy ±10 -4 g , and st ored them into suitably st op p ered flasks in the dark at constant humidity and temp erature in order to p revent the samples from p referential evap oration. The excess molar volumes were calculated from the densities of the p ure liquids and mixtures. The densities were measured with the help of st andard bicapillary p y knometer technique used by other workers [22].T he py knometer was self-filling in ty p e and offers accuracy up to 1 to 4 p arts in 10 4 , this p y knometer was immersed in the thermost atic bath maintained at 298.15 K . The viscosities of the p ure liquids and mixtures were determined by using a susp ended-level Ubbelohde viscometer. An electronically op erated constant temp erature water bath is used to circulate water through the double walled measuring cell made up of st eel containing the exp erimental solution at the desired temp erature in a bath controlled to ±0.01 K at 298.15 K . The flow time was determined electronically by using an electronic timer with a p recision ±0.01 s. . Before each series of measurements , the instrument was calibrated with doubly distilled water and dry air at atmosp heric p ressure . The accuracy of the technique described was checked by measuring the V E data for the test binary mixture benzene + cyclohexane at 298.15 K , which nearly ideal solutions has been used as reference sy st em , the results agree satisfactorily with those of other authors. Result and Discussion The excess molar volumes V E , excess viscosities Δ ln η and molar excess Gibbs energies for t he activation of viscous flow ΔG E of the binary DM F + benzene ,+ o-xy lene , + 1-4 dioxane and tetrahy drofuran mixtures were determined at 298.15 K. The excess molar volumes were calculated from the density measurements using the equation: V E (cm 3 mol -1 ) = [( x1M 1 + x2M 2 ) / ρ ] – [(x1M 1)/ ρ1] – [(x2M 2) / ρ2] (1) IHJPAS IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 Where x1 and x2 the mo le fraction of the components , M 1 and M 2 rep resents t he molar mass and ρ1, ρ2 st and for the densities of the p ure components and the liquid mixture , resp ectively .The imprecision of the determination of the V E is estimated to be less t han 2 x 10 -4 cm 3 mol -1 . The exp erimental values of V E are given in Table 3 and presented gr aphically in Figs 1,2 . Exp erimental viscosities η are list ed in Table 3 . Excess molar viscosities Δ ln η and excess molar activation energies ΔG E were calculated from the following equations: Δ ln η(cP) = ln η– ( x 1 ln η1 + x2 ln η2 ) (2) ΔG E (J.mol -1 ) = RT [ln η m Vm – (x1 ln η1V1 + x2 ln η2V2)] (3) Where ηm and Vm are resp ectively of the viscosity and molar volume of the binary mixture, η1 and V1 represent t he viscosity and molar volume of the comp onent (x1) DM F, η2 and V2 represent the viscosity and molar volume of p ure liquids ( benzene, o-xy lene , 1,4- dioxane and tetrahy drofuran ) (x2) . T temp erature (K), R gas constant. The obtained results of the exp erimental and calculated p rop erties for the binary mixture are list ed in table 3 and illustrated in Figs 3, 4 resp ectively over the whole mole fraction range. The X E p rop erties ( V E , Δ ln η and ΔG E ) were fitted to variable degree fun ction using the Redlich-Kister equation [23]: X E = x1 x2 Σ Ai ( x1- x2 ) (4) Where x1 (DM F) and x2 (p ure liquids) are the mole fraction. The n Ai coefficients were processed by unweighted least –squares fitt ing and are list ed in Table 2 . Volumetric behaviour In order to understand more about the nature of interaction between the comp onents of liquid mixtures, it is necessary to discuss the same in terms of excess p arameters rather than actual values. They can y ield an idea about the non linearity of the sy st em as association or other ty p e of interactions. The excess molar volumes V E for the binary mixtures (DM F+ benzene ,o-xy lene) Fig. 1 were negative over the whole mole fraction range at 298.15 K. The p olar molecule may associate with the non-p olar solvent molecules it is p rop osed that the molecular association rise because of the interaction of the p ositive fractional charge at t he sight of carbon atoms in DM F and π-delocalized electron cloud in the benzene ring of the benzene molecule [8]. The V E values were p ositive for the binary mixtures (DM F + dioxane , tetrahy drofuran ) (Fig.2) can be exp lained by the p redominance of exp ansion in volume , caused by the loss of dipolar association and difference in size and shap e of comp onent molecules , over contraction in volumes , due to t he dip ole –dipole and dip ole-induced dip ole interactions . Viscometric behaviour The exp erimental data of the mixing viscosities and excess free energies are p lott ed in Figs.(3,4,5) as a function of the mole fraction x of a polar and nonpolar solvent . All mixtures deviate from ideality . The Δ ln η (cP ) values were negative deviation for all the mixtures in Fig. 3, this might reflect the effect of several factors, i.e. inductive, st eric, geometrical and orientational disordered. The ΔG E ( J.mol -1 ) values were positive for the mixtures ( Fig. 4 ) often as a sign of st rong association by H-bonding or as a singn of fitt ing of one molecule into the cavities of the other or as a consequence of both , the DM F molecules behave similarly if surrounded by 1,4- dioxane and tetrahy drofuran molecules or by other DM F molecules [24] Interaction between the carbonyl group in the N,N-dimethy lforamide and the benzene ring is IHJPAS IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 greater than the dipole breaking interaction . Interaction of the dimethy lforamide molecule with 1,4- dioxane and tetrahy drofuran molecules can occur through the free electron p air of the DM F oxy gen atom only , since the electron p air on the nitrogen atom is p rotected by two methy l group s . Fig. (5 ) Shows negative deviation from ideality , negative values can be exp lained by the p redominance of exp ansion in volume, caused by loss of dipolar association and difference in size and shap e of comp onent molecules, over contraction in volume, due to the dip ole-dipole and dipole-induced dip ole interaction . The Δ ln η (cP ) and ΔG E (J.mol-1 ) values determined at different comp ositions reflect the ty p e of intermolecular interaction , and are app roximately p rop ortions to the extent of t he interactions , t hese two magnitudes may also be considered as a reliable measure of the extant of t he interaction between unlike molecules . Conclusions The excess molar volumes V E , excess viscosities Δ ln η and molar excess Gibbs energies for the activation of viscous flow ΔG E for all binary mixtures st udied are p ositive with ( DM F + p olar solvent ), and negative with ( DM F + non-p olar solvent ) over the whole mole fraction range . Such behaviors in these binary mixtures may arise due to dipole-dipole interaction and the polar nature of different molecular entities in the mixture. Re ferences 1- Kanbour , F. ; Awwad , A.M . (1980), Iraqi . J. Sci. 4 , 21 . 2- Kannapp an, AN. ; Kesavasamy , R. and Ponnuswamy , V. ( 2008), J. of Eng. Ap p l. Sci. ; 3 :( 4), 41 . 3- Venkatesu , P. and Rao , M . V. P. (1998 ) J. Chem. Thermo. 30 :207 . 4- Garcia , B. ; Alcalde , R. ;Leal J. M . and M atos J. S. ( 1997) J. Chem. Soc. Farady Trans. , 93 , 1115 . 5- M orrison, R.T. and Nelson B.R. (2001) , Organic Chemist ry , Prentice Hall of India Pvt . Ltd. , New Delhi , 6 th Ed. pp .1071 . 6- Zielkiewicz , j. (1998),J. Chem. Eng. Data , 43 : 650-653 . 7- Zielkiewicz , j. (1994) , J. Chem. Thermo. 26 : 1317-1322 . 8- Sandeep, K.; Sharma, D.R. ; Thakur, N. ;Negi N.S. and Rangra V.S. (2006) J. Ap p l. Phy s. 44 : 939-942 . 9- Petong P. ;Pot tel R. and Kaatze U. (2000),J. Phy s. Chem. A ,104 , 7420 . 10- Zielkiewicz, j. (1995)J. Chem. Thermo. 27 :1275-1279 . 11- Zielkiewicz, j. (1997)J. Chem. Thermo. 29 :229-237 . 12- M aham ,Y. ; Boivienau, M . and M ather, A.E. (2001), J. Chem. Thermo. 33, 1725 . 13- Ivonar G. ; Aleksadar Z.T. ; Bojan D.D. and M irjanalj K.(2002) , J. Serb. Chem. Soc. ; 67 , 581 . 14- Peter, A. and Dolecek, V. (2000),Acta. Chem. Slov. 45 , 153 . 15- Nitta, T. ; Turek, E.A. , and Greenhorn, R.A. (2000), J. Ami. Chem. Eng., 7 , 5 . 16- Ort ega, J. and Susial, P. (1989), Can. J. Chem., 67 , 1120 . 17- Glasst one, S. (1977) Thermody namics for chemist s , 1 st ed. , D.Van Nostard Co., Inc. Newy ork ,. 18- Kannapp an, A.N. ; Kesavasamy , R. and Ponnuswamy V. (2008),ARPN J. of Eng. And Ap p . Sci. 3 , 4. 19- Aralagup p i , M .I. :and Barragi J.C. (2006), j. Chem. Therm. , 38 , 434 . 20- Kannapp an, A.N . and Rajendran, V. (2005),J. Pure. Ap p l. Phy s. 43 , 750 . 21- Lep ori,L.; M engheri, M .; M ollica V. (1983), J. Phy s. Chem., 87: 3520-3525. IHJPAS IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 22- M agazir, S. ; M agliardo, P.; M usclino, A.M . and Sciorction M . T. (1997)J. Phy s. Chem. 101 , 2348 . 23- Redlich, O. and Kist er, T.A., (1948 ),Ind.Eng. Chem. 40 , 345 . 24- Kinart, C.M . ; Kinart ,W.P. ;Kolasinski, A. (1998), Phy s. Chem . Liq. 36 , 133 . 25- Heric, E.L. and Couresy , B.M . (1972),J. Chem. Eng. Data , 17 , 41 . 26- Awwad, A.M . and Al-Dujaili ,A.H. (2001), J. Chem. Eng. Data , 64 , 1349 . 27- Handa, V.P. and Beuson , G,C. (1979), Fluid p hase Equili. 3 , 185 . Table (I): De nsi ties ρ (g.cm -3 ) and viscosi ties (cP), of the pure compone nt liquids used in this wok, measured at 298.15 K. Component ρ (g.cm 3 ) η (cP) Obs. Lit. Obs. Lit. Benzene 0.78447 0.78452 (a ) 0.611 0.599 (a ) o-Xy lene 0.89705 0.89714 (a ) 0.832 0.811 (a ) 1,4- Dioxane 1.03014 1.03008 (b) 1.083 1.087 (c ) Tetrahy drofuran 0.88596 0.88591 (b) 0.456 0.451 (c ) DM F 0.9213 0.92230 0.900 0.920 (c ) (a) = [20] (b)= [21] (c)= [22] Table (2): Coefficients Ai of eq. [4] and standard deviations S D in cm 3 . mol -1 for binary systems M ixture A0 A1 A2 A3 SD DM F+Benzene 0.781 -0.8382 0.8941 2.095 0.0007 DM F+o-Xy lene 0.653 -0.4563 0.4753 1.678 0.0002 DM F+ 1-4 Dioxane 0.342 2.9540 3.8760 1.043 0.0003 DM F+Tetrahy drofuran 1.103 -0.4350 0.5620 2.851 0.0008 IHJPAS IHJPAS IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 Table( 3): Excess mol ar volumes V E , viscosi ties η , excess viscosities Δ ln η and excess molar activation ene rgies of viscous flow ΔG E of x DMF + (1-x) ( Benzene , o-xylene , 1- 4 Di oxane and Tetrahydrofuran ) at 298.15 K. IHJPAS X VE (cm3 mol -1 ) η(cP ) Δ ln η (cP ) ΔG E (J.mol-1 ) 0.0 000 0.03817 0.11354 0.24118 0.32218 0.45213 0.5 212 0.59987 0.6 895 0.74581 0.82541 0.89632 0.98152 1.0 000 0.0 000 0.05693 0.09896 0.18962 0.29654 0.38411 0.47581 0.55412 0.65432 0.73215 0.82132 0.89991 0.95891 1.0 000 0.0 000 0.11254 0.17432 0.22987 0.29635 0.33544 0.41257 0.49856 0.56423 0.63513 0.75623 0.84236 0.95623 1.0 000 0.0 000 0.11211 0.19845 0.25812 0.32115 0.41265 0.49625 0.52418 0.63213 0.78412 0.85413 0.95324 0.98926 1.0 000 xDMF + (1-x) benzene at 298 .15 K 0.00 00 10.01 8 0.0 00 0 -0.1391 9.819 -0 .02 01 -0.3748 8.120 -0 .06 52 -0.5918 7.653 -0 .08 91 -0.7135 6.901 -0 .12 1 -0.8965 5.452 -0 .15 2 -1.0539 4.653 -0 .15 9 -1.1412 3.379 -0 .13 2 -1.0972 2.438 -0 .11 2 -0.9954 1.217 -0 .07 89 -0.7945 0.963 -0 .06 48 -0.6682 0.791 -0 .04 32 -0.2852 0.579 -0 .01 06 0.0 000 0.00 00 0.00 00 xDMF + (1-x) o-xylene at 29 8.15 0.000 0 9.87 1 0 .00 00 -0.2452 7.991 -0 .04 52 -0.4512 6.841 -0 .06 99 -0.7825 5.783 -0 .09 32 -0.9996 4.863 -0 .12 3 -1.2996 3.874 -0 .14 61 -1.4521 2.986 -0 .18 2 -1.6451 1.975 -0 .19 2 -1.8364 0.987 -0 .17 9 -1.9912 0.842 -0 .13 2 -1.73 0.783 -0 .08 4 -0.932 0.687 -0 .06 3 -0.59 0.601 -0 .03 21 0.0 0 0.00 0.000 xDMF + (1-x) 1-4 di oxane at 2 98.15 0.00 00 10.94 1 0.0000 0.0 755 9.7 41 -0.0221 0.0 899 8.9 41 -0.02 53 0.1 085 7.5 41 -0.02 81 0.1 524 6.0 31 -0.04 23 0.1 653 5.7 21 -0.05 45 0.1 763 4.9 10 -0.06 68 0.1 632 3.8 73 -0.05 46 0.1 582 2.5 43 -0.04 51 0.1 421 1.3 28 -0.03 01 0.1 256 0.9 52 -0.02 78 0.1 058 0.7 01 -0.01 21 0.0 21 0.6 82 -0.00 5 0. 00 00 0.00 00 0 .00 00 xDMF + (1-x) tetrahydrofuran at 298.15 0 .00 00 10 .051 0.0 000 0.0 958 9.04 2 -0.0318 0.1 218 8.96 4 -0.0431 0.1 601 7.97 6 -0.0525 0.1 893 6.55 2 -0.0673 0.2 128 5.64 4 -0.0837 0.2 317 4.43 2 -0.0942 0.2 291 3.65 1 -0.0879 0.1 972 2.98 6 -0.0600 0.1 65 1.03 2 -0.0364 0.1 00 0.98 1 -0.0247 0.0 798 0.85 4 -0.0156 0.0 122 0.70 1 -0.004 0.0 00 0.00 0 0.00 00 0.0 0 -82 -198 -300 -374 -402 -436 -442 -380 -325 -275 -228 -56 0.0 0 0.0 0 -156 -200 -380 -476 -596 -662 -631 -587 -432 -384 -299 -88 0.0 0 0.0 0 -94 -245 -394 -468 -686 -761 -783 -728 -628 -542 -434 -112 0.0 0 0.0 0 -27 -138 -295 -382 -496 -677 -680 -556 -460 -321 -165 -30 0.0 0 IHJPAS IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 -2. 5 -2 -1. 5 -1 -0. 5 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Fig.( 1) Excess mol ar volumes, for x an DMF + (1-x) benzene (♦); o-xylene (■) at 298.15 K. 0 0.05 0.1 0.15 0.2 0.25 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Fig. (2) Excess mol ar volumes, for x an DMF + (1-x) 1-4 Dioxane (♦); Tetrahydrofuran (■)at 298.15 K. X1 X1 V E ( cm 3 m o l- 1 ) V E ( cm 3 m o l- 1 ) IHJPAS IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 -0.25 -0.2 -0.15 -0.1 -0.05 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Fig.(3) Excess mol ar viscosi ties Δ ln η(cP) for x an DMF + (1-x) benz ene (■ ) , o-xylene (♦) , 1,4- Di oxane ( x ) , and Tetrahydrofuran (▲) at 298.15 K . 0 100 200 300 400 500 600 700 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Fig.( 4) Excess mol ar Gibbs free energy of activation of viscous flow, ΔGE for x an DM (1-x) 1-4,Di oxane (♦); Tetrahydrofuran (■) at 298.15 K. X1 Δ G E (J .m o l- 1 ) X1 Δ ln η ( cp ) IHJPAS IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.23 (2) 2010 -900 -800 -700 -600 -500 -400 -300 -200 -100 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Fig. (5 ) Excess mol ar Gibbs free energy of activation of viscous flow, ΔG E for x an DMF+(1-x) benzene1-4 Dioxane (♦); o-xylene (■) at 298.15 K . X1 Δ G E (J .m o l- 1 ) IHJPAS 2010) 2( 32المجلد مجلة ابن الهیثم للعلوم الصرفة والتطبیقیة الحجوم المولیة الفا ئضة واللزوجة للمخالیط الثنائیة للدایمثیل فوراماید مع 298.15دایوكسان وتیترایهیدروفیوران عند درجة -4,1 ،اورثوزایلین،البنزین مطلقة عباس عبداالمیر كاظم جامعة القادسیة،كلیة التربیة ،قسم الكیمیاء الخالصة یــد مـع البنـزین والورثــوزایلین اثیـل فـورم امواللزوجــة لمخـالیط مختلفـة مــن دایم البحـث قیـاس كــل مـن الكثافـة ذاتـم فـي هــ اللزوجـة الفائضــة و ، الحجـوم الفائضـة كمـا حســبت. مطلقـة 298.15حـرارة تراهیـدروفیوران فـي درجــة داي اوكسـان والت 1,4و م ي تـتبـین مـن النتـائج التـ. یبات النقیـة ومخالیطهـا ذعملیـا للمـ التـي تـم قیسـتوطاقـة التنشـیط الفائضـة مـن الكثافـة واللزوجـة مــع ي مخـالیط داي مثیــل فــورم امیــد لموجــب فــاتجــاه البحـث أن هنــاك حیــودأ عــن المثالیـة باال ذاالحصـول علیهــا فــي هــ ییات الالقطبیـة وقـد تــم ذیبات القطبیـة وحیـودا عـن المثالیـة باالتجـاه السـالب فـي مخــالیط داي مثیـل فـورم امیـد مـع المـذالمـ .یبات في المزیج ذخالت الجزیئیة بین جزیئات الماضوء التد فيلك ذتفسیر IHJPAS