ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2014, Vol. 88, No. 1, pp. 37 41. Pleiades Publishing, Ltd., 2014. PHYSICAL CHEMISTRY OF SOLUTIONS Molecular Interactions in Substituted Pyrimidines Acetonitrile Solutions at 298.15 318.15 K 1 A. B. Naik a, M. L. Narwade b, P. S. Bodakhe b, and G. G. Muley c a Physical Chemistry Laboratory, Department of Chemical Technology, SGB Amravati University, Amravati-444602 (M.S.) India b Vidyabharati Mahavidyalaya, Amravati-444602 (M.S.) India c Department of Physics, SGB Amravati University, Amravati-444602 (M.S.) India e-mail: anilnaik@sgbau.ac.in; naikabn@gmail.com Received January 14, 2013 Abstract Density, ultrasonic speed in pure solvent acetonitrile () and ligand solution of substituted pyrimidine in pure were measured at different temperatures (298.15, 303.15, 308.15, 313.15, and 318.15 K). Acoustical parameters such as adiabatic compressibility, intermolecular free length, acoustical impedance and relative association were determined from the experimental data of density and ultrasonic speed. The effect of temperature variations on the strength of molecular interaction has been studied. An excellent correlation represents in terms of solute solvent interaction at all temperatures. Keywords: density, ultrasonic velocity, acoustical parameter, molecular interaction, pyrimidine, acetonitrile. DOI: 10.1134/S0036024414010324 1 INTRODUCTION Ultrasonic methods have established an important place in science and new applications are found for the solution of many theoretical and practical problems [1]. Most important features of ultrasonic systems are robustness, non-invasiveness, precision, low cost, rapidity, and easy automation. Investigation of changes in thermodynamical properties of mixtures and the degree of their deviations from ideal mixing behavior are an excellent qualitative way to elicit information about molecular structure and intermolecular forces in liquid mixture. This has given impetus to the theoretical and experimental investigation of excess thermodynamic properties of liquid mixtures [2 5].The measurements of physicochemical properties such as density, viscosity, ultrasonic velocity and refractive indices of pure components and their mixtures are being increasingly used as tools for investigations of the properties of pure and the nature intermolecular interaction between components of liquid mixtures [6, 7]. The knowledge of fluid properties is important for many industrial applications. Among these properties density plays an important role in many industrial processes [8]. Ultrasonic studies have found wide applications owing to their ability to characterize the physicochemical behavior of solutions. The measurements of ultrasonic velocity in solutions thus provide useful information regarding the degree of deviation from 1 The article is published in the original. ideality, molecular association in solution and important correlation with various acoustical parameters [9 11]. Ultrasonic speed measurements are useful when dealing with the problems of structure and molecular interaction in liquids because of their accuracy. The concentration and temperature dependence of acoustic properties has proved to be a significant observation of intermolecular interaction in liquids and liquid mixtures [12, 13]. The thermodynamical functions like adiabatic compressibility, acoustic impedance, intermolecular free length, molar sound velocity have proved to be of immense value in predicting nature and strength of molecular association in liquid medium [14]. Bachu et al. [15] have reported the densities, viscosities and speed of sound of binary mixtures of phenylacetonitrile with some aliphatic alcohols at 308.15 K. This result reveals that the position of hydroxyl group, alkyl chain length and branching of alkyl chain have significant effects on thermodynamic properties of the system investigated. The substantial work also has been reported on the excess properties of acetonitrile + alkanols [16], acrylonitrile + alkanols [17], and benzonitrile + alkanols [18]. Abraham et al. [19] reported densities and sound speeds of + toluene mixture and observed negative variations in deviations of isentropic compressibility thereby suggesting strong interactions between toluene molecules. These considerations prompted us to assess the densities, ultrasonic velocities and acoustical parameters of the mixture of with L 1, L 2, L 3, and L 4 mixtures at different tem- 37
38 NAIK et al. ρ, kg m 3 780 760 740 720 Fig. 1. The temperature dependences of experimental density of solutions of, L 1, L 2, L 3, and L 4 in with solute concentration of 1 10 3 M. peratures (298.15, 303.15, 308.15, 313.15, and 318.15 K). Heterocyclic compounds are of a great synthetic and structural versatility because they have a number of potential substitution positions. Furthermore heteroatoms offer the possibility of several modes of coordination. Heterocycle containing pyrimidine moiety possesses pharmaceutical, medicinal, agricultural, industrial and biotechnological significances. belong to nitrile series having functional group ( C N). It is a part of several biologically important molecules such as proteins, lipids and hormones. molecules are highly polar with their dipoles arranged in antiparallal pairs and this strongly ordered structure is stabilized by dipole dipole interactions. is used mainly as a solvent in the purification of butadiene [20] in battery applications and also in the manufacture of DNA oligonucleotides from monomers. Industrially, it is used as a solvent for the manufacture of pharmaceuticals and photographic film. The great potential along with their interesting molecular structure promoted us to study molecular interaction in non aqueous media. In the view of applications of these solvents and solutes in chemistry and modern technology for four binary mixtures they have been studied at different temperatures (297.15, 303.15, 308.15, 313.15, and 318.15 K). EXPERIMENTAL The ligands L 1, L 2, L 3, and L 4 were synthesized in the laboratory by known literature method [21]. The concentrated solutions of ligands were prepared by dissolving an accurate amount in solvent in standard flasks with airtight caps and the mass measurements were performed using high precision digital balance (Adair Datta of accuracy ±0.01 mg). The ultrasonic velocity in pure components and their mixtures were measured by ultrasonic interferometer (Mittal enterprises, model F-81s) at 2 MHz with frequency tolerance ±0.03%. It consists of high frequency generator and a measuring cell. The densities of and ligands were measured by the specific gravity bottle with capacity 10 ml (Fig. 1). The accuracy of instrument was examined with pure distilled water and. THEORY Numerous methods are available in the literature for measuring ultrasonic velocity in solids and liquids. The ultrasonic interferometer is considered as more reliable and precise instrument. The expression used to determine ultrasonic velocity using ultrasonic interferometer is; u = νλ, (1) where u is ultrasonic velocity, and λ is wavelength. The adiabatic compressibility (β s ) was calculated from Newton Laplace equation. It is extensively applicable in understanding physicochemical behavior of liquid mixtures such as molecular association, dissociation and formation. The adiabatic compressibility is given by equation: β s = 1/ρ s u 2, (2) where ρ s is density of solution, and u is speed of ultrasonic velocity. The intermolecular free length between molecules in the liquid state is an essential and characteristic feature for interaction. Intermolecular force is one way or another to determine the properties of liquids of attractive and repulsive forces [22]. The intermolecular free length (L f ) is calculated by using the standard expression; L f = Kβ 1/2 s, (3) where K is a temperature dependent constant known as Jacobson constant. The acoustic impedance (Z) of a wave can be mathematically defined as the product of the wave velocity in the medium and its density. As the waves encounter the interface between the liquid and solid, they sense a change in acoustic impedance and are obtained by equation: Z = uρ. (4) The relative association (R A ) was calculated by the following equation; R A = ( ρ s /ρ 0 )( u 0 /u s ) 1/3, (5) where ρ 0 is density of solvent, and u 0 is velocity of solvent. RESULTS D DISCUSSION The calibration of the ultrasonic interferometer and specific gravity bottle were done by measuring the ultrasonic velocities and densities of pure and distilled water respectively. The measured values reported in Table 1 are good concordance with literature values. Small difference may result from differences in the RUSSI JOURNAL OF PHYSICAL CHEMISTRY A Vol. 88 No. 1 2014
MOLECULAR INTERACTIONS IN SUBSTITUTED 39 Table 1. Comparison of densities (ρ) and ultrasonic velocities (u) of distilled water and along with their literature values at different temperatures Liquid ρ, g cm 3 u, m s 1 exptl. lit. exptl. lit. Water 298.15 0.9962 0.9900 [23], 0.9970 [24] 1497 1480 [23], 1520 [24], 293.15 0.9982 [26] 1496.9 [25], 1483.1 [26] 298.15 0.7771 0.7765 [27], 0.775 [28] 1268 1271.3 [28] 303.15 0.7728 0.7699 [27] 1252 1250 [27] 308.15 0.7705 0.7652 [26] 1234 313.15 0.7646 1218 318.15 0.7496 1206 Table 2. Experimental density and ultrasonic velocity of L 1, L 2, L 3, and L 4 in at different temperatures with solute concentration of 1 10 3 M ρ, kg m 3 u, m s 1 298.15 777.1 785.3 778.9 774.7 773.7 1268 1288 1296 1292 1289 303.15 772.8 774.6 757.7 768.8 765.5 1252 1260 1260 1262 1262 308.15 770.5 775.8 743.0 751.0 753.8 1234 1248 1245 1247 1253 313.15 764.6 734.8 738.1 743.7 741.8 1218 1232 1224 1220 1232 318.15 749.6 718.6 714.8 725.3 720.2 1206 1212 1184 1192 1208 purity of chemicals, measurements, techniques and calibrations. The values of densities and ultrasonic velocities of L 1, L 2, L 3, and L 4 listed in Table 2 showed that decreases with increase in temperature [29, 30]. As the temperature increased available thermal energy facilitates the breaking of the bonds between the associated molecules into their monomers. Moreover, increases of thermal energy weaken the molecular forces which tend the decrease the ultrasonic velocity. Figure 2 shows the variation of ultrasonic velocity with substituted pyrimidine in at different temperatures. The thermodynamic parameters, adiabatic compressibility, free length, acoustic impedance and relative association are presented in Tables 3 and 4. Figure 3, it can be seen that the values of adiabatic compressibility increase by increasing temperature u, m s 1 1280 1240 1200 β s 10 10, m 2 N 1 10.0 9.5 9.0 8.5 8.0 7.5 Fig. 2. The temperature dependences of ultrasonic velocity in solutions of, L 1, L 2, L 3, and L 4 in with solute concentration of 1 10 3 M. Fig. 3. The temperature dependences of adiabatic compressibility (β s ) of solutions of, L 1, L 2, L 3 and L 4 in with solute concentration of 1 10 3 M. RUSSI JOURNAL OF PHYSICAL CHEMISTRY A Vol. 88 No. 1 2014
40 NAIK et al. Table 3. Variation of adiabatic compressibility (β s ) and linear free length (L f ) and acoustic impedance (Z) of L 1, L 2, L 3, and L 4 in at different temperatures with solute concentration of 1 10 3 M β s 10 10, m 2 N 1 298.15 8.0035 7.6759 7.6437 7.7328 7.7789 303.15 8.2551 8.1317 8.3130 8.1671 8.1490 308.15 8.5230 8.4670 8.6830 8.5630 8.3390 313.15 8.8159 8.9662 9.0431 9.0341 8.6883 318.15 8.9338 9.4734 9.9795 9.7035 9.3847 L f 10 10, m 298.15 5.6182 5.4845 5.4730 5.5048 5.5211 303.15 5.7331 5.6901 5.7258 5.7024 5.6961 308.15 5.8715 5.8522 5.8798 5.8853 5.8078 313.15 6.0279 6.0790 6.1051 6.1021 5.9841 318.15 6.1153 6.3168 6.4833 6.3930 6.2871 Z, N s m 5 298.15 985.36 1011.46 1009.45 1000.91 997.29 303.15 967.54 975.99 954.70 970.22 972.37 308.15 950.79 946.35 925.03 936.49 957.63 313.15 931.28 905.27 903.43 907.31 934.22 318.15 904.01 870.94 846.32 864.55 882.08 this is because at higher temperature ion solvent interactions are weakened and therefore the number of molecules affected by the ions decreases with increasing temperature [31]. In the system the interaction becomes weak due to the thermal agitation of component molecules and this is indicated by the decrease in velocity values [32]. Figure 4 shows the variation of free length at different temperatures. The adiabatic compressibility and free length show an opposite trend to that of velocity. The decreased compressibility brings the molecules to a closer packing resulting a decrease in intermolecular free length. This may be due to presence of solvent molecules around the ions. According to a model proposed by Erying and Kinkaid [11], ultrasonic velocity decreases with increase in free length and vice versa. Increase in compressibility and free length with temperature for all system suggests breaking of hetero and homo association of molecules at higher temperature [33]. Acoustic impedance (Z) is dependent on both material and its geometry. It is seen from Fig. 5 the acoustic impedance decreases with increasing temperature in all the system [34]. The relative association (R A ) is influenced by two factors (i) the breaking up of L F 10 10, m Z, N s m 5 6.4 6.0 5.6 1000 960 920 880 840 Fig. 4. Variation of linear free length (L f ) of L 1, L 2, L 3, and L 4 in at different temperatures T (K) with solute concentration of 1 10 3 M. Fig. 5. The temperature dependences of acoustic impedance (Z) of L 1, L 2, L 3, and L 4 in different temperatures T (K) with solute concentration of 1 10 3 M. RUSSI JOURNAL OF PHYSICAL CHEMISTRY A Vol. 88 No. 1 2014
MOLECULAR INTERACTIONS IN SUBSTITUTED 41 Table 4. Variation of relative association (R A ) of L 1, L 2, L 3, and L 4 in at different temperatures with solute concentration of 1 10 3 M 298.15 1.0052 0.9950 0.9907 0.9901 303.15 1.0002 0.9783 0.9921 0.9943 308.15 0.9804 0.9614 0.9712 0.9862 313.15 0.9573 0.9637 0.9721 0.9879 318.15 0.9570 0.9594 0.9713 0.9735 the solvent molecules on addition of solute to it and (ii) the solvation of solute that are simultaneously present [35]. CONCLUSIONS Ultrasonic method is a powerful tool for characterizing physicochemical properties and existence of molecular interaction in the mixture. The result reveals that the density and ultrasonic velocity of pure acetonitrile and ligand solutions increases with decreased with temperature. It is also seen that the formation of linear plot between temperature and respective parameters indicated that the stronger solute solvent interaction. The plot between temperature and relative association are found to be nonlinear showed that the weaker solute solvent interaction. REFERENCES 1. A. M. E. Raj, L. B. Rasmi, V. B. Jothy, M. Jayachandran, and C. Sanjeeviraja, Fluid Phase Equlib. 281, 78 (2009). 2. S. Singh, S. Parveen, D. V. Shukla, M. Yasmin, M. Gupta, and J. P. Shukla, J. Solution Chem. 40, 889 (2011). 3. D. Shukla, S. Singh, S. Parveen, M. Gupta, and J. Shukla, Chin. J. Chem. 28, 371 (2010). 4. N. G. Tsierkezos, M. M. Palaiologou, and I. E. Molinou, J. Chem. Eng. Data 45, 272 (2000). 5. A. Ali, A. K. Nain, V. K. Sharma, and S. Ahamad, Ind. J. Phys. B 75, 519 (2001). 6. D. V. Jahagirdar, B. R. Arbad, A. A. Walvekar, A. G. Shankarwar, and M. K. Lande, J. Mol. Liq. 85, 361 (2000). 7. B. R. Arbad, M. K. Lande, M. K. Wankhede, and N. N. Wankhede, J. Chem. Eng. Data 51, 68 (2006). 8. M. R. Francisca, Mesquita, X. Fillipe, Feitosa, R. S. Santiago, and H. B. S. Ana, J. Chem. Eng. Data 56, 153 (2011). 9. R. Palani and S. Balakrishna, Ind. J. Pure Appl. Phys. 48, 644 (2010). 10. R. Palani and K. Meenakshi, Ind. J. Chem. A 46, 252 (2007). 11. J. F. Kincaid and H. Eyring, J. Chem. Phys. 6, 587 (1938). 12. S. L. Oswal and N. B. Patel, J. Chem. Eng. Data 45, 225 (2000). 13. K. Tumura, T. Sonada, and S. Murakami, J. Solution Chem. 28, 777 (1999). 14. D. Bhatnagar, D. Joshi, Ashok Kumar, and C. L. Jain, Ind. J. Pure Appl. Phys. 48, 31 (2010). 15. R. K. Bachu, M. K. Patwari, S. Boodida, S. J. Tangeda, and S. Nallani, Ind. J. Chem. A 47, 1026 (2008). 16. P. S. Nikam, L. N. Sirsat, and M. Hasan, J. Chem. Eng. Data 43, 732 (1998). 17. M. I. Aralguppi, C. V. Jadar, and T. M. Aminabhavi, J. Chem. Eng. Data 44, 216 (1999). 18.P. S. Nikam, B. S. Jagdale, A. B. Sawant, and M. Hasan, J. Chem. Eng. Data 45, 214 (2000). 19. R. Abraham, M. Abdul Khader, and C. V. Asokan, J. Chem. Thermodyn. 32, 1 (2000). 20. K. Sarojini and T. Thenappan, J. Mol. Liq. 151, 39 (2010). 21. P. S. Bodkhe, PhD Thesis (Amravati Univ., India, 2002). 22. B. Jacobson, Acta Chem. Scand. 6, 1485 (1952). 23. M. Vatandas, A. B. Koe, and C. Koe, Eur. Food Res. Technol. 225, 525 (2007). 24. V. K. Sharma and Satishkumar, J. Sol. Chem. 34, 387 (2005). 25. J. M. Resa, C. Goensalez, J. M. Goenaga, and M. Iglesias, J. Therm. Anal. Calorim. 87, 237 (2007). 26. M. M. Palaiologou, G. K. Arianas, and N. Tsierkezos, J. Solution Chem. 35, 1551 (2006). 27. N. Sharma, S. Rana, and A. Sharma, Iron. J. Energy Environ. 1, 280 (2010). 28. K. Rajgopal, S. Chenthilnath, and A. K. Nain, J. Mol. Liq. 151, 23 (2010). 29. F. M. R. Mesquita, F. X. Feitosa, R. S. Santiago, and H. B. Ana, J. Chem. Eng. Data 56, 153 (2011). 30. M. Hasan, A. P. Hiray, U. B. Kadam, D. F. Shinde, K. J. Kurhe, and A. B. Sawant, J. Chem. Eng. Data 55, 535 (2010). 31. R. Sadeghi, R. Golabiazar, and M. Zialii, J. Chem. Eng. Data 55, 125 (2010). 32. J. D. Pandey, S. Shukla, R. D. Rai, and K. Misra, J. Chem. Eng. Data 34, 29 (1989). 33. T. Sumathi, S. Priyatharshini, and S. Punithasri, Ind. J. Pure Appl. Phys. 49, 328 (2011). 34. A. N. Kannappan, R. Kesavasamy, and V. Ponnuswamy, ARPN J. Eng. Appl. Sci. 3 (4), 41 (2008). 35. P. B. Agrawal and M. L. Narwade, Ind. J. Chem. A 42, 1047 (2003). RUSSI JOURNAL OF PHYSICAL CHEMISTRY A Vol. 88 No. 1 2014