Densities, Viscosities, and Excess Molar Enthalpies of 2-Pyrrolidone + Butanol Isomers at T ) (293.15, 298.15, and 303.15) K Ahlam M. Farhan † and Akl M. Awwad* ,‡ College of Science for Women, Baghdad University, Al-Jadiriyah, Baghdad, Iraq, and Industrial Chemistry Centre, Royal Scientific Society, P.O. Box 1438 Al-Jubaiha 11941, Amman, Jordan The experimental densities F, and viscosities η, of binary mixtures of 2-pyrrolidone with butanol isomers: 1-butanol, 2-methyl-1-propanol, 2-butanol, and 2-methyl-2-propanol have been measured at T ) (293.15, 298.15, and 303.15) K and atmospheric pressure over the whole mole fraction range. From these data, excess molar volumes, V E , and viscosity deviations, η, have been calculated at various temperatures. Both excess molar volumes and viscosity deviations are negative for all investigated systems. The excess molar enthalpies, H E , measured at 298.15 K and at atmospheric pressure for the four systems are positive over the whole mole fraction range. The experimental results have been correlated using Redlich-Kister polynomial equation, and parameters from least-squares analysis have been reported. Introduction The physicochemical properties of liquid mixtures have attracted much attention from both theoretical and engineering applications points of view. 2-Pyrrolidone has an important industrial applications, as a solvent for surface treatment of textiles, metal coating plastics, paint removing, and intermediate for the synthesis of agrochemicals, pharmaceuticals, plasticizers, polymer solvents, and stabilizers specially inks. Mixtures of 2-pyrrolidone with other solvents are also of particular interest. Understanding the mixing behavior of 2-pyrrolidone with alkanols is therefore important and has applications in many engineering industries. Many engineering applications require quantitative data on the density of liquid mixtures. It is also provides information about the nature and molecular interactions between liquid mixture components. This work continues our systematic studies for determination of the thermodynamic properties of the binary mixtures contain- ing 2-pyrrolidone as one component. 1,2 In recent publication, 2 we have presented the volumetric properties for mixtures of 2-pyrrolidone + aromatic hydrocarbons at various temperatures. A survey of the literature shows that Blumenshine and Sears 3 have measured the dielectric constants, viscosities, densities, and refractive indices of aqueous solution of 2-pyrrolidone at temperatures from (31 to 50) °C. Garcia et al. 4-6 studied excess viscosities, excess volumes, free energies of activation for viscous flow, enthalpies, and entropies of the binary mixtures of 2-pyrrolidone + methanol, + ethanol, + 1-propanol, + 1-butanol, + 1-pentanol, + hexan-1-ol, + heptan-1-ol, octan- 1-ol, + nonan-1-ol, and decan-1-ol at temperatures from (298.15 to 318.15) K. Recently. Mehta et al. 7 reported the excess molar volumes, speed of sound, transport parameter viscosity, and IR, 1 H NMR, and 13 C NMR spectroscopic parameters for the mixtures of R,ω-alkanediols in 2-pyrrolidone at T ) 308 K. To examine the effect of branching in alkanols on mixing properties of mixtures of 2-pyrrolidone and butanol isomers, we report in the present paper, the density F, excess molar volumes V E , viscosity η, viscosity deviations η, and excess molar enthalpies H E for the binary mixtures of 2-pyrrolidone + 1-butanol, + 2-methyl-1-propanol, + 2-butanol, and + 2-methyl-2-propanol over the whole mole fraction range at temperatures from (293.15 to 303.15) K. Experimental Section Materials. 1-Butanol (stated purity 99.8 %), 2-methyl-1- propanol (stated purity 99.5 %), 2-butanol (stated purity 99.5 %), and 2-methyl-2-propanol (stated purity 99.5 %) were obtained Aldrich and 2-pyrrolidone (stated purity 99 %) from Fluka AG and used without further purification. All liquids were kept over activated molecular sieves of type 4A (Union Carbide) and filtered before use. The purity of liquids was confirmed by gas-liquid chromatographic analysis. The measured density and viscosity data of the pure liquids at temperatures from (293.15 to 303.15) K are shown in Table 1 together with literature data. Binary mixtures were prepared by mass using a Mettler balance (model AE-240) with a precision of ( 0.01 mg. * Corresponding author. Tel: +962-6-534 4701. Fax: +962-6-534 4806. E-mail: amawwad2000@yahoo.com, aklm@rss.gov.jo. † Baghdad University. ‡ Royal Scientific Society. Table 1. Densities, G, and Viscosities, η, of Pure Liquids at T ) (293.15 to 303.15) K F/g · m -3 η/mPa · s liquid T/K exptl lit. exptl lit. 1-butanol 293.15 0.80952 2.941 298.15 0.80554 0.8059 a 2.572 2.560 b 303.15 0.80192 0.8019 a 2.275 2.560 c 2-butanol 293.15 0.80554 0.80648 d 3.625 3.6316 d 298.15 0.80206 0.80206 b 2.998 3.068 b 303.15 0.79845 2.489 2-methyl-1-propanol 293.15 0.80128 0.80168 d 3.943 4.0336 d 298.15 0.79774 0.79742 b 3.332 3.410 b 303.15 0.79432 2.884 2-methyl-2-propanol 293.15 0.79568 0.80961 d 5.486 5.108 d 298.15 0.78065 0.78049 b 4.436 4.444 b 303.15 0.77576 0.77573 b 3.378 3.361 b 2-pyrrolidone 293.15 1.10984 15.842 298.15 1.10698 1.1080 a 13.068 13.0927 a 303.15 1.10338 1.1034 a 10.687 10.6983 a a Reference 6. b Reference 8. c Reference 9. d Reference 10. J. Chem. Eng. Data 2009, 54, 2095–2099 2095 10.1021/je801006q CCC: $40.75  2009 American Chemical Society Published on Web 04/27/2009