Kinematic Viscosity Studies of the Binary Ethane- zy 1,2-diol/ N, N-Dimethylformamide Solvent System at Various Temperatures zyx FULVIO CORRADINI, ANDREA MARCHETTI, MARA TAGLIAZUCCHI, LORENZO TASSI* and GIUSEPPE TOSl University of Modena, Department of Chemistry, via G. Campi, 183, 41100 Modena, Italy Kinematic viscosity data zyxwvuts (v) are presented for ethane-I,2-diol, for N,N-dimethylformamide and for nine binary mix- tures in the zyxwvutsrqp - 10°C to 80°C temperature range. The experimental data were fitted by several empirical relations such zyx as Grunberg-Nissan (1949), McAllister (19601, Heric (1966), Lobe (1973), Auslander (1964) and polynomial equa- tions. Some considerations regarding the meaning of the obtained adjustment parameters are made. Furthermore. a new best fit equation is proposed and its validity has been compared to that of the other relations on the basis of the reproducibility of the experimental data. __ ~~~~ On prCsente des donnCes de viscositk cinkmatique (v) pour I’ethane-1, 2-dio1, le N, N-dimCthylformamide ainsi que pour neuf mClanges binaires dans une gamme de temperatures de - 10 zyxwvu h 80°C. Les donnies expCrimentales ont it6 cakes a I’aide de plusieurs relations empiriques telles que celles de Grunberg-Nissan (1949), McAllister (1960). Heric (1966), Lobe (1973), Auslander (1964) et par des Cquations polynbmiales. Certaines considerationsconcernant la sig- nification des parambtres de calage obtenus sont prksentees. En outre, on propose une meilleure Cquation de calage dont la validit6 est comparke i celle des autres relations par rapport h la reproducibiliti des donnCes exptrimentales. Keywords: kinematic viscosity, binary liquid mixtures, ethane-] ,2-diol, N,N-dimethylformamide. he use of binary, or more complex, solvent systems in T electrochemical studies represents a powerful tool of investigation because it makes possible the variation “in con- tinuum” of the thermomechanical parameters such as density, viscosity, dielectric constant, refractive index and some other related properties that influence the real behavior of the solutes and any physical-chemical process that takes place in solution. In previous papers, we have reported some studies about acid-base equilibria in ethane- 1,2-diol (hereafter abbreviated ED) (Franchini et al., 1989) and 2-methoxyethanol (ME) (Preti et al., 1982); both the solvents are amphyprotic, poten- tially acidic media. They have been used as nonaqueous pure solvents, in their binary mixtures (Franchini et al., 1990) and in mixtures with water (Franchini et al., 1988; Marchetti et al., 1989). Now, we have in progress some investigations about amido-alcoholic solvent systems containing N,N- dimethylformamide (DMF), a quite dipolar protophylic, potentially basic solvent, and the above-mentioned ED and ME, in order to cover the largest variability range of non- thermodynamic properties. In order to further our knowledge about the above men- tioned research field, we report in this paper an extensive study on kinematic viscosities of the EDiDMF binary mix- tures, in a reasonably wide temperature range (- 10 zyxwvu I t I 80°C) and covering the whole miscibility field expressed by the molar fraction of ED (0 I X, I 1). This solvent system appears very interesting from the viewpoint of the specific interactions between the components in the liquid state; these interactions should involve ED as electron acceptor and the cosolvent DMF as a- or n-electron donor. Experimental MATERIALS Ethane- 1,2-diol and N,N-dimethylformamide (containing both < 0.10% g water found by Karl-Fischer titration) *To whom correspondence may be addressed. were Carlo Erba (Milan) high purity grade. The N,N- dimethylformamide was purified by passage on neutral alu- mina column before use, whereas the ethane-I ,2401 was utilized without further purification. The mixtures were gravimetrically prepared on a Mettler analytical balance just before their use, operating in a dry nitrogen atmosphere in order to avoid the contact with the atmospherical moisture and at 26”C, and then preserved on 3A (0.3 nm) molecular sieves. The probable error in the ED mole fraction (X,) is estimated to be less than 1.5 X lop4. APPARATUS The apparatus for the viscosity and density measurements have been described elsewhere (Franchini et al.. 1989 and Marchetti et al., 1989, respectively). For the kinematic viscosity (v) determinations, in all the cases the experiments were generally performed at least in five replicates for each composition and at each temperature and the results were averaged. The experimental reproduci- bility of the viscosity measurements at each temperature and composition was +0.2%, with a standard deviation (a) of 1.4 X loe3. The estimated accuracy (95% contidence interval) was k 4 X The temperature control was provided by a Lauda K2R (Messgerlte-Werk Lauda, Ger- many) thermostatic bath maintained to +0.02”C. Karl Fischer titrations were performed with an automatic titra- tion system Crison model KF431 (Crison Instruments, Spain) equipped with a digital buret (Crison model 738). Results and discussion Table 1 reports the experimental values of the kinematic viscosities (v) for the two pure solvents and for nine their binary mixtures, where XA indicates the mole fraction of ED, in the temperature range - 10 5 t i 80°C with thennal scanning of 5°C. For the aim of this paper, we have preferred to use the kinematic viscosity rather than the absolute one, I24 THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, VOLUME 71, FEBRUARY. 1993