Static dielectric constants of the N,N-dimethylformamide/2-methoxyethanol solvent system at various temperatures

Abstract

Measurements of static dielectric constants (E) have been made for binary liquid mixtures of N,N-dimethylformamide (DMF)/2-methoxyethanol (ME) at 19 temperatures ranging from -10 to +80°C. Some empirical equations of the type E = E(T), E = c(X,), and E = s(T,X,) have been applied to check their validity. The E~ values, which refer to the deviation of the dielectric constants of the binaries from the values arising from mole fraction mixture law, have been calculated. Deviations from ideal behaviour have been found to be positive at all temperatures. The positive E~ values are attributed to a specific interaction between unlike molecules, which leads to the formation of complexes between DMF and ME in the liquid state. These nDMF.mME complex moieties were found to have the stoichiometric ratios 2 : 1, 1 : 1, and 1 : 2 in the temperature range of -10 to +80°C.FULVIO CORRADINI, LUIGI MARCHESELLI, LORENZO TASSI et GIUSEPPE TOSI. Can. J. Chem. 70, 2895 (1992).On a determine les constantes dielectriques statiques (E) de melanges liquides binaires N, N-dimCthylformamide(DMF)/ 2-methoxyCthanol(ME), a 19 temeratures allant de -10 a +80°C. Dans le but d'kvaluer leur validit6 dans le cas present, on a applique quelques equations empiriques du type E = E(T), E = E(X,) et E = s(T,X,). On a calculk les valeurs de la quantite E~ qui se refere a la deviation des constantes dielectriques des binaires par rapport aux valeurs decoulant de la loi de melange des fractions molaires. On a trouvk que, 5 toutes les temperatures CtudiCes, le dkplacement par rapport au comportement ideal est positif. On a attribue les valeurs positives de E~ a l'existence d'une interaction spkcifique, entre les molecules dissemblables, conduisant a la formation de complexes entre le DMF et le ME, a l'etat liquide. On a detect6 que les rapports stoechiomCtriques de ces entites complexes nDMF.mME passent de 2: 1 i 1 :

Excess molar volumes and deviations of the relative permittivity of the binary mixtures of 2-propoxyethanol with diethylene, triethylene, and tetraethylene glycols at various temperatures

“…As suggested by other authors [29][30][31], the study of this structural parameter for liquid systems is a very efficient tool for investigating the formation of intermolecular complexes, and provides a valuable aid for determining their stoichiometry and their relative thermostability. The position of the relative maxima in the plots of De versus x 1 , could be taken as the true composition of these intermolecular complexes [29][30][31]. Obtained results seem to indicate that the stable intermolecular complexes of the PE AE DEG, PE AE TEG, and PE AE TETRAEG types, are, respectively, formed in the studied binary mixtures.…”

Acetonitrile - 2-Methyl-Propan-1-ol and Acetonitrile - 2-Methyl-Propan-2-ol Binary Mixtures and their Physicochemical Properties

“…As suggested by other authors, the small negative " E 12 value for various solvent systems may be attributed either to homoconjugation phenomena of the more polar component induced by the presence of an apolar or quasi-apolar one, and/or to associations between unlike molecules in the mixtures [13][14][15][16].…”

“…The study of this extrathermodynamic structural parameter of liquid binary mixtures represents a unique tool for investigating the formation of intermolecular complexes, and provides a valuable aid for determining their stoichiometric composition. Therefore, a very slight shift " 12 from the linear behavior of a non-interacting ''ideal'' system should correspond to very weak complexes [13][14][15].…”

Thermodynamic and physicochemical properties of binary mixtures of nitromethane with {2-methoxyethanol+2-butoxyethanol} systems at T=(293.15, 298.15, 303.15, 308.15, and 313.15)K

“…The literature review shows that the study of this extra thermodynamic parameter for binary liquid systems represents a unique tool for investigating the formation of intermolecular complexes and provides a valuable aid for determining their stoichiometry and their relative thermostability [53][54][55]. The position of the relative maxima or minima in the plots of De versus x 1 could be taken as the true composition of these intermolecular complexes [53][54][55][56][57][58][59]. In the mixtures studied, the negative De values suggest that the formation of H-bonded heteromolecular interactions between NM and ME or BE decreases the effective number of parallel aligned dipoles in the mixtures, which may be due to the breaking of some of the linear polymeric H-bonded structures of ME and BE molecules.…”