Thermodynamics of aqueous solutions of nonelectrolytes. II. Enthalpies of transfer of 1-methyl-2-pyrrolidinone from water to many aqueous alcohols

Molar excess enthalpies were measured for 1-methyl-2-pyrrolidinone mixed with various pure alcohols and with aqueous alcohols at a low mole fraction of 1-methyl-2-pyrrolidinone at 298°K, using a LKB flow microcalorimeter. Enthalpies of transfer of 1-methyl-2-pyrrolidinone from water to the aqueous alcohol mixtures are estimated from the molar excess enthalpies. The results are discussed from the point of view of the effect of 1-methyl-2-pyrrolidinone on the structure of aqueous alcohol solutions.     

Dielectric properties of binary mixtures of n-methylbenzenesulfonamide

The dielectric permittivities of binary mixtures of N-methylbenzenesul-fonamide (N-MBS) with benzyl alcohol, 1,2-dichloroethane, 1,4-dioxane and hexamethylphosphortriamide were measured as a function of mole fraction over the whole composition range at 30 and 50°C. The excess dielectric permittivities and the excess molar polarizations were also calculated. The excess dielectric permittivities ^E and excess molar polarizations P_E were found to be negative for N-methylbenzene-sulfonamide mixtures with benzyl alcohol and 1,4-dioxane, ^E values were positive and P^E values negative for mixtures with 1,2-dichloroethane, and ^E and P^E values were clearly positive for mixtures with hexamethylphosphortriamide. The results are discussed in terms of the strength of the dipolar and hydrogen-bonding interactions between the molecules in various binary mixtures.     

Density and relative permittivity of (pyridine + 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol,and 2-butoxyethanol) binary mixtures at 298.15 K

The densities and relative permittivities of binary mixtures of pyridine with 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol and 2-butoxyethanol have been measured as a function of composition, at T = 298.15 K. From the experimental data the excess molar volume (V^E) and the deviation in the relative permittivity (Δε) from a mole fraction average have been calculated. The results are discussed in terms of intermolecular interactions and structure of studied binary mixtures.     

Thermodynamics of aqueous solutions of nonelectrolytes. I. Enthalpies of transfer of 1-methyl-2-pyrrolidinone from water to aqueous methanol

Molar excess enthalpies were measured for 1-methyl-2-pyrrolidinone mixed with water and with methanol over the whole concentration range and with aqueous methanol at the low mole fraction of 1-methyl-2-pyrrolidinone at 298.15°K, using a LKB flow microcalorimeter. Enthalpies of transfer of 1-methyl-2-pyrrolidinone from water to aqueous methanol were estimated from the molar excess enthalpies. The result was qualitatively in agreement with the conclusion described by Arnett et al.     

Studies on the internal structure of the binary mixtures of N,N-dimethylacetamide with 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol and 2-butoxyethanol by means of measuring their densities and relative permittivities at 298.15 K

ABSTRACT

The densities and relative permittivities of binary mixtures of N,N-dimethylacetamide with 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol and 2-butoxyethanol have been measured as a function of composition, at T = 298.15 K. From the experimental data the excess molar volume (V^E) from a mole fraction and the excess relative permittivity (ε^E) from a volume fraction average have been calculated. The results are discussed in terms of intermolecular interactions and structure of studied binary mixtures.     

Thermodynamic properties of binary mixtures of N-methyl-2-pyrrolidinone with cyclohexane,benzene, toluene at (303.15 to 353.15) K and atmospheric pressure

Densities and viscosities for binary mixtures of N-methyl-2-pyrrolidinone with cyclohexane, benzene, and toluene were determined at different temperatures and atmospheric pressure. The measurements were carried out over the whole range of composition, using a vibrating-tube density meter and Ubbelohde viscometer. Density, viscosity were used to compute the excess mole volumes, V^E, viscosity deviations, Δη and the excess energies of activation, ΔG^1E. Results have been fitted to Redlich–Kister equation to derive the coefficients and estimate the standard error values. A discussion on these quantities in terms of molecular interactions is reported. The experimental data of molar volumes are regressed by the Peng–Robinson equation with different alpha function. The mean root mean square deviations between experimental and calculated values for different binary mixtures are no more than 3.5%.     

Measurements of vapour-liquid equilibria,densities, viscosities and dielectric properties of cyclohexanone + triethylamine mixtures with respect to keto-enol tautomerism

Densities, ?, kinematic viscosities ν, refractive indices n_D referred to the sodium D-line, static relative permittivities ε, specific conductances κ and vapour-liquid equilibrium data for cyclohexanone + triethylamine mixtures have been determined at two temperatures. Excess properties of mixing calculated from these data indicate that in such mixtures considerable amounts of enol-amine associates are formed. The permittivity data indicate that the formation of associates is an exothermic process, which also has a marked influence on the thermodynamic excess properties of the mixtures. The enol-amine associates may undergo electrolytic dissociation. A common evaluation of static relative permittivities and specific conductances shows that for the mixture the conductance data are affected considerably by the formation of undissociated ion pairs in the sense of Bjerrum theory, especially at concentrations of the mixture where it is less polar. The conductance data are also influenced considerably by the fact that the ion pairs are solvated if the molar ratio of triethylamine exceeds 0.5.     

Determination of the intermolecular interaction parameters in the water-amide systems based on the data of the excess thermodynamic functions

The molar excess enthalpiesH ^E for the water +N-methyl-2-pyrrolidinone binary mixtures have been measured as functions of mole fraction at 298.15, 308.15 and 318.15 K, using isoperibol rotating calorimeter. A hydrogen bonding pairs model proposed by Luzar was fitted to the experimental dataH ^E,G ^E for the binary mixtures of water with hexamethylphosphoric triamide, N,N-dimethylformamide, N,N-dimethylacetamide and N-methyl-2-pyrrolidinone.     

Heats of solution and the influence of solutes on the temperature of maximum density of water

The influence of N,N-dimethylformamide, N,N-dimethylacetamide, 2-pyrrolidinone, N-methyl-2-pyrrolidinone, and N-t-butyl-2-pyrrolidinone on the temperature of maximum density (TMD) of water has been investigated. Heats of solution for these compounds and for diethylsulfoxide, tetramethylene sulfoxide, tetramethylene sulfone, dimethyl sulfoxide, and tetrahydrofuran in water at 23°C are also reported. These data, together with published TMD and heat of solution data for other solutes, are used to examine the relationship between the enthalpy change on dissolution of a solute in water and the effect of the dissolved substance on the structure of water as reflected by changes in the temperature of maximum density of the system.     

Static permittivities of ethanol mixtures with isomers of propanol and butanol at temperatures from 288.15 to 308.15 K

The relative permittivities of five binary mixtures of ethanol with propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol and 2-methylpropan-2-ol are reported for twenty-one mole fractions over the entire concentration range at 288.15, 293.15, 298.15, 303.15 and308.15 K. The excess static permittivity, the permittivity temperature coefficient (?lnε _r/?T) and its excess values were calculated. The excess parameters were fitted to the Redlich–Kister polynomial equation. The results were used in the analysis of hydrogen-bond inter molecular interactions occurring in the alcoholic binary mixtures having different natures of their constituents with varying carbon chain lengths.     

Excess enthalpies of alkane-1-amines {CnH2n+1NH2, n = 3-8} + methyl methylthiomethyl sulfoxide and +dimethyl sulfoxide at 298.15 K

Excess enthalpies of binary mixtures between each of alkane-1-amines {C_nH_2n+1NH₂, n=3-8} and methyl methylthiomethyl sulfoxide (MMTSO) or dimethyl sulfoxide (DMSO) have been determined at 298.15 K. All mixtures showed positive enthalpy changes over the whole range of mole fractions.The limiting excess partial molar enthalpies of the aliphatic amines, H₁^E,∞, of all the mixtures with MMTSO or DMSO studied were smaller than those of MMTSO or DMSO, H₂^E,∞, respectively. Linear relations are obtained between limiting excess partial molar enthalpies and number of methylene groups.     

Densities and relative permittivities for mixtures of 2-methoxyethanol with DEA and TEA, at various temperatures

Densities () and relative permittivities () of numerous binary mixtures of 2-methoxyethanol (ME) (1)+diethylamine (DEA) (2) at four temperatures and 2-methoxyethanol (1)+triethylamine (TEA) (2) at five temperatures, between (291.15 and 313.15) K, are reported. These results are used to calculate excess molar volumes, and deviations in the relative permittivities. The results are fitted to the Redlich-Kister polynomial equation to estimate the binary coefficients and standard errors. Furthermore, the experimental results are used to disclose the nature of binary interactions in the bulk of studied the binary mixtures.This revised version was published online in November 2005 with corrections to the Cover Date.     

Volumetric properties of binary mixtures of alcoxyethanols with tert-butyl ethyl ether at various temperatures

Densities at 293.15, 298.15, 303.15, 308.15 and 313.15 K of the binary liquid mixtures made of tert-butyl ethyl ether with either 2-ethoxyethanol, or 2-(2-ethoxy)ethoxyethanol, or 2-[2-(2-ethoxy)ethoxy]ethoxyethanol have been measured over the whole mixture compositions. These data have been used to compute the excess molar volumes (V^E). The excess molar volumes always are negative over the entire range of composition for all the binary mixtures investigated. The changes of V^E with variations of the composition and the chain-length of the alkyl groups in the alkoxyethanol molecules are discussed in terms of possible intermolecular interactions.     

Compressibility of ethylene glycol-dimethyl sulfoxide mixtures over the pressure range 0.1–100 MPa at 308.15 K

Compressibility coefficients k were measured for binary ethylene glycol (EG)-dimethyl sulfoxide (DMSO) mixtures over the whole composition range at pressures of 0.1–100 MPa and temperature 308.15 K. Excess molar volumes of mixtures, partial molar volumes of EG and DMSO, and changes in the excess molar Gibbs energy were calculated. The concentration dependences of compressibility factors k passed a minimum at pressures of ∼10 MPa. The k coefficient increased as the pressure grew, and the dependence became linear. The composition dependences of the specific volumes of mixtures passed minima at x ∼ 0.5 as the pressure increased (x is the mole fraction of dimethyl sulfoxide). The excess molar volumes were negative (EG-DMSO mixtures formed with compression). Changes in the excess molar Gibbs energy characterized the stabilizing action of pressure on the EG-DMSO system.     

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

Densities and relative permittivities at T = (293.15, 298.15, and 303.15) K in the binary liquid mixtures of 2-propoxyethanol with diethylene glycol, triethylene glycol, and tetraethylene glycol have been measured over the entire mixture compositions. These data have been used to compute the excess molar volumes and deviations of the relative permittivity. The results are discussed in terms of intermolecular interactions in the bulk of studied the binary mixtures.     

The 2-Methoxyethanol + 1,2-Dimethoxyethane + Water Ternary System. Static Relative Permittivities from −10 To +80°C

Static relative permittivities of the 2-methoxyethanol + 1,2-dimethoxyethane + water ternary solvent system were measured as a function of temperature (-10 = t/°C = 80) and of composition, over the whole molar fractions range 0 = x₂, x₂, x₃ = 1. The experimental values have been used to test some empirical relationships accounting for the dependence of e on T, x_i, and on T, x_i couples of values. A comparison between calculated and experimental data shows that these relationships can be profitably employed to predict e values in correspondence to experimental data gaps. The excess dielectric permittivity, e^E, assumes, in the most cases, negative values for any compositions of the mixtures, while the values of the excess molar polarization, P^E, are positive. The large values of the excess quantities are indicative of the strong specific interactions among similar, as well as different molecules in the mixtures. Discussion of the data in terms of Kirkwood correlation factor also gives information on the short-range intermolecular interactions among the components, suggesting the formation of two-components adducts rather than of than more complex moieties involving all three molecular species.     

Excess Volumetric and Spectroscopic Properties of Mixtures of Some <Emphasis Type="Italic">n</Emphasis>-Alkoxyethanols and of Some Polyethers with 2-Pyrrolidinone and <Emphasis Type="Italic">N</Emphasis>-Methyl-2-Pyrrolidinone at 298.15 K

Excess molar volumes V_m^E for binary liquid mixtures of n-alkoxyethanols or polyethers + 2-pyrrolidinone or N-methyl-2-pyrrolidinone have been measured with a continuous dilution dilatometer at 298.15 K and atmospheric pressure as a function of composition. The alkoxyethanols are diethylene glycol monomethylether, 2-(2-methoxyethoxy) ethanol, CH₃(OC₂H₄)₂OH; diethylene glycol monoethylether, 2-(2-ethoxyethoxy) ethanol, C₂H₅(OC₂H₄)₂OH; and diethylene glycol monobutylether, 2-(2-butoxyethoxy) ethanol, C₄H₉(OC₂H₄)₂OH; whereas the polyethers are diethylene glycol dimethylether, bis(2-methoxyethyl)ether, CH₃(OC₂H₄)₂OCH₃; diethylene glycol diethylether, bis(2-ethoxyethyl)ether, C₂H₅(OC₂H₄)₂OC₂H₅; and diethylene glycol dibutylether, bis(2-butoxyethyl)ether, C₄H₉(OC₂H₄)₂OC₄H₉. In all mixtures the excess molar volumes are negative and symmetric across the entire composition range. The excess volumes are fitted to the Redlich–Kister polynomial equation to obtain the binary coefficients and the standard errors. The experimental results have also been discussed on the basis of IR measurements.     

Dielectric properties of mixtures of acetylene tetrachloride with toluene and acetone

Relative permittivities are reported for binary liquid mixtures of acetylene tetrachloride (ATC) with toluene and acetone at 35°C. Measurements of refractive indices have also been made for the mixtures. The values of the quantity , the deviations of the relative permittivities of these mixtures from ideality, have been calculated. The negative values of obtained for ATC+ toluene mixtures may be explained as being due to a decrease in the degree of alignment of the molecular dipoles with changing composition of the mixture, whereas the positive values of obtained for ATC+acetone mixtures are attributed to the formation of molecular complex between acetone and CHCl₂CHCl₂. The values of the Kirkwood correlation parameter g for both sets of mixtures have been calculated using the relative permittivity data.     

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

The 1 H-NMR spectra of liquid binary mixtures of acetonitrile with 2-methyl-propan-1-ol (i-BtOH) and 2-methyl-propan-2-ol (t-BtOH), were recorded at 298 K over almost the whole range of mixed solvent compositions. From these data the values of spectral parameters, j i (ACN-i-BtOH) and j i (ACN-t-BtOH) were found. The relative permittivities ( k 12 ) and the densities ( d 12 ) of the mixed solvents were measured at 288.15 K, 293.15 K, 298.15 K, 303.15 K and 308.15 K. The experimental data were used to test some empirical equations of the type: y 12 = y 12 ( t ) and y 12 = y 12 ( X 1 ) [where: y 12 = d 12 or k 12 ]. From all these data, the deviations from ideality molar volumes , temperature coefficients of relative permittivities ( f 12 ) and the excess extrathermodynamic parameters were calculated. The values of these structural parameters are discussed in terms of interactions of acetonitrile with both alcohols.     

Isotopic substitution effects on the volumetric and viscosimetric properties of water-dimethylsulfoxide mixtures at 25°C

Densities and viscosities of binary mixtures (H₂O or D₂O) (1) + (DMSO or DMSO-D6)(2) have been measured over the entire mole fraction range; and the excess volumes, excess viscosities, and excess partial molar volumes Vf of the components have been obtained. All systems show negative excess volume V^e at all compositions, values for mixtures containing D₂O being more negative than those with H₂O byca. 0.03 cm³-mol^-1 at x₁, = 0.6, where a minimum is observed. The difference between DMSO and DMSO-D6 containing mixtures is negligible. The excess viscosity η^e is always positive and shows a maximum at x₁ = 0.65; at this composition, the substitution of H₂O with D₂O causes an excess viscosity increment ofca. 0.35 mPa-s, while deuteration of DMSO brings about a smaller increase,ca. 0.1 mPa-s. The trend of V ₂ ^E with concentration shows the characteristic features of moderately hydrophobic solutes in water (negative values and a minimum in the water-rich region), features that are slightly but significantly more marked in D₂O than in H₂O. The V ₂ ^E values in the water-diluted region and at x₁, =0 are more negative for D₂O than for H₂O.