Excess enthalpies of binary solvent mixtures of N-methylacetamide with aliphatic alcohols

The molar excess enthalpies H _m ^E of binary solvent mixtures of N-methylacetamide with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and t-butanol have been measured with a flow microcalorimeter at 40°C. The excess enthalpies are negative for methanol and positive for the other alcohols over the whole composition range, except for t-butanol which exhibits a sigmoid curve with a deep minimum at low mole fractions of the amide. The values for the primary alcohols increase in the order methanol < ethanol < 1-propanol < 1-butanol. The partial molar excess enthalpies have also been evaluated. Intermolecular interactions in these mixtures are discussed through comparison of the results with those for the corresponding binary mixtures of N,N-dimethylacetamide.     

Excess thermodynamic parameters of binary mixtures of methanol,ethanol, 1-propanol,and 2-butanol + chloroform at (288.15–323.15 K) and comparison with the Flory theory

In this work we used the experimental result for calculating the thermal expansion coefficients α, and their excess values α ^E , and isothermal coefficient of pressure excess molar enthalpy and comparison the obtain results with Flory theory of liquid mixtures for the binary mixtures {methanol, ethanol, 1-propanol and 2-butanol-chloroform} at 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15 K. The excess thermal expansion coefficients α ^E and the isothermal coefficient of pressure excess molar enthalpy ((∂H _m^E/∂P) _T,x for binary mixtures of {methanol and ethanol + chloroform} are S-shaped and for binary mixtures of {1-propanol and 2-butanol + chloroform} are positive over the mole fraction. The isothermal coefficient of pressure excess molar enthalpy (∂H _m^E/∂P) _T,x , are negative over the mole fraction range for binary mixture of {1-propanol and 2-butanol + chloroform}. The calculated values by using the Flory theory of liquid mixtures show a good agreement between the theory and experimental.     

Excess Molar Enthalpies and Excess Molar Volumes of Binary Mixtures of Benzene and Alkanols with Quinoline

Molar excess enthalpies H _m ^E have been determined over the whole composition range for mixtures of benzene, methanol, ethanol, 1-propanol, 2-propanol and 1-butanol with quinoline at 298.15 K using a Thermometric flow calorimeter. The results reflect a strong H-bond association between an alkanol and quinoline which decreases with increasing length of the alkanol chain. The small H _m ^E for (benzene+quinoline) reflects the similarity of the two molecules. This revised version was published online in August 2006 with corrections to the Cover Date.     

Excess enthalpies of binary solvent mixtures of 2-butanone with aliphatic alcohols

The molar excess enthalpies of binary solvent mixtures of 2-butanone with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-methyl-2-propanol have been measured with a flow microcalorimeter at 313.15 K. The excess enthalpies are positive over the whole composition range for all alcohols studied. The values for the primary alcohols increase with the length of the alkyl chain of the alcohol. The values for the secondary and the tertiary alcohol are slightly greater than those for the primary analogues. The partial molar excess enthalpies have also been evaluated. The results are discussed in terms of intermolecular interactions in the mixtures.     

Thermodynamics of Mixtures with Strongly Negative Deviations from Raoult's Law. VII. Excess Molar Volumes at 25°C for 1-Alkanol + N-Methylbutylamine Systems—Characterization in Terms of the ERAS Model

Excess molar volumes, V ^E _m, at 25^°C and atmospheric pressure, over the entire composition range for binary mixtures of methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol with-methylbutylamine are reported. They are calculated from densities measured with a vibrating-tube densimeter. All the excess volumes are large and negative over the entire composition range. This indicates strong interactions between unlike molecules, which are greatest for the system involving methanol, characterized by the most negative V ^E _m. For the other solutions, V ^E _m at equimolar composition, is approximately the same. The V ^E _m curves vs. mole fraction are nearly symmetrical. The ERAS model is applied to 1-alkanol + N-methylbutylamine, and 1-alkanol + diethylamine systems. The ERAS parameters confirm that the strongest interactions between unlike molecules are encountered in solutions with methanol. The model consistently describes V ^E _m and excess molar enthalpies H ^E _m of the mixtures studied.     

Excess Molar Volumes,Viscosity Deviations and Isentropic Compressibility of Binary Mixtures Containing 1,3-Dioxolane and Monoalcohols at 303.15 K

The excess molar volume (V ^E), viscosity deviations (Δη) and Gibbs excess energy of activation for viscous flow (G^∗E) have been investigated from density (ρ) and viscosity (η) measurements of eight binary mixtures of 1,3-dioxolane with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, and i-amyl alcohol over the entire range of mole fractions at 303.15 K. The viscosity data have been correlated with the Grunberg and Nissan equation. Furthermore, excess isentropic compressibilities (K_S^E) have been calculated from ultrasonic speed measurements of these binary mixtures at 303.15 K. The deviations have been fitted by a Redlich–Kister equation and the results are discussed in terms of molecular interactions and structural effects. The excess properties are found to be either negative or positive depending on the molecular interactions and the nature of the liquid mixtures. The systems studied exhibit very strong cross association through hydrogen bonding.     

Thermodynamics of mixtures with strongly negative deviations from Raoult’s law: Part 6. Excess molar volumes at 298.15 K for 1-alkanols + dibutylamine systems. Characterization in terms of the ERAS model

Excess molar volumes, V_m^E, at 298.15 K and atmospheric pressure over the entire composition range for binary mixtures of methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol and 1-octanol with dibutylamine are reported. They are calculated from densities measured with a vibrating-tube densimeter. All the excess volumes are large and negative over the whole mole fraction range, indicating strong interactions between unlike molecules, which are more important for the systems involving methanol or ethanol, characterized by the most negative V_m^E. For the other mixtures, V_m^E at equimolar composition, is approximately constant. The V_m^E curves are nearly symmetrical. The V_m^E and excess molar enthalpies (H_m^E) of the mixtures studied are consistently described by the ERAS model. The ERAS parameters confirm that the strongest interactions between unlike molecules are encountered in the methanol+dibutylamine system.     

Excess Molar Volumes and Excess Partial Molar Volumes of Triethylene Glycol Monoethyl Ether–n-Alcohol Mixtures at 25°C

We have measured excess molar volumes V^E _m of binary mixtures of triethylene glycol monoethyl ether with methanol, ethanol, 1-propanol, 1-pentanol, and 1-hexanol over the full range of compositions at 25°C. The measurements were carried out with a continuous-dilution dilatometer. The excess molar volumes V^E _m are negative over the entire range of composition for the systems triethylene glycol monoethyl ether + methanol, + ethanol, and + 1-propanol and positive for the remaining systems, triethylene glycol monoethyl ether + 1-pentanol, and + 1-hexanol. The excess V^E _m increases in the positive direction with increasing chain length of the n-alcohol. The measured excess volumes have been compared to our previous published data with an effort to assess the effects of replacing methyl by ethyl groups and of inserting oxyethylene groups. The results have been used to estimate the excess partial molar volumes V^E _m,i of the components. The behavior of V^E _m and V^E _m,i with composition and the number of carbon atoms in the alcohol molecule is discussed.     

Excess molar enthalpies at 298.15 k of the binary mixtures

We have determined the excess molar enthalpies H _m ^E at 298.15 K and normal atmospheric pressure for the binary mixtures containing tert-butyl methyl ether (MTBE)+(methanol, ethanol, 1-propanol, 1-pentanol) using a Calvet microcalorimeter. This revised version was published online in July 2006 with corrections to the Cover Date.     

Excess molar enthalpy for methanol,ethanol, 1-propanol, 1-butanol + <Emphasis Type="Italic">n</Emphasis>-butylamine mixtures at 288.15 and 308.15 K at atmospheric pressure

Experimental data of excess molar enthalpy (H _m^E) of binary liquid mixtures containing (methanol or ethanol or 1-propanol, or 1-butanol) + n-butylamine mixtures have been determined as a function of composition at temperatures 288.15 and 308.15 K, at atmospheric pressure, using a modified 1455 PARR mixture calorimeter. The H _m^E values are negative for both systems over the whole composition range. The applicability of the ERAS Model to correlate H _m^E of mixtures studied is tested, and the agreement between experimental and theoretical results is satisfactory. The model results are discussed in terms of the cross-association interactions with temperature variation as well as in terms of the variation of the carbon chain in the alcohols presents in the mixtures.     

Measurement and Correlation of Excess Molar Enthalpy of Binary Mixtures Containing Butyl Acetate + 1-Alkanols (C1–C6) at 298.15 K

Excess molar enthalpies, ?H _m ^E , for the binary mixtures of butyl acetate + 1-alkanols, namely (methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, and 1-hexanol), were measured over the whole range of composition at 298.15 K using a Parr 1455 solution calorimeter. The excess partial molar enthalpies, ?H _m,i ^E , were calculated from the experimental excess molar enthalpies using the Redlich–Kister polynomial equation. The sign of ?H _m ^E for all systems are positive because of the disruption of hydrogen bonding and dipole–dipole interactions in the alkanols and esters, respectively. The magnitude of the ?H _m ^E values increases with increasing alkyl chain length. The behavior of ?H _m ^E was analyzed in terms of the length of the alkanol chain, the nature and type of intermolecular interactions and the balance between positive and negative effects on deviations from ideality. The experimental excess molar enthalpy data have also been correlated using the Redlich–Kister and SSF equations and two local composition models (UNIQUAC and NRTL).     

Excess Molar Volumes and Partial Molar Volumes of Dipropylene Glycol Monomethyl Ether + n-Alkanol Mixtures at 25°C

The excess molar volumes V^E for binary liquid mixtures containing dipropylene glycol monomethyl ether and methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, and 1-heptanol have been measured using a continuous dilution dilatometer over the whole mole fraction range at 25°C at atmospheric pressure. V^E are negative over the whole composition range except for the systems containing 1-pentanol, 1-hexanol, or 1-heptanol which are positve at every composition. V^E increases in a positive direction with increase in chain length of the n-alcohol. The results have been used to estimate the excess partial molar volumes V_i^E of the components. The change of V^E and V_i^E with composition and the number of carbon atoms in the alcohol molecule are discussed as a basis to understand some of the molecular interactions present in the mixtures:     

A Study of Excess Molar Enthalpies and Excess Molar Volumes of Binary Mixtures of 1-Chloropentane + 1-Alkanol (from 1-Butanol to 1-Octanol) at 25°C.

Excess molar enthalpies H ^E _mand excess molar volumes V ^E _m at 25°Cand normal atmospheric pressure for the binary mixtures 1-chloropentane + 1-alkanol(from 1-butanol to 1-octanol) have been determined using a Calvet microcalorimeterand from density measurements using a vibrating tube densimeter. The H ^E _m valuesfor all the mixtures are positive and V ^E _m values are positive or negative dependingon the mole fraction of the chloroalkane. Experimental H ^E _m results are comparedwith the predictions of UNIFAC group-contribution models proposed by Dang andTassios and by Larsen et al., and are discussed in terms of molecular interactions.     

Excess Molar Volumes and Excess Partial Molar Volumes of Triethylene Glycol Monomethyl Ether–n-Alcohol Mixtures at 25°C

The excess molar volumes V ^E have been measured for binary mixtures of triethylene glycol monomethyl ether with methanol, ethanol, 1-propanol, 1-pentanol, and 1-hexanol as a function of composition using a continuous–dilution dilatometer at 25°C at atmosphere pressure. V ^E are negative over the entire range of composition for the systems triethylene glycol monomethyl ether + methanol, + ethanol, and + 1-propanol, and positive for the remaining systems, containing 1-pentanol and + 1-hexanol. V ^E increases in a positive direction with increasing carbon chain length of the n-alcohol. The excess partial molar volumes V _i ^E of the components were evaluated from the V ^E results. The behavior of V ^E and V _i ^E with composition and the number of carbon atoms in the alcohol molecule is discussed.     

Thermodynamic Properties of Binary Mixtures of Cyclohexanone with n-Alkanols (C1–C5) at 293.15 K

The excess molar volumes (V^E), excess surface tensions (σ^E), and deviations in molar refraction (R^E) and isentropic compressibility (k_s^E) of binary mixtures of cyclohexanone with methanol, ethanol, 1-propanol, 1-butanol, and 1-pentanol have been determined over the entire composition range at 293.15 K. The results were fitted by the Redlich–Kister polynomial equation and the corresponding binary coefficients A_k have been derived. The standard deviations between the calculated and the experimental excess properties have been determined. The results provide information on the interactions of the molecules in the pure liquids as well as in the binary mixtures.     

Excess volumes of the binary mixtures 1,2-dichloroethane ? n -alkanols [C2?C6]

Volume changes on mixing of binary systems formed by 1,2-dichloroethane andn-alcohols, namely, ethanol,n-propanol,n-butanol,n-pentanol andn-hexanol were measured as a function of composition at 30, 35, 40 and 45 °C. At all compositions theV ^E values are all positive for all systems. The molar excess volumes of mixing for equimolar mixtures increase as the length of carbon chain increases.V ^E becomes more positive on increasing temperature. The positive value of the excess volume has been attributed to breaking of hydrogen bonds of associated species of alcohol by dilution with 1,2-dichloroethane.     

Density and excess molar volumes of binary mixtures of sulfolane with methanol,n -propanol,n -butanol,and n -pentanol at 298.15–323.15 K and atmospheric pressure

Densities, ρ and excess molar volumes, V?^E of the binary mixtures of sulfolane, +methanol, +n-propanol,?+n-butanol, and +n-pentanol were measured at temperatures 298.15, 303.15, 308.15, 313.15, and 318.15?K, respectively, covering the whole composition range except methanol at 303.15–323.15?K. The V ^E for the systems were found to be negative and large in magnitude. The values of V ^E of the sulfolane, +n-butanol and sulfolane, +n-pentanol mixtures are being positive at lower and higher mole fractions of the alkanols (x ₂). The magnitudes of the V ^E values of the mixtures are in the order sulfolane?+?methanol?>?sulfolane?+?n-propanol?>?sulfolane?+?n-butanol?>?sulfolane?+?n-pentanol. The observed values of V ^E for the mixtures have been explained in terms of (i) effects due to the differences in chain length of the alcohols, (ii) dipole–dipole interactions between the polar molecules, and (iii) geometric effect due to the differences in molar volume of the component molecules. These are more noticeable in the case of lower alcohols. All these properties have been expressed satisfactorily by appropriate polynomials.     

Ternary excess molar enthalpies for the mixtures of methanol and ethanol with tetrahydropyran or 1,4-dioxane at 298.15 K

Ternary excess molar enthalpies, H_m^E, at 298.15 K and atmospheric pressure measured by using a flow microcalorimeter are reported for the (methanol+ethanol+tetrahydropyran) and (methanol+ethanol+1,4-dioxane) mixtures. The pseudobinary excess molar enthalpies for all the systems are found to be positive over the entire range of compositions. The experimental results are correlated with a polynomial equation to estimate the coefficients and standard errors. The results have been compared with those calculated from a UNIQUAC associated solution model in terms of the self-association of alcohols as well as solvation between unlike alcohols and alcohols with tetrahydropyran or 1,4-dioxane. The association constants, solvation constants and optimally fitted binary parameters obtained solely from the pertinent binary correlation predict the ternary excess molar enthalpies with an excellent accuracy.