Excess enthalpies of binary solvent mixtures of N,N-dimethylacetamide with aliphatic alcohols

The excess enthalpies H _m ^E of binary solvent mixtures of N,N-dimethylacetamide 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 increase as the length of the alkyl chain of the primary alcohol increases. The values for methanol are negative, those for ethanol change sign, and those for 1-propanol, and more clearly those for 1-butanol, are positive. The mixtures of the secondary and the tertiary alcohol exhibit mainly positive values of H _m ^E . Solute-solute and solute-solvent interactions in these mixtures are discussed on the basis of the results.     

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.     

Enthalpy of dilution of tetra-n-butylammonium bromide in mixtures of water and N-methylacetamide

The enthalpy of dilution of tetra-n-butylammonium bromide in mixtures of water and N-methylacetamide has been measured from approximately 0.1 to 1.0m at 35°C. The mole fraction of water in the solvent varied from 0.250 to 0.969. The results are strikingly nonlinear in the mole fraction of water. As the mole fraction of water varies from 0 to 0.7, there is only a small change in the enthalpy of dilution. At higher mole fractions of water, the excess enthalpy rises sharply to the unusually high values found in water. This indicates that the unusually high values of excess enthalpy associated with hydrophobic bonding in water are destroyed by relatively small amounts of N-methylacetamide.Taken in part from the Ph.D. thesis of J. S. Falcone, Jr., University of Delaware, Newark, Delaware, June 1972.     

Excess molar enthalpies for binary mixtures of different amines with water

The isothermal excess molar enthalpies for binary mixtures of different amines with water were measured with a C-80 Setaram calorimeter. The experimental results indicate that the excess molar enthalpy is related to the molecular structure. The experimental excess molar enthalpies were satisfactorily fitted with the Redlich–Kister equation. They were also used to test the suitability of the NRTL model, and the deviations are a little larger than the R–K equation.     

Excess enthalpies of binary solvent mixtures of 1-butanol and 2-methyl-2-propanol with aniline,N-methylaniline,and N,N-dimethylaniline

The excess molar enthalpies of binary solvent mixtures of 1-butanol and 2-methyl-2-propanol with aniline, N-methylaniline, and N,N-dimethylaniline were measured with a flow microcalorimeter at 40°C. The excess enthalpies are positive for all the systems, and smaller for the mixtures of 1-butanol than the corresponding mixtures of 2-methyl-2-propanol. With respect to the anilines, the values increase in the order aniline < N-methylaniline < N,N-dimethylaniline.     

Excess molar enthalpies of binary mixtures containing dimethylcarbonate, diethylcarbonate or propylene carbonate + three chloroalkenes at 298.15 K

Excess molar enthalpies H^E_m of dimethylcarbonate, diethylcarbonate or propylene carbonate + trans-1,2-dichloroethylene, + trichloroethylene, and + tetrachloroethylene, respectively have been determined at 298.15 K using an LKB flow-microcalorimeter. Experimental data have been correlated by means of the Redlich-Kister equation and adjustable parameters have been evaluated by least-squares analysis. The H^E_m values range from a minimum value of − 1000 J mol⁻¹ for diethylcarbonate + trans-1,2-dichloroethylene up to a maximum of 920 J mol⁻¹ for dimethylcarbonate + tetrachloroethylene. For each series of mixtures, a systematic increase in H^E_m with an increase in the number of Cl atoms in the chloroalkene molecule has been noted. The results are discussed in terms of the molecular interactions.     

Excess enthalpies and excess volumes of binary mixtures containing tetrahydrofuran

Heat of mixing data at 318.15 K are reported for the binary systems made up of tetrahydrofuran (THF) with pyridine and with thiazole.The volumes of mixing at 298.15 K and atmospheric pressure have also been measured for the following binary mixtures: THF+pyridine, THF+thiazole THF + benzene, THF + cyclohexane, THF + hexafluorobenzene.     

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 enthalpies for mixtures of cyclohexanone with isomeric propanols and butanols at 298.15 K

Excess enthalpies (H ^E ) for mixtures of cyclohexanone with propan-1-ol. propan-2-ol, butan-1-ol, butan-2-ol and 2-methyl propan-1-ol at 298.15 K have been measured over the entire composition range. All mixed endothermically with the maximum values ofH ^E occurring at equimole fraction. Comments about the molecular interactions contributing to the excess enthalpies of a cyclic ketone + an alcohol are made on the basis of these results.     

Excess enthalpies of binary mixtures of 2-ethyl-1-butanol with hexane isomers

Molar excess enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for binary mixtures of 2-ethyl-1-butanol with the five isomeric hexanes. The results are compared with previously published excess enthalpies for mixtures of 1-hexanol and 2-methyl-1-pentanol with the same hexane isomers.     

Excess molar enthalpies for binary liquid mixtures of furfural with some aromatic hydrocarbons

The excess molar enthalpies H _m ^E for the binary mixtures of furfural with the aromatic hydrocarbons namely benzene, toluene, ethylbenzene and o-, m-, and p-xylenes were determined at 35°C. The values for all the mixtures studied are positive over the entire range of composition and follow the order: o-xylene>m-xylene>ethylbenzene>p-xylene>benzene>toluene. The results are discussed in terms of the unlike specific interactions present in the binary mixtures.     

Excess enthalpies of binary mixtures of 2-methyl-1-pentanol with hexane isomers

Kimura, F. and Benson, G.C., 1982. Excess enthalpies of binary mixtures of 2-methyl-1-pentanol with hexane isomers. Fluid Phase Equilibria, 8:107-112.Molar excess enthalpies, measured in a flow microcalorimeter, are reported for binary mixtures of 2-methyl-1-pentanol with n-hexane and its four isomers. There is a roughly linear correlation between the results for equimolar mixtures and the mean number of gauche conformations of the isomer.     

Excess molar enthalpies of binary mixtures of 1-hexene with some cyclic and aromatic hydrocarbons at 298.15 K

Microcalorimetric measurements of excess molar enthalpies, at 298.15 K, are reported for the four binary systems formed by mixing 1-hexene with the cycloalkanes: cyclohexane and methylcyclohexane, and with the aromatic hydrocarcons: benzene and toluene. Smooth Redlich-Kister representations of the results are presented. It was found that the Liebermann-Fried model also provided good representations of the results.     

Molar excess enthalpies and volumes of mixtures of 2,4,6-trimethyl-pyridine with some aliphatic alcohols

The relationship enthalpy of mixing and excess molar volume of mixing versus composition were studied at 313.15 K for binary systems of 2,4,6-collidine with normal aliphatic alcohols. It was found that at this temperature the values ofH ^E andV ^E are negative and change with the length of the alkyl group of the alcohol.     

Static permittivity and molecular interactions in binary mixtures of ethanolamine with alcohols and amides

The relative static permittivity at 1 MHz and high frequency limit permittivity at wavelength of sodium-D line of the binary mixtures of ethanolamine (2-aminoethanol) with alcohols (ethyl alcohol, ethylene glycol and glycerol) and amides (formamide, N,N-dimethylformamide and N,N-dimethylacetamide) have been investigated over the entire concentration range at 30 °C. The excess permittivity and Kirkwood correlation factor of the binary mixtures were determined to explore the hydrogen-bonded hetero-molecular interactions and their dependence on the number of hydroxyl groups of alcohols molecules and the extent of substitution in amides molecules. Results confirm that ethanolamine form weak H-bond interactions with alcohols, N,N-dimethylformamide and N,N-dimethylacetamide, but the dipolar alignments in these mixtures vary with number of hydroxyl group of alcohols and their molecular size. Comparatively strong H-bond interactions were found between ethanolamine and formamide molecules with reduce in number of parallel aligned effective dipoles.     

Thermodynamics of weak interactions: Excess enthalpies of some binary bromoform mixtures

Excess enthalpies of bromoform + toluene, +o-xylene +m-xylene and +p-xylene have been determined at 308.15 K. These compounds have been examined for Barker's theory in order to understand the magnitude and nature of various interactions between the components of these mixtures. It has been concluded that the H-atom and one bromine atom of bromoform interact with the π cloud of the aromatic ring. These conclusions have been supplemented by n.m.r. studies. An approximate distance of the bromoform proton from the plane of the aromatic ring has also been calculated and examined in the light of the proposed geometry of the molecular complexes. Equilibrium constants for the complexations reaction have also been determined.     

Thermochemistry of 1-bromoadamantane in binary mixtures of water-aprotic solvent

Solution enthalpies of 1-bromoadamantane in the mixed solvents water-N,N-dimetylformamide, water-N,N-dimethylacetamide and water-acetone were determined at 298.15 K, within the range of solubility of 1-bromoadamantane (1-BrAd) in the mixed solvents. The solution enthalpy of 1-bromoadamantane in water was determined based on extrapolation from the three mixtures. Enthalpies of transfer from the mixed solvents to cyclohexane were calculated. The effect of the composition of the mixtures on the thermochemical values obtained was also investigated.     

Thermodynamic study of binary mixtures of isomeric butylamines with methanol enthalpy of hydrogen bonded complex

Heats of mixing of the binary mixtures ofn-, sec-, iso- andt-butylamines with methanol were determined in the entire concentration range. All the four systems showed a strong exothermic behaviour. The exothermic heats of mixing vary in the ordert-BuNH₂ >n-BuNH₂ > sec-BuNH₂ > iso-BuNH₂. The enthalpy of hydrogen bond in the methanol-butylamine complexes was calculated by means of a thermochemical cycle and found to vary in the ordert-BuNH₂ >n-BuNH₂ > iso-BuNH₂ > sec-BuNH₂. This order is different than that found for the hydrogen bond due to self-association. The difference has been explained in the light of steric and electromeric effects arising out of the substitution of the methyl groups in the alkyl chain of the butylamine. NCL Communication No. 2356 (Part of the Ph.D. Thesis submitted to the Bombay University by the first author).     

Ultrasonic investigation of molecular association in binary mixtures of aniline with aliphatic alcohols

Sound velocity, density and viscosity values have been measured at 303 K in the three binary systems of aniline + methanol, ethanol and 1-propanol. From these data, acoustical parameters such as adiabatic compressibility, free length, free volume and internal pressure have been estimated using the standard relations. The results are interpreted in terms of molecular interaction between the components of the mixtures. Observed excess value in all the mixtures indicates that the molecular symmetry existing in the system is highly disturbed by the polar alcohol molecules' dipole–dipole and induced dipole–dipole type interactions that are existing in the systems.     

Excess enthalpies of binary and ternary mixtures of acetonitrile with methanol,ethanol and benzene

Excess molar enthalpies are measured for the binary mixtures methanol—acetonitrile and ethanol—acetonitrile at 25 and 35°C and for the ternary mixtures methanol—acetonitrile—benzene and ethanol—acetonitrile—benzene at 25°C using an isothermal dilution calorimeter. The binary results are well reproduced with an association model which contains four equilibrium constants for the association of alcohol, two equilibrium constants for that of acetonitrile, and two solvation equilibrium constants between alcohol and acetonitrile molecules. The ternary results are compared with those calculated from the model with binary parameters.