Binary Mixtures Of Methanol Research Articles

Volumetric and viscometric studies on 1,4-dioxane and methanol binary mixtures at different temperatures

Densities and viscosities of binary liquid mixtures of 1,4-dioxane with polar solvent viz. methanol have been measured at 303.15, 308.15, 313.15 and 318.15 K. From the density and viscosity data, the values of various properties viz. excess molar volume (V E ), excess viscosity (η E ) and excess Gibb's free energy of activation of flow (ΔG E ) have been determine 1. Further the viscosities of binary mixtures have been correlated to various viscosity models. On the basis of the values of interaction parameters of these viscosity models and also on the basis of the values of various excess properties, the nature of molecular interactions between the components of mixtures have been explained.

Aromatic nitro substitution reaction between 4‐nitro‐N‐n‐butyl‐1,8‐naphthalimide and n‐heptanethiol in water–methanol binary mixtures

AbstractThe second‐order rate constants of thiolysis by n‐heptanethiol on 4‐nitro‐N‐n‐butyl‐1,8‐naphthalimide (4NBN) are strongly affected by the water–methanol binary mixture composition reaching its maximum at around 50% mole fraction. In parallel solvent effects on 4NBN absorption molar extinction coefficient also shows a maximum at this composition region. From the spectroscopic study of reactant and product and the known H‐bond capacity of the mixture a rationalization that involves specific solvent H‐donor interaction with the nitro group is proposed to explain the kinetic data. Present findings also show a convenient methodology to obtain strongly fluorescent imides, valuable for peptide and analogs labeling as well as for thio‐naphthalimide derivatives preparations. Copyright © 2008 John Wiley & Sons, Ltd.

Dielectric Properties of Methanol Mixtures with Ethanol, Isomers of Propanol, and Butanol

The relative permittivities of seven binary mixtures of methanol with ethanol, isomers of propanol, and butanol are reported for various mole fractions at (288.15, 293.15, 298.15, 303.15, and 308.15) K. The excess dielectric permittivity, the temperature coefficients, (∂lner)/(∂T), and their excess values were calculated. The excess parameters have been fitted to the Redlich−Kister polynomial equation. The results of measurements were used in the analysis of the molecular interactions occurring in the alcoholic solutions.

Prediction of Transport Properties by Molecular Simulation: Methanol and Ethanol and Their Mixture

Transport properties of liquid methanol and ethanol are predicted by molecular dynamics simulation. The molecular models for the alcohols are rigid, nonpolarizable, and of united-atom type. They were developed in preceding work using experimental vapor-liquid equilibrium data only. Self- and Maxwell-Stefan diffusion coefficients as well as the shear viscosity of methanol, ethanol, and their binary mixture are determined using equilibrium molecular dynamics and the Green-Kubo formalism. Nonequilibrium molecular dynamics is used for predicting the thermal conductivity of the two pure substances. The transport properties of the fluids are calculated over a wide temperature range at ambient pressure and compared with experimental and simulation data from the literature. Overall, a very good agreement with the experiment is found. For instance, the self-diffusion coefficient and the shear viscosity are predicted with average deviations of less than 8% for the pure alcohols and 12% for the mixture. The predicted thermal conductivity agrees on average within 5% with the experimental data. Additionally, some velocity and shear viscosity autocorrelation functions are presented and discussed. Radial distribution functions for ethanol are also presented. The predicted excess volume, excess enthalpy, and the vapor-liquid equilibrium of the binary mixture methanol + ethanol are assessed and agree well with experimental data.

Correlation of the Rates of Solvolysis of Diphenylthiophosphinyl Chloride Using an Extended form of the Grunwald-Winstein Equation

Rate of solvolysis of diphenylthiophosphinyl chloride in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluoroethanol (TFE) or 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are reported. Solvolyses were also carried out in TFE-ethanol mixtures. For five representative solvents, studies were made at several temperatures and activation parameters determined. The 29 solvents gave a reasonably precise extended Grunwald-Winstein equation plot, correlation coefficient (R) of 0.933, which improved to 0.983 when the four TFE-ethanol points were excluded. The sensitivities (l = 1.00 and m = 0.64) were similar to those obtained for dimethyl phosphorochloridate and phosphorochloridothionate and diphenylphosphinyl chloride (1). As with the four previously studied solvolyses, an <TEX>$SN_2$</TEX> pathway is proposed for the solvolyses of diphenylthiophosphinyl chloride. The activation parameters, <TEX>${\Delta}H^{\neq}$</TEX> and <TEX>${\Delta}S^{\neq}$</TEX>, were determined and they are also in line with values expected for an <TEX>$S_N2$</TEX> reaction.

Thermophysical Properties of Binary Mixtures of Methanol with Chlorobenzene and Bromobenzene from 293 K to 313 K

Densities and viscosities have been measured for the binary mixtures of methanol with chlorobenzene and with bromobenzene from 293 K to 313 K over the complete composition range. Densities were used to compute the excess molar volume (\({V_{\rm m}^{\rm E})}\) , for these binary systems. The results have been discussed in terms of molecular interactions. Furthermore, viscosity results were compared with a corresponding-states model. The average absolute deviation was found to be 1.9 %.

Complexation of 4′-nitrobenzo-15-crown-5 with Li+, Na+, K+, and NH 4 + cations in acetonitrile–methanol binary solutions

The complexation processes between Li+, Na+, K+ and NH4+ cations with macrocyclic ligand, 4′-nitrobenzo-15C5, were studied in acetonitrile–methanol (AN–MeOH) binary mixtures at different temperatures using conductometric method. The conductance data show that the stoichiometry of the complexes formed between the ligand and Li+, Na+, K+ and NH4+ cations is 1:1(M:L). Addition of 4′-nitrobenzo-15C5 to these cations solution, causes a continuous increase in the molar conductivities which indicates that the mobility of the complexed cations is more than the uncomplexed ones. The values of stability constants of the complexes were determined from conductometric data using GENPLOT computer program. The obtained results show that the selectivity order of the ligand for Li+, Na+, K+ and NH4+ cations changes with the nature and composition of the binary mixed solvent. The values of thermodynamic parameters (ΔH°c, ΔS°c) for formation of the complexes were obtained from temperature dependence of the stability constants using the van’t Hoff plot. The results show that the complexes are both enthalpy and entropy stabilized. A non-linear behavior was observed between the stability constants (log Kf) of the complexes and the composition of the AN–MeOH binary solution.

VISCOSITY AND EXCESS MOLAR VOLUME OF BINARY MIXTURES OF METHANOL AND ETHANOL WITH TRIETHYLAMINE AND TRI-N-BUTYLAMINE AT 303.15, 313.15, and 323.15 K: CHARACTERIZATION IN TERMS OF ERAS MODEL

The excess molar volume VE, viscosity deviation Δη, and excess Gibbs energy of activation ΔG*E of viscous flow have been investigated from the density ρ and viscosity η measurements of four binary mixtures of methanol and ethanol with triethylamine and tri-n-butylamine over the entire range of mole fractions at 303.15, 313.15, and 323.15 K. The viscosity data have been correlated with the equations of Grunberg and Nissan, Hind, McLaughlin, and Ubbelohde, Tamura and Kurata, and McAllister. The systems studied exhibit very strong cross association through strong O–H…N bonding between –OH and –N < groups. As a consequence of this strong intermolecular association, all four systems have very large negative VE. The VE of the studied mixtures is consistently described by the ERAS model. The values of cross association constants KAB illustrate the fact that cross-associates are more pronounced in a mixture of a short-chain tertiary amine.

On the Formation of Glycolaldehyde (HCOCH2OH) and Methyl Formate (HCOOCH3) in Interstellar Ice Analogs

Binary mixtures of methanol (CH3OH) and carbon monoxide (CO) ices were irradiated at 10 K with energetic electrons to mimic the energy transfer processes that occur in the track of the trajectories of MeV cosmic-ray particles. The formation of glycolaldehyde (HCOCH2OH) was established through the appearance of new bands in the infrared spectrum at 1757, 1700, 1690, 1367, 1267, and 1067 cm-1. A second C2H4O2 isomer, methyl formate (HCOOCH3), was also identified by absorptions appearing at 1718, 1159, and 914 cm-1. Mass spectrometer signals during the warm-up of the ice sample showed sublimation of both the glycolaldehyde and methyl formate; these species were monitored via the C2H4O2+ molecular ion at mass-to-charge ratio, m/e, of 60 originating from both glycolaldehyde and the methyl formate isomer. The latter was distinguishable by the presence of a second signal at m/e = 45, i.e., the HCO2+ ion. Kinetic fits of the column densities of the reactants and products suggest the initial step of the formation process is the cleavage of a C–H bond in the methanol molecule to generate either the hydroxymethyl (CH2OH) or methoxy (CH3O) radical plus atomic hydrogen. The hydrogen atom holds excess kinetic energy, allowing it to overcome entrance barriers required; therefore, a hydrogen could add to a CO molecule, generating the formyl radical (HCO). This can recombine with the hydroxymethyl radical to form glycolaldehyde or with the methoxy radical to yield methyl formate. Similar processes are expected to form glycolaldehyde and methyl formate in the interstellar medium on grains and possibly on cometary ices, thus providing alternatives to gas-phase processes for the generation of complex species whose fractional abundances compared with H2 of typically a few times 10-9 cannot be accounted for solely by gas-phase chemistry.

Volumetric Properties of the Binary Methanol + Chloroform and Ternary Methanol + Chloroform + Benzene Mixtures at (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K

Densities ρ of the ternary system of methanol + chloroform + benzene and binary mixture of methanol + chloroform have been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure with an Anton Paar DMA 5000 digital vibrating tube densimeter. Excess molar volumes V E were calculated from the densities data and correlated by the Redlich−Kister (for binary data) and Nagata−Tamura (for ternary data) equations.

Comparison of the SRK and CPA equations of state for physical properties of water and methanol

Accurate modelling of reservoir fluids containing hydrocarbons, water, and a hydrate inhibitor is an important area for the petroleum industry. Often cubic Equations of State as for example the SRK equation are used. It is desirable that the applied thermodynamic model is applicable not only to calculate phase compositions and saturation conditions but also phase properties like density and heat capacity. Hydrocarbon phase properties can generally be simulated quite accurately using a conventional cubic equation of state with a volume shift parameter. As petroleum reservoir fluids are often produced together with water, properties of water and additives like methanol and glycol is another target area. Being more polar than hydrocarbons, water, alcohols and glycols may require more advanced models for example an association model like CPA (Cubic-Plus-Association). This type of model has previously been found to be well suited for phase equilibrium calculations on mixtures of hydrocarbons and polar compounds. In this work, SRK (with and without Peneloux volume correction) and CPA are compared for pure water, pure methanol and water–methanol binary mixtures with the purpose of evaluating the performance of the models for associating compounds found in produced reservoir fluids. The properties considered are density, constant pressure heat capacity, velocity of sound, the derivative ( ∂V/ ∂P) T , enthalpy and Joule–Thomson coefficient. It is shown that the CPA model performed better than SRK-Peneloux in most cases and better than SRK without Peneloux correction for all properties considered.

Densities, Viscosities, and Sound Speeds of Some Acetate Salts in Binary Mixtures of Tetrahydrofuran and Methanol at (303.15, 313.15, and 323.15) K

The densities and viscosities of ammonium acetate, potassium acetate, sodium acetate, and lithium acetate have been measured in 10, 20, and 30 mass % of tetrahydrofuran + methanol binary solvent mixtures at (303.15, 313.15, and 323.15) K. Apparent molar volumes (Vφ), partial molar expansibility (E2), viscosity B-coefficients, and free energy of activation for viscous flow (Δμ0*) are obtained from these data. The limiting apparent molar volumes (Vφ0) and experimental slopes ( ) derived from the Masson equation have been interpreted in terms of ion−solvent and ion−ion interactions, respectively. The viscosity data have been analyzed using the Jones−Dole equation, and the derived parameters B and A have also been interpreted in terms of ion−solvent and ion−ion interactions. The sound speeds measured at 303.15 K have been used to study the apparent molal isentropic compressibility (KS,φ), intermolecular free length (Lf), relative association (RA), relaxation strength (r‘), and specific acoustic impedance (Z) of the solutions.

MD Simulations of Diffusivities in Methanol‐n‐hexane Mixtures Near the Liquid‐liquid Phase Splitting Region

AbstractMolecular Dynamics (MD) simulations have been carried out to determine the self‐diffusivities in binary mixtures of methanol and n‐hexane with varying compositions at four different temperatures of 303.15 K, 307.7 K, 310.7 K, and 313.15 K. The Darken relation was used to determine both the Fick diffusivity and the Maxwell‐Stefan diffusivity. The values of the Fick diffusivity obtained from the simulations are in very good agreement with published experimental data of Clark and Rowley [17]. These diffusivities approach zero near composition regions where liquid‐liquid phase splitting occurs. On the other hand, the Maxwell‐Stefan diffusivity is well‐behaved and appears to be practically insensitive to the complex thermodynamics.

Isothermal Vapor Liquid Equilibrium for 2-Methylpropene + Methanol, + 1-Propanol, + 2-Propanol, + 2-Butanol, and + 2-Methyl-2-propanol Binary Systems at 364.5 K

Vapor−liquid equilibrium data were measured using an automatic static total pressure apparatus for binary mixtures of 2-methylpropene + methanol, + 1-propanol, + 2-propanol, + 2-butanol, and + 2-methyl-2-propanol at 364.5 K. The measured p, T, z data were fitted against Legendre polynomials and reduced using Barker's method to obtain phase equilibrium data. In addition to Legendre polynomials, binary interaction parameters were also optimized for Wilson, UNIQUAC, and NRTL activity coefficient models. All binary data showed a positive deviation from the Raoult's law. In addition, azeotropic behavior was observed for the 2-methylpropene + methanol binary mixture.

Determination of Aldehydes and Ketones in Fuel Ethanol by High-Performance Liquid Chromatography with Electrochemical Detection

A new methodology was developed for analysis of aldehydes and ketones in fuel ethanol by high-performance liquid chromatography (HPLC) coupled to electrochemical detection. The electrochemical oxidation of 5-hydroxymethylfurfural, 2-furfuraldehyde, butyraldehyde, acetone and methyl ethyl ketone derivatized with 2,4-dinitrophenylhydrazine (DNPH) at glassy carbon electrode present a well defined wave at +0.94 V; +0.99 V; +1.29 V; +1.15 V and +1.18 V, respectively which are the basis for its determination on electrochemical detector. The carbonyl compounds derivatized were separated by a reverse-phase column under isocratic conditions with a mobile phase containing a binary mixture of methanol / LiClO4(aq) at a concentration of 1.0 × 10−3 mol L−1 (80:20 v/v) and a flow-rate of 1.1mL min−1 . The optimum potential for the electrochemical detection of aldehydes-DNPH and ketones-DNPH was +1.0 V vs. Ag/AgCl. The analytical curve of aldehydes-DNPH and ketones-DNPH presented linearity over the range 5.0 to 400.0 ng mL−1, with detection limits of 1.7 to 2.0 ng mL−1 and quantification limits from 5.0 to 6.2 ng mL−1, using injection volume of 20 μL. The proposed methodology was simple, low time-consuming (15 min/analysis) and presented analytical recovery higher than 95%.

Electrical conductance of alkali chlorides in mixed solvents : Methanol + carbon tetrachloride and methanol + 1,4-dioxane at 298.15 K

Conductance measurements for selected alkali metal chlorides, MCl (M + = Li, Na, K) are performed in the binary mixtures of methanol with carbon tetrachloride and 1,4-dioxane at 298.15 K. The limiting equivalent conductance (Λ 0 ), the association constant (K A ), and the Walden products (A 0 η 0 ) for the three salts are evaluated at all the mole fractions of the solvent mixtures using the 1978 Fuoss conductance-concentration equation. Analysis of data indicates presence of strong association of the electrolytes in the solvent mixtures studied here. The results have been discussed and interpreted in terms of ion-solvent interactions and structural changes in the mixed solvent systems.

Molecular-dynamics simulations of dimethylsulfoxide-methanol mixtures

We present molecular-dynamics (MD) computer simulation results for the local structures, hydrogen (H)-bond distribution, and dynamical properties of methanol (MeOH) and dimethylsulfoxide (DMSO) binary mixtures at ambient conditions over the entire composition range. The simulated heat of mixing and site-site pair distribution functions suggest that the intermolecular structures of the pure liquids are not markedly altered upon mixing. Nevertheless, H-bonding statistics show that aggregates of the type 1DMSO:1MeOH are formed and represent the predominant form of molecular association in these mixtures. Only a small fraction (10%) of DMSO molecules in MeOH-rich mixtures (85% in mole) forms H-bonding trimers of type 1DMSO:2MeOH. No evidence of other types of interspecies association is found. The self-diffusion coefficient for DMSO (MeOH) increases (decreases) upon mixing. The characteristic reorientation time tau1 of both species increases in the mixture, but the composition dependence is weak. The frequency spectrum of MeOH reorientational time-correlation function shows significant redshifts of the principal librational band as DMSO is added to the system, whereas the librational band of DMSO shows small alterations upon mixing. Our results are discussed in the light of previous simulation analyses for a similar system, DMSO-water mixtures, and compared with available experimental results.

Density, Refractive Index, Speed of Sound at 298.15 K, and Vapor−Liquid Equilibria at 101.3 kPa for Binary Mixtures of Methanol + 2-Methyl-1-butanol and Ethanol + 2-Methyl-1-butanol

Densities, refractive indices, and speeds of sound at 298.15 K and isobaric vapor−liquid equilibria (VLE) data at 101.3 kPa were reported for the binary mixtures methanol + 2-methyl-1-butanol and ethanol + 2-methyl-1-butanol. Excess molar volumes, refractive index deviations, and changes of speed of sound on mixing were calculated from the measurement results that were fitted with Redlich−Kister polynomials. VLE experimental data were tested for thermodynamic consistency by means of a modified Dechema test and were demonstrated to be consistent. The activity coefficients were correlated with the Margules, van Laar, UNIQUAC, NRTL, and Wilson equations. The ASOG model also was used for prediction.

Vapor−Liquid Equilibrium and Mixing Properties of Methanol + Diethyl Carbonate and Vinyl Acetate + Diethyl Carbonate Systems

Different mixing properties (speed of sound, density, and refractive index on mixing) of the binary mixtures methanol + diethyl carbonate and vinyl acetate + diethyl carbonate have been measured at 298.15 K and atmospheric pressure. Corresponding derived properties have been calculated by experimental data. Values of the physical properties were fitted to Redlich−Kister polynomials. The isobaric vapor−liquid equilibrium (VLE) experimental data at 101.3 kPa were satisfactorily tested for thermodynamic consistency by means of a modified Dechema test. Activity coefficients were correlated with Margulles, Van Laar, UNIQUAC, NRTL, and Wilson equations. The ASOG group contribution method was used for prediction.

Study of Kinetics of Bromophenol Blue Fading in Alcohol-Water Binary Mixtures by SESMORTAC Model

Solvent effects on the kinetics of bromophenol blue fading have been investigated within a temperature range in binary mixtures of methanol, ethanol, 1-propanol, ethylene glycol and 1,2-propanediol with water of varying solvent compositions up to 40% by weight of organic solvent component. Correlation of logk with reciprocal of the dielectric constant was linear. Finally a mechanism was proposed for the bromophenol blue fading upon SESMORTAC (study of effect of solvent mixture on the one-step reaction rates using the transition state theory and cage effect) model, by means of this model, the fundamental rate constants of the fading reaction in these solvent systems were calculated.