Mole Fraction Of Alcohol Research Articles

Kinetic Study of Corrosion of Copper in Phosphoric Acid Tert-Butanol Electropolishing Mixtures

The rate of copper dissolution in presence of phosphoric acid tert-butanol electropolishing mixtures was studied by measuring the limiting current which represents the rate of electropolishing. The rate of dissolution decreases by increasing phosphoric acid concentration, electrode height and the mole fraction of alcohol. The data show that addition of tert-butanol to phosphoric acid decreases the rate of dissolution of copper by an amount ranging from 68 % to 90 % depending on the dielectric constant of mixtures. Thermodynamic parameters are given.

NMR and Excess Volumes Studies in DMF–Alcohol Mixtures

Chemical shifts of the alcohol and DMF protons in DMF–alcohol mixtures with the mole fraction of alcohol are reported in order to study the hydrogen bond interaction present in the mixtures. The densities of DMF–methanol mixture at 22°C are also measured. Excess volumes and excess chemical shifts are correlated by the Redlich–Kister equation. The relation between excess volumes and excess chemical shifts in the mixtures is discussed. It is found that the maximum excess chemical shifts δE(CHO-OH) and δE(CH3-OH) are positioned at about mole fraction methanol = 0.57 for the DMF–methanol system, as is VE. The results show that the NMR spectral method offers a valuable approach to similar future studies of interactions in mixtures.

Enthalpies of mixing, heat capacities, and viscosities of alcohol (C 1–C 4) + olive oil mixtures at 298.15 K

Enthalpies of mixing, heat capacities, and viscosities of the binary systems involving alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol) + olive oil were measured at 298.15 K. The enthalpy was measured in the range of concentrations in which alcohols were miscible with the oils. The highest measured enthalpies of mixing per mole of mixture were (3450 J/mol) for 2-butanol-olive oil at an alcohol mole fraction of 0.55. Enthalpy of mixing of 2-propanol with sunflower and soybean oil and viscosities of the same mixtures were investigated at 298.15 K. Very similar results were found for the different oils. The mixing of alcohols with oils was strongly endothermic. Viscosities of the same mixtures were measured with a rotational viscometer.

Low-frequency Raman Spectroscopy of Aqueous Solutions of Aliphatic Alcohols

Abstract Low-frequency Raman spectra have been measured at room temperature as functions of the alcohol mole fraction in aqueous solutions of methanol, ethanol, 1-propanol, 2 -propanol, and /er/-butylalcohol (TBA). Intrinsic Raman spectra R (ῡ) were obtained from depolarized Rayleigh wing spectra. Isosbestic points have been observed in R (ῡ) of the aqueous solutions of ethanol, 1-propanol, and 2 -propanol, suggesting that the structure o f the solutions is characterized by individual alcohol aggregates and water clusters without a significant amount of alcohol-water mixed aggregates. The R (ῡ) spectra have been expressed as R (ῡ ,x ) = w R (ῡ ,0 ) + aR(D, 1), where R(ῡ, 0) and R(ῡ, 1) are those for pure water and pure alcohols, respectively, and x is the mole fraction of alcohols. The coefficients w and a show the inflection points at characteristic alcohol mole fractions, where microhetrogeneity and structural transition of the solvent clusters take place, as previously shown by X-ray diffraction. In the aqueous solutions of methanol, where no microhetrogeneity takes place, no clear isosbestic point in R(ῡ) has been observed. For aqueous solutions of TBA, an isosbestic point in R(ῡ) has appeared when xTBA > 0.05. Two inflections points in the coefficients have been observed at xTBA « 0.1 and 0.35; the former composition corresponds to the transition composition from the TBA-TBA intermolecular contact to the TBA water molecular association, as previously reported by neutron diffraction.

Vapor−Liquid Equilibria of Methanol, Ethanol, Propan-2-ol, and 2-Methylpropan-2-ol with a Five-Component Hydrocarbon Mixture at 101.3 kPa

Isobaric vapor−liquid equilibria (VLE) were measured at 101.3 kPa for the systems of methanol, ethanol, propan-2-ol, and 2-methylpropan-2-ol separately with a five-component hydrocarbon mixture. The relative volatilities of alcohol with respect to the hydrocarbon mixture were also derived. Analysis of the experimental VLE data exhibits a minimum boiling temperature for all the systems. The experimental data have been correlated with the mole fraction of alcohol using the Redlich−Kister and Wisniak−Tamir equations.

Pulse Radiolysis Studies of Solvated Electrons in Supercritical Ethane with Methanol as Cosolvent

Pulse radiolysis has been used to study the solvated electron in supercritical ethane with methanol as a cosolvent. These measurements give information about the liquid structure of the cosolvent in these systems. The results show that at temperatures below 110 °C, there are high local concentrations of alcohol molecules (clusters), which are capable of solvating an electron. The agglomeration number of methanol clusters depends on mole fraction of alcohol at a fixed temperature. Addition of salts increases the size of methanol clusters.

Molecular–Dynamic Simulation of Mixed Water–Methanol Clusters: 3. Local Energy and the Work of Formation

Dependences of the total and partial energies in mixed water–methanol clusters on the size of the cluster and its overall composition were considered. Changes in the total and partial local energies in a spherical cluster with an increase of the alcohol molar fraction in the system were investigated. Profiles of the normal component of the pressure tensor were calculated for all systems under investigation, and the work of the formation of mixed cluster from the vapor phase was estimated.

Study of the effect of ethylene glycol and glycerol on the rate of electropolishing of copper by the rotating disk technique

The rate of copper dissolution in the presence of phosphoric acid‐alcohol mixtures was studied by measuring the limiting current density which represents that the rate of electropolishing is decreased by increasing phosphoric acid concentration, electrode height, and mole fraction of alcohol. Thermodynamic parameters are calculated. The rotating disk electrode is being used as a tool to study the influence of organic solvent addition on the rate of electropolishing of copper. Different reaction conditions such as temperature, speed of rotation of copper disk, the physical properties of solution are studied to obtain a dimensionless correlation between all these parameters. The data can be correlated by the following equations: Sh = 1.835 (Sc)0.33 (Re)0.36 (for ethylene glycol) Sh = 1.25 (Sc)0.33 (Re)0.5 (for glycerol) It is obvious that the exponent in the two cases denotes a laminar flow mechanism.

Micellization of ionic surfactants in aqueous-rich region of organic solvants: A conductometric study of micellization behaviour of sodium dodecylsulfate in aqueous-rich region of 1-BuOH, 2-BuOH, t-BuOH at different temperatures

The critical micelle concentration (cmc) of sodium dodecyl sulfate (SDS) is determined in aqueous-rich region of 1-butanol (1-BuOH), 2-butanol (2-BuOH) and tertiary-butanol (t-BuOH) at 25, 35 and 45°C from conductance measurements. In the range of alcohol mole fraction, x 2, 0< x 2<0.008 the cmc decreased by a function of x 2 in the order: 1-BuOH>2-BuOH>t-BuOH. Though not very significant, a relatively weak effect of temperature was observed in increasing the cmc in this narrow composition range. As the concentration of these additives was increased, cmcs levered off and the effect of temperature tends to be insignificant. Thermodynamic parameters of micellization, enthalpy (Δ H m 0), entropy (Δ S m 0) and free energy (Δ G m 0) were determined from temperature dependence of cmc. The solvent composition dependence of these thermodynamic parameters is determined in terms of the effect of additives on micellizaffon of SDS. It is observed that both Δ H m 0 and Δ S m 0 bear out not only the observed order of decrease in cmc, but also account reasonably the effects produced by differences in alkyl chain configuration for these isomeric alcohols. In all cases Δ G m 0<0, and remained practically constant over the entire solvent composition range studied. It is suggested that due to different structural consequences of intermolecular interactions both enthalpy and entropy must differ in a mutually compensating manner so that Δ G m 0 is not significantly affected.

Kinetic studies of specific solvent effect on the thermal isomerization of palladium dithizonate in toluene-alcohol mixtures

The kinetics of the thermal isomerization of palladium dithizonate (Pd(HDZ)2) in the binary mixture of toluene and alcohols has been studied. In the solvent effects on the Pd(HDZ)2 isomerization rates, we found that the maximum lies in the range x = 0.02 ∼ 0.2 (x represents the mole fraction of alcohols). The experimental kinetic data for the specific solvent effect with maximum can be reproduced well by taking into account hydrogen bonding and coordination of alcohols with Pd(HDZ)2. The rate constants for the thermal isomerization of Pd(HDZ)2 involving hydrogen bonding and the coordinate interaction with 1-butanol are evaluated. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 542–547, 2000

Viscosity of Aqueous Solutions of Some Alcohols

Viscosities of aqueous solutions of 1-Propanol, 2-Propanol, t-Butanol, allyl alcohol and propargyl alcohol were measured at temperatures 30°, 35°, 40°, 45° and 50°C covering the whole range of composition. On addition of alcohols to water, viscosity increases rapidly. Except for propargyl alcohol, viscosities pass through maxima and then decline continuously as the addition of alcohol is continued. the heights of the maxima occuring between 0.2 and 0.3 mole fraction of alcohols are in the order, t-Butanol > 2-Propanol > 1-Propanol > allyl alcohol. Contrary to this, propargyl alcohol shows no such maximum. After the fast initial rise, the viscosity rises slowly and monotonically up to its pure state for this alcohol. the excess viscosities are found to be positive and large in magnitude. for all alcohols, excess viscosities show maxima in water-rich region. Shallow minima are observed for 2-Propanol and t-Butanol, each at the alcohol-rich end of viscosity curves, which disappear gradually with the rise of temperature. the viscosity and excess viscosity vs. composition curves of all the systems were interpreted mainly in terms of hydrophobic hydration and hydrophilic interaction.

Structural effects of the solvent composition in colloidal liquids

This paper is concerned with the microstructure observed in colloidal dispersions of charged polymeric particles and their interaction potential at very low ionic strength. Both aspects are probed with the aid of new experimental data for nonaqueous media. The structure factor of ordered dispersions (with methanol–water and ethanol–water solvent mixtures) was determined using static light scattering. A different behavior (in the studied range of molar fraction) depending on the alcohol type is found. These results are analyzed assuming a Yukawa potential and applying integral equation theories (the Ornstein–Zernike equation and the HNC closure). The obtained effective charge is almost constant for methanol–water mixtures, whereas a decrease with the alcohol molar fraction is observed for ethanol–water. In order to account for these effects, a charge renormalization procedure is applied and discussed. The surface charge turns out to be an unsuitable input parameter for such an approach.

Self-association and complex formation in alcohol-unsaturated hydrocarbon systems Heat capacities of linear alcohols mixed with alkenes and alkynes

Apparent molar heat capacities, Cmapp, at dilute alcohol concentrations and excess molar heat capacities, CpE throughout the concentration range were determined at 25°C for the following systems: methanol, ethanol, propan-1-ol, hexan-1-ol and decan-1-ol mixed with n-octane, oct-1-ene and oct-1-yne; in addition, the following mixtures were also measured: hexan-1-ol with oct-4-yne, cyclohexane, cyclohexene, benzene, hex-1-ene, dec-1-ene and an equimolar mixture of n-octane+oct-1-yne. The experimental Cmapp show a maximum against alcohol concentration; this maximum is reduced in magnitude and displaced to higher alcohol concentrations when the inert n-octane is substituted by the unsaturated oct-1-ene, oct-1-yne, oct-4-yne, cyclohexene or benzene which act as weak proton acceptors, forming complexes or cross-associated species with the alcohol molecules. The present data clearly indicate that there are alcohol–alkene complexes in solution, which are weaker than the alcohol–alkyne ones, but detectable through heat capacity measurements. The Cmapp data for alkan-1-ols when plotted against ψ1, the concentration of hydroxyl groups in the mixture, follow a single corresponding states curve for each of the solvents. For all alkan-1-ols, CpE display the following behaviour: CpE (oct-1-yne) CpE (oct-1-ene)>CpE (n-octane) at higher alcohol concentrations, the cross-over point being between 0.1 and 0.2 alcohol mole fraction. To interpret the data, the Treszcanowicz–Kehiaian (TK) model for associated liquids has been used. The parameters of the model, i.e. volumetric equilibrium constants and enthalpies of formation for alcohol–unsaturated hydrocarbon 1:1 complexes have been fitted to the dilute alcohol data. With these parameters, the TK model is able to give correct qualitative predictions of the CpE results throughout the concentration range. Using the Flory lattice model, the volumetric equilibrium constants were transformed into a unique or intrinsic equilibrium constant, which is independent of molecular size and describes the alcohol–alkene and alcohol–alkyne association. A detailed analysis of the data for hexan-1-ol+oct-1-yne and hexan-1-ol+oct-4-yne indicates that the dominating interaction in the formation of the alcohol–unsaturated hydrocarbon complex is that occurring between the proton of the hydroxy group of the alcohol and the negative electron density in the double or triple bond, producing what can be termed a H-bond. Using the parameters obtained when analyzing excess volumes VE and excess enthalpies HE for similar and common systems (T. M. Letcher etal., FluidPhaseEquilib., 1995, 112, 131), the ERAS model was used to predict CpE, finding that it is unable to give a satisfactory rendering of the present heat capacity data.

Diffusion and Structure in Dilute Aqueous Alcohol Solutions: Evidence for the Effects of Large Apolar Solutes on Water

By measuring the dependence of molecular motion on pressure, p, using diffusion measurements as a probe, one can obtain information regarding the structure of solutions containing amphiphilic solutes having apolar or hydrophobic groups. We have found that at low temperatures, the intra-diffusion coefficient (D) of water in a dilute solution of aqueous tert-butyl alcohol (mole fraction, x = 0.025) shows a maximum with increasing p, to a greater relative extent than in pure water under the same conditions. This suggests the water in these solutions is more “structured” than in pure water, though there is a clear distinction from the effects produced by large “structure breaking” ions as solutes where the absolute water diffusion coefficient may show a maximum as concentration or pressure is increased. We have made a survey of a number of other water−alcohol systems; a similar large enhancement occurs in 2-propanol solutions. In solutions of methanol, ethanol, and 2,2,2-trifluoroethanol, the enhancement is similar to that of water with no additional effect. Volumes of activation (ΔVD) have been calculated from the diffusion data. From an analysis of the T and p dependence of D and ΔVD, we have concluded that the mechanism for the diffusion of water in these solutions seems likely to be the same as for pure water. The molecules can move around the obstacle solute molecules via the labile hydrogen-bonded network. Where the temperature is low and the solute alcohol molecules are large, the network appears to be distorted such that the effect of pressure on water diffusion is greater with the maximum appearing at higher pressures than in pure water.

Alcohol Chain Length and Mole Fraction Dependence of the Stability of Tetrakis(cumylphenoxy)phthalocyanine and Alcohol Langmuir Films

While it has been known for about 10 years that octadecanol stabilizes Langmuir−Blodgett films of copper tetrakis(cumylphenoxy)phthalocyanine films, the mechanism for this stabilization is not fully understood. To understand more completely the molecular interactions responsible for making octadecanol a good transfer promoter, we studied mixed films' isotherms of tetrakis(cumylphenoxy)phthalocyanine and various saturated alcohols ranging in length from 13 to 24 carbons. By varying mole fraction and alcohol chain length in the various mixed films, a model of interaction was deduced based on pressure-versus-area isotherms obtained from a Langmuir trough. In this model, the aliphatic chains of the alcohols act as a stabilizing, hydrophobic support around phthalocyanine mounds of a preferred stack height. As film pressure increases, the mounds are forced above the alcohol sea, removing favorable ether−water interactions. Depending on chain length, a single or double collapse is observed, suggesting an adjustable physical barrier to forcing the stacks above the alcohols.

Viscosity and Density of Dilute Aqueous Solutions of 1-Pentanol and 2-Methyl-2-butanol

Density and viscosity of dilute aqueous solutions of 1-pentanol and 2-methyl-2-butanol, for the mole fraction of alcohol ranging from 0 to 0.0036 and temperatures ranging from 10 °C to 50 °C, have been measured. The viscosity data were correlated by the Grunberg−Nissan equation and the Heric equation.

Solvation of amide group by water and alcohols investigated using the Kirkwood–Buff theory of solutions

The Kirkwood–Buff theory of solutions has been used to investigate the preferential solvation of N-methylformamide by water and alcohol. Binary mixtures (N-methylformamide–A), where A = water, methanol or ethanol and ternary mixtures (N-methylformamide–alcohol–water), were studied at 313.15 K. The results are compared with those obtained previously for analogous mixtures containing N,N-dimethylformamide at the same temperature. It was found that the differences between the local mole fractions of water or alcohol in the immediate vicinity of the amide molecule and the bulk ones can be mainly explained by the differences in molecular sizes, the deviations are only a few per cent. From the calculation of the entropy change resulting from the orientation effects it follows that for amide–alcohol mixtures, for the investigated amides, this entropy change is positive, increasing systematically in the order: methanol<ethanol<propanol. For the N,N-dimethylformamide–water mixture the orientational entropy is strongly negative, and for N-methylformamide–water this value is expected also to be strongly negative. For ternary mixtures containing amide, alcohol and water, preferential hydration is weak and it is observed in the alcohol-rich region only. Both the amides are solvated in the mixture in a very similar manner, which means that replacing a methyl group by hydrogen and exposing the lone electron pair on the nitrogen atom to interactions with water or alcohol molecules shows insignificant influence on the local mole fractions of the components around the amide molecule and on the solvation process.

Viscosity of Alcohol–Ethene Mixtures at Pressures up to 195 MPa

Viscosities of several alcohol–ethene and vinyl acetate–ethene mixtures were measured with a rolling-ball viscometer. The viscosity measurements were performed at temperatures from 298 to 413 K and pressures up to 195 MPa with an estimated uncertainty of ±2%. The appearance of hydrogen bonds forming alcohol associates has a notable effect on the viscosity of alcohol–ethene mixtures above an alcohol mole fraction of about 0.2. This could be noticed from the deviation of the viscosity from the Arrhenius law, which occurs when alcohol associates are formed. An effect of pressure on the association of alcohol molecules through hydrogen bonding was not observable from the viscosity data. A new method for the description of the temperature- and pressure-dependent parameters in the McAllister and Dizechi models is proposed.

Dielectric properties of some ternary mixtures of normal alcohols and aliphatic diols with heptane

The static permittivity has been investigated for the ternary mixtures of 1,6-hexanediol/n-dodecanol/heptane, 1,2-ethanediol/n-dodecanol/heptane, and 1,6-hexanediol/n-hexanol/heptane. In addition, the static properties of pure n-hexanol and binary solutions of n-hexanol, cyclohexanol and n-heptanol in n-heptane have been studied together with the binary mixture hexanediol/hexanol. The results are discussed. Broadband dielectric relaxation spectra (at 20 to 40 °C) are reported for the three ternary systems. The concentration of the polar substances ranges from alcohol mole fraction x = 0.1 to 1. The dependence of relaxation parameters on concentration and temperature of the ternary mixtures is discussed.

Dielectric Properties of Solutions of a Binary Mixture Resorcinol/n-Dodecanol in Heptane

The static and broadband dynamic dielectric properties of the title mixtures, which contain the diol to an only minor fraction, are reported for the whole concentration range (al-cohol mole fraction 0.1 to 1). As with similar systems, the diol leads to increased association effects.