Excess Molar Refraction Research Articles

Densities, Refractive Indices, Speeds of Sound, and Isentropic Compressibilities of Water + Methanol + 2-Methoxy-2-methylbutane at 298.15 K

The densities, refractive indices, and speeds of sound of homogeneous mixtures of water + methanol + 2-methoxy-2-methylbutane at 298.15 K were determined and used to calculate excess molar volumes (VE), molar refractions (R), and isentropic compressibilities (kS). The VE data and the deviations of R(ΔR) and kS(ΔkS) from mole fraction and volume fraction averages, respectively, of these properties of the pure components, were satisfactorily correlated with the composition data using the Redlich−Kister polynomial.

Excess molar volumes and molar refraction of 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone+water water from 5 to 45�C

The excess molar volumes and molar refractionsR12 of 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU)+water have been determined over the entire mole fraction range at 10° intervals from 5 to 45°C and at atmosphere pressure. The excess volumes are all negative and they become more positive with increase of temperature. Limiting partial molar volumes for DMPU in water and water in DMPU are also reported.

Densities and Refractive Indices for 1-Hexene + o-Xylene, + m-Xylene, + p-Xylene, and + Ethylbenzene

Densities and refractive indices were measured at 298.15 K for binary mixtures of 1-hexene + o-xylene, + m-xylene, + p-xylene, and + ethylbenzene over the entire composition range. The results were fitted to a polynomial relation to obtain the coefficients and standard errors. Excess volumes and molar refraction deviations were derived. Also, the refractive indices were compared with the predictions of the Lorentz-Lorenz, Gladstone-Dale, and Arago-Biot equations

Hydrogen bonding. Part 40. Factors that influence the distribution of solutes between water and sodium dodecylsulfate micelles

The partition of 132 assorted compounds between water and sodium dodecyl sulfate (SDS) micelles at 298 K has been correlated through eqn. (i). The mol fraction water–SDS micelle partition coefficient is denoted as Kx, and the solute explanatory variables, or descriptors, are R2 the excess molar refraction, πH2 the dipolarity/polarizability, ∑αH2 and ∑βO2 the hydrogen-bond acidity and basicity, and Vx the McGowan characteristic volume. The number of solutes is denoted as n, the correlation coefficient as ρ, the standard deviation as sd, and the F-statistic as F. log Kx= 1.201 + 0.542 R2– 0.400 πH2– 0.133 ∑αH2– 1.580 ∑βO2+ 2.793 VX(i), n= 132, ρ= 0.9849, sd = 0.171, F= 817.

Factors that influence tadpole narcosis. An LFER analysis

Application of the new solvation equation to the results of Overton on tadpole narcosis yield the correlation given by eqn. (a), where Cnar is the narcotic concentration of solute in mol dm–3 and the log (1/Cnar)= 0.579 + 0.824R2– 0.334π2H– 2.871Σβ2o+ 3.097Vx(a) descriptors are R2 the solute excess molar refraction, π2H the solute dipolarity/polarizability, Σβ2o the solute hydrogen-bond basicity and Vx the solute volume. For 84 solutes, the correlation coefficient, ρ, is 0.9730 and the standard deviation, sd, is 0.246 log units. The above equation shows that the two main factors that influence tadpole narcosis are solute hydrogen-bond basicity that decreases toxicity and solute volume that increases toxicity. Solute hydrogen-bond acidity has no effect at all.The use of water–octanol partition coefficients as log P(oct) leads to the regression equation [eqn. (b)] log (1/Cnar)= 1.129 + 0.833log P(oct)(b) where ρ= 0.9212 and sd = 0.407 for the same 84 solutes. This equation is not improved by addition of [log P(oct)]2 as a descriptor, but it is if Vx is included [eqn. (c)]. Now ρ= 0.9400 and sd = 0.359 log (1/Cnar)= 0.621 + 0.743log P(oct)+ 0.668Vx(c) log units. When additional data are added to the Overton set, similar equations to the above are obtained for 114 varied solutes, showing that tadpole narcosis is a general phenomenon.Results on the narcosis of α,ω-diols and cycloalkanols can be interpreted using the analysis of Franks and Lieb. It is suggested that the anaesthetic binding site on the primary protein target is a large or flexible pocket, extending inward from the external water-facing surface, that is rather aqueous and of limited hydrophobicity.

Hydrogen bonding. Part 29. Characterization of 14 sorbent coatings for chemical microsensors using a new solvation equation

Gas-liquid partition coefficients, K, have been obtained for 20–70 solute analytes on 14 candidate phases for chemical microsensors at 298 K and on three of the phases at higher temperatures. The phases can then be characterized through the equation log K=c+rR2+sπ2H+aΣαH2+bΣβH2+llog L16 where log K relates to a series of solutes on the same phase. The explanatory variables are solute parameters, R2 an excess molar refraction, πH2 the solute dipolarity–polarizability, ΣαH2 and ΣβH2 the solute hydrogen bond acidity and basicity and L16 where L16 is the K-value on hexadecane. The coefficients in the above equation then characterize the particular phase, the most important being s the phase dipolarity–polarizability, a the phase basicity, b the phase acidity and I a constant that reflects a combination of cavity effects and general dispersion interactions and is related to the ability of the phase to distinguish between homologues. Derivation of the constants for the various phases provides a quantitative method for the analysis of the selectivity of phases for particular solute analytes and a termby-term investigation of log K values shows exactly the solubility interactions that lead to sorption of a solute by a phase and hence to the analytical determination of the solute through chemical microsensors.

Hydrogen bonding. 38. Effect of solute structure and mobile phase composition on reversed‐phase high‐performance liquid chromatographic capacity factors

AbstractReversed‐phase HPLC capacity factors, as log k′, have been correlated through the LFER equation: where k′ is the capacity factor for a series of solutes in a given stationary phase–mobile phase system, and the explanatory variables are the solute descriptors: R2 an excess molar refraction, π the dipolarity/polarizability, Σα the overall hydrogen‐bond acidity, Σβ the overall hydrogen‐bond basicity and Vx the McGowan volume. This equation was applied to various C18 stationary phases with methanol–water, acetonitrile–water and tetrahydrofuran–water buffered mobile phases. The solute and mobile phase factors that influence log k′ values are set out, and a comparison is made between log k′ values and water–octanol partition coefficients.

Hydrogen bonding: XXXV. Relationship between high-performance liquid chromatography capacity factors and water-octanol partition coefficients

The solvation equation log SP = c + rR 2 + sπ 2 H + aΣα 2 H + bΣβ 2 H + vV x has been applied to reversed-phase HPLC capacity factors, as log k', for solutes on a C 18 bonded phase, with various water-methanoi mobile phases, using data by Yamagami and Takao. Here. SP is a property for a series of solutes in a fixed solvent system, and the explanatory variables are solute descriptors as follows: R 2, is an excess molar refraction, π 2 H is the solute dipolarity/polarizability, Σα 2 H and Σβ 2 H are the solute overall or effective hydrogen-bond acidity and basicity, and V x, is the McGowan characteristic volume; c. r, s, a. h and v are constants. It is shown that the blend of factors that influence log k in any given system is not the same as that which influences log P oct. In particular, solute hydrogen-bond acidity considerably influences log k', but has no effect on log P oct. It follows that when log k' values are used to estimate log P oct. great care has to be taken to match the training set of solutes in the correlation equation, with the solutes for which log P oct is to be determined.

Hydrogen Bonding. 30. Solubility of Gases and Vapors in Biological Liquids and Tissues

The general solvation equation logL=c+rR2+sπ2H+aα2H+bβ2H+llogL16has been used to analyze the solubility of solute gases and vapors, as logLvalues, in water, blood, and a variety of other biological fluids and tissues. The explanatory variables areR2, the solute excess molar refraction; π2H, the solute dipolarity/polarizability; α2Hand β2Hthe solute hydrogen-bond acidity and basicity; and logL16, whereL16is the solute Ostwald solubility coefficient of hexadecane. The obtained coefficients then serve to characterize the biological phase as follows:r + sis the phase dipolarity/polarizability,ais the phase hydrogen-bond basicity,bis the phase hydrogen-bond acidity, andlis the phase lipophilicity. In addition to characterization of phases, the equation can be used to determine quantitatively solute/phase interactions and predict further logLvalues. A similar equation in which McGowan's characteristic volume,Vx, replaces the logL16descriptor can be used to analyze partitions between phases. For example, water/phase and blood/phase partition coefficients are analyzed, and the analysis leads again to coefficients that characterize phases and to the prediction of partition coefficients.

Hydrogen Bonding. 33. Factors That Influence the Distribution of Solutes between Blood and Brain

It is shown that neither the set of directly determined blood–brain concentration ratios (BB) of Young and Mitchell nor the set of indirectly obtained values of Abraham and Weathersby are suitable for the construction of a general equation for the interpretation and prediction of log BB values. However, combination of both sets leads to the general equation log BB = -0.038 + 0.198R2- 0.687πH2- 0.715αH2- 0.698βH2+ 0.995Vx(n= 57,Q= 0.9522, sd = 0.197, F = 99.2), where the solute descriptors areR2, an excess molar refraction; πH2, the dipolarity/polarizability, αH2and βH2, the effective or summation hydrogen-bond acidity and basicity; andVx, the characteristic volume of McGowan. Thus solute dipolarity/polarizability, hydrogen-bond acidity, and hydrogen-bond basicity favor blood, and solute size, asVx, favors brain. Methods are given for the estimation of solute descriptors through fragment schemes, so that log BB values themselves may be obtained simply from knowledge of solute molecular structure.

Hydrogen Bonding. 32. An Analysis of Water-Octanol and Water-Alkane Partitioning and the Δlog P Parameter of Seiler

A general linear solvation energy equation has been used to analyze published partition coefficients in the systems water-octanol (613 solutes), water-hexadecane (370 solutes), water-alkane (200 solutes), and water-cyclohexane (170 solutes). The descriptors used in the equation areR2, an excess molar refraction; π2H, the solute dipolarity/polarizability; ∑α2Hand ∑β2H, the effective solute hydrogen-bond acidity and basicity; and VX, the characteristic volume of McGowan. It is shown that the water-octanol partition coefficient is dominated by solute hydrogen-bond basicity, which favors water, and by solute size, which favors octanol, but solute excess molar refraction and dipolarity/polarizability are also significant. For the water-alkane partition coefficients, the same factors are at work, together with solute hydrogen-bond acidity as a major influence that favors water. An analysis of 288 ΔlogPvalues shows that solute hydrogen-bond acidity is the major factor but that solute hydrogen-bond basicity and, to a lesser extent, solute dipolarity/polarizability and size are also significant factors that influence the ΔlogPparameter.

Dielectric and Index of Refraction Properties of Binary Mixtures of Polyoxyethene Glycol Monobutyl Ethers with Water

Abstract Dielectric constants and indices of refraction of aqueous mixtures of the homologous series of polyoxy-ethene glycol mono-n-butyl ethers C4H9O(CH2CH2O) m H (where m = 1 to 3) were measured. From the experimental data, excess dielectric permittivities, dielectric molar susceptibilities, molar and molar orientational polarizabilities were evaluated. Also excess Lorentz-Lorentz molar refractions were evaluated and the results were discussed in terms of departure from ideality and intermolecular interactions in the mixtures.

On the prediction of polymer-probe χ and Ω values from inverse gas-chromatographic data

The solvation equation Log V G=c+rR 2+s π 2 H +a α 2 H +b β 2 H +1 logL 16 has been applied to the solubility of 24 probes on poly(butadiene) at 353, 363 and 373 K using V G values obtained by Romdhane and Danner by inverse gas-chromatography. In the above equation the explanatory variables are solute probe parameters as follows: R 2 is an excess molar refraction, π 2 H is the probe dipolarity/polarizability, α 2 H and β 2 H are the probe hydrogen-bond acidity and basicity, and L 16 is the probe gas-liquid partition coefficient on hexadecane at 298 K. It is shown that log V G can be predicted to ± 0.04 log units, using this equation, and that from the predicted log V G values, the weight fraction activity coefficient, Ω ∞ , can be predicted to around ± 0.04 log units, and the Flory-Huggins polymer-probe χ coefficient to within ± 0.10 units. The same general equation has also been applied to literature data on the solubility of 50 probes on poly(trifluoropropyl)methyl siloxane at 298 K, with similar results.

Hydrogen bonding. Part 34. The factors that influence the solubility of gases and vapours in water at 298 K, and a new method for its determination

The solubility of 408 gaseous compounds in water at 298 K has been correlated through eqn. (i), where the solubility is expressed as the Ostwald solubility coefficient, Lw, and the solute explanatory variables are R2 an excess molar refraction, π2H the dipolarity/polarizability, Σα2H and Σβ2H the effective hydrogen-bond acidity and basicity, and Vx the McGowan characteristic volume. A similar equation using the log L16 parameter instead of Vx can also be used; L16 is the Ostwald solubility coefficient on hexadecane at 298 K. log Lw=–0.994 + 0.577R2+ 2.549 π2H+ 3.813Σα2H+ 4.841Σβ2H– 0.869 Vx(i), n= 408 ρ= 0.9976 sd = 0.151 F= 16810 The main factors leading to increased solubility are solute π2H, Σα2H and Σβ2H values; conversely, the corresponding properties of water are dipolarity/polarizability, hydrogen-bond basicity and hydrogen-bond acidity. Solute size plays a minor role, and slightly decreases solubility, contrary to observations on all non-aqueous solvents. It is shown that this peculiar behaviour of water is due to (a) a greater increase in the unfavourable cavity effect with increase in solute size, for solvent water, and (b) a smaller increase in the favourable general dispersion interaction with size, for solvent water.A new method for the determination of log Lw values is put forward, using the relationship Lw=L16/P where L16 is as above, and P is either the water–hexadecane partition coefficient or the water–alkane partition coefficient. For 14 solutes using the former P-value, agreement with values calculated through eqn. (i) is 0.08 log units on average and for 45 solutes using the latter P-value, the corresponding agreement is 0.15 log units, with log Lw values ranging up to 8 log units.

Hydrogen bonding. 31. Construction of a scale of solute effective or summation hydrogen‐bond basicity

AbstractThe β scale of solute hydrogen‐bond basicity, formulated from 1:1 hydrogen‐bond complexation constants in tetrachloromethane, has been used to set up a scale of effective or summation hydrogen‐bond basicity, appropriate for the situation in which a solute is surrounded by solvent molecules. The method is based on the equation, where SP is, in this work, a set of solute water–solvent partition coefficients in a given system. The explanatory variables are solute parameters as follows: R2 is an excess molar refraction, π is the solute dipolarity/polarizability, Σα and Σβ2 are the effective solute hydrogen‐bond acidity and basicity and Vx is McGowan's characteristic volume. Various equations are established using β in the equation, and then amended β values are back‐calculated and new Σβ values obtained. It is found that for most solutes, the effective basicity Σβ is invariant over the systems used to within an experimental error of around 0·03 units. About 350 Σβ values obtained from two or more experimental log P values are listed, together with values for homologous series and a number of singly determined values. For some specific solutes, such as sulphoxides, alkylanilines and alkylpyridines, Σβ2 is not constant, and an additional solute basicity denoted as Σβ is needed in order to deal with partitions from water to solvents that are partially miscible with water, such as isobutanol and octanol. Values of Σβ, and where possible Σβ also, are listed for 80 additional solutes.

Excess volumes and refractions and liquid-liquid equilibria of the ternary system water + ethanol + hexyl acetate

Arce, A., Blanco, A., Soto, A., Souza, P. and Vidal, I., 1993. Excess volumes and refractions and liquid-liquid equilibria of the ternary system water + ethanol + hexyl acetate. Fluid Phase Equilibria, 87: 347-364. Densities, refractive indices, excess molar volumes and excess molar refractions at 25°C, and liquid-liquid equilibrium (LLE) data at 25, 35 and 45°C, are reported for the system water + ethanol + hexyl acetate. NRTL and UNIQUAC equations have been fitted to the experimental data, and the sensitivity of the correlation to changes in the composition of the phases in equilibrium has been analysed. The validity of the parameters obtained from the ternary system data for representation of the binary systems was also assessed.

Hydrogen bonding: XXVII. Solvation parameters for functionally substituted aromatic compounds and heterocyclic compounds, from gas—liquid chromatographic data

The truncated solvation equation log SP = c + rR 2 + l log L 16 has been applied to a very large number of sets of gas—liquid chromatographic data on non-polar stationary phases. Here, log SP can be log V G or can be the retention index I. R 2 is the excess molar refraction of the solute and c, r and l are constants. A set of solutes of known log L 16 values is used to construct the equation, and then further values of log L 16 can be obtained for any solute of known log SP value. In this way, new log L 16 values for over 1000 solutes have been obtained. Then knowing log L 16, and R 2, the equation log SP = c + rR 2 + sπ 2 H + l log L 16 ( s is a constant) can be applied to GLC data on polar non-acidic stationary phases, and the dipolarity/polarisability parameter, π 2 H determined similarly. Values of π 2 H for over 700 compounds are reported, including those for functionally substituted aromatic compounds and heterocyclic compounds. It is shown that π 2 H, is a blend of dipolarity/polarisability, and cannot simply be calculated from solute dipole moments.

Densities, viscosities, refractive indices, and speeds of sound for methyl acetoacetate + aliphatic alcohols (C1-C8)

Densities, viscosities, refractive indices, and speeds of sound have been measured at 298.15, 303.15, and 308.15 K for the binary mixtures of methyl acetoacetate with methyl alcohol, ethyl alcohol, 1-propanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 1-pentanol, 1-heptanol, 1-heptanol, and 2-octanol. From these results, excess molar volumes, excess molar refractions, viscosity deviations, and isentropic compressibility deviations have been calculated. These results are further Pitted to the polynomial relation to estimate the coefficients and standard errors

Thermodynamic behaviour of mixtures. Part 2.—Mixtures of acetonitrile with β-picoline, γ-picoline, 2,6-lutidine, isoquinoline and benzene at 25 °C

Ultrasonic velocities (u), densities (ρ), static relative permittivities (Iµ) and refractive indices (nD) of mixtures of acetonitrile (AN) with β-picoline, γ-picoline, 2,6-lutidine, isoquinoline and benzene have been measured over the entire composition range at 25 °C. Intermolecular interaction parameters, such as the molar sound velocity (um) and the solvation number of the co-solvent (Nc) have been calculated for all the binary mixtures. The partial molar volumes (text-decoration:overlineV0) and the partial isentropic compressibilities (text-decoration:overlineκ0S) at infinite dilution have been calculated for all the co-solvents as well as for AN. Excess properties, such as the excess isentropic compressibility (κES), volume (VE), relative permittivity (ΔIµ), molar polarisation (PE) and molar refraction (RE) have also been computed for these binary mixtures. Weak specific interactions are present between the components of AN–β-picoline and AN–γ-picoline in comparison to all other AN–base mixtures.

Hydrogen bonding. Part 25. The solvation properties of methylene iodide

Ostwald solubility coefficients, L, have been determined for 37 gases and vapours in methylene iodide at 298 K, and have been correlated through equation (i), where the solute explanatory log L=–0.74 + 0.32R2+ 1.34π2H+ 0.83α2H+ 1.19β2H+ 0.87 log L16(i) variables are R2 an excess molar refraction, π2H the solute dipolarity/polarisability, α2H and β2H the solute hydrogen-bond acidity and basicity, and log L16 where L16 is the solute Ostwald solubility coefficient on hexadecane at 298 K. Similar equations have been constructed for solvation of solutes in tetrachloromethane, trichloromethane and 1,2-dichloroethane using literature data. It is shown that polarisability effects favour solvation in methylene iodide, through the R2 term, but that such effects enhance the solubility of polarisable solutes only moderately: thus the R2 term contributes 0.4 log units more in methylene iodide than in trichloromethane for the solute benzene. Examination of ΔG°, ΔH° and ΔS° for solvation of gaseous solutes suggests also that polarisability effects in methylene iodide are not very much larger than in the other halogenated solvents.