Total Solubility Parameter Research Articles

Micellar properties of non-ionic surfactants in relation to their solubility parameters

The solubility parameters of various polyoxyethylated non-ionic surfactants were calculated according to 3 different methods: by Fedors approach; from molar attraction constants; by including a hydrogen-bonding component to account for hydration. The computed solubility parameters for the surfactants were then correlated with their critical micelle concentrations (CMC). The relationships included 3 homologous surfactant series based on polyoxyethylated ethers, octyl- and nonyl-phenols, and fatty acid esters of sorbitan. The total solubility parameters, δ 0, corrected for hydrogen bonding increased linearly with increasing the CMC. The resulting linear relationships permit the prediction of the CMC of any surfactant within a homologous series from any of its calculated solubility parameters. Branching of decaoxyethylated octylphenol to give t-octylphenol decreased the CMC by a factor of 1.3, and increased δ 0 by 0.31 (cal/ml) 1 2 . The presence of double bond in TWEEN 80 decreased the CMC by a factor of 2, and increased δ 0 by only 0.03 (cal/ml) 1 2 . A greater double bond effect on solubility parameter of ~1.0 (cal/ml) 1 2 was noticed in the case of long-chain polyoxyethylated ethers than in TWEENs. The double bond contribution to CMC and to the total solubility parameter is not additive for the different homologous series and varies with the surfactant structure. The solubility parameter concept was also applied to analyse some solubilization data.

Solvent/nonsolvent solubility and polarity parameters in fractional separation of oligomers 2. Styrene‐acrylic acid copolymers

AbstractStyrene‐acrylic acid (St‐AA) low molecular weight copolymers (M̄w < 15,000) synthesized at high temperatures (230 – 300°C) in a continuous stirred tank reactor were fractionally precipitated in solvent/nonsolvent systems. Fractional precipitation experiments were done in the system methanol‐dichloromethane/hexane to remove residual monomers and the lowest molecular weight oligomers (1st step). Solubility limits of St‐AA copolymers as a function of copolymer composition were determined using the same solvent/nonsolvent system in the 2nd step of precipitation tests (cloud point base). GPC on Styragel‐type columns, low‐angle laser light scattering (LALLS), and volumetric titration of carboxylic groups were applied for copolymer characterization. Two solvent‐derived parameters the total solubility parameter δT and the polarity index P′ are used to determine the solubility diagrams of St‐AA low molecular weight copolymers.

Determination of Partial and Total Cohesion Parameters of Caffeine, Theophylline, and Methyl p-Hydroxybenzoate by Gas–Solid Chromatography

For the first time, the total and partial solubility parameters, δt, δd, and δs, of caffeine, theophylline, and methyl p-hydroxybenzoate were obtained by gas-solid chromatography (from the adsorption internal energy), by using the Keller, Karger, and Snyder equation. In comparison with the solubilization techniques, this method has the advantage of giving single solubility parameter values. The experimental work has been reduced to a minimum by the optimization of the matrix of experiments, according to the D-criterion, without any diminution in the quality of the results.

Solvent/nonsolvent solubility and polarity parameters in fractional separation of oligomers. 1. Epoxy resins

AbstractEpoxy resins from epichlorohydrin and bisphenol A have been fractionated in various binary solvent/nonsolvent systems. Low molecular weight (M ⋍ 400) and higher molecular weight (M ⋍ 1000) resins were fractionated using solvent/nonsolvent pairs in a wide range of polarities. Two solvent‐derived parameters: total solubility parameter δT and polarity index P′ have been applied to correlated experimental data. An empirical solubility diagram in coordinates P′ = f(δT) prepared on the basis of phase separation experiments, makes it possible to predict whether other solvent/nonsolvent pairs will work as efficient systems for epoxy resin fractionation. Two areas of solvent/nonsolvent parameters have been found for efficient epoxy resin fractionation: the first δT ⋍ 15.4–19.0 MPa1/2; P′ ⋍ 0.4−2.8 and the second of δT ∼ 19.5, P′ ∼ 6.0. In addition, the fractional precipitation of epoxy resins permits an evaluation of δT and P′ range of the resin for specific fractionation mixtures.

Retention behavior of suwannee river fulvic acid components in RP-HPLC

Chromatographic data of RP - HPLC hasbeen used to provide additional information on the properties of the reference Suwannee River fulvic acid components. The polarities of the fulvic acid components were found to range from 5.86 to 10.15, and the total solubility parameters to range from 14.12 to 20.92. The estimated hydrocarbonaceous surface areas of the polar moieties range from 30 to 120Å 2. The hydrophobic neutral constituents represent ∼ 30% of the total fulvic acid peaks and can be resolved into five components with k' ranging from 0.5 to 2.0. Their uv and fluorescence chromatograms show what appears to be a regular retention pattern of a homologous series. The uv-visible scans of three of these peaks provide further evidence to this interpretation.

Prediction of retention of hydroxyl aromatics in normal-phase liquid chromatography with slope-intercept relationships

Total solubility parameters for normal-phase n-heptane-2-propanol compositions were used to empirically predict the retention of unknown hydroxyl aromatic compounds at different mobile phase compositions on μBondapak NH 2, CN and μPorasil columns. A single experimental k′ value was needed to predict k′ values at other mobile phase compositions for an unknown compound. The method of predicting retention was based on two linear relationships derived from the experimental data. A linear relationship was obtained from plots of log k′ vs. log total solubility parameter of the mobile phase for standard hydroxyl aromatic compounds. Next, a linear relationship was obtained by plotting the slope as a function of the intercept from the slope and intercept values derived from the log k′ plots. Combined, the two linear relationships permitted the prediction of retention at different mobile phase compositions for compounds structurally similar to the original data set.

Influence of Preadsorbed Water on Chromatographic Detention of Organic Volatiles by Cellulosic Substrates

A modified gas chromatographic system was used to measure the effects of pread sorbed water on the adsorption and desorption of various organic volatiles by cellulosic substrates. To minimize diffusion effects, short columns and fast carrier gas flow rates were used. The data yielded sticking coefficients, residence times, equilibrium constants (adsorption isotherms), and surface concentrations for a group of adsorbates including a homologous series of alcohols. In general, sticking coefficients increased, and residence time, equilibrium constants, and surface concentrations decreased as the concentration of water vapor increased. Sticking coefficients correlated with the total solubility pa rameters of the adsorbates.

Expanded Solubility Parameter Approach II: P-Hydroxybenzoic Acid and Methyl P-Hydroxybenzoate in Individual Solvents

The recently introduced four-parameter extended Hansen approach was used to study the solubility of p-hydroxybenzoic acid and methyl p-hydroxybenzoate in 32 and 35 individual solvents, respectively. The results are compared with those for benzoic acid in 40 solvents. Seventeen of the thirty-two or 53% of the calculated solubilities of p-hydroxybenzoic acid were within the established solubility criterion (i.e., <30% error from the experimental value). Twenty-two of thirty-six or 61% of the calculated solubility values for methyl p-hydroxybenzoate met the solubility criterion. Experimental excess free energies of solution for p-hydroxybenzoic acid and methyl p-hydroxybenzoate were plotted against theoretical values using the expanded four-parameter solubility regression equations. From such results, adjustments may be made in the partial solubility parameters to bring the calculated solubilities in line with experimental results. Multiple regression analyses were used to estimate the total solubility parameter and the four partial solubility parameters of the two benzoic acid derivatives. Satisfactory results were obtained for methyl p-hydroxybenzoate, but poor agreement was found for p-hydroxybenzoic acid for the total parameter when compared with the Fedors group contribution method. Both the multiple regression and group contribution methods may yield inaccurate solubility parameters for relatively polar solid solutes. Factor analysis was used to test the adequacy of three- and four-parameter approaches in the evaluation of drug solubility. A principal factor method without iteration and orthogonal factor rotation were used to compare the two expanded solubility parameter approaches. Factor analysis showed that four solubility parameters were significantly more independent and presumably more satisfactory than three parameters.

Extended Hansen Approach: Calculating Partial Solubility Parameters of Solid Solutes

A multiple linear regression method, known as the extended Hansen solubility approach, was used to estimate the partial solubility parameters, δd, δp, and δh for crystalline solutes. The method is useful, since organic compounds may decompose near their melting points, and it is not possible to determine solubility parameters for these solid compounds by the methods used for liquid solvents. The method gives good partial and total solubility parameters for naphthalene; with related compounds, less satisfactory results were obtained. At least three conditions, pertaining to the regression equation and the solvent systems, must be met in order to obtain reasonable solute solubility parameters. In addition to providing partial solubility parameters, the regression equations afford a calculation of solute solubility in both polar and nonpolar solvents.

Use of the solubility parameter for predicting selectivity and retention in chromatography

The theoretical and practical aspects of the solubility parameter (“polarity”) model for predicting retention behaviour and partition coefficients have been investigated. A critical discussion of the theoretical basis shows that sufficiently accurate data for the total solubility parameter can be obtained from generalized thermodynamic functions, rather than from the usual vapour pressure data. Partial polarities are obtained from theoretical and semi-empirical relations with simple physical parameters such as refractive index, dielectric constant and dipole moment. Internal pressure, calorimetric and spectroscopic experimental data are used for estimating the contributions of charge and proton transfer (acid-base interaction). Tables of partial and total polarities are presented which replace older, less accurate data. The multicomponent model is tested with chromatographic and partition experiments and is proposed as an alternative method for selecting a proper phase system (in both chromatography and partition methods where, for example the Hansch method is frequently used).

Interactions of Nonaqueous Solvents with Textile Fibers Part III: The Dynamic Shrinkage of Polyester Yarns in Organic Solvents1

'rhe broad spectrum of interactions hetween a polyester yarn and different organic solvents has been investigated with a new experimerltal methocl called dynamic shrinkage. This technique is based on the measurement of the length changes of polyester yarns immersed in a solvent at programmed rates of heating. The dynamic shrinkage curves of a polyester yarn in various solvents are usually composed of a noncquilibrium and an equilibrium shrinkage region. From the former, it is possible to estimate the activation energies for the shrinkage process. From the equilibrium shrinkages, two analytical approaches have been used to estimate the glass-transition temperatures of about 22 polyester-solvent systems. The lowering of the glass-transition temperature of polyester by organic solvents is expressed as a function of their total solubility parameter. A bimodal distribution with interaction maxima at solu bitity parameter values of 10 and 12 is observed. 'I'he effects of solvent-induced crystallization on the transition tempera tures of polyester-solvent systems are discussed.