Stanley P. Wasik

Use of a nematic liquid crystal for the gas-liquid chromatographic separation of naphthalene homologues

Abstract The gas-liquid chromatographic separations of methyl-, ethyl-, and dimethylnaphthalene isomers on the nematic and supercooled regions of N,N′-bis( p -methoxybenzylidene)-α,α′-bi- p -toluidine are presented and compared with the results obtained on other materials. The unique selectivity of this liquid crystal, based upon differences in the molecular length-to-breadth ratio of the solute positional isomers, has enabled the complete separation of these naphthalene homologues.

Aqueous solubilities and octanol-water partition coefficients of binary liquid mixtures of organic compounds at 25°C

From thermodynamics and certain assumptions it is shown that, under the usual experimental conditions, the octanol-water partition coefficient (Ko/w) of a given organic liquid should be the same whether the substance is partitioned neat or as part of a mixture. Measurements of several mixtures of n-propylbenzene (log Ko/w=3.71±0.04)+ethylbenzene (log Ko/w=3.16±0.01) clearly confirm this. It is also shown that the aqueous solubility (Sw) of a neat organic liquid can be related to its aqueous solubility (Sw′), when it is present at volume fraction ϕ in an organic liquid mixture, by Sw′=γϕSw, where γ is its activity coefficient in the organic mixture. The measured Sw′ values for n-propylbenzene + ethylbenzene (γ≈1), n-hexane + nitrobenzene (γ>1) and di-isopropyl ether + chloroform (γ<1) are found to be in good agreement with the predicted values (average differences of, respectively, <2%, ≈8% and ≈6%). In general, the bounds on Sw′ are expected to be 0

Aqueous solubilities and enthalpies of solution of adenine and guanine

A generator column—liquid chromatographic technique was used to determine the aqueous solubility of adenine from 20 to 30°C, and of guanine from 15 to 40°C. The 95% confidence limits of the solubilities and molar enthalpies of solution at 25°C are: 8.7±0.1×10−3M and 33.5±0.5 kJ-mol−1 for adenine; 3.9±0.1×10−5M and 49.2±0.6 kJ-mol−1 for guanine. the adenine enthalpy value includes a small correction for association in the saturated solutions. The previously undetermined molar enthalpy of the second ionization step of guanine (to form the doubly-charged guanine anion) is estimated from our data combined with other measurements to equal 33.8±2.9 kJ-mol−1.

Partition coefficients and solubility measurements of dimethylmercury in fresh and sea water over a temperature range 0–25°C

Abstract The partition coefficients and solubilities of dimethylmercury in distilled and sea water over a temperature range 0–25°C, have been measured using a head‐space technique.

Calculation of Aqueous Solubility of Organic Compounds

The aqueous solubility of 14 organic solutes has been calculated from their octanoL/water partition coefficient and from their solute activity coefficient in octanol at infinite dilution. The solute activity coefficients were calculated from the Flory-Huggins and Hildebrand-Scatchand (FH-HS) equations and were found to be in good agreement with the activity coefficients detennined from GC specific retention volume measurements. The calculated solubilities were in good agreement with the experimental solubilities.

Fluorometric determination of partition coefficients of naphthalene homologues in octanol‐water mixtures

Abstract The octanol/water partition coefficients of 12 naphthalene homologues have been measured using a newly developed fluorometric technique. The log P values of alkyl substituents obtained by this method were found to be in reasonable agreement with the literature values.

Determination of Hydrocarbon Solubility in Sea Water and the Analysis of Hydrocarbons in Water-Extracts

ABSTRACT An apparatus is described for measuring the solubility of hydrocarbons in sea water and for analyzing hydrocarbons in water-extracts. The relative concentrations of the hydrocarbons in the gas phase in equilibrium with the water extract were determined by gas chromatography. A known volume of the gas phase was purged out from the apparatus and replaced with helium. The concentration of the hydrocarbons were measured after the second equilibration. The solubility of the hydrocarbon solutes in the sea water extract were determined from the peak area ratios of the solute peaks and the volume of the apparatus. Complex mixtures of hydrocarbons in aqueous solutions may be analyzed using this apparatus by examining the chromatograms obtained after each flush out. The peaks are identified as to hydrocarbon group (olefinic, aromatic, paraffinic) from the rate that the solute peak area decreases after each flush out. Overlapping peaks may be resolved using this technique. By extrapolating peak areas to zer...

A Head-Space Method for Measuring Activity Coefficients, Partition Coefficients, and Solubilities of Hydrocarbons in Saline Solutions

An apparatus is described which measures the equilibrium distribution of a hydrocarbon between a gas and aqueous phase. Soluble hydrocarbons are extracted from an aqueous salt solution by very small bubbles of hydrogen generated electrolytically from a gold electrode located at the bottom of a cylindrical cell. The partition coefficient is determined from the volume of the aqueous solution and the solute concentration in the head-space after a measured volume of hydrogen has bubbled through the cell. The concentration of the solute in the head-space is measured by gas chromatography. The observed distribution is supplemented by vapor pressure and molar volume data and can be used to calculate the solubility and the activity coefficient of the solute in the aqueous phase. The partition coefficient, activity coefficient, and solubility for 18 alkylbenzenes in aqueous 0.5 M NaCI at 25°C were measured by this method.