ON THE APPLICATION OF REGULAR SOLUTION THEORY TO THE ESTIMATION OF SOLUBILITY PARAMETERS OF CRYSTALLINE ORGANIC COMPOUNDS FROM SOLUBILITY DATA.

Description

Main Author

NEAU, STEVEN HENRY

Language(s)

English

Published

1988.

Subjects

CHEMISTRY, PHARMACEUTICAL

Summary

parameter estimates based on the two simplifying assumptions differed by no more than 0.2 hildebrands, an increment equal to the presumed inherent error of estimation. These data, then, indicate that solubility parameters and, thus, cohesive energies of crystalline organic solids can be determined from their solubilities in London solvents.
heat capacity. These estimated differential heat capacities were generally of the magnitude of the entropies of fusion of the n-alkyl para-aminobenzoates. These data, pooled with literature values, support the conclusion that, except for rigid aromatic molecules, the entropy of fusion is a better estimate for the differential heat capacity. Solubility-based solubility parameters, however, were found to be relatively insensitive to the assumption made concerning the differential heat capacity. Solubility
n-dodecane, cyclohexane, carbon tetrachloride, toluene and benzene. The heat capacities of the solid and liquid forms of the test compounds were determined by comparison of the vertical height of the sample endotherm generated by a differential scanning calorimeter with that of an aluminum oxide endotherm, both at the same temperature. The solid and liquid heat capacity lines were extrapolated so that the difference between them at the melting point could be assigned as the value of the differential
compound at the solution temperature. It has been assumed that the differential heat capacity can be considered zero or can be approximated by the entropy of fusion. In the present work, we have experimentally estimated the differential heat capacities for a series of n-alkyl para-aminobenzoates to consider the validity of these assumptions. We have also considered the extent to which these assumptions influence the magnitudes of solubility parameters estimated from solubilities in n-hexane, n-heptane,
Regular solution theory indicates that the solubility parameters of crystalline organic compounds might be estimated from their solubilities in London solvents as all parameters in the equation necessary to estimate the solute solubility parameter can be readily determined experimentally, except the term involving the solute heat capacities in the solid and liquid states. Simplifying assumptions have been made concerning the differential in heat capacity between the liquid and solid forms of the

Note

CHAIRMAN: GORDON L. FLYNN

Physical Description

161 p.

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