Abstract
The solubility of antipyrine derivatives has been determined in water and several organic solvents. Aminopyrine and isopropylantipyrine exhibited a solubility minimum near 25° and 15°, respectively, corresponding to a zero heat of solution. Hildebrand's solubility parameters were assigned to these compounds. The experimental results in benzene and ethylene chloride were compared with the theoretical solubility calculated from the Hildebrand's equation for regular solutions at 25°. Fair agreement was found for aminopyrine and isopropylantipyrine in benzene, but the agreement was not close for antipyrine and 4-aminoantipyrine in benzene and ethylene chloride. These discrepancies are the reflection of specific solute-solvent interaction.
