The Solubilities and Heats of Solution of Disperse Dyes in Water

The aqueous solubilities of 16 carefully purified disperse dyes have been measured over the temperature range 60–90°C. From these results, the heats of solution in water have been found to lie mainly in the range 10–20 kcal./mole. It is suggested that the higher heats of solution are associated with the presence of hydroxyl groups in the dye molecules, and the possibility of intermolecular hydrogen bonding in the crystalline state. Values for the melting points, wavelengths of maximum absorption and molar extinction coefficients are also given.