The solubility of benzanilide in sixteen pure organic solvents, including N, N-dimethylformamide, tetrahydrofuran, butanone, acetone, ethyl acetate, dichloromethane, n-butanol, diethyl ether, n-propanol, acetonitrile, ethanol, methanol, isobutanol, isopropanol, toluene, and carbon tetrachloride, was measured at temperatures ranging from 274.15 to 313.15 K using the static equilibrium method at atmospheric pressure. The modified Apelblat model, Buchowski-Ksiazczak λh model, and Non Random Two Liquid (NRTL) model were used to correlate the experimental solubility data. It was found that in all these solvents the solubility of benzanilide increases in different pace as the temperature increases. The modified Apelblat model gave the best fit. Guided by the solubility data, preliminary experimental study was conducted for cooling crystallization of benzanilide in ethanol and n-propanol. The result indicated that the solvent, stirring speed and cooling rate all have significant impact on crystal morphology and particle size distribution.

The solubility of 2, 2-azobisisobutyronitrile (AIBN) in pure methanol, ethanol, acetone, benzene, ethyl acetate and a mixture of methanol and water was measured in the temperature range from 268.15 K to 325.15 K at atmospheric pressure. The AIBN solubility was sensitive to the temperature in all the pure solvents. The solubility in the binary mixture of methanol and water increased as the methanol fraction and temperature increased. The data were correlated with the modified Apelblat equation, Van't Hoff equation and Buchowski-Ksiazczak h equation. Other results showed two AIBN polymorphs formed after the crystallization, form I, in a monoclinic cell, and form II, in a triclinic cell, which confirmed the two AIBN crystal structures reported in the literature. Additionally, the initial concentration and cooling rate of the AIBN crystallization had dominant roles in affecting the polymorphic forms of the AIBN crystals. The crystallization conditions were optimized in a 2 L crystallizer to yield crystals with the desired morphology and polymorphs, which resolved the caking issue experienced in the industrial production of AIBN. The optimized conditions were tested in a 20 L crystallizer.

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