Solubility in Different Solvents, Crystal Polymorph and Morphology, and Optimization of Crystallization Process of AIBN

Abstract

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.

Thermodynamic Modeling and Solubility Parameter of 2,6-Pyridinedicarboxylic Acid in Selected Solvents at Different Temperatures

“…22 describes the solid−liquid equilibrium (SLE) relationship of SLE systems. 30 We used the λh equation (shown below) to process our experimentally obtained solubility data:…”

“…The Buchowski–Ksiazaczak λ h two-parameter model, developed by Buchowski et al, describes the solid–liquid equilibrium (SLE) relationship of SLE systems . We used the λ h equation (shown below) to process our experimentally obtained solubility data: where T m is the melting point of PDCA, and λ and h are the parameters obtained by applying a non-linear regression to the experimentally obtained PDCA data.…”

Solubility of N-tert-Butylbenzothiazole-2-sulfenamide in Several Pure and Binary Solvents

“…In order to ensure the reliability and accuracy of the gravimetric method, the mole fraction solubility of 2,2'-azobisisobutyronitrile (AIBN) in ethanol was measured as a validation experiment. The validation measurement results were compared with the literature values 16 , as presented in Table 2. The relative deviations between the experimental data and the literature data, defined as eq 4, were less than 5%.…”

“…where G ij and ij are the model parameters, which can be defined as eqs 15 (16) where ∆g ij represents the Gibbs energy of cross interaction, ij represents a criterion of the nonrandomness of the system.…”

“…Comparison of the experimental solubility of AIBN in ethanol from 273.2 K to 313.2 K with the literature data (p 0.101 MPa). is the experimental solubility of AIBN in ethanol and 1lit is mole fraction solubility of AIBN in ethanol reported by Li et al16 . RD is the relative deviation between the experimental data and the literature data.…”