METHOD OF OCTOGENE RECRYSTALLIZATION Russian patent published in 2018 - IPC C06B21/00 

FIELD: technological processes.

SUBSTANCE: invention relates to a method for the recrystallization of an octogene. Process is carried out by carrying out isohydric crystallization from an octogene-saturated solution ε-caprolactam in acetonitrile with the addition of a seed of an octogene to the heated solution, followed by cooling at a constant rate with stirring. In this case, a 40–60 % solution of e-caprolactam in acetonitrile is used, the mass ratio of the octogene to the primer : octogene for dissolution : crystallization mixture is 1:(7–17):(100–160). Octogene seed with a particle size of 5–30 mcm is added at a solution temperature of 75–80 °C. Then hold for 15–60 minutes, and cooling is carried out at a rate of 0.15–0.20°C/min.

EFFECT: technique provides stably reproducible production of a target product with a narrow range of particle sizes (400–600 mcm fraction is more than 80 %) and simultaneous achievement of the shape of particles close to isometric, with minimization of the number of defects of their surface without the stage of mechanical coiling due to the realization of conditions, allowing to exclude uncontrolled nucleation of new particles from the octogene used for dissolution in the crystallization medium and uncontrolled growth of the particle size of the octogene used for the seed.

1 cl, 2 dwg, 2 ex