METHOD OF CRYSTALLIZATION OF HEXAMETHYLENETETRAMINE Russian patent published in 2002 - IPC

FIELD: pharmacy, pharmaceutical technology. SUBSTANCE: invention describes the improved method of crystallization of hexamethylenetetramine, i. e. urotropin used in medicinal practice. Method involves preparing 40% solution of hexamethylenetetramine, separation of impurities by filtration, vacuum evaporation at 65-68 C at the rarefying value 40-60 kPa. Crystallization is carried out in the sealing volume where the parent rarefying corresponding to saturated vapors pressure at evaporation point is developed and the solution is loaded at the constant initial pressure value followed by continuous pressure decrease by exponential law. The linear feature of temperature change at exponential pressure decrease provides the leveling of rates of internal and external diffusion values and preparing crystals of the required size. EFFECT: improved method of crystallization. 1 cl, 1 tbl, 1 dwg, 1 ex