METHOD OF PURIFYING GLYCOLURIL FROM HYDANTOIN IMPURITY Russian patent published in 2019 - IPC B01D9/02 C07B63/00 C07D487/08 

FIELD: manufacturing technology.

SUBSTANCE: invention relates to methods of purifying substances from related hardly-separable impurities by crystallization, specifically to a method of purifying glycoluril (2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione) from hard-separable impurities of hydantoin (2,4-imidazolidinedione), wherein hydantoin is formed as a by-product (product of condensation of urea and glyoxal at high temperature in acidic medium) and content thereof should not exceed 0.1 %. Method of purifying glycoluril from admixture of hydantoin to hydantoin level of less than 0.1 % involves applying a crystallization method by successively dissolving glycoluril with a hydantoin admixture in 85 % orthophosphoric acid while heating to 60 °C, cooling the obtained solution to room temperature and adding acetonitrile in ratio, pts. wt.: glycoluril with a hydantoin impurity of 1, 85 % orthophosphoric acid 5, acetonitrile 4, followed by washing the residue with acetonitrile, filtering and drying.

EFFECT: disclosed is a method of purifying glycoluril from hydantoin impurities.

1 cl, 1 dwg