METHOD OF THIOUREA ISOLATION Russian patent published in 1995 - IPC

FIELD: chemical technology. SUBSTANCE: mixture of isomers after thermic isomerization of ammonium thiocyanate is treated with water at the ratio isomeric mixture: water = (5.4-20):1 or with 50-70% aqueous solution of ammonium thiocyanate at the ratio isomeric mixture:solution = (2.8-9.0):1 following by crystallization at 60-90 C with isolation of part of pure ammonium thiocyanate. Mother liquor is diluted with water and hexachloroethane and fed to the separation stage of thiourea adduct with hexachloroethane. Then adduct is decomposed for the parent components at heating. Thiourea formed is recrystallized. Hexachloroethane is circulated in the process. EFFECT: improved method of thiourea isolation.