METHOD FOR PRODUCING METHYLENE DIPHENYL DIISOCYANATE Russian patent published in 2021 - IPC C07C263/10 C07C265/14 

FIELD: product with 4,4'-methylene diphenyl diisocyanate production.

SUBSTANCE: invention relates to a method for continuous production of a product with a target 4,4'-methylene diphenyl diisocyanate content of 95-98% in a displacement reactor. The method is characterized in that phosgenation of a 10-30 wt.% Solution of methylenediphenyldiamine with a solution of triphosgene with a content of 10 to 30 wt.% is carried out at a temperature of 0-10°C and further heating of the reaction mass to a temperature of 120-130°C. The raw material used is methylenediphenyldiamine with a content of 95.1-98.7% of all isomers of methylenediphenyldiamine, which contains off-target isomers of 2,4- and 2,2-methylenediphenyldiamine in an amount of less than 10 and 3 wt.%, respectively, and the solvent is chlorobenzene.

EFFECT: allows to obtain the target product in a continuous way without the use of toxic phosgene.

1 cl, 3 ex