METHOD OF PRODUCING UNSYMMETRICAL DIMETHYLHYDRAZINE Russian patent published in 2019 - IPC C07C241/02 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing asymmetric dimethylhydrazine, involving production of methylamines, recovery of dimethylamine, nitrosation thereof, recovering the obtained nitrosodimethylamine followed by hydrogenation thereof and separating commercial UDMH, wherein step of producing dimethylamine is carried out in molar ratio of methyl groups to amino groups of not more than 0.5, and nitrosodimethylamine hydrogenation is carried out in the displacing flooded mode with volume ratio of the gas and liquid phases flows of not less than 3,000, with the contact load on the catalyst by the liquid phase from 0.2 (h)^-1 up to 0.5 (h)^-1, density of gas phase flow in hydrogenation reactor from 3 to 10 nm³/m²⋅with, at reaction mass temperature of not more than 40 °C. After that separation of products of stage of dimethylamine production is carried out by azeotropic rectification with extraction of commercial product in five stages in the following order: distillation of ammonia and trimethylamine azeotrope and their recycling; distillation of monometilamine and trimethylamine azeotrope and their recycling; monomethylamine distillation and recycling thereof; distillation of dimethylamine and its supply to the nitrosation stage; distillation of methanol and residual methylamines and their recycling.

EFFECT: there is created a closed stage of obtaining methylamines, where, along with extraction of target dimethylamine from the reaction mixture, return to the stage of synthesis of mixtures consisting of ammonia, monomethylamine and trimethylamine, without separation of these products; returned (recycled) products react again with ammonia, increasing yield of dimethylamine.

4 cl, 2 dwg, 19 ex