METHOD OF PRODUCING N-METHYL-PARA-ANISIDINE Russian patent published in 2017 - IPC C07C209/24 C07C217/68 

FIELD: chemistry.

SUBSTANCE: alkylation of para-anisidine with formalin is carried out separately, simultaneously feeding them into a mixer located in the reactor just before the catalytic reduction zone, forming intermediate azomethine-4-methoxy-(N-phenylmethanimine, in the liquid phase. Resulting azomethine is then reduced on a hydrogenating catalyst at a temperature of 20-120°C, in a hydrogen medium at elevated pressure, followed by isolation of the desired product. Starting para-anisidine is used as a solution in a solvent selected from the group: ethanol, methanol, isopropanol. The process can be carried out both in a periodic and continuous mode. It is desirable to carry out the process in the presence of tertiary aliphatic amines as a stabiliser in an amount of 1 to 10 moll. % of the loading of para-anisidine. Typically, tertiary aliphatic amines selected from the group: triethylamine, tetramethylethylenediamine, diisopropylethylamine, dimethylbenzylamine, diazabicyclooctane, tripropylamine, aqueous solution of trimethylamine are used. The stabiliser is introduced into the reactor when charging the hydrogenating catalyst and/or feeding para-anisidine. The hydrogenation catalyst is used as a suspension in a solvent selected from the group: ethanol, methanol, isopropanol, or as a fixed bed. The isolation of N-methyl-para-anisidine is carried out by rectification. The stabiliser from the catalyst is isolated by simple distillation or rectification with subsequent reuse. The method makes it possible to increase the yield of the desired product to 70.6-94.2% and to reduce the formation of N,N-dimethyl-para-anisidine.

EFFECT: increasing the yield.

10 cl, 1 tbl, 15 ex