4,4'-DIAMINO-3,3'-DIMETHYLDIPHENYLMETHANE

50-00-0

95-53-4

838-88-0

(1) o-toluidine, water and 37% hydrochloric acid were added into the reactor in the ratio of o-toluidine to hydrochloric acid at the molar ratio of 1:1.2 and the weight ratio of o-toluidine to water at the ratio of 1:4, and the reaction was stirred for 30 minutes; (2) the 37% formaldehyde solution was diluted to 10%; (3) the reaction solution from step (1) and the diluted formaldehyde solution from step (2) were transported via advective pumps to each of the microreactor's two inlets, controlling the molar ratio of o-toluidine to formaldehyde to be 3:1; (4) in the microreactor, the two raw materials were contacted, mixed and reacted, the reaction temperature was controlled at 40 °C, the liquid-time air velocity was 3000 h-1, and the reacted solution flowed out from the reactor outlet; (5) the reaction solution was cooled down to room temperature, and the aqueous sodium hydroxide was added dropwise to adjust pH to about 9, and a large amount of white precipitate precipitated, which was filtered, drying to obtain 3,3'-dimethyl-4,4'-diaminodiphenylmethane (MDT) crude product; (6) the crude MDT was recrystallized by ethanol, filtered and dried to obtain the pure MDT with a molar yield of 86% and a purity of 99%.