Basic Red 9

101-77-9

62-53-3

569-61-9

Basic magenta was prepared by synthesizing 4,4'-((4-iminocyclohexane-2,5-diene-1-idene)methylene)diphenylamine hydrochloride by air oxidation reaction in the presence of a cesium vanadate catalyst using 4,4'-diaminodiphenylmethane and aniline as raw materials in the following steps: (1) in a four-necked flask, a mixture of 4,4'-diaminodiphenylmethane and aniline was added at a weight ratio of 20:1 to obtain Mixture A. Four ports of the four-necked flask were fitted with a condenser, a water separator, a thermometer and an air introduction tube, and the flask was equipped with a stirrer. aniline in a four-necked flask at a weight ratio of 20:1 to obtain mixture A. The four ports of the four-necked flask were respectively fitted with a condenser, a water separator, a thermometer, and an air introduction tube, and the flask was equipped with a stirrer; (2) under stirring conditions, a 30% HCl solution weighing 0.77 times the weight of 4,4'-diaminodiphenylmethane was added to mixture A until it was completely dissolved, obtaining solution B; (3) solution B was added to solution B weighing 1% to 4% by weight of 4,4'-diaminodiphenylmethane as cesium vanadate catalyst to solution B to obtain solution C; (4) heating solution C to 140° C. and continuously passing air at this temperature for 5 hours until no water is generated, and product D is obtained at the end of the reaction; and (5) azeotropic distillation of the product D, removing and recovering excess aniline to obtain crude oil. The crude oil was poured out of a four-neck flask and cooled to become brittle; (6) the brittle crude oil was ground and stirred with a dilute hydrochloric acid solution to pH ≤ 1 to obtain solution E; (7) solution E was stirred continuously for 6.5 hr, and then filtered through diatomaceous earth to obtain filtrate F; (8) the pH of the filtrate F was adjusted to 5 with a 0.4 mol/L NaOH solution at 24 °C, and filtered to obtain the filter cake G; ( (9) The filter cake G was dissolved in boiling water at pH=4, cooled to room temperature and left to crystallize for 16 hours, and finally filtered to obtain the solid product basic magenta crystals in 70% yield.