Synthetic Route of Aromatic Amination of Acid Blue 140
Xiaoping Chen, et al. Dyestuffs and coloration, 2015, 4, 19-20.
There are two synthetic routes for the aromatic amination of acid blue 140. One is to use the reactant 2-methyl-4-n-butylaniline as the solvent and boric acid as the catalyst. The yield of this route does not exceed 70%. The other is obtained by using n-butanol as the solvent and reacting at 115°C-120°C for more than 24 hours. The yield of this route does not exceed 65%.
Improved preparation process of aromatic amination
· Put 100g of 2-methyl-4-n-butylaniline (98%) and 2.2g of 31% hydrochloric acid into a 500ml four-neck bottle.
· Ventilate nitrogen, add 20g of 1,4-dihydroxyanthraquinone (99%) and 6.5g of boric acid (99%).
· Raise the temperature to 80°C to 85°C, add 0.5g of zinc powder, stir for 10 minutes, then raise the temperature to 98°C to 100°C, and turn on the vacuum pump to maintain appropriate vacuum for dehydration.
· The temperature is maintained at 98°C ~ 100°C, and the purple monosubstituted substance disappears after 2 hours of insulation.
· After another 1 hour of incubation, the yellow leuco body disappears, turn off the nitrogen, and then slowly add 200 ml of 90°C hot water.
· Add hydrochloric acid to adjust pH=1~2, stir at 90°C ~95°C for 10 minutes and then filter with suction. Rinse the filter cake with 200ml of 1% hydrochloric acid water, and then wash it with hot water until it is clear. The filter cake was dried to obtain acid blue 140 product.