Synthesis
3-Methoxyaniline (0.50mol, 65.6g, 1eq) was mixed well with 416g 18% H2O-HCl (2.0mol, 213g, 4eq) solution and cooled down to 0 to -5C. Sodium nitrite (0.51 mol, 35 g, 1.02 eq) was weighed to prepare a 30% aqueous solution with 82 g of water, and the solution was slowly added dropwise to the system, and no raw material was detected after 1 h. The diazonium salt system was obtained.
Potassium sulfite (0.87 mol, 144 g, 1.74 eq) was dissolved in 800 g of water, and dilute hydrochloric acid was added to adjust the pH to between 6-8, and cooled down to 0 C. The diazonium salt system was added dropwise into potassium sulfite, while 15% potassium hydroxide aqueous solution was added dropwise to control the PH between 6-8, after dropping and adding, the system was kept warm at 0 for 1h, then the system was heated at 60 for 2h, and no diazonium salt was detected. Move the system to the reactor, add 1.06g of palladium carbon, pressurized with hydrogen at 4MPa, heated at 90 for 6h, and detected.
To the system add hydrochloric acid (2mol, 200g, 4eq, 36%), heating at 100 for 2h, the system is clarified, filtration, filtrate cooling precipitation crystals; the system is filtered, the cake is 130g of wet product, content of 63%; yield 93.8%.
