Continuous flow nitration of 5-nitrosalicylic acid

In order to overcome the technical bottlenecks associated with the traditional synthesis of 5-nitrosalicylic acid, this study constructs a continuous nitration system using a microchannel reactor. Systematic process optimization of the nitration reaction of salicylic acid is conducted, focusing on the influence of reactor channel type, material ratio, residence time, and reaction temperature on product yield. The optimal process parameters identified are as follows: umbrella-shaped microchannel reactor is employed, using acetone as the solvent with a mass ratio of salicylic acid to acetone of 1:5.0. The molar ratio of salicylic acid to HNO 3 to H 2 SO 4 is controlled at 1:4:0.5. Under the conditions of 60 °C and a residence time of 4 min for continuous reaction, the product yield reaches 85.9% after recrystallization and purification with a 75% ethanol aqueous solution, achieving a purity of 97.2% as determined by liquid chromatography. Compared to traditional batch nitration processes, this method significantly reduces the consumption of concentrated sulfuric acid and substantially shortens reaction times, providing a technical reference for the safe and environmentally friendly industrial production of 5-nitrosalicylic acid.