Multiphase nitrosation based on N2O3 intermediate and process intensification in a microflow reactor

Nitrosation of alcohols with nitrous acid is widely used to prepare alkyl nitrites, but the reaction mechanism and formation pathways of gaseous side products remain unclear. Here, we propose a nitrosation mechanism based on a highly reactive intermediate, dinitrogen trioxide (N 2 O 3 ). The N 2 O 3 -based mechanism shows a lower energy barrier than the previously reported acid-catalyzed and nitrosyl cation mechanism. Furthermore, a microfluidic platform was established to investigate the gas–liquid-liquid reaction system and characterize the gas holdup of the multiphase reaction system. The results suggest that the reaction rate and selectivity primarily depend on the interfacial mass transfer of N 2 O 3 between the aqueous-organic and gaseous-organic phases. A tubular microreactor was employed to intensify the nitrosation process of isopropanol. In contrast to the batch process operated by adding reactants dropwise in several hours, the product yield of 95 % can be achieved in a residence time of only 10 s in the microflow reactor.