Intensification of Nitrobenzaldehydes Synthesis from Benzyl Alcohol in a Microreactor

A one-step process to produce 2- and 3-nitrobenzaldehyde isomers starting from benzyl alcohol in aqueous mixed nitric and sulfuric acid was developed as an inherently safe continuous flow process in a microreactor. The previously published kinetic model was validated in a microreactor and used to optimize operating conditions in silico to attain the desired product distribution. The molar fractions of nitric and sulfuric acids were increased up to 0.35, 0.45, and temperature to 68 °C, which was impossible to do under batch conditions. Experiments under continuous flow conditions have shown that yields of about 42% and 96% for the ortho- and the meta- isomers, respectively, can be achieved.