Continuous Flow Nitration of Benzaldehyde

Abstract

The nitration of benzaldehyde can be carried out in a safe manner in continuous mode using a microreactor system. Choice of a micromixer was seen to affect the performance of this two-phase reaction significantly. The reaction time could be brought down to 2 min by increasing the reaction temperature and thereby taking advantage of higher heat transfer area. The simple T-micromixer is seen to be inefficient for two-phase reactions. Further scope of process intensification is also discussed.

CRE for MAGIC (modular, agile, intensified & continuous) processes

“…Example of a single phase/single step reaction: nitration of benzaldehyde As a first example, here we consider a case of nitration of benzaldehyde [74] which is an exothermic reaction (DH R = À172 kJ/ mol). In a conventional process, nitrating agents like mixed acid are used for nitration of benzaldehyde with huge excess of sulfuric acid to absorb the heat as well as the water generated in the reaction.…”

A Two-Step Continuous Flow Synthesis of 4-Nitropyridine

“…[15][16][17](3) The nitration of 3-alkylpyrazoles on 100 g scale with a productivity of 0.82 g h -1 was developed by Pelleter and Renaud 18 as a continuous process. (4) Kulkarni et al 19,20 have reported the nitration of benzaldehyde and salicylic acid in continuous flow in equipment involving syringe pumps and self-made apparatus.…”

Managing Hazardous Reactions and Compounds in Process Chemistry

“…Conditions can be varied so that a mononitro aromatic derivative is almost the sole product (36,37). An example is the nitration of benzaldehyde using nitric acid and a catalytic amount of sulfur acid in which efficient mixing was an important factor (38). Pyridine has been nitrated on large scale using this approach (39).…”