Nitration is one of the most studied organic reaction. Both aromatic and aliphatic compounds can be nitrated by various methods such as heterolytic (electrophilic and nucleophilic) and radical nitrations. Aromatic nitration is most frequently electrophilic, aliphatic is free radical. Nitroaromatic compounds are of substantial use as intermediates in the synthesis of plastics, pharmaceuticals, dyes, explosives and insecticides. Nitroaliphatics are used as solvents and synthons in organic synthesis. The most common nitrating mixtures are the nitric acid and sulfuric acid combinations, but many different ways are known from the literature.
Nowadays, the subject of nitration is still of substantial interest and activity. Therefore, more effective and selective nitration methods are investigated continuously. Selectivity can be a challenge in nitrations because as a rule, more than one compound may result but only one is desired, so alternative products act as contaminants or are simply wasted. Accordingly, it is desirable to design syntheses with suitable selectivity, for example, by controlling the reaction conditions.
Continuous flow technology, especially the IceCube™ Reactor, is one of the tools to revise the current knowledge from nitration. Due to the advantages of this methodology, the time-consuming acid mixture preparation can be managed in an easy and continuous manner. The reliable control of the residence time gives the chance to produce nitrated products more selectively than previously.