Nitration of aromatic compounds by mixed acid is the most general process for the preparation of aromatic nitro compounds. Many large-volume chemicals are prepared by these methods such as, nitrobenzene (used as a solvent and in the manufacture of aniline), nitrochlorobenzenes (used as intermediates for dyes, pharmaceuticals and perfumes) and nitrotoluenes (which are converted into toluene diisocyanates for the manufacture of polyurethanes). Acid catalyzed nitration is used in the manufacture of high explosives such as trinitrotoluene (TNT), glycerol trinitrate (nitroglycerin), cellulose nitrate, cyclo-1,3,5-trimethylenetrinitramine (RDX) and cyclo-1,3,5,7-tetramethylenetetranitramine (HMX). Overall, nitration is a ubiquitous reaction in pharmaceuticals (bulk drug and intermediates), agrochemical, specialty and fine chemicals, dyes and dye intermediates, and explosives.
Our research is based on mass transfer and kinetic aspects of nitration in concentrated sulfuric acid. We have found that high yield of nitro products can be achieved even for deactivated aromatic compounds (e.g., nitrobenzene and chlorobenzene) at moderate temperatures and low stirring speeds in concentrated sulfuric acid.
1. Rahaman, M., Mandal, B. P., and Ghosh, Ghosh, P., "Nitration of nitrobenzene at high-concentrations of sulfuric acid", AIChE J., 53, 2476-2480 (2007).
2. Rahaman, M., Mandal, B., and Ghosh, P., "Nitration of nitrobenzene at high-concentrations of sulfuric acid", AIChE J., 56, 737-748 (2010).