Nitration of nitrobenzene at high concentrations of sulfuric acid

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Aromatic nitration by mixed acid (a mixture of concentrated nitric and sulfuric acids) is one of the most widely used reactions in the organic chemical industries. Aromatic nitro compounds find wide use in the manufacture of dyes and explosives. It is a heterogeneous liquid-liquid reaction which occurs almost- exclusively in the aqueous phase. The organic compound diffuses into the aqueous mixed- acid phase and reacts with the nitronium ion (NO2+) generated by the reaction between concentrated sulfuric acid and nitric acid. In this thesis, nitration of nitrobenzene using high concentration of sulfuric acid (i.e., between 14 kmol/m3 and 17.2 kmol/m3) was studied in a batch reactor at room temperature and at moderately higher temperatures. Nitration of nitrobenzene is a very slow reaction at room temperature when sulfuric acid concentration is 14.9 kmol/m3 or below due to the deactivating nitro group in the benzene ring. But at high concentration of sulfuric acid (> 16.6kmol/m3) and at high temperatures, the reaction is fast enough to obtain high conversion and yield. The advantage of this reaction is the absence of sulfonation reaction. The behavior of each aromatic nitration system is unique in terms of the physicochemical properties of the heterogeneous organic acid mixture.
Supervisor: Pallab Ghosh AND Bishnupada Mandal