Nitration is the class of chemical process that introduces nitro group into an organic chemical compound. The term is also applied incorrectly to different processes forming nitrate esters among nitric acid and alcohols which take place in synthesizing nitroglycerin. The major difference among the final structure of nitrates and nitro compounds is, the nitrogen atom is bonded directly to a non-oxygen atom, mainly carbon or other nitrogen atom. While in organic nitrates, the nitrogen shares a bond with an oxygen atom which is bonded to a carbon atom.
Nitration finds various industrial applications of nitration and the most critical by volume is the production of Nitroaromatic compounds like nitrobenzene. Nitration reactions are used notably in the production of explosives like conversion of toluene to trinitrotoluene and conversion of guanidine to nitroguanidine.They are used widely as precursors and chemical intermediates.
Electrophilic Substitution Reaction Between Benzene and Nitric Acid
Benzene is treated with a solution of concentrated sulfuric acid and concentrated nitric acid at a temperature, not more than 50oC. As the temperature rises, there exist higher chances of obtaining more than one nitro group -NO2 being substituted in the ring.
Nitrobenzene is formed.
The concentrated sulfuric acid acts as a catalyst.
The formation of Electrophile
An electrophile is the nitryl cation or the nitronium ion, NO2+, formed by the reaction between sulphuric acid and nitric acid.
Electrophilic Substitution Mechanism
Nitration is one of the most researched and studied organic reactions. Both aromatic and aliphatic compounds can be nitrated by different methods like heterolytic (nucleophilic and electrophilic) and radical nitrations. Aliphatic is a free radical and Aromatic nitration is the most frequent electrophilic. Nitroaromatic compounds are used as intermediates in the synthesis of plants, dyestuffs, pharmaceuticals, and insecticides.