Why nitrification is a key monitoring process?

Nitrification is the process of introducing nitro (-NO2) into the molecules of organic compounds, and it is a monovalent group formed by the loss of hydroxyl groups in nitric acid. The reaction mechanism of nitration of aromatic compounds is that the -OH group of nitric acid is protonated, then a molecule of water is removed by dehydrating agent to form an intermediate nitronium ion (NO2), and finally an electrophilic aromatic substitution reaction occurs with benzene ring to remove a molecule of hydrogen ion.

In this nitration reaction, the electron density of aromatic ring will determine the reaction rate of nitration. The higher the electron density of aromatic ring, the faster the reaction rate. Because nitro itself is electrophile, the nitration reaction after the first nitration and the second nitration is often inhibited by the decrease of electron density of aromatic ring. It must be carried out under more severe reaction conditions (such as high temperature) or stronger nitrating agent.

Commonly used nitrating agents mainly include concentrated nitric acid, fuming nitric acid, mixed acid of concentrated nitric acid and concentrated sulfuric acid or dehydrating agent combined with nitrating agent.

Dehydrating agent: concentrated sulfuric acid, glacial acetic acid, acetic anhydride and phosphorus pentoxide;

Nitrifying agent: nitric acid, nitrogen pentoxide (N2O5)