dinitración

Dinitration is a chemical reaction that involves the introduction of two nitro groups (-NO2) onto a molecule. Typically, this process occurs in organic chemistry, often on aromatic rings. The nitration of benzene, for instance, can proceed to dinitration under more vigorous conditions than mononitration. This usually requires stronger nitrating agents, such as a mixture of concentrated nitric acid and sulfuric acid, and often elevated temperatures.

The regioselectivity of dinitration, meaning the positions at which the two nitro groups attach to the ring, is influenced by the electronic properties of any existing substituents on the aromatic ring. Electron-donating groups tend to direct incoming nitro groups to ortho and para positions, while electron-withdrawing groups typically direct them to the meta position. If the first nitro group is already on the ring, it acts as a deactivating and meta-directing group for the second nitration.

Dinitration is an important synthetic step in the production of various chemicals. For example, dinitrotoluene is an intermediate in the synthesis of toluene diisocyanate (TDI), a key component in the production of polyurethane foams. Similarly, dinitrobenzene isomers can be precursors to diamines, which are used in the manufacture of dyes and explosives. The reaction conditions must be carefully controlled to avoid over-nitration or side reactions, which can lead to lower yields and product purity. The presence of two strongly electron-withdrawing nitro groups makes the aromatic ring significantly deactivated towards further electrophilic substitution.