The nitration of benzene refers to the substitution of a nitro group (-NO2) onto the benzene ring. The process involves the reaction of benzene with a mixture of nitric acid (HNO3) and sulfuric acid (H2SO4) as a catalyst. The ascending order of nitration products in terms of substitution is as follows:
Mononitrobenzene (nitrobenzene): C6H6 + HNO3 → C6H5NO2 + H2O In this reaction, one hydrogen atom on the benzene ring is replaced by a nitro group (-NO2).
Dinitrobenzene: C6H6 + 2HNO3 → C6H4(NO2)2 + 2H2O In this reaction, two hydrogen atoms on the benzene ring are replaced by two nitro groups (-NO2).
Trinitrobenzene: C6H6 + 3HNO3 → C6H3(NO2)3 + 3H2O In this reaction, three hydrogen atoms on the benzene ring are replaced by three nitro groups (-NO2).
It's important to note that the ascending order represents the increasing number of nitro groups substituted onto the benzene ring, resulting in a higher degree of substitution and increased reactivity.