Nitrobenzene on reaction with concentrated HNO3/H2SO4 at 80-100°C forms which one of the following products?

The reaction of nitrobenzene with concentrated HNO3/H2SO4 at 80-100°C is an example of electrophilic aromatic substitution. The nitronium ion (NO2+), generated from the reaction of HNO3 and H2SO4, acts as the electrophile.

The nitro group (-NO2) is a meta-directing group. This means that in subsequent electrophilic aromatic substitution reactions, the incoming electrophile will preferentially substitute at the meta position (position 3) relative to the existing nitro group. However, at higher temperatures and with excess nitrating agent, further nitration can occur, leading to the formation of dinitrobenzene isomers.

While the meta-directing nature of the nitro group favors the formation of 1,3-dinitrobenzene, the presence of excess nitrating mixture and elevated temperature favors the formation of 1,3-dinitrobenzene as the major product and some 1,2,4-trinitrobenzene as a minor product. The steric hindrance at the ortho positions makes it less likely for further nitration to occur at the ortho position. Thus, 1,3-dinitrobenzene is the major product. Therefore, the correct answer is 1,3-Dinitrobenzene. However, some 1,2,4-trinitrobenzene might also form as a byproduct at these conditions.