how the presence of nitro group in benzene effect the substitution for the next electrophile?

Question

based on aromatic reaction..please explain how does the presence of nitro group in benzene effect the substitution of the next electrophile

Answer 1

the nitro- group is a ring deactivating group. therefore it is harder for the next nucleophile to get into the ring.

Answer 2

The nitro group is an electronic withdrawing group, so it abstracts electrons from the benzene ring. The ring is desactivated.
If you now draw the resonance structures, you will see that the meta-position is the thermodynamic best position for a 2nd electrophilic substitution.

But a desactivated benzenring is leading to a slower reaction, so you need higher temperatures, concentrations, etc.

Answer 3

Nitro is electron-withdrawing. Nitrobenzene, C6H5-NO2, is in resonance with three structures, (+)C6H5=NO2(-), in which the (+)-charges are on the 2-, 4, and 6-positions of the ring. Because of the positive charge in the ring generally, the ring is not as attracting to incoming electrophiles, and so nitrobenzene is less reactive than benzene. In particular, the 2-, 4-, and 6-positions are disfavored. So incoming electrophiles react at the 3- and 5-positions (meta-positions) preferentially. That's why nitro is called meta directing.

Answer 4

the nitrobenzene, is really less reactive than benzene towards the electrophilic sustitution.
because the electron density map of the nitrobenzene shows that the largest partial charge is in 3 and 5 position, you can also predict that the susbitution will occour mainly in that positions (so called meta orientating effect)