Why does NO2 deactivate benzene ring?

Most elements other than metals and carbon have a significantly greater electronegativity than hydrogen. Consequently, substituents in which nitrogen, oxygen and halogen atoms form sigma-bonds to the aromatic ring exert an inductive electron withdrawal, which deactivates the ring (left-hand diagram below).

Why is NO2 deactivating a group?

Since NO2 is an electron withdrawing group, a look at the resonance structures suggests that at the ortho-para positions the positive charge is localised. These positions are then deactivated in the direction of electrophilic aromatic substitution.

Why is ch3 an activating group?

Alkyl substituents (e.g. -CH3, -CH2CH3) are also electron donating groups – they activate the aromatic ring by increasing the electron density on the ring through an inductive donating effect. This is the same effect that allows alkyl groups to stabilise simple carbocations.

Is ch3 ring activating or deactivating?

As we just saw, CH3 is a perfect example of an activating group; when we substitute a hydrogen on benzene for CH3, the rate of nitration is increased. A deactivating group, on the other hand, decreases the rate of an electrophilic aromatic substitution reaction, relative to hydrogen.

What is activating and deactivating group?

Activating and Deactivating Groups Activating groups are substituents that increase the rate of a reaction (by lowering the activation energy). Deactivating groups are substituents that decrease the rate of a reaction (by increasing the activation energy).

Which group activates the benzene ring?

It is even less acidic than carbonic acid but more acidic than water. Thus, phenol is unable to protonate HCO3−​ anion but easily protonates OH− anion. The OH− group activates the benzene ring so much that electrophilic substitution takes place readily.

Is nitro group ring activating or deactivating?

Under identical conditions, Reaction 2 is slower than Reaction 1. Thus, the nitro group is a deactivating group. All deactivating groups are electron-withdrawing groups.

Is ch3 a meta directing group?

1: Thus, the methyl group is an ortho, para directing group. Thus, the nitro group is a meta directing group. Ortho, para directing groups are electron-donating groups; meta directing groups are electron-withdrawing groups.

Is No2 an activating group?

Common activating groups (not a complete list): Alkyl, NH2, NR2, OH, OCH3, SR. Common deactivating groups (not a complete list): NO2, CF3, CN, halogens, COOH, SO3H. If you think about it, you’ll also see that where you put the group E on the ring will also influence the carbocation.

Is a methyl group activating or deactivating?

Thus, the methyl group is an activating group. All activating groups are electron-donating groups.

Is NO2 an activating group?

What are ring activating and deactivating groups?

Activated rings: the substituents on the ring are groups that donate electrons. Deactivated rings: the substituents on the ring are groups that withdraw electrons.

What is the function of activating and deactivating groups in benzene?

Activating groups serve as ortho‐para directors when they are attached to a benzene ring, meaning that they direct an incoming electrophile to the ortho or para positions. An atom or group that makes the benzene molecule less reactive by removing electron density from the ring acts as a deactivating group.

What determines the reactivity of rings in benzene?

Substituents determine the reactivity of rings. The reaction of a substituted ring with an activating group is faster than benzene. On the other hand, a substituted ring with a deactivated group is slower than benzene. Activating groups speed up the reaction because of the resonance effect.

Is CH3 an activating or deactivating group?

As we just saw, CH 3 is a perfect example of an activating group; when we substitute a hydrogen on benzene for CH 3, the rate of nitration is increased. A deactivating group, on the other hand, decreases the rate of an electrophilic aromatic substitution reaction, relative to hydrogen.

Do halogen atoms remove electrons from benzene rings?

Halogen atoms show both activating and deactivating characteristics. Because they have three pairs of unshared electrons, halogen atoms can supply electrons toward the ring. However, because of their high electronegativities, halogen atoms also tend to remove electrons from the benzene ring.