How does activator differ from deactivator?

Generally speaking, electron donators / activators have a lone pair of electrons or an electron density that “pushes” into the benzene. Electron withdrawers / deactivators have a positive charge on the substituent or a very electronegative atom attached to it, which “pulls” electrons out of the benzene.

How does activating and deactivating groups affect the reactivity of benzene ring?

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.

What is the effect of substituents on benzene ring?

Experiments have shown that substituents on a benzene ring can influence reactivity in a profound manner. For example, a hydroxy or methoxy substituent increases the rate of electrophilic substitution about ten thousand fold, as illustrated by the case of anisole in the virtual demonstration (above).

What activates the benzene ring?

In the following diagram we see that electron donating substituents (blue dipoles) activate the benzene ring toward electrophilic attack, and electron withdrawing substituents (red dipoles) deactivate the ring (make it less reactive to electrophilic attack). The first is the inductive effect of the substituent.

What are ring activators?

Ring activators are groups that increase the electron density on the benzene ring and thereby make the ring more susceptible to electrophilic aromatic substitution reactions.

Which substituent on a benzene ring is the most activating and why?

Rule #1: When two or more substituents are present on an aromatic ring, the directing group will be the most activating substituent.

What substituents activate the ring towards substitution?

The methyl group directs or orients the incoming substituent into positions ortho and para to itself, and is therefore an ortho, para director. All groups that activate the aromatic ring toward further substitution are ortho, para directors. The weakly deactivating halogens also act as ortho, para directors.

What is the effect of substituents?

Substituent effects are the changes on a reaction or property in the unchanged part of the molecule resulting from substituent variation. Some Reactions or Properties.

Why methyl group is an activator?

If electrophilic aromatic substitution of a monosubstituted benzene is faster than that of benzene under identical conditions, the substituent in the monosubstituted benzene is called an activating group. Thus, the methyl group is an activating group. All activating groups are electron-donating groups.

What is deactivator?

Deactivator (deactivating group): In electrophilic aromatic substitution, an aromatic ring substituent that decreases nucleophilicity and arenium ion stability (relative to a hydrogen atom), thereby causing the reaction to be slower than the same reaction on benzene itself.