Question #1ad34

1 Answer
May 28, 2015

An activator or activating group is a substituent that increases the rate of a substitution reaction on an aromatic ring.

A deactivator or deactivating group is a substituent that decreases the rate of a substitution reaction on an aromatic ring.

The terms are usually applied to electrophilic aromatic substitution reactions such as the nitration of benzene.

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Substituents on the ring change the rate of nitration.

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For example, toluene and t-butylbenzene react about 20 times as fast as benzene.

We say that the methyl and t-butyl groups are activating groups.

Similarly, the rate of nitration of methyl benzoate is decreased by a factor of about 250.

We day that the #"COOCH"_3# group is a deactivating group.

Here's a list of some common activating and deactivating groups.

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