Question

What is `"activated benzene"`?

Answer 1

I am guessing at what you mean.............

Explanation:

But activated benzene would be a benzene substituted by groups that would make the benzene more reactive than `C_6H_6` in electrophilic aromatic substitution reactions...........

For example, the reaction of benzene with bromine to give bromobenzene is relatively sluggish:

`C_6H_6 + Br_2 stackrel("Fe(II) salt")rarrC_6H_5Br+HBr`

And usually some Lewis-acid catalysis is added in the form of a ferrous or ferric salt.

On the other hand, the reaction with a benzene substituted by an activating group, say `-OH`, `-NH_2`, would activate the aryl ring towards electrophilic substitution, in fact so much so that di- and trisubstitution would be observed even in the absence of catalysis.

`C_6H_5OHstackrel(Br_2)rarrC_6H_4BrOH + C_6H_3Br_2OH`

The aryl ring is thus `"activated"` towards substitution by electrophiles.