# What is "activated benzene"?

Jun 5, 2017

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 ${C}_{6} {H}_{6}$ in electrophilic aromatic substitution reactions...........

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

${C}_{6} {H}_{6} + B {r}_{2} \stackrel{\text{Fe(II) salt}}{\rightarrow} {C}_{6} {H}_{5} B r + H B r$

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 $- O H$, $- N {H}_{2}$, 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.

${C}_{6} {H}_{5} O H \stackrel{B {r}_{2}}{\rightarrow} {C}_{6} {H}_{4} B r O H + {C}_{6} {H}_{3} B {r}_{2} O H$

The aryl ring is thus $\text{activated}$ towards substitution by electrophiles.