What is #"activated benzene"#?

1 Answer
Jun 5, 2017

Answer:

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.