Question

Explain how an oh group attached to a carbon in the benzene ring activates benzene towards electrophilic substitution.

Answer 1

When OH- grp is attached to benzene; activates benzene...
this is because OH- contain lone pairs on O and this loan pair can go into benzene by resonance thus incresing electron density in Benzene ring at Ortho and Para position...

Answer 2

$\huge\textcolor{orange}{\texttt{Answer :-}}$

As a result of + R effect of the — OH group, the electron density in the benzene ring increases and thereby facilitating the attack of the electrophile.

Hence, presence of — OH group activate the benzene ring towards electrophile substitution reaction. Thus, because the — OH group is an activating group, these reactions occur at a faster rate than reactions of benzene itself.

The — OH group is ortho-para directing and therefore, incoming group comes at ortho or para position. This is due to the reasons that because of electronic effects caused by — OH group, the ortho and para position become electron rich.