Question

Which of the following is an electrophilic substitution reaction?

• A. $C_6{H}_6+B{r}_2\stackrel{FeB{r}_3}{\to }{C}_6{H}_{5}Br+HBr$
• B. $R_2-\stackrel{H}{\stackrel{|}{C}}-Cl\to R_{2}C:$
• C. $C{l}_2\to 2Cl$
• D. None of these

Answer 1

The correct option is A

$C_6{H}_6+B{r}_2\stackrel{FeB{r}_3}{\to }{C}_6{H}_{5}Br+HBr$

What is Electrophilic substitution?

Replacement of an atom/ ion from a molecule by an electrophile.

(i) Formation of electrophile :

$Br-Br+FeB{r}_3⟶B{r}^{+}+FeB{r}_4^{-}$

(ii) Br⁺ is an electrophile and it attacks the electron-rich benzene ring :

Aromatic carbonium ion is resonance stabilised

(i)Elimination of proton :