Question

The reaction of toluene with Cl${}_2$ in presence of FeCl${}_3$ gives 'X' and reaction in presence of light gives 'Y'. Thus, 'X' and 'Y' are:

• A. X = Benzal chloride,
  Y = o-chlorotoluene
• B. X = m chlorotoluene,
  Y = p- chlorotoluene
• C. X = o-and p- chlorotoluene
  Y = Trichloromethyl benzene
• D. X = Benzyl chloride,
  Y = m- chlorotoluene

Answer 1

The correct option is C X = o-and p- chlorotoluene

Y = Trichloromethyl benzene

In presence of $Fe{Cl}_3$ and in dark, electrophilic substitution on the benzene ring by ${Cl}^{+}$ ion at ortho and para positions occurs to give o- and p- chlorotoluene.

Since methyl group activates the ring at ortho and para positions more than meta positions, the electroscopic substitution occurs mostly at these positions.

$C_6{H}_5-C{H}_3+{Cl}_2\stackrel{Fe{Cl}_3}{\to }\underset{\left(X\right)}{\{\text{o-chlorotoluene}+\text{p-chlorotoluene}\}}$

Hence, X is o- and p- chlorotoluene.

On the other hand, if chlorine reacts with toluene in the absence of a catalyst but in the presence of UV light, substitution happens in the methyl group rather than the ring.

$C_6{H}_5-C{H}_3+{Cl}_2\stackrel{\text{UV light}}{\to }\underset{\left(Y\right)}{C_6{H}_5-C{Cl}_3}$

Hence, Y is trichloromethylbenzene.