The reaction of toluene with in presence of gives ‘X' and the reaction in presence of light gives 'Y'. 'X' and 'Y' are respectively:
X= Benzal chloride, Y= o-chlorotoluene
X= m-chlorotoluene, Y= p-chlorotoluene
X= o and p-chlorotoluene, Y= trichloromethyl benzene
X= Benzyl chloride, Y= m-chlorotoluene
Reaction producing X (Electrophilic Aromatic Substitution): When toluene reacts with chlorine () in the presence of a Lewis acid catalyst like iron(III) chloride () or iron (), an electrophilic substitution reaction occurs on the benzene ring. The methyl group () is an ortho-para directing group. Therefore, the entering chlorine atom attacks the ortho and para positions relative to the methyl group, yielding a mixture of o-chlorotoluene and p-chlorotoluene .
Reaction producing Y (Free Radical Substitution): When the reaction is carried out in the presence of light () or heat, the conditions favour a free radical mechanism. This leads to substitution in the alkyl side chain (benzylic position) rather than the ring, similar to the halogenation of alkanes . The hydrogen atoms of the methyl group are replaced by chlorine atoms. Depending on the extent of reaction, mono-, di-, or tri-chlorinated products (benzyl chloride, benzal chloride, or benzotrichloride) are formed. Option 3 specifies trichloromethyl benzene (benzotrichloride), which is the product of exhaustive side-chain chlorination.
Conclusion: X is the mixture of ring-substituted isomers (o and p-chlorotoluene), and Y is the side-chain substituted product (trichloromethyl benzene).
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