Question 54 of 83
Q.How is benzyl chloride obtained from toluene?
Tamil Nadu DgeTamil Nadu HSC First Year (DGE) Board 2018Subjective· 2mImportance★★★★★
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Start your 14-day free trial to unlock the full solution →Passing Cl2 gas into toluene under sunlight/UV substitutes a hydrogen on the side-chain -CH3 group (via a free-radical mechanism) to give benzyl chloride.
Toluene (C6H5-CH3) can be chlorinated in two different ways depending on the reaction conditions:
- In the presence of a Lewis acid catalyst (like anhydrous FeCl3 or AlCl3) in the dark, chlorine substitutes onto the aromatic RING (electrophilic aromatic substitution), giving a mixture of ortho- and para-chlorotoluene.
- In the presence of sunlight or UV light (and absence of a halogen-carrier catalyst), chlorine substitutes onto the SIDE-CHAIN (-CH3 group) via a free-radical chain mechanism, because light homolytically cleaves Cl2 into chlorine free radicals which abstract a hydrogen from the methyl group. C6H5CH3 + Cl2 --(sunlight)--> C6H5CH2Cl + HCl …
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