Assertion (A): Treating benzene with excess CH3Cl and AlCl3 gives polymethylbenzenes, whereas excess CH3COCl and AlCl3 gives only acetophenone. Reason (R): A methyl group activates the benzene ring, whereas an acetyl group deactivates it.

Both A and R are true and R is the correct explanation of A

Both A and R are true but R is not the correct explanation of A

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JEE Advanced levelSingle correct optionDifficulty 3 of 3o2156

Assertion (A): Treating benzene with excess $CH X_{3} Cl$ and $AlCl X_{3}$ gives polymethylbenzenes, whereas excess $CH X_{3} COCl$ and $AlCl X_{3}$ gives only acetophenone. Reason (R): A methyl group activates the benzene ring, whereas an acetyl group deactivates it.

ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true

Answer: A

The product of alkylation (toluene) is more reactive than benzene, so it is alkylated further. The product of acylation (acetophenone) is deactivated by the acyl group, so reaction stops at the monoacyl stage. A and R are both true and R is the explanation.

Practice Organic Reaction Mechanisms II: Electrophilic and Radical Reactions More on Electrophilic aromatic substitution: mechanism and directing effects

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Assertion (A): Treating benzene with excess CHX3​Cl and AlClX3​ gives polymethylbenzenes, whereas excess CHX3​COCl and AlClX3​ gives only acetophenone. Reason (R): A methyl group activates the benzene ring, whereas an acetyl group deactivates it.

Answer: A

More questions on Electrophilic aromatic substitution: mechanism and directing effects

Assertion (A): Treating benzene with excess $CH X_{3} Cl$ and $AlCl X_{3}$ gives polymethylbenzenes, whereas excess $CH X_{3} COCl$ and $AlCl X_{3}$ gives only acetophenone. Reason (R): A methyl group activates the benzene ring, whereas an acetyl group deactivates it.