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Aldehydes Ketones and Carboxylic Acids question

2007 · Shift 0 · Q1
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Aldehydes Ketones and Carboxylic Acids question

2007 · Shift 0 · Q1

JEE MainChemistryAldehydes Ketones and Carboxylic AcidsMCQ+4 / −1
The compound formed as a result of oxidation of ethyl benzene by KMnO4KMnO_4KMnO4​ is :
  1. A
    benzophenone
  2. B
    acetophenone
  3. C
    benzoic acid
  4. D
    benzyl alcohol
View written solutionFree

Correct answer: C

  1. Identify the substrate

    Ethyl benzene is: C6H5−CH2CH3C_6H_5-CH_2CH_3C6​H5​−CH2​CH3​

    It contains a benzene ring with an alkyl side chain.

  2. Recall the reaction with KMnO4KMnO_4KMnO4​

    Strong oxidizing agents like hot alkaline or acidic KMnO4KMnO_4KMnO4​ oxidize the entire benzylic side chain of an alkyl benzene to a carboxylic acid, provided there is at least one benzylic hydrogen.

    In ethyl benzene, the benzylic carbon is: C6H5−CH2−CH3C_6H_5-CH_2-CH_3C6​H5​−CH2​−CH3​ The benzylic carbon is the CH2CH_2CH2​ attached directly to the ring, so benzylic hydrogens are present.

  3. Apply oxidation

    Therefore, the side chain is completely oxidized to: C6H5COOHC_6H_5COOHC6​H5​COOH

    This compound is benzoic acid.

  4. Check options

    • A: benzophenone — not formed by side-chain oxidation of ethyl benzene.
    • B: acetophenone — not the final oxidation product with strong KMnO4KMnO_4KMnO4​.
    • C: benzoic acid — correct.
    • D: benzyl alcohol — oxidation does not give this product.

  5. Final answer

    The compound formed is benzoic acid.

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