Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Alcohols, Phenols and Ethers

Question:

Read the passage carefully and answer the questions based on the passage:

Alcohols are versatile compounds as they can act as both nucleophile and electrophiles. They undergo reactions based on cleavage of O-H and C-O bonds. The cleavage of O-H bond reflects the acidic character of alcohols. However they are weaker acids than water, phenol and carboxylic acids. Alkoxide ion formed by loss of proton from the OH group of alcohols react with water to form the corresponding conjugate acid-base pair. They act as Bronsted base due to presence of unshared electron pairs on oxygen.Both alcohols and phenol react with carboxylic acids, acid chlorides and anhydrides to form esters. The introduction of acetyl group in alcohols or phenol is known as acetylation. Alcohols react with hydrogen halides to form alkyl halides which form the basis of Lucas test. They also undergo acid catalyzed dehydration to form alkenes. Alcohols can be easily oxidized with variety of oxidizing agents. The nature of the product depends on the type of oxidizing agent and the nature of alcohol.

Oxidation of alcohols involves formation of carbon oxygen double bond with

Options:

Cleavage of an O-H bond

Cleavage of C-H bond

Cleavage of of O-H bond and C-H bond

Cleavage of C-C bond

Correct Answer:

Cleavage of of O-H bond and C-H bond

Explanation:

The correct answer is Option (3) → Cleavage of of O-H bond and C-H bond **

To oxidize an alcohol to a carbonyl compound (aldehyde or ketone), the key step is:

 Removal of hydrogen from the carbon attached to the –OH group (C–H bond).

Because:

  • In primary alcohols, oxidation removes two hydrogens
    → one from O–H and one from the α-carbon (C–H).
  • In secondary alcohols, oxidation removes one hydrogen from O–H and one from C–H.

So overall:

Oxidation requires cleavage of both O–H and C–H bonds.