MCQ Detailed View

Phenol (C₆H₅OH) is an aromatic alcohol in which a hydroxyl group (-OH) is directly attached to a benzene ring. When phenol undergoes catalytic hydrogenation in the presence of nickel (Ni) catalyst and heat, hydrogen atoms are added to the benzene ring. This reaction breaks the aromaticity of benzene and converts the ring into a saturated six-membered ring.

The product formed is cyclohexanol (C₆H₁₁OH), which is a saturated cyclic alcohol. The reaction can be summarized as:

C₆H₅OH + 3H₂ → C₆H₁₁OH
(in the presence of Ni catalyst, high temperature, and pressure).

Cyclohexanol is an important compound in organic and industrial chemistry. It is used as a solvent and as an intermediate in the manufacture of nylon, plasticizers, and other polymers.

The other options can be explained as incorrect:

• 
  

  Cyclohexane (C₆H₁₂) is obtained by complete hydrogenation of benzene, but phenol does not produce cyclohexane under these conditions because the hydroxyl group remains attached.

  
  


• 
  

  n-Hexane is a straight-chain alkane, and it cannot be obtained from phenol hydrogenation.

  
  


• 
  

  1-Hexanol is a straight-chain alcohol, not a cyclic compound, so it is not formed here.

  
  

Thus, the correct product is cyclohexanol, because hydrogenation saturates the benzene ring but does not remove the hydroxyl group from phenol.

This reaction is an example of catalytic reduction of aromatic compounds and is significant in industrial processes where aromatic compounds are converted into useful saturated alcohols.