Assertion: 2,2-Dimethylpropanal undergoes Cannizzaro reaction with concentrated NaOH.
Reason: Cannizzaro reaction is a disproportionation reaction.
Answer & explanation
Correct answer: option 2
The correct answer is option 2. Both Assertion and Reason are correct but the Reason is not the correct explanation for the Assertion.
Assertion: 2,2-Dimethylpropanal undergoes Cannizzaro reaction with concentrated NaOH.
Cannizzaro Reaction: This reaction occurs with aldehydes that lack alpha-hydrogen atoms. In the presence of a strong base, such as concentrated NaOH, one molecule of the aldehyde is reduced to an alcohol, and another molecule is oxidized to a carboxylic acid. The structure of 2,2-dimethylpropanal is:
In 2,2-dimethylpropanal, there are no alpha-hydrogen atoms (hydrogen atoms attached to the carbon adjacent to the carbonyl group). This lack of alpha-hydrogens makes it a suitable candidate for the Cannizzaro reaction.
The assertion that 2,2-dimethylpropanal undergoes the Cannizzaro reaction with concentrated NaOH is correct because 2,2-dimethylpropanal lacks alpha-hydrogen atoms, making it a suitable candidate for this reaction.
Reason: Cannizzaro reaction is a disproportionation reaction.
Disproportionation Reaction: A reaction in which a single reactant is both oxidized and reduced, forming two different products. In the Cannizzaro reaction, one aldehyde molecule is reduced to an alcohol, while another is oxidized to a carboxylic acid.
The reason is also correct in describing the nature of the Cannizzaro reaction as a disproportionation reaction. However, this reason does not directly explain why 2,2-dimethylpropanal undergoes the reaction. The key to understanding why 2,2-dimethylpropanal undergoes the Cannizzaro reaction is the absence of alpha-hydrogen atoms, which is not mentioned in the reason.
While both the assertion and the reason are correct, the reason does not specifically explain why 2,2-dimethylpropanal undergoes the Cannizzaro reaction. The absence of alpha-hydrogen atoms in 2,2-dimethylpropanal is the crucial factor enabling it to undergo the Cannizzaro reaction.
Therefore, the correct answer is: Both Assertion and Reason are correct but the Reason is not the correct explanation for the Assertion.