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Which of the Following Compounds Would Undergo Aldol Condensation, Which the Cannizzaro Reaction and Which Neither? Write the Structures of the Expected Products of Aldol Condensation and Cannizzaro Reaction. - CBSE (Science) Class 12 - Chemistry

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Question

Which of the following compounds would undergo aldol condensation, which the Cannizzaro reaction and which neither? Write the structures of the expected products of aldol condensation and Cannizzaro reaction.

(i) Methanal 

(ii) 2-Methylpentanal

(iii) Benzaldehyde 

(iv) Benzophenone

(v) Cyclohexanone 

(vi) 1-Phenylpropanone

(vii) Phenylacetaldehyde 

(viii) Butan-1-ol

(ix) 2, 2-Dimethylbutanal

Solution 1

Aldehydes and ketones having at least one α-hydrogen undergo aldol condensation

The compounds (ii) 2−methylpentanal, (v) cyclohexanone, (vi) 1-phenylpropanone, and (vii) phenylacetaldehyde contain one or more α-hydrogen atoms. Therefore, these undergo aldol condensation.

Aldehydes having no α-hydrogen atoms undergo Cannizzaro reactions. The compounds (i) Methanal, (iii) Benzaldehyde, and (ix) 2, 2-dimethylbutanal do not have any α-hydrogen. Therefore, these undergo cannizzaro reactions

Compound (iv) Benzophenone is a ketone having no α-hydrogen atom and compound (viii) Butan-1-ol is an alcohol. Hence, these compounds do not undergo either aldol condensation or cannizzaro reactions.

Aldol condensation

(ii)

(v)

(vi)

(vii)

Cannizzaro reaction:-

(i)

(iii)

(ix)

Solution 2

2-Methylpertfanal, cyclohexanone, 1-phenylpropanone and phenylacetaldehyde contain one or more a-hydrogen and hence undergo aldol condensation. The reactions and the structures of the expected products are given below:

2)

5)

6)

7)

Methanal, benzaldehyde and 2,2-dimethylbutanal do not contain α-hydrogen and hence undergo Cannizzaro reaction. The reaction. The reactions and the structures of the expected products are given below:

1)

3)

9)

Benzophenone (iv) is a ketone having no α-hydrogen while butan-1-ol (8) is an alcohol. Both of these neither underfo aldol condensation nor cannizzaro reaction.

 

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APPEARS IN

 NCERT Solution for Chemistry Textbook for Class 12 (2018 to Current)
Chapter 12: Aldehydes, Ketones and Carboxylic Acids
Q: 7 | Page no. 378
Solution Which of the Following Compounds Would Undergo Aldol Condensation, Which the Cannizzaro Reaction and Which Neither? Write the Structures of the Expected Products of Aldol Condensation and Cannizzaro Reaction. Concept: Aldehydes and Ketones - Chemical Reactions of Aldehydes and Ketones - Reactions Due to A-hydrogen.
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