NEETChemistryAldehydes and Ketones
Which of the following compounds CANNOT be obtained as a product from the base-catalyzed aldol condensation reaction between 2-butanone and 4-methylbenzaldehyde (p-tolualdehyde) upon heating?
Options
- A5-(4-methylphenyl)pent-4-en-2-one
- B1-(4-methylphenyl)pent-1-en-3-one
- C3-methyl-4-(4-methylphenyl)but-3-en-2-one
- D5-methylhept-4-en-3-one
Correct answer
A. 5-(4-methylphenyl)pent-4-en-2-one
Step-by-step solution
The reaction is a base-catalyzed aldol condensation between 2-butanone and 4-methylbenzaldehyde. 2-butanone ( CH₃-CO-CH₂-CH₃ ) has two different types of -hydrogens, located at C1 and C3. Thus, it can form two different enolates under basic conditions. 1. If the enolate forms at C1, it attacks the carbonyl carbon of 4-methylbenzaldehyde. Subsequent dehydration yields the cross-aldol product 1-(4-methylphenyl)pent-1-en-3-one. 2. If the enolate forms at C3, it attacks 4-methylbenzaldehyde, and dehydration yields the