Unit 19: Aldehydes & Ketones: Nucleophilic Addition
Carbonyl addition chemistry is a major second-semester hub because one polarized bond can generate alcohols, acetals, imines, cyanohydrins, and C–C bond-forming products.
Explain why aldehydes are usually more reactive than ketones toward nucleophilic addition.
Predict products of hydride reduction, alcohol addition, amine addition, cyanide addition, and organometallic attack.
Understand hemiacetal/acetal and imine/enamine formation as reversible, acid-catalyzed processes.
Use carbonyl addition patterns strategically in synthesis and protecting-group logic.
Checkpoint Questions
Q: What product forms when acetone reacts with methanol under acid and water is removed?
A: The ketal (acetal analogue) forms after hemiacetal formation followed by substitution of OH by a second methoxy group.
Q: Why does NaBH4 usually reduce aldehydes and ketones but not esters under standard conditions?
A: It is a milder hydride donor and typically is not reactive enough toward less electrophilic carboxylic acid derivatives.