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Aldehydes and Ketones - Problem Set Review
May 28, 2024
Lecture Notes: Aldehydes and Ketones - Problem Set Review
Problem 1: Carbonyl Group Properties
Identify the false statement about carbonyl:
(A) Carbonyl carbon is electrophilic -
True
(B) Carbonyl oxygen is electron withdrawing -
True
(C) Resonance structure places positive charge on carbonyl carbon -
True
(D) Pi electrons are mobile and are pulled toward the carbonyl carbon - False
Problem 2: Boiling Points of Compounds
Ordering compounds by increasing boiling point:
Compounds: Butane (alkane), Butanol (alcohol), Butanone (ketone)
Order:
Butane (lowest boiling point)
Butanone (higher boiling point due to dipole interactions)
Butanol (highest boiling point due to hydrogen bonding) -
Answer: B
Problem 3: Reaction Product Identification
Reaction: Ketone + 1 equivalent of primary alcohol
Product: Hemiketal (due to single equivalent of alcohol)
Answer: C
Problem 4: Ketone + Primary Amine Reaction
Reaction between ketone and primary amine results in Imine formation
Double bond between carbon and nitrogen
Answer: A
Problem 5: Oxidation Reaction
Reaction: Aldehyde + Potassium Permanganate
Product: Carboxylic Acid
Answer: B
Problem 6: Ketone + Lithium Aluminum Hydride Reaction
Lithium Aluminum Hydride reduces ketones to secondary alcohols
Answer: B
Problem 7: Aldehyde + Excess Ethanol Reaction
Reaction: Benzaldehyde with excess ethanol in presence of anhydrous HCl
Product: Acetal (due to two equivalents of alcohol)
Answer: D
Problem 8: Isolation Difficulty of Hemiacetals and Hemiketals
Reasons for instability:
Molecules are unstable
Hydroxy group is rapidly protonated and lost as water under acidic conditions
Answer: B (Statements 1 and 2)
Problem 9: Structure of Hemiacetal
Central carbon in hemiacetal is bonded to:
Hydrogen, Alkyl group, OH group, OR group
Answer: A
Problem 10: Major Product Formation - Aldehyde vs. Ketone
Reaction: Hydrogen Cyanide + Butyraldehyde vs. Ethyl Methyl Ketone
Aldehyde is more reactive towards nucleophiles
Major product: Aldehyde + Hydrogen Cyanide forms cyano-hydrin
Answer: A
Problem 11: Pyridinium Chlorochromate (PCC) Properties
PCC as an oxidant:
Forms aldehydes from primary alcohols
Oxidizes secondary alcohols to ketones
Answer: C (Statements 1 and 3)
Problem 12: Formation of Geminal Diol
Hydration reaction: Water adds to carbonyl forming geminal diol
Answer: B (Water)
Problem 13: Ammonia + Aldehyde Reaction
Reaction: Ammonia + Glutaraldehyde
Product: Imine (carbon double bonded to nitrogen)
Answer: A
Problem 14: Ketone to Secondary Alcohol Reduction
Reducing Agent: Lithium Aluminum Hydride (LiAlH₄)
Answer: C
Problem 15: Enamine Formation
Tautomerization of imines results in enamine formation
Answer: D
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