Deck 17: Reactions at the Α-Carbon

Question 1

Which is the correct order of decreasing acidity (increasing pK_a)?

A) 4>3>2>1>5
B) 3>2>1>4>5
C) 5>4>2>1>3
D) 1>2>3>4>5
E) 3>1>2>4>5

Answer 1

3>1>2>4>5

Question 2

Which method cannot be used to form an enolate ion from a ketone?

A) KOH, ethanol
B) NaOCH₂CH₃/ethanol
C) LDA
D) CH₃CO₂Na
E) NaNH₂

Answer 2

CH₃CO₂Na

Question 3

Alpha halogenation of a ketone can be accomplished using____________.

A) Br₂, acid catalyst
B) Br₂, base catalyst
C) 1. LDA 2. Br₂
D) NaBr, H₂O, heat
E) all except D

Answer 3

all except D

Question 4

Which compound is the starting material for the following reaction?

A)
B)
C)
D)
E)

Question 5

Which set of reagents can be used to synthesize the following compound?

A) 1. CH₃NH₂/H⁺ 2. C₆H₅-Br
B) 1. NaOH 2. C₆H₅-CH₂OTs
C) 1. NaH 2. CH₃CH₂Br
D) 1. LDA 2. C₆H₅-CH₂Br
E) 1. CH₃MgBr 2. C₆H₅-CH₂Br

Question 6

A Michael reaction ____________.

A) forms a 1,5-dicarbonyl compound
B) forms a beta-hydroxyaldehyde or beta-hydroxyketone
C) forms a cyclic beta-keto ester
D) forms a methyl ketone with three more carbons than the alkyl halide
E) forms a carboxylic acid with two more carbons than the alkyl halide

Question 7

What type of reaction was used to synthesize the following compound?

A) aldol condensation
B) acetoacetic ester synthesis
C)Claisen condensation
D) malonic ester synthesis
E) Robinson annulation

Question 8

What type of reaction was most likely used to prepare the following compound?

A) aldol condensation
B) acetoacetic ester synthesis
C) mixed Claisen condensation
D) malonic ester synthesis
E) Robinson annulation

Question 9

What is the major product of the following reaction?

A)
B)
C)
D)
E)