Deck 16: Substitution Reactions of Carbonyl Compounds at the Α Carbon

Question 1

Which of the following is the least acidic compound?

A) II
B) I
C) III
D) IV

Answer 1

I

Question 2

Treatment of 2-hexanone with NaOCH₂CH₃ followed by CH₃Br affords compound X (C₇H₁₄O) as the major product. X shows a strong absorption in the IR spectrum at 1713 cm^?1, and its ¹H NMR data is given below. What is the structure of X?


$\begin{array}{llcc} \text {Signal \# } & \text { Shift (ppm) } & \text {Multiplicity } & \text {Integration }\\1&0.96& \text {triplet}&3 \mathrm{H}\\2&1.16& \text {doublet}&3 \mathrm{H}\\3&1.33& \text {multiplet}&2 \mathrm{H}\\4&1.53&\text {multiplet}&2 \mathrm{H}\\5&2.09& \text {singlet}&3 \mathrm{H}\\6&2.52& \text {multiplet}&1 \mathrm{H}\end{array}$

A) IV
B) III
C) II
D) I

Answer 2

IV

Question 3

The reaction below is a direct enolate alkylation. It has been found that this reaction only works well with unhindered methyl and 1° alkyl halides. Pick the statement that best explains this observation.

A) Hindered alkyl halides do not undergo S_N1 reactions.
B) The nucleophilic enolate requires a reaction center that has a positive charge.
C) Hindered alkyl halides do not undergo S_N2 reactions.
D) Methyl and 1° alkyl halides can form carbocations that can readily react with the nucleophilic enolate.

Answer 3

Hindered alkyl halides do not undergo S_N2 reactions.

Question 4

Which of the following compound would most likely undergo racemization under basic conditions?

A) (S)-4-Iodo-2-pentanone
B) (R)-5-Iodo-5-bromo-2-pentanone
C) (R)-3-Iodo-2-pentanone
D) (R)-4-Iodo-2-pentanone

Question 5

The following molecule is called

A) an ethyl acetoacetate.
B) a 1,3-diketopentanoate.
C) a b-keto ester.
D) a diethyl malonate.

Question 6

What is the product of the following reaction?

A) IV
B) I
C) III
D) II

Question 7

Select the appropriate sequence of reactions to accomplish the following synthesis.

A) [1] LDA; [2] BrCH₂CH₂CH₂CH₂Br; [3] NaOEt
B) [1] Br₂, CH₃CO₂H; [2] Li₂CO₃, LiBr, DMF; [3] CH₃CH₂CH₂CH₂Br
C) [1] Br₂, CH₃CO₂H; [2] Mg, Et₂O; [3] CH₃CH₂CH₂CH₂Br
D) [1] NaOEt; [2] BrCH₂CH₂CH₂CH₂Br; [3] LDA

Question 8

What is the product of the following reaction?

A) II
B) I
C) IV
D) III

Question 9

What is the major product of the following reaction?

A) IV
B) I
C) III
D) II

Question 10

Which of the following is the most acidic compound?

A) I
B) III
C) IV
D) II

Question 11

Which of the following organic molecules will undergo decarboxylation to form an amine?

A) Histidine
B) Isoamyl acetate
C) Ethyl acetoacetate
D) Pyridine

Question 12

Starting with cyclohexanone, how could you prepare the diketone below?

A) Convert cyclohexanone into the a-bromoketone and then react this with the enolate of cyclohexanone.
B) Convert cyclohexanone into an enamine with diethylamine and then react this with more cyclohexanone.
C) Treat cyclohexanone with a base under thermodynamic conditions.
D) Hydrogenate cyclohexanone with Raney nickel.