Deck 22: Alpha Carbon Chemistry: Enols and Enolates

Question 1

Which of the following statements explains the ketone-enol equilibrium shown below?

A) simple enols are more stable
B) the enol tautomer is stabilized by the conjugated $\pi$ system
C) the enol tautomer is stabilized by the intramolecular hydrogen bonding
D) the diketone is less coplanar
E) both B & C

Answer 1

both B & C

Question 2

Which of the following bases will completely convert 1,4-cyclohexanedione into an enolate?

A) sodium hydroxide
B) sodium ethoxide
C) LDA
D) sodium hydride
E) both C & D

Answer 2

both C & D

Question 3

Which one of the following compounds is most likely to favor the enol tautomer over the ketone tautomer?

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

Answer 3

I

Question 4

Which is the most acidic hydrogen in the following compound?

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

Question 5

Provide the structure of the enol when 3,3,6-trimethyl-4-heptanone is treated with acid.

Question 6

Which is the most acidic hydrogen in the following compound?

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

Question 7

Which of the following is (are) a keto-enol tautomeric pair(s)?

A) I
B) II
C) III
D) IV
E) None of these

Question 8

Arrange the following indicated hydrogens in decreasing order (most to least) of acidity.

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

Question 9

Provide the structure of the enolate when acetophenone is treated with strong base.

Question 10

Which of the following compounds represents an enolate?

A) I
B) II
C) III
D) IV
E) both B & C

Question 11

Which one of the following compounds is most likely to favor the enol tautomer over the ketone tautomer?

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

Question 12

Which of the following indicated $\alpha$ - hydrogens is most acidic?

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

Question 13

Explain why the following equilibrium favors the enol tautomer.

Question 14

Which one of the following compounds is most acidic?

A) ethyl acetoacetate
B) 2-butanone
C) ethyl pentanoate
D) 1-butanol
E) 3-pentanone

Question 15

Which is the most acidic hydrogen in the following compound?

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

Question 16

Which of the following is (are) a keto-enol tautomeric pair(s)?

A) I
B) II
C) III
D) I & II
E) I & III

Question 17

Which is the most acidic hydrogen in the following compound?

A) I
B) II
C) III
D) IV
E) all of these

Question 18

Which of the following is (are) a keto-enol tautomeric pair(s)?

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

Question 19

Which one of the following indicated hydrogens is most acidic?

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

Question 20

Explain why the following equilibrium favors the enol tautomer.

Question 21

Predict the major product for the following reaction.

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

Question 22

Predict the major product for the following reaction.

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

Question 23

Predict the major product for the following reaction.

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

Question 24

Which of the following ketones will give a positive iodoform test?

A) 3-heptanone
B) 3-hexanone
C) cyclohexanone
D) 2-pentanone
E) 2-methyl-3-hexanone

Question 25

Predict the major product for the following reaction.

A) I
B) II
C) III
D) IV
E) none of these

Question 26

Predict the major product for the following reaction.

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

Question 27

Provide the reagents necessary to carry out the following conversion.

Question 28

Which of the following compounds would undergo racemization in presence of a base?

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

Question 29

Provide both resonance structures of the enolate formed when the following ketone is treated with a base.

Question 30

Provide the reagents necessary to carry out the following conversion.

Question 31

Provide the reagents necessary to carry out the following conversion.

Question 32

Predict the major product for the following reaction sequence.

Question 33

Predict the major product for the following reaction.

A) I
B) II
C) III
D) IV
E) none of these

Question 34

Predict the major product for the following reaction.

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

Question 35

Which one of the following compounds would undergo racemization at the $\alpha$ -stereocenter in presence of a base?

A) I
B) II
C) III
D) IV
E) none of these

Question 36

Provide both resonance structures of the enolate formed when the following ester is treated with a base.

Question 37

Provide both resonance structures of the enolate formed when the following ketone is treated with a base.

Question 38

Provide the reactant that would yield m-chlorobenzoic acid using the haloform reaction.

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

Question 39

Provide the reagents necessary to carry out the following conversion.

Question 40

Predict the major product for the following reaction and provide a curved arrow mechanism for the formation of the product.

Question 41

Provide the reactant(s) that would give the following possible aldol condensation product.

Question 42

Provide the reactants that would give the following aldol condensation product.

A) I
B) II
C) III
D) IV
E) none of these

Question 43

Provide the reactant(s) that would give the following aldol condensation product.

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

Question 44

Predict the major product for the following reaction.

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

Question 45

Which one of the following compounds does not undergo an aldol addition reaction in the presence of aqueous sodium hydroxide?

A) butanal
B) 2-methylbutanal
C) 3-methylpentanal
D) 2,2-dimethylbutanal
E) none of these

Question 46

Predict the product for the following reaction.

Question 47

Predict the major product for the following reaction.

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

Question 48

Predict the major product(s) for the following reaction.

A) I
B) II & IV
C) III
D) I & III
E) V

Question 49

Which one of the following is not a possible product when a crossed aldol addition reaction is carried out with ethanal and butanal as reactants?

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

Question 50

Predict the product when cyclohexanone reacts with aqueous sodium hydroxide at 100 ^$\degree$ C.

A) I
B) II
C) III
D) IV
E) none of these

Question 51

Predict the major product for the following reaction.

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

Question 52

Predict the product for the following reaction.

A) I
B) II
C) III
D) IV
E) none of these

Question 53

Provide the reactants that would give the following aldol condensation product.

A) I
B) II
C) III
D) IV
E) none of these

Question 54

Predict the major product for the following reaction.

A) I
B) II
C) III
D) IV
E) none of these

Question 55

Provide the reactant(s) that would give the following aldol condensation product.

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

Question 56

Predict the product for the following reaction.

A) I
B) II
C) III
D) IV
E) none of these

Question 57

Predict the product for the following reaction.

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

Question 58

Provide the reactant(s) that would give the following possible aldol condensation product.

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

Question 59

Provide the reactants that would give the following aldol condensation product.

Question 60

Predict the product for the following reaction.

Question 61

Predict the product(s) for the following reaction.

A)I
B)II
C)III
D)IV
E) all of these

Question 62

Provide the structure of reactant (X) for the following reaction.

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

Question 63

Provide the reactants that will yield the following compound as crossed Claisen condensation product.

Question 64

Predict the major product for the following reaction.

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

Question 65

Predict the product(s) for the following reaction.

A)I
B)II
C)III
D). I&IV
E) I & III

Question 66

Provide the reactant(s) that will yield the following Claisen condensation product.

Question 67

Explain why CH₃ONa should not be used for Claisen condensation of ethylbutanoate.

Question 68

Predict the product for the following Dieckmann-like cyclization.

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

Question 69

Which of the following compounds can be prepared using the Dieckmann condensation?

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

Question 70

Predict the major product for the following reaction sequence.

Question 71

Provide a stepwise synthesis for the following compound starting with cycloheptene and using the Dieckmann cyclization.

Question 72

Which one of the following is a major product in a Claisen condensation?

A) $\infty$ -keto ester
B) $\beta$ -keto ester
C) $\beta$ -hydroxy ester
D) $\gamma$ -hydroxyester
E) $\beta$ -diketone

Question 73

Predict the product(s) for the following reaction.

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

Question 74

Predict the major product for the following reaction.

Question 75

Predict the product(s) for the following reaction.

A)I
B)II
C)III
D)IV
E) All of these

Question 76

Predict the product(s) for the following reaction.

A)I
B)II
C) III
D)IV
E) none of these

Question 77

Provide the reactant(s) that would give the following possible aldol condensation product.

Question 78

Predict the major product for the following reaction.

A) I
B) II
C) III
D) IV
E) none of these

Question 79

Predict the product(s) for the following reaction.

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

Question 80

Predict the product(s) for the following reaction.

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