Deck 22: Condensations and Alpha Substitutions of Carboxyl Compounds

Question 1

The structure below is in equilibrium with what tautomer? Draw the structure of the tautomer.

Answer 1

Question 2

Provide a detailed, stepwise mechanism for the base-catalyzed enolization of acetaldehyde.

Answer 2

Question 3

For the equilibrium shown below, is the K_eq greater or less than 1?

Answer 3

less than 1

Question 4

For the equilibrium shown below, is the K_eq greater or less than 1?

Question 5

Provide the major organic product of the following reaction.

Question 6

The relationship between ketones and their corresponding enols is one of:

A) allotropes.
B) tautomers.
C) enantiomers
D) diastereomers.
E) cis-trans isomers.

Question 7

Disregarding stereoisomers, how many different enols can phenylacetone form?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 8

Disregarding stereoisomers, how many different enols can the β-diketone CH₃COCH₂COCH₂CH₃ form?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 9

Which of the following compounds will not undergo reaction with an enolate?

A) 1-pentene
B) bromine
C) propanal
D) 1-bromobutane
E) benzoyl chloride

Question 10

Show how an enolate can add to a carbonyl.

Question 11

When 2-methylcyclohexanone is treated with catalytic base in excess D₂O, how many deuterium atoms become incorporated in the organic compound?

A) 0
B) 1
C) 2
D) 3
E) 5

Question 12

What name is given to the alpha substitution of a carbonyl compound where the electrophilic component is another carbonyl compound?

Question 13

The reaction of LDA with acetophenone produces:

A) an enol.
B) an enolate.
C) an ylide.
D) alkylation.
E) halogenation.

Question 14

Provide the structure of the enol of 2,2,4-trimethyl-3-pentanone.

Question 15

Provide the structure of lithium diisopropylamide.

Question 16

For the equilibrium shown below, is the K_eq greater or less than 1?

Question 17

Which of the following reagents will quantitatively convert an enolizable ketone to its enolate salt?

A) lithium hydroxide
B) lithium diisopropylamide
C) methyllithium
D) diethylamine
E) pyridine

Question 18

Provide a detailed, stepwise mechanism for the acid-catalyzed enolization of acetaldehyde.

Question 19

Provide the structure of the more stable enol tautomer of 1-phenyl-2-octanone.

Question 20

What type of product results when 3-pentanone is treated with LDA (lithium diisopropylamide) at low temperature?

A) enolate
B) enol
C) amide
D) imine
E) enamine

Question 21

Which of the following will alkylate a lithium enolate most rapidly?

A) methyl bromide
B) isopropyl bromide
C) neopentyl bromide
D) bromobenzene
E) 2-methylbromobenzene

Question 22

Methylamine reacts with acetophenone to yield the:

A) iminium salt.
B) imine.
C) acetal.
D) amide
E) enamine.

Question 23

When aldehydes are subjected to the same conditions that α-halogenate ketones (i.e., X₂ and aqueous acid or base), they are:

A) α-halogenated as well.
B) reduced to alcohols.
C) converted to the acid halide.
D) oxidized to the acid or carboxylate.
E) esterified.

Question 24

When a ketone and its enol are in equilibrium, under most conditions the concentration of the enol is ________ the concentration of the ketone.

A) slightly higher than
B) equal to
C) much higher than
D) much lower than
E) exactly half of

Question 25

Provide the major organic product of the following reaction.

Question 26

What iminium salt is produced in the reaction shown below?

Question 27

(S)-2-Methylbutanal ________ upon sitting in an acidic or a basic aqueous solution.

A) racemizes
B) esterifies
C) inverts completely to the R configuration
D) hydrolyzes
E) irreversibly forms the hydrate

Question 28

Provide the major organic product of the following reaction.

Question 29

In the iodoform reaction, a methyl ketone is converted to the ________ upon treatment with excess iodine and hydroxide.

A) carboxylate
B) acyl iodide
C) primary alkyl iodide
D) aldehyde
E) primary amide

Question 30

Provide the major organic product of the reaction shown below.

Question 31

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

A) 4-heptanone
B) 3-hexanone
C) 2-hexanone
D) cyclohexanone
E) 2-methyl-3-pentanone

Question 32

What type of product results when 3-pentanone reacts with dimethylamine?

A) enolate
B) enol
C) amide
D) imine
E) enamine

Question 33

The α-halogenation of cyclohexanone:

A) is catalyzed by base.
B) is slowed by the presence of acid.
C) requires one equivalent of base.
D) requires one equivalent of acid.
E) is catalyzed by the sodium halide salt.

Question 34

Which of the following will react most slowly with an enamine?

A) isopropyl chloride
B) methyl bromide
C) acetyl chloride
D) benzyl chloride
E) allyl bromide

Question 35

What is the carbon nucleophile which attacks molecular bromine in the acid-catalyzed α-bromination of a ketone?

A) an enolate
B) a Grignard reagent
C) an acetylide
D) a carbocation
E) an enol

Question 36

Provide the major organic product of the reaction shown below.

Question 37

What are the two key resonance structures for an enamine? Label the major and minor contributors.

Question 38

Provide the major organic product of the following reaction.

Question 39

What compound is produced in the reaction of cyclopentanone with Br₂ in acetic acid?

Question 40

What species results when cyclopentanone is treated with lithium diisopropylamide at low temperature?

Question 41

Provide the sequence of synthetic steps required to produce N-cyclohexyl-2-bromopropanamide from propanoic acid.

Question 42

Provide a mechanism for the following reaction:
butanoic acid + Br₂ + PBr₃ → 2-bromobutanoyl bromide

Question 43

Complete the following short synthesis by providing the necessary sequence of reagents.

Question 44

Provide the structure of the major organic product which results when PhCH₂CHO is treated with NaOH.

Question 45

Provide the major organic product of the following reaction.

Question 46

Complete the following reaction by filling in the necessary reagents.

Question 47

Show how the following compound can be synthesized using an Aldol Condensation reaction.

Question 48

Provide a detailed, stepwise mechanism for the a-bromination of acetone in base.

Question 49

The following compound was found to inhibit HIV-1 (J. Med. Chem. $\textbf{ 2011, }$ 1812). Predict the structure of the hydrolysis product.

A)

B)

C)

D)

Question 50

The aldol condensation is:

A) an irreversible reaction.
B) an equilibrium reaction.
C) a tautomerization.
D) an isomerization.
E) a type of esterification.

Question 51

What organic compounds are produced when 2-pentanone undergoes the haloform reaction upon treatment with HO^- and excess Br₂?

Question 52

Which of the following is another name for the product of an aldol condensation?

A) β-hydroxyaldehyde
B) α-hydroxyaldehyde
C) acetal
D) β-ketoester
E) 1,3-dialdehyde

Question 53

Provide the major organic product of the following reaction.

Question 54

Provide a detailed, stepwise mechanism for the formation of acetate and bromodiiodomethane from bromoacetone, hydroxide and iodine.

Question 55

What reagents are needed to complete the following synthesis?

A) 1) NaOH / heat, 2) HCl (aq)
B) 1) NaOH / I₂, 2) HCl (aq)
C) 1) warm conc. KMnO₄ / NaOH, 2) HCl (aq)
D) 1) Ag(NH₃)₂OH, 2) HCl (aq)

Question 56

The Hell-Volhard-Zelinsky reaction involves:

A) the α-bromination of carboxylic acids.
B) the α-bromination of ketones.
C) the bromination of alcohols.
D) the oxidation of aldehydes to acids.
E) none of the above.

Question 57

Provide the major organic product of the following reaction.

Question 58

Why is the acid-catalyzed halogenation of ketones generally preferred over the base-promoted halogenation?

Question 59

Which set of reagents would best accomplish the following transformation?

A) Br₂ / HBr
B) Br₂ / PBr₃
C) Br₂ / NaOH
D) PBr₃

Question 60

An enolate attacks an aldehyde and the resulting product is subsequently protonated. What type of reaction is this?

A) a Fischer esterification
B) an acid-catalyzed aldol condensation
C) a base-mediated aldol condensation
D) a Hell-Volhard-Zelinsky reaction
E) a Selman-Jones reaction

Question 61

Provide the sequence of steps necessary to synthesize the compound shown below from cyclohexene.

Question 62

What product results when an aldol is dehydrated?

A) conjugated alkyne
B) β-diketone
C) β-ketoester
D) α,β-unsaturated aldehyde
E) β,γ-unsaturated aldehyde

Question 63

Predict the pK_a unit of the indicated proton within +/- 1 pK_a unit.

A) 5
B) 11
C) 19
D) 24

Question 64

Provide the structure of the ester that would undergo self-condensation to yield the β-ketoester shown below.

Question 65

Provide the structure of the aldol product that results when 4-methylpentanal is treated with sodium hydroxide.

Question 66

In theory a poorly planned crossed aldol reaction can produce how many different aldol regioisomers?

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

Question 67

What two molecules were condensed in an aldol reaction to produce PhCH=CHCOPh?

Question 68

Which of the following could result from the dehydration of a self-aldol condensation product?

A) 4-methyl-3-penten-2-one
B) 4-methyl-4-penten-2-one
C) 4-methyl-5-hexen-2-one
D) 4-methyl-4-hexen-2-one
E) 3-methyl-4-penten-2-one

Question 69

What crossed-aldol product results when propanal is heated in the presence of excess 2,2-dimethylpropanal and sodium hydroxide?

Question 70

Predict the outcome of the following reaction.

Question 71

What two molecules were condensed in an aldol reaction to produce (CH₃)₃CCH=CHCOCH₃?

Question 72

What two organic starting materials are required to produce cinnamaldehyde (PhCH=CHCHO) via a crossed aldol condensation followed by dehydration?

Question 73

What product results when pentanal is heated with sodium hydroxide?

Question 74

Provide the structure of the aldol product that results when 5-methylhexanal is treated with hydroxide.

Question 75

Provide the structure of the product which results from the base-catalyzed condensation followed by dehydration between benzophenone and propanal.

Question 76

The following compound isolated from a marine sponge has been found to have anti-tubercular activity (Tet. Lett. $\textbf{ 2007, }$ 8851). Show how it may be constructed by an aldol reaction by drawing a structure of the starting material.

Question 77

What crossed-aldol product results when butanal is heated in the presence of excess benzaldehyde and sodium hydroxide?

Question 78

Provide the major organic product of the following reaction.

Question 79

Provide the structure of the intramolecular aldol condensation/dehydration product that results when 2,6-heptanedione is heated in base.

Question 80

Name the aldol produced when butanal is treated with NaOH.