Deck 19: Nucleophilic Addition to Polar Π Bonds 1: Addition of Strong Nucleophiles

Question 1

Which of the following solvents would be the best choice to use for the reduction of a ketone using LiAlH₄?

A)Isopropanol
B)Water
C)Acetic acid
D)Diethyl ether
E)Ethanol

Answer 1

Diethyl ether

Question 2

Predict the product of the following reaction.

A)
B)
C)
D)
E)

Answer 2

Question 3

Which of the following compounds would you expect to react with a nucleophile at the lowest rate?

A)A
B)B
C)C
D)D
E)E

Answer 3

A

Question 4

Which of the following correctly explains why LiAlH₄ is a stronger reducing agent than NaBH₄?

A)LiAlH₄ has less steric hindrance than NaBH₄.
B)The electronegativity of Al is lower than that of B.
C)The electronegativity of Li is higher than that of Na.
D)Hydrogen has a greater partial positive charge in LiAlH₄ than in NaBH₄.
E)The electronegativity difference between Li and H is greater than the difference between Na and H.

Question 5

Predict the major product of the following synthetic scheme.

A)
B)
C)
D)
E)

Question 6

Which of the following structures does not contain an ylide?

A)
B)
C)
D)
E)

Question 7

Choose an appropriate set of reagents to carry out the synthetic step shown below.

A)
B)
C)
D)
E)

Question 8

Which of the following nucleophiles would tend to favor conjugate addition to an α,β-unsaturated carbonyl?

A)CH₃CH₂O^
B)LiAlH₄
C)CH₃(CH₂)₃MgBr
D)CH₃Li
E)(C₆H₅)₃P^- ^ CH₂

Question 9

The chemical behavior of ¹³C is essentially identical to that of ¹²C.If the reaction below is carried out,what percentage of the carbon atoms in the product will be ¹³C?

A)0 percent
B)10 percent
C)20 percent
D)30 percent
E)50 percent

Question 10

What is the major driving force for the mechanistic step shown below?

A)Stability of C C bond
B)Completing the octet around P
C)Electron rich to electron poor
D)Formation of strong P⁺O^ bond
E)Release of ring strain

Question 11

Which of the following reactions would not result in the formation of a racemic mixture of products?

A)
B)
C)
D)
E)

Question 12

With respect to direct and conjugate addition,which of the following statements is false?

A)Reversible addition of a nucleophile generally favors conjugate addition.
B)Very strong nucleophiles often yield the kinetic product.
C)The reaction pathway with the lowest activation energy leads to the thermodynamic product.
D)Irreversible addition of a nucleophile favors the product that is formed most rapidly.
E)The conjugate addition product is more stable.

Question 13

Which of the following is not a feasible Grignard reagent?

A)
B)
C)
D)
E)

Question 14

Which of the following functional groups contains a polar π bond with no leaving group?

A)Nitrile
B)Carboxylic acid
C)Ester
D)Acid chloride
E)Amide

Question 15

Which of the following alkyl halides could not be used to generate a Wittig reagent?

A)
B)
C)
D)
E)

Question 16

Which of the following compounds would you expect to react with a nucleophile at the highest rate?

A)A
B)B
C)C
D)D
E)E

Question 17

Which nucleophile would you expect to add reversibly to an α,β-unsaturated carbonyl?

A)NaBH₄
B)CH₃Li
C)CH₃(CH₂)₃MgBr
D)NaCN
E)LiAlH₄

Question 18

Which of the following molecules would be unlikely to undergo a nucleophilic addition reaction?

A)A
B)B
C)C
D)D
E)E

Question 19

Which of the following compounds would you expect to have the highest percent hydration at equilibrium?

A)A
B)B
C)C
D)D
E)E

Question 20

Which of the following reactions would you expect to result in formation of the highest percentage of the conjugate addition product?

A)
B)
C)
D)
E)

Question 21

Which of the following would not yield the alcohol shown below?

A)
B)
C)
D)
E)

Question 22

When the following compound is treated with dimethyl sulfide followed by sodium hydride,a product is formed whose formula is C₇H₁₂O.Draw a complete,detailed mechanism for this reaction,and predict the structure of the product.

Question 23

Which of the following is the correct order of reactivity for this set of nucleophiles?

A)(CH₃CH₂)₂CuLi > CH₃CH₂MgBr > CH₃CH₂Li
B)CH₃CH₂Li = CH₃CH₂MgBr > (CH₃CH₂)₂CuLi
C)(CH₃CH₂)₂CuLi > CH₃CH₂Li > CH₃CH₂MgBr
D)CH₃CH₂Li > CH₃CH₂MgBr > (CH₃CH₂)₂CuLi
E)CH₃CH₂MgBr > (CH₃CH₂)₂CuLi > CH₃CH₂Li

Question 24

Determine which of the following molecules is most susceptible to nucleophilic attack,and explain why.

Question 25

Two students decide to use different polar aprotic solvents to carry out the reaction below.Student A chooses acetonitrile,while student B chooses tetrahydrofuran.Which is the better choice,and why?

Question 26

Draw the product of the reaction below.

Question 27

From the two routes shown below,choose the one that would be best for carrying out the reduction.Explain your choice.

Question 28

Which of the following reagents would be the best choice to carry out the reaction shown below?

A)NaH
B)(CH₃CH₂)₂CuLi
C)CH₃MgCl
D)CH₃CH₂Li
E)CH₃CH₂MgBr

Question 29

Reductions using LiAlH₄ require a separate acid workup step,while reductions using NaBH₄ do not.Explain why.

Question 30

Which of the following proposed syntheses could be used to produce the molecule shown below as the major product?

A)
B)
C)
D)
E)All of the above would be successful.

Question 31

Fill in the boxes below with the appropriate reagent or product.

Question 32

Could the alkyl halide below be used to generate a sulfonium ylide? Show a mechanism to support your answer.

Question 33

Propose a detailed mechanism for the Knoevenagel condensation,shown below.

Question 34

Devise a synthesis of the compound shown below starting with ethanol and using any other reagents necessary.Provide detailed mechanisms of all reactions used.

Question 35

Give one example of a hypothetical Grignard reagent that contains an incompatible functional group.

Question 36

Which of the following compounds could be synthesized via more than one possible route using a Gilman reagent?

A)
B)
C)
D)
E)

Question 37

Identify compounds X,Y,and Z in the three-step synthesis shown below.

Question 38

Draw both enantiomers formed in the reaction below.

Question 39

Give an example of a ketone that would react with a nucleophile at a higher rate than acetone,and explain why it would be more reactive.
Acetone:

Question 40

The Horner-Wadsworth-Emmons reaction is a modification of the Wittig reaction that utilizes a phosphonate-stabilized carbanion to produce an alkene.Propose a detailed mechanism for the Horner-Wadsworth-Emmons reaction shown below.

Question 41

Propose a synthesis of the following compound,starting with propionaldehyde and using any other reagents necessary.Note: This may require more than one step!

Question 42

Circle the two sites in the molecule below that are electron poor and susceptible to nucleophilic attack.

Question 43

Predict the major organic product and provide a detailed mechanism for the reaction that would occur in the molecule shown below.

Question 44

Propose two syntheses of the following compound,each using a different Gilman reagent.

Question 45

A student proposes the following synthetic step.Briefly explain the problem with this proposed reaction,and suggest an alternative way to synthesize the target molecule using 1-bromopropane and any other necessary reagents.

Question 46

Which is more thermodynamically stable,the product of a conjugate addition or that of a direct addition? Give two specific reasons to support your answer.

Question 47

Fill in the starting material needed to carry out the reaction below.

Question 48

Propose a synthesis to carry out the following transformation,using any reagents necessary.Note: This may require more than one step!

Question 49

A reaction was carried out,and the two products shown below were obtained.Fill in the boxes with the starting material and the reagents that were used,and then draw a mechanism for the formation of the major product.

Question 50

Predict the major organic product for the following sequence of reactions.