Deck 21: Aldehydes and Ketones Nucleophilic Addition

Question 1

Which of the following oxidants would work for the following reaction?

A) H₂Cr₂O₇
B) FeCl₃
C) I₂
D) Ag₂O

Answer 1

H₂Cr₂O₇

Question 2

What is the first step in nucleophilic addition under acidic conditions?

A) Protonation of the nucleophile
B) Addition of the nucleophile
C) Loss of water
D) Protonation of the carbonyl

Answer 2

Protonation of the carbonyl

Question 3

What is the major organic product obtained from the following sequence of reactions?

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

Answer 3

III

Question 4

Which is the most reactive carbonyl compound?

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

Question 5

What is the driving force for the Wittig reaction?

A) The formation of an alkene
B) The deprotonation of a phosphonium salt
C) The elimination of triphenylphosphine oxide
D) The formation of a phosphonium salt

Question 6

Why are strongly acidic conditions not used in the formation of enamines and imines?

A) The carbonyl will be protonated.
B) The amine will be completely protonated.
C) The product is not stable to strong acid.
D) An enol will be formed.

Question 7

What is the IUPAC name for the following compound?

A) pivaldehyde
B) 2,2-dimethylpropanal
C) tert-butyl aldehyde
D) 2,2-dimethylpentanal

Question 8

What is the structure of 2-trifluoromethyl-2-methoxybutanal?

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

Question 9

What would you use to prepare the following ylide from the starting phosphonium salt?

A) butyl lithium
B) 1-bromo-2-methylpropane
C) triphenylphosphine
D) acetic acid

Question 10

What compound is consistent with the following ¹H NMR spectrum?

A) Acetone
B) Propanal
C) Cyclobutanone
D) 2-butanone

Question 11

What is the structure of benzophenone?

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

Question 12

Is the following reaction reversible and, if so, under what conditions?

A) No
B) Yes, under acidic conditions
C) Yes, using Pd/C
D) Yes, under basic conditions

Question 13

Why can't you use acidic conditions (such as aqueous hydrochloric acid) for the addition of a Grignard reagent to a ketone?

A) Because the Grignard reagent will react with the acid and be quenched.
B) Because the ketone will be protonated and thus unreactive.
C) Because the ketone will form an unreactive enol.
D) Because the Grignard reagent won't dissolve in aqueous solutions.

Question 14

What is the structure of 3-methylcyclohexanone?

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

Question 15

What is the product of the following reaction?

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

Question 16

What is the product of the following reaction?

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

Question 17

Using ¹H NMR spectroscopy, how can you tell the difference between an aldehyde and a ketone?

A) An aldehyde has a C-H stretch (one or two) between 2700-2830 cm^-1.
B) An aldehyde has a proton signal between 9-10 ppm.
C) A ketone has signals around 2-3 ppm.
D) A ketone has a signal around 200 ppm.

Question 18

Using IR spectroscopy, how can you tell the difference between a ketone and an aldehyde?

A) A ketone has no carbonyl stretch at 1720 cm^-1.
B) An aldehyde has a carbonyl stretch at 1820 cm^-1.
C) An aldehyde has two C-H stretches between 2700-2850 cm^-1.
D) A ketone has no C-H stretches.

Question 19

Which of the following will have the highest wave number for the carbonyl stretch in the IR spectrum?

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

Question 20

What is the product of the following reaction?

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

Question 21

What is the product of the following reaction?

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

Question 22

Name the following aldehyde.

A) 1-methylcyclopentanal
B) 2-methylcyclopentanal
C) 2-methylcyclopentanecarbaldehyde
D) 1-methylcyclopentanylcarbaldehyde

Question 23

What sequence of reactions is required for the following transformation?

A) [1] NaOMe, [2] acetone
B) [1] Ph₃P, [2] acetone
C) [1] Ph₃P, [2] KOtBu, [3] acetone
D) acetone, heat

Question 24

What is the IUPAC for the following compound?

A) 1-formyl-2-nitropropane
B) 1-formyl-3-nitrobutane
C) 2-nitrobutanal
D) 3-nitrobutanal

Question 25

What is the product of the following reaction?

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

Question 26

What is the missing reagent in the reaction below?

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

Question 27

Which of the following products is (are) formed by Wittig reaction of CH₃CH₂CH₂CHO with Ph₃P = CHCH₃?

A) Only I
B) Only II
C) Only III
D) Only I and II

Question 28

What needs to be done to make the following reaction proceed?

A) Heat the reaction.
B) Add an acid catalyst only.
C) Add a base catalyst only.
D) Heat the reaction and add an acid catalyst.

Question 29

What needs to be done to make the following reaction go to starting materials?

A) Heat the reaction.
B) Add aqueous acid.
C) Add aqueous base.
D) Add water.

Question 30

What is (are) the product(s) of the following reaction?

A) I only
B) II only
C) III only
D) II and III

Question 31

What is the product of the following sequence of reactions?

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

Question 32

What is the missing reagent in the reaction below?

A) Ethyl amine, mild acid
B) Diethylamine, mild acid
C) Diethylamine, strong acid
D) Diethylamine, NaOMe

Question 33

What is the missing reagent in the reaction below?

A) Methanol, acid
B) Ethanol, acid
C) NaOEt
D) NaOMe

Question 34

What is the product of the following reaction?

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

Question 35

Butanal (MW= 72) has a boiling point of 76 °C while butanol (MW= 74) has a boiling point of 118 °C. What accounts for this difference in boiling points?

A) Butanol is polar while butanal is not polar.
B) Butanol can exhibit dipole-dipole interactions while butanal cannot.
C) Butanol can hydrogen bond and butanal cannot hydrogen bond.
D) Butanal is less sterically hindered than butanol.

Question 36

How would the following compounds be distinguishable using IR and ¹H NMR spectroscopy?

A) The ¹H NMR spectrum of compound I will have two singlets.
B) The C=O absorption in the IR spectrum of compound I will be at a higher wave number than that of compound II.
C) The ¹H NMR spectrum of compound II will have one triplet at a chemical shift of about 4.
D) The ¹H NMR spectrum of compound I will have two singlets AND the C=O absorption in the IR spectrum of compound I will be at a higher wave number than that of compound II.

Question 37

What is the cyclic hemiacetal product formed from intramolecular cyclization of the following hydroxy aldehyde?

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

Question 38

What is the product?

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

Question 39

What is (are) the product(s) of the following reaction?

A) I only
B) II only
C) III only
D) II and III

Question 40

What is the product of the following reaction?

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

Question 41

When an aldehyde is reacted with excess ethanol with an acid as a catalyst, what is the product called?

A) Hemiacetal
B) Di-ether
C) Di-alkoxy alkane
D) Acetal

Question 42

Cyclic acetals are used as protecting groups for ketones or aldehydes because they are inert to all of the following reagents except

A) aqueous acid.
B) aqueous base.
C) oxidizing reagents.
D) reducing reagents.

Question 43

What is the product of the following reaction?

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

Question 44

Which of the following statements about carbohydrates is not true?

A) Carbohydrates are sugars and starches.
B) Carbohydrates often contain acetals and hemiacetals.
C) In solution, glucose is in the cyclic acetal form only.
D) Glucose can form a cyclic hemiacetal from the acyclic polyhydroxy aldehyde.

Question 45

Identify how you could synthesize an enamine.

A) React a ketone or an aldehyde with a secondary amine.
B) React a ketone or an aldehyde with a primary amine.
C) React a ylide with a primary amine.
D) React a ylide with a secondary amine.