Question 1

Which of the following statements best explains why the C=O bond in a ketone is shorter and stronger than the C=C bond in an alkene?

Accepted Answer

The C=O bond involves a double bond with a more electronegative atom, resulting in greater s-character and stronger overlap.

Question 2

Given the following structure, what is the correct IUPAC name for the compound: $$\mathrm{CH_3CH_2COCH_3}$$?

Accepted Answer

2-butanone

Question 3

Which of the following functional groups has the highest priority in IUPAC nomenclature?

Accepted Answer

Carboxylic acid

Question 4

Why do simple aldehydes and ketones have lower boiling points than alcohols of similar molecular weight?

Accepted Answer

Aldehydes and ketones cannot act as hydrogen-bond donors.

Question 5

Which IR absorption is most characteristic of a simple aldehyde?

Accepted Answer

$$1725\ \mathrm{cm}^{-1} (C=O $$stretch) and $$2710\ \mathrm{cm}^{-1} (C$$–H stretch)

Question 6

A compound shows a $$^1\mathrm{H}$$ NMR signal at $$\delta = 9.8$$ ppm. Which functional group is most likely present?

Accepted Answer

Aldehyde

Question 7

Which synthetic method would you use to prepare a ketone from a carboxylic acid?

Accepted Answer

React the carboxylic acid with an organolithium reagent, then protonate and dehydrate.

Question 8

Which reagent can selectively reduce an acid chloride to an aldehyde?

Accepted Answer

$$\mathrm{LiAlH(O-t-Bu)_3}$$

Question 9

What is the product of the reaction between acetone and propylmagnesium bromide followed by aqueous workup?

Accepted Answer

2-methyl-2-pentanol

Question 10

Which of the following statements about the reactivity of carbonyl compounds is correct?

Accepted Answer

Aldehydes are more reactive toward nucleophilic addition than ketones.

Question 11

Which of the following best describes the mechanism of cyanohydrin formation from a ketone?

Accepted Answer

Base-catalyzed nucleophilic addition of cyanide ion to the carbonyl carbon, followed by protonation.

Question 12

Which of the following is a correct statement about the use of acetals in organic synthesis?

Accepted Answer

Acetals are used as protecting groups for aldehydes and ketones because they are stable in basic and neutral solutions.

Question 13

Which of the following reagents will reduce a ketone to a secondary alcohol but will NOT reduce an ester?

Accepted Answer

$$\mathrm{$$NaBH_4$$}$$

Question 14

A student wants to synthesize 1-phenyl-1-propanone. Which of the following synthetic routes is most appropriate?

Accepted Answer

Friedel-Crafts acylation of benzene with propanoyl chloride

Question 15

Which of the following best explains why formaldehyde is a gas at room temperature while acetaldehyde and acetone are liquids?

Accepted Answer

Formaldehyde has a lower molecular weight and weaker intermolecular forces.

Question 16

Which of the following is a correct statement about the McLafferty rearrangement in mass spectrometry?

Accepted Answer

It involves a hydrogen transfer via a six-membered ring and requires a gamma hydrogen.

Question 17

Which of the following is the correct product of the Wittig reaction between benzaldehyde and methyltriphenylphosphonium ylide?

Accepted Answer

Styrene ($$\mathrm{C_6H_5CH=CH_2$})$$

Question 18

A chemist wants to oxidize an aldehyde to a carboxylic acid. Which reagent would be most appropriate?

Accepted Answer

Tollens reagent ($$\mathrm{Ag(NH_3$)_2^+})$$

Question 19

Which of the following statements about the hydration of ketones and aldehydes is correct?

Accepted Answer

The equilibrium favors the unhydrated keto form for ketones.

Aldehydes and Ketones: Structure, Properties, Nomenclature, and Reactions

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