Question 1

Which of the following statements best explains why the boiling points of aldehydes and ketones are lower than those of alcohols with similar molecular weights?

Accepted Answer

Aldehydes and ketones cannot form hydrogen bonds with each other because they lack an O—H group.

Question 2

What is the IUPAC name for the following compound: $$\mathrm{CH_3CH_2CH_2CH=O}$$?

Accepted Answer

Butanal

Question 3

Which of the following compounds will show a strong IR absorption near $$1700\ \mathrm{cm}^{-1}$$ and a weak absorption near $$2710\ \mathrm{cm}^{-1}$$?

Accepted Answer

An aldehyde

Question 4

Which of the following best describes the effect of conjugation on the IR absorption frequency of the carbonyl group in aldehydes and ketones?

Accepted Answer

Conjugation lowers the C=O stretching frequency.

Question 5

Which of the following is the correct product when acetone reacts with HCN under basic conditions?

Accepted Answer

$$\mathrm{(CH_3$)_2C(OH)CN}$$

Question 6

Which of the following statements about the reactivity of aldehydes and ketones toward nucleophilic addition is correct?

Accepted Answer

Aldehydes are generally more reactive than ketones due to less steric hindrance and fewer electron-donating groups.

Question 7

Which of the following methods can be used to synthesize a ketone from a secondary alcohol?

Accepted Answer

Oxidation with $$\mathrm{Na_2Cr_2O_7}$$ and $$\mathrm{H_2SO_4}$$

Question 8

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

Accepted Answer

Acetals are commonly used as protecting groups for aldehydes and ketones because they are stable to base and reducing agents.

Question 9

Which of the following reagents will selectively reduce an aldehyde to a primary alcohol without affecting an ester group in the same molecule?

Accepted Answer

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

Question 10

A compound with the structure $$\mathrm{C_6H_5COCH_3} is $$best named as:

Accepted Answer

Acetophenone

Question 11

Which of the following best describes the McLafferty rearrangement observed in the mass spectrometry of ketones?

Accepted Answer

A hydrogen atom is transferred from the gamma position to the carbonyl oxygen, resulting in a neutral alkene and an enol fragment.

Question 12

Which of the following reactions is used to convert an aldehyde or ketone to an alkene via a phosphorus ylide?

Accepted Answer

Wittig reaction

Question 13

Which of the following statements about the reaction of aldehydes and ketones with primary amines is correct?

Accepted Answer

The reaction forms an imine (Schiff base) and is reversible under acidic or basic conditions.

Question 14

Which of the following is the correct IUPAC name for the compound shown below?

$$\mathrm{CH_3CH_2CH(CH_3$)CH=O}$$

Accepted Answer

2-methylbutanal

Question 15

Which of the following statements about the Tollen’s test is correct?

Accepted Answer

Aldehydes give a positive Tollen’s test, forming a silver mirror, while ketones do not.

Question 16

Which of the following best explains why electron-withdrawing groups increase the reactivity of a carbonyl compound toward nucleophilic addition?

Accepted Answer

They increase the partial positive charge on the carbonyl carbon, making it more electrophilic.

Question 17

Which of the following is the correct product when benzaldehyde reacts with ethylamine under mildly acidic conditions?

Accepted Answer

An imine (Schiff base)

Question 18

Which of the following is the correct IUPAC name for the compound shown below?

$$\mathrm{OHC-(CH_2$)_4-CHO}$$

Accepted Answer

Hexanedial

Question 19

Which of the following statements about the reduction of aldehydes and ketones with $$\mathrm{$$NaBH_4$$}$$ and $$\mathrm{$$LiAlH_4$$} is $$correct?

Accepted Answer

$$\mathrm{$$NaBH_4$$} is $$selective for aldehydes and ketones, while $$\mathrm{$$LiAlH_4$$}$$ can also reduce esters and carboxylic acids.

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

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