Question 1

Which statement best explains why the C=O bond in a ketone is shorter and more polar than the C=C bond in an alkene?

Accepted Answer

The carbonyl carbon is sp2 hybridized, and the oxygen is more electronegative than carbon, resulting in a shorter, stronger, and more polar bond.

Question 2

Which of the following compounds will show a strong IR absorption near $1725\ \mathrm{cm}^{-1}$ and two additional absorptions near $2710\ \mathrm{cm}^{-1}$ and $2810\ \mathrm{cm}^{-1}$?

Accepted Answer

A simple aldehyde

Question 3

Which reagent would you use to selectively oxidize a primary alcohol to an aldehyde without further oxidation to a carboxylic acid?

Accepted Answer

Pyridinium chlorochromate (PCC)

Question 4

A student wants to synthesize a ketone from a carboxylic acid. Which sequence of reagents would be most appropriate?

Accepted Answer

Organolithium reagent followed by protonation

Question 5

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

Accepted Answer

Ketones and aldehydes have lower boiling points than comparable alcohols because they cannot hydrogen-bond to each other.

Question 6

Which method would you use to synthesize an aldehyde from a nitrile?

Accepted Answer

Reduction with diisobutylaluminum hydride (DIBAL-H)

Question 7

In the Wittig reaction, what is the role of the phosphorus ylide?

Accepted Answer

It acts as a nucleophile, converting the carbonyl group into a new C=C double bond.

Question 8

Which of the following reactions is used to deoxygenate ketones and aldehydes to hydrocarbons?

Accepted Answer

Clemmensen reduction

Question 9

A chemist wants to protect an aldehyde group during a multi-step synthesis. Which strategy should they use?

Accepted Answer

Form a cyclic acetal using a diol

Question 10

Which of the following statements about nucleophilic addition to carbonyl compounds is correct?

Accepted Answer

Aldehydes are more reactive than ketones toward nucleophilic addition due to less steric hindrance and greater partial positive charge on the carbonyl carbon.

Question 11

Which reagent can reduce both ketones and aldehydes, but not esters or carboxylic acids?

Accepted Answer

Sodium borohydride ($\mathrm{NaBH_4}$)

Question 12

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

$\mathrm{CH_3CH_2CH_2COCH_3}$

Accepted Answer

2-pentanone

Question 13

Which test is commonly used to distinguish aldehydes from ketones in the laboratory?

Accepted Answer

Tollens test

Question 14

What is the major product when 2-butanone reacts with sodium borohydride ($\mathrm{NaBH_4}$) in methanol?

Accepted Answer

2-butanol

Question 15

Which of the following statements about IR spectroscopy of carbonyl compounds is correct?

Accepted Answer

Ring strain increases the C=O stretching frequency.

Question 16

Which of the following is the correct order of functional group priority for IUPAC nomenclature (highest to lowest)?

Accepted Answer

Acids > esters > aldehydes > ketones > alcohols

Question 17

A chemist performs ozonolysis on 2-butene. What are the expected products?

Accepted Answer

Two molecules of acetaldehyde

Question 18

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

Accepted Answer

It involves the transfer of a proton from the alpha carbon to the oxygen, resulting in the formation of an alkene.

Question 19

Which of the following is true about the formation of imines from aldehydes or ketones?

Accepted Answer

Aldehydes or ketones react with ammonia or a primary amine to form imines via acid-catalyzed addition and dehydration.

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

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