Question 1

Which of the following statements best explains why aldehydes are generally more reactive than ketones toward nucleophilic addition reactions?

Accepted Answer

Aldehydes have less steric hindrance and a greater partial positive charge on the carbonyl carbon compared to ketones.

Question 2

Which of the following carbonyl-containing functional groups is most reactive toward nucleophilic acyl substitution?

Accepted Answer

Thioester

Question 3

In the mechanism of nucleophilic addition to a carbonyl compound, what is the role of the tetrahedral intermediate?

Accepted Answer

It is a transient species formed after nucleophilic attack and before the ejection of a leaving group.

Question 4

Which factor most directly increases the rate of nucleophilic attack at the carbonyl carbon in a C=O group?

Accepted Answer

Increasing the magnitude of the partial positive charge ($$\delta^+) on $$the carbonyl carbon.

Question 5

Which of the following is NOT a possible fate of a carbonyl group in organic reactions?

Accepted Answer

Directly forming a carbocation at the carbonyl carbon without any nucleophilic or electrophilic attack.

Question 6

In Fischer esterification, why must the carbonyl oxygen be protonated before nucleophilic attack by alcohol?

Accepted Answer

Protonation increases the electrophilicity of the carbonyl carbon, making it more susceptible to nucleophilic attack.

Question 7

Which of the following best describes the rate-determining step (RDS) in nucleophilic addition to a carbonyl compound?

Accepted Answer

Nucleophilic attack on the carbonyl carbon.

Question 8

Which of the following functional groups has the best leaving group for nucleophilic acyl substitution?

Accepted Answer

Thioester ($$-SR)$$

Question 9

Consider the following reaction:

$$\ce{RCOCl + H2O \rightarrow RCOOH + HCl}$$

Which factor makes acyl chlorides highly reactive toward nucleophilic substitution?

Accepted Answer

The chloride ion is a good leaving group and the carbonyl carbon is highly electrophilic.

Question 10

Which of the following statements about resonance effects in carbonyl chemistry is correct?

Accepted Answer

Resonance between carbon and oxygen is stronger than between carbon and sulfur in the same row of the periodic table.

Question 11

Which of the following best explains why amides are less reactive than esters in nucleophilic acyl substitution?

Accepted Answer

Amides have greater resonance stabilization due to nitrogen's ability to donate electrons.

Question 12

Which of the following is the correct order of nucleophilic acyl substitution reactivity for the following functional groups: thioester, ester, amide, carboxylate ion?

Accepted Answer

Thioester \u003e ester \u003e amide \u003e carboxylate ion

Question 13

A student is asked to compare the rates of nucleophilic addition to an aldehyde and a ketone. Which factor should they consider most important?

Accepted Answer

The steric hindrance around the carbonyl carbon.

Question 14

Which of the following statements about enolate formation is correct?

Accepted Answer

Enolate formation is assisted by resonance stabilization of the conjugate base.

Question 15

In the flowchart for carbonyl mechanisms, what is the significance of asking 'Is there a leaving group?' after the tetrahedral intermediate is formed?

Accepted Answer

It determines whether the reaction will proceed via nucleophilic addition or nucleophilic acyl substitution.

Question 16

Which of the following best describes the effect of steric hindrance on the reactivity of ketones compared to aldehydes?

Accepted Answer

Steric hindrance is higher in ketones, making them less reactive than aldehydes.

Question 17

Which of the following is a correct statement about the role of resonance in amides?

Accepted Answer

Resonance in amides decreases the reactivity of the carbonyl carbon toward nucleophilic attack.

Question 18

Which of the following is the best explanation for why carboxylate ions are the least reactive toward nucleophilic acyl substitution?

Accepted Answer

Carboxylate ions have a poor leaving group and strong resonance stabilization.

Question 19

Which of the following steps is necessary for the formation of an enolate ion from a carbonyl compound?

Accepted Answer

Deprotonation of the alpha carbon adjacent to the carbonyl group.

Carbonyl Chemistry: Mechanisms, Reactivity, and Functional Groups

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