Question 1

Which of the following carbonyl compounds is the most reactive toward nucleophilic acyl substitution?

Accepted Answer

$$\mathrm{RCOCl} ($$acyl chloride)

Question 2

What is the main reason amides have the highest boiling points among carboxylic acid derivatives?

Accepted Answer

They can form extensive intermolecular hydrogen bonds and dipole-dipole interactions.

Question 3

In the nucleophilic acyl substitution mechanism, what is the role of the tetrahedral intermediate?

Accepted Answer

It is a high-energy intermediate that collapses to expel the leaving group and reform the carbonyl.

Question 4

Which leaving group is the most stable (least basic) in nucleophilic acyl substitution reactions?

Accepted Answer

$$\mathrm{Cl^-}$$

Question 5

Why is acid catalysis required for the hydrolysis of esters but not for the hydrolysis of amides?

Accepted Answer

Esters are less electrophilic and require protonation to increase their reactivity toward nucleophiles.

Question 6

Which of the following best explains why saponification (base-catalyzed hydrolysis of esters) is used in soap making?

Accepted Answer

It generates sodium salts of fatty acids, which aggregate into micelles that can trap grease.

Question 7

Which of the following statements about the resonance stabilization of carboxylic acid derivatives is correct?

Accepted Answer

Amides have the greatest resonance stabilization due to the ability of nitrogen to donate electron density.

Question 8

A student attempts to synthesize an amide directly from a carboxylic acid and an amine. What is the most likely outcome?

Accepted Answer

A salt is formed due to acid-base reaction, and no amide is produced.

Question 9

Which laboratory reagent is commonly used to convert a carboxylic acid to an acyl chloride?

Accepted Answer

$$\mathrm{$$SOCl_2$$} ($$thionyl chloride)

Question 10

Which of the following best describes the structure and function of a micelle formed by soap molecules in water?

Accepted Answer

A spherical aggregate with hydrophilic heads on the outside and hydrophobic tails on the inside, trapping nonpolar substances.

Question 11

Why do detergents not form 'soap scum' in hard water, unlike traditional soaps?

Accepted Answer

Detergents contain sulfonate groups that do not precipitate with divalent cations.

Question 12

Which of the following correctly ranks the reactivity of carboxylic acid derivatives toward nucleophilic acyl substitution (from most to least reactive)?

Accepted Answer

Acyl chloride \u003e anhydride \u003e ester \u003e carboxylic acid \u003e amide

Question 13

In a Fischer esterification reaction, which of the following is required to drive the reaction toward ester formation?

Accepted Answer

Removal of water from the reaction mixture

Question 14

Which of the following best explains why thioesters are more reactive than regular esters in biological systems?

Accepted Answer

Thioesters have poorer resonance overlap, making the carbonyl carbon more electrophilic.

Question 15

Which of the following statements about the mechanism of acid-catalyzed ester hydrolysis is correct?

Accepted Answer

The acid catalyst protonates the carbonyl oxygen, increasing the electrophilicity of the carbonyl carbon.

Question 16

Which of the following is a real-world application of nucleophilic acyl substitution in medicine?

Accepted Answer

Hydrolysis of the $$\beta-$$lactam ring in penicillin by $$\beta-$$lactamase enzymes in resistant bacteria.

Question 17

Which of the following best describes the role of ATP in activating carboxylic acids in biochemical pathways?

Accepted Answer

ATP forms a mixed anhydride with the carboxylic acid, increasing its reactivity toward nucleophilic attack.

Question 18

A fat or oil is hydrolyzed with NaOH to produce which of the following products?

Accepted Answer

Glycerol and sodium salts of fatty acids (soap)

Question 19

Which of the following statements about the basicity of leaving groups in carboxylic acid derivatives is correct?

Accepted Answer

$$\mathrm{NH_2$^-} is a $$stronger base than $$\mathrm{Cl^-}.$$

Carboxylic Acids and Their Derivatives: Structure, Properties, and Reactions

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