Question 1

Which of the following factors most significantly stabilizes the conjugate base of a carboxylic acid, thereby increasing its acidity?

Accepted Answer

Resonance delocalization of the negative charge

Question 2

Consider the following acids: (1) $$\mathrm{CF_2COOH}$$, (2) $$\mathrm{ClCH_2COOH}$$, (3) $$\mathrm{CH_3CH_2COOH}. $$Rank them from most acidic to least acidic and explain the trend.

Accepted Answer

(1) \u003e (2) \u003e (3); Electron-withdrawing groups like F and Cl stabilize the conjugate base by induction, increasing acidity.

Question 3

In the alkylation of a carboxylic acid with two equivalents of $$\mathrm{PhLi}$$, what is the role of the first equivalent of $$\mathrm{PhLi}$$?

Accepted Answer

It acts as a base, deprotonating the carboxylic acid.

Question 4

Which of the following best describes the purpose of the acid catalyst ($$\mathrm{H^+}) in $$the Fischer esterification reaction?

Accepted Answer

It protonates the carboxylic acid carbonyl oxygen, increasing the electrophilicity of the carbonyl carbon.

Question 5

A student mixes a carboxylic acid with excess methanol and a catalytic amount of $$\mathrm{H_2SO_4}. $$Which of the following will drive the Fischer esterification reaction to completion?

Accepted Answer

Removing water as it forms during the reaction

Question 6

Which of the following carboxylic acids will undergo decarboxylation upon heating?

Accepted Answer

$$\mathrm{CH_3COCH_2COOH} (3-$$oxobutanoic acid)

Question 7

Why does 3-oxobutanoic acid undergo decarboxylation upon heating, but 4-oxopentanoic acid does not?

Accepted Answer

Because the carbonyl groups in 3-oxobutanoic acid are in a 1,3-relationship, allowing a six-membered transition state.

Question 8

Which of the following statements about the tetrahedral intermediate in Fischer esterification is correct?

Accepted Answer

It is formed when the alcohol nucleophile attacks the protonated carboxylic acid.

Question 9

Which of the following compounds is the most acidic?

Accepted Answer

$$\mathrm{p}-$$Nitrobenzoic acid

Question 10

A carboxylic acid is treated with two equivalents of $$\mathrm{PhLi}$$ followed by aqueous acid. What is the final organic product?

Accepted Answer

A ketone

Question 11

Which of the following best explains why the conjugate base of 2-chloroethanoic acid is more stable than that of ethanoic acid?

Accepted Answer

The chlorine atom withdraws electron density through induction, stabilizing the negative charge.

Question 12

Which of the following is a necessary structural requirement for a carboxylic acid to undergo decarboxylation upon heating?

Accepted Answer

A carbonyl group at the $$\beta-$$position, forming a 1,3-dicarbonyl system

Question 13

In the mechanism of decarboxylation of a $$\beta-$$keto acid, what is the immediate organic product formed after loss of $$\mathrm{CO_2$}$$?

Accepted Answer

An enol

Question 14

Which of the following statements about the acid-catalyzed formation of an acetal from a ketone and an alcohol is correct?

Accepted Answer

The acid catalyst protonates the ketone, making it a better electrophile.

Question 15

Which of the following best describes the relationship between the two conformers of a $$\beta-$$keto acid that can undergo decarboxylation?

Accepted Answer

They are conformational isomers.

Question 16

Which of the following is NOT a factor that stabilizes the conjugate base of a carboxylic acid?

Accepted Answer

Electron-donating alkyl groups

Question 17

Which of the following statements about the mechanism of Fischer esterification is correct?

Accepted Answer

The alcohol attacks the carbonyl carbon after the carboxylic acid is protonated.

Question 18

Which of the following best explains why amides are less acidic than carboxylic acids?

Accepted Answer

The nitrogen atom in amides is less electronegative than the oxygen atom in acids, so the conjugate base is less stabilized.

Question 19

Which of the following statements about the reaction of a carboxylic acid with $$\mathrm{NaOH} is $$correct?

Accepted Answer

The reaction produces a carboxylate anion and water.

Step-by-Step Guidance for Carboxylic Acids Worksheet (Organic Chemistry)

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