Question 1

Which of the following best describes the process of decarboxylation as shown for 3-oxo carboxylic acids?

Accepted Answer

Removal of the entire $\mathrm{C=O}$ unit from a carboxylic acid, often by heating.

Question 2

In the malonic ester synthesis, what is the role of the base in the first step?

Accepted Answer

It deprotonates the alpha carbon, generating an enolate nucleophile.

Question 3

Which sequence correctly describes the steps in the malonic ester synthesis?

Accepted Answer

1. Deprotonation, 2. Alkylation, 3. Hydrolysis and decarboxylation

Question 4

What is the main difference between the malonic ester synthesis and the acetoacetic ester synthesis?

Accepted Answer

Acetoacetic ester synthesis uses a methyl group in place of one ethoxy group of diethyl malonate.

Question 5

During the Gabriel Synthesis, what is the purpose of using phthalimide?

Accepted Answer

To protect the nitrogen and allow selective alkylation via $\mathrm{S_N2}$ reaction.

Question 6

Which of the following is a key advantage of the Gabriel Synthesis over direct alkylation of ammonia?

Accepted Answer

It prevents over-alkylation, yielding only primary amines.

Question 7

In the Stork reaction, what type of nucleophile is used instead of an enolate?

Accepted Answer

An enamine

Question 8

Which of the following best describes the mechanism of the Strecker amino acid synthesis?

Accepted Answer

Aldehyde reacts with ammonia and cyanide to form an aminonitrile, which is hydrolyzed to an amino acid.

Question 9

Which of the following is the correct equation for the decarboxylation of a 3-oxo carboxylic acid?

Question 10

In the malonic ester synthesis, which type of reaction occurs when the enolate attacks the alkyl bromide?

Accepted Answer

$\mathrm{S_N2}$

Question 11

Which of the following statements about the decarboxylation of 3-oxo carboxylic acids is correct?

Accepted Answer

It is facilitated by heating and the presence of a carbonyl group at the beta position.

Question 12

What is the final product of the acetoacetic ester synthesis after hydrolysis and decarboxylation?

Accepted Answer

A substituted ketone

Question 13

In the Gabriel Synthesis, what is the function of acid hydrolysis in the final step?

Accepted Answer

To deprotect the nitrogen, releasing the primary amine.

Question 14

Which of the following is a key intermediate in the Strecker amino acid synthesis?

Accepted Answer

An aminonitrile

Question 15

In the Stork reaction, what is the product after the enamine undergoes 1,4-addition to the alpha, beta-unsaturated ketone?

Accepted Answer

A substituted ketone after hydrolysis

Question 16

Which of the following best explains why direct alkylation of ammonia with alkyl bromide can lead to a mixture of products?

Accepted Answer

Ammonia can react multiple times, leading to primary, secondary, tertiary, and quaternary amines.

Question 17

Which of the following is the correct order of reagents for the Strecker amino acid synthesis?

Accepted Answer

1. $\mathrm{NH_3}$, 2. $\mathrm{KCN}$, 3. $\mathrm{H_3O^+}$

Question 18

Which of the following reactions is most likely to be used for the synthesis of a substituted carboxylic acid from diethyl malonate?

Accepted Answer

Malonic ester synthesis

Question 19

In the mechanism of the malonic ester synthesis, what is the fate of the ester groups after acid hydrolysis and heating?

Accepted Answer

They are hydrolyzed to carboxylic acids, then one is lost as $\mathrm{CO_2}$ via decarboxylation.

Decarboxylation, Ester Synthesis, and Amine Formation in Organic Chemistry

Study Guide - Practice Questions