Q: Which of the following is the correct order of reactivity toward electrophilic aromatic substitution?

$$\text{pyrrole} \u003e \text{furan} \u003e \text{thiophene} \u003e \text{benzene}$$

Q: What is the product of the reaction between pyridine and methyl iodide ($$\text{CH}_3\text{I}$$)?

$$\text{N-methylpyridinium iodide}$$

Q: Which of the following reactions is used to synthesize a primary amine from a nitrile?

Reduction with $$\text{LiAlH}_4$$

Question 1

Which of the following statements best explains why pyrrole is a much weaker base than pyrrolidine?

Accepted Answer

Pyrrole's nitrogen lone pair is delocalized into the aromatic ring, making it unavailable for protonation.

Question 2

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

Accepted Answer

A pyridine ring with a bromine at the 2-position and a methoxy group at the 4-position.

Question 3

Which of the following best describes the Gabriel synthesis?

Accepted Answer

It converts an alkyl halide to a primary amine using phthalimide as an intermediate.

Question 4

Which of the following is the correct order of reactivity toward electrophilic aromatic substitution?

Accepted Answer

$$	ext{pyrrole} \u003e 	ext{furan} \u003e 	ext{thiophene} \u003e 	ext{benzene}$$

Question 5

What is the product of the reaction between pyridine and methyl iodide ($$	ext{CH}_3	ext{I}$$)?

Accepted Answer

$$	ext{N-methylpyridinium iodide}$$

Question 6

Which of the following statements about the acidity of the methyl group in 2-methylpyridine is correct?

Accepted Answer

The methyl group is more acidic due to resonance stabilization of the resulting carbanion.

Question 7

Which of the following best explains why the keto form of cytosine is more stable than the enol form?

Accepted Answer

The keto form allows for greater resonance stabilization and hydrogen bonding.

Question 8

In the reaction of aniline with $$	ext{NaNO}_2$$ and $$	ext{HCl} at$$ $$0^\circC$$, what intermediate is formed?

Accepted Answer

$$	ext{Arenediazonium salt}$$

Question 9

Which of the following heterocycles is found in the amino acid histidine?

Accepted Answer

Imidazole

Question 10

Which of the following best describes the orbital structure of pyridine?

Accepted Answer

The nitrogen lone pair is in an $$sp^2$$ orbital perpendicular to the $$\pi$$ system.

Question 11

Which of the following is a correct statement about the basicity of pyridine compared to aniline?

Accepted Answer

Pyridine is a stronger base than aniline because its nitrogen lone pair is not delocalized into the aromatic ring.

Question 12

Which of the following reactions is used to synthesize a primary amine from a nitrile?

Accepted Answer

Reduction with $$	ext{LiAlH}_4$$

Question 13

Which of the following best explains why substitution in pyrrole occurs at the 2-position in electrophilic aromatic substitution?

Accepted Answer

The intermediate formed by substitution at the 2-position is more stabilized by resonance.

Question 14

Which of the following is the correct product of the reaction between an acyl chloride and two equivalents of methylamine ($$	ext{CH}_3	ext{NH}_2$$)?

Accepted Answer

$$	ext{Amide} + 	ext{CH}_3	ext{NH}_3^+	ext{Cl}^-$$

Question 15

Which of the following statements about the delocalization energy of aromatic heterocycles is correct?

Accepted Answer

$$	ext{Benzene}$$ has the highest delocalization energy among the compounds listed.

Question 16

Which of the following is a real-world application of the porphyrin ring system?

Accepted Answer

It ligates iron in heme, which is found in hemoglobin.

Question 17

Which of the following best describes the difference between the orbital structures of pyrrole and furan?

Accepted Answer

In pyrrole, the nitrogen lone pair is part of the $$\pi$$ cloud, while in furan, one lone pair on oxygen is in an $$sp^2$$ orbital perpendicular to the $$\pi$$ system.

Question 18

Which of the following is the correct product of the reaction between a primary amine and a ketone in the presence of trace acid?

Accepted Answer

An imine

Question 19

Which of the following statements about nucleophilic aromatic substitution in pyridine is correct?

Accepted Answer

Nucleophilic substitution occurs preferentially at the 2- and 4-positions.

More About Amines and Reactions of Heterocyclic Compounds

Guida di studio - Domande di pratica

Study guide - Flashcard