Q: Which of the following is the correct formula for the base-dissociation constant ($$K_b) of an $$amine?

$$K_b = \frac{[\text{RNH}_3^+][\text{OH}^-]}{[\text{RNH}_2]}$$

Q: Which reagent is commonly used to convert a tertiary amine to an amine oxide for the Cope elimination?

Hydrogen peroxide ($$\text{H}_2\text{O}_2)$$

Question 1

Which of the following statements best explains why tertiary amines have lower boiling points than primary and secondary amines of similar molecular weight?

Accepted Answer

Tertiary amines cannot form hydrogen bonds with themselves because they lack N–H bonds.

Question 2

Which of the following amines would be expected to have the highest solubility in water?

Accepted Answer

Diisopentylamine (secondary, branched)

Question 3

What is the major product when aniline is treated with excess bromine in aqueous NaHCO$$_3$$?

Accepted Answer

2,4,6-tribromoaniline

Question 4

Which of the following best describes the mechanism of imine formation from a primary amine and an aldehyde?

Accepted Answer

Acid-catalyzed addition of the amine to the carbonyl, followed by acid-catalyzed dehydration

Question 5

Why are alkyl amines generally stronger bases than ammonia?

Accepted Answer

Alkyl groups stabilize the ammonium ion through inductive effects, making the amine a stronger base.

Question 6

Which of the following is true regarding the chirality of amines?

Accepted Answer

Chiral amines with three different groups and a lone pair cannot be resolved into enantiomers due to rapid nitrogen inversion.

Question 7

Which of the following best explains why aromatic amines such as aniline are less basic than aliphatic amines?

Accepted Answer

Resonance delocalization of the nitrogen lone pair into the aromatic ring decreases basicity.

Question 8

Which of the following is the correct formula for the base-dissociation constant ($$K_b) of an $$amine?

Accepted Answer

$$K_b = \frac{[	ext{RNH}_3^+][	ext{OH}^-]}{[	ext{RNH}_2]}$$

Question 9

Which of the following statements about the Hofmann elimination is correct?

Accepted Answer

The major product is the least substituted alkene due to steric effects of the bulky leaving group.

Question 10

Which reagent is commonly used to convert a tertiary amine to an amine oxide for the Cope elimination?

Accepted Answer

Hydrogen peroxide ($$	ext{H}_2	ext{O}_2)$$

Question 11

Which of the following best describes the regioselectivity of the Cope elimination?

Accepted Answer

The least substituted alkene (Hofmann product) is favored.

Question 12

Which of the following is a key step in the purification of amines using acid-base extraction?

Accepted Answer

Conversion of the amine to its water-soluble ammonium salt by treatment with aqueous HCl.

Question 13

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

Accepted Answer

Protonation of pyrrole disrupts its aromaticity, making it unfavorable.

Question 14

Which of the following is the best method to synthesize a primary amine from an alkyl halide with an additional carbon atom?

Accepted Answer

Form the nitrile by SN2 reaction, then reduce with $$	ext{LiAlH}_4 or$$ $$	ext{H}_2.$$

Question 15

Which of the following statements about sulfanilamide is correct?

Accepted Answer

Sulfanilamide is an analogue of p-aminobenzoic acid and inhibits bacterial growth by interfering with folic acid synthesis.

Question 16

Which of the following is a limitation of the Gabriel synthesis for amines?

Accepted Answer

It is limited to the synthesis of primary amines.

Question 17

Which of the following best describes the directing effects of the amino group (–NH$$_2) in $$electrophilic aromatic substitution?

Accepted Answer

It is a strong activator and directs substitution to the ortho and para positions.

Question 18

Which of the following is the best leaving group for nucleophilic aromatic substitution on pyridine?

Accepted Answer

Chloride ion (Cl$$^-$$), because it is a good leaving group and stabilizes the negative charge on nitrogen.

Amines: Structure, Properties, and Reactions (Organic Chemistry II, Chapter 19)

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