Question 1

Which of the following statements best describes the role of a leaving group in a nucleophilic substitution reaction?

Accepted Answer

It departs from the substrate, allowing the nucleophile to bond to the carbon.

Question 2

In the reaction below, which species acts as the nucleophile?

$$\mathrm{CH_3Br} + \mathrm{OH^-} \rightarrow \mathrm{CH_3OH} + \mathrm{Br^-}$$

Accepted Answer

$$\mathrm{OH^-}$$

Question 3

A student is attempting to synthesize an alkyl halide from an alcohol using $$\mathrm{HBr}. $$Which of the following steps is most likely to occur first in the reaction mechanism?

Accepted Answer

The alcohol is protonated by $$\mathrm{H^+}$$, making it a better leaving group.

Question 4

Which of the following compounds would most likely undergo an $$\mathrm{S_N1}$$ reaction mechanism?

Accepted Answer

2-bromo-2-methylpropane

Question 5

Consider the following reaction:

$$\mathrm{CH_3CH_2Cl} + \mathrm{NaOH} \rightarrow \mathrm{CH_3CH_2OH} + \mathrm{NaCl}$$

Which type of reaction mechanism is most likely involved?

Accepted Answer

$$\mathrm{S_N2}$$

Question 6

A tertiary alkyl halide reacts with water to form an alcohol. Which intermediate is most likely formed during this process?

Accepted Answer

Carbocation

Question 7

Which of the following is the best leaving group in nucleophilic substitution reactions?

Accepted Answer

$$\mathrm{Br^-}$$

Question 8

A student mixes 2-bromopropane with sodium cyanide ($$\mathrm{NaCN}) in $$ethanol. What is the major organic product?

Accepted Answer

2-cyanopropane

Question 9

Which factor most increases the rate of an $$\mathrm{S_N2}$$ reaction?

Accepted Answer

A strong nucleophile

Question 10

In a medical case, a patient is exposed to methyl bromide ($$\mathrm{CH_3Br}). $$Which nucleophile in the body is most likely to react with methyl bromide, potentially causing toxicity?

Accepted Answer

Glutathione ($$\mathrm{GSH})$$

Question 11

Which of the following statements about carbocation stability is correct?

Accepted Answer

Tertiary carbocations are stabilized by hyperconjugation and inductive effects.

Question 12

A chemist wants to convert 1-chlorobutane to 1-butanol. Which reagent should be used?

Accepted Answer

$$\mathrm{NaOH}$$

Question 13

Which of the following best explains why $$\mathrm{Br^-} is a $$better leaving group than $$\mathrm{F^-}$$?

Accepted Answer

$$\mathrm{Br^-} is $$less basic and more stable in solution.

Question 14

Which of the following reactions is most likely to proceed via a concerted mechanism?

Accepted Answer

$$\mathrm{S_N2}$$ substitution

Question 15

A student observes that the rate of a reaction between 1-bromobutane and hydroxide ion doubles when the concentration of both reactants is doubled. What does this suggest about the reaction mechanism?

Accepted Answer

It is a bimolecular reaction.

Question 16

Which of the following is a common misconception about nucleophilic substitution reactions?

Accepted Answer

All nucleophilic substitution reactions proceed via a carbocation intermediate.

Question 17

A chemist wants to synthesize tert-butyl chloride from tert-butyl alcohol. Which reagent should be used?

Accepted Answer

$$\mathrm{HCl}$$

Question 18

Which of the following best describes the transition state of an $$\mathrm{S_N2}$$ reaction?

Accepted Answer

The nucleophile and leaving group are both partially bonded to the central carbon.

Question 19

A pharmaceutical company is designing a drug that must avoid nucleophilic substitution by glutathione in the body. Which functional group should be avoided in the drug's structure?

Accepted Answer

Alkyl halide

Question 20

Which of the following statements is true regarding the effect of solvent on $$\mathrm{S_N1}$$ and $$\mathrm{S_N2}$$ reactions?

Accepted Answer

$$\mathrm{S_N1}$$ reactions are favored by polar protic solvents.

Alkyl Halides, Leaving Groups, and Nucleophilic Substitution: Key Concepts and Mechanisms

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