Question 1

Which of the following statements best explains why alkyl halides are useful as starting materials in organic synthesis?

Accepted Answer

Alkyl halides contain a halogen atom bonded to a sp\^3 hybrid carbon, which can be easily replaced by a wide variety of nucleophiles, allowing for the synthesis of diverse functional groups.

Question 2

Which compound would have the highest boiling point among the following ethyl halides: $$\mathrm{C_2H_5F}$$, $$\mathrm{C_2H_5Cl}$$, $$\mathrm{C_2H_5Br}$$, $$\mathrm{C_2H_5I}$$?

Accepted Answer

$$\mathrm{C_2H_5I}$$

Question 3

Which of the following best describes the difference between a geminal and a vicinal dihalide?

Accepted Answer

Geminal dihalides have two halogen atoms bonded to the same carbon atom, while vicinal dihalides have two halogen atoms bonded to adjacent carbon atoms.

Question 4

Which of the following alkyl halides would be most reactive in an $$\mathrm{S_N2}$$ reaction with sodium ethoxide ($$\mathrm{Na^+OCH_2CH_3^-}$$)?

Accepted Answer

methyl chloride

Question 5

Which factor most strongly affects the nucleophilicity of an anion in a polar protic solvent?

Accepted Answer

Solvation by hydrogen bonding

Question 6

In the $$\mathrm{S_N2}$$ reaction mechanism, what is the stereochemical outcome when a nucleophile attacks a chiral carbon center?

Accepted Answer

Inversion of configuration

Question 7

Which of the following is the best leaving group for a nucleophilic substitution reaction?

Accepted Answer

$$\mathrm{Br^-}$$

Question 8

Why is free-radical halogenation rarely used in the laboratory to prepare alkyl halides?

Accepted Answer

It rarely provides good selectivity and yield, often resulting in a mixture of products.

Question 9

Which of the following statements about the $$\mathrm{S_N2}$$ reaction is correct?

Accepted Answer

The reaction occurs in a single step with a single transition state.

Question 10

Which of the following solvents would most enhance the nucleophilicity of an anionic nucleophile in an $$\mathrm{S_N2}$$ reaction?

Accepted Answer

Dimethyl sulfoxide (DMSO)

Question 11

Which of the following best explains why tertiary alkyl halides do not undergo $$\mathrm{S_N2}$$ reactions?

Accepted Answer

Tertiary alkyl halides are too sterically hindered for the nucleophile to approach the electrophilic carbon.

Question 12

Which of the following is the correct rate law for an $$\mathrm{S_N2}$$ reaction?

Accepted Answer

$$\mathrm{rate = k[substrate][nucleophile]}$$

Question 13

Which of the following statements about nucleophilicity and basicity is true?

Accepted Answer

A base is always a stronger nucleophile than its conjugate acid.

Question 14

Which of the following alkyl halides would be most likely to undergo rearrangement during an $$\mathrm{S_N1}$$ reaction?

Accepted Answer

Tertiary alkyl chloride

Question 15

In the free-radical bromination of cyclohexene using N-bromosuccinimide (NBS), which position does bromine substitute?

Accepted Answer

On the allylic carbon atom next to the double bond

Question 16

Which of the following is a common use of alkyl halides in industry?

Accepted Answer

As solvents for cleaning and degreasing

Question 17

Which of the following factors does NOT increase the rate of an $$\mathrm{S_N2}$$ reaction?

Accepted Answer

Increasing steric hindrance around the electrophilic carbon

Question 18

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

Accepted Answer

It polarizes the C-X bond and must be able to leave as a stable, weak base.

Question 19

Which of the following statements about the effect of charge on nucleophilicity is correct?

Accepted Answer

A species with a negative charge is a stronger nucleophile than a similar neutral species.

Chapter 6: Alkyl Halides and Nucleophilic Substitution – Study Notes

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