Question 1

Which of the following statements best explains why tertiary alkyl halides do not undergo SN2 reactions?

Accepted Answer

Steric hindrance around the electrophilic carbon prevents the nucleophile from effectively attacking from the backside.

Question 2

Which of the following solvents would most likely increase the rate of an SN2 reaction involving sodium iodide and 1-bromopropane?

Accepted Answer

Dimethyl sulfoxide (DMSO)

Question 3

Which of the following best describes the stereochemical outcome of an SN2 reaction at a chiral center?

Accepted Answer

Inversion of configuration (Walden inversion)

Question 4

Which of the following is the correct IUPAC name for the compound shown below?

$$\mathrm{CH_3CH_2CH_2CHBrCH_3}$$

Accepted Answer

4-bromopentane

Question 5

Which of the following factors does NOT increase the nucleophilicity of a species in a polar protic solvent?

Accepted Answer

Decreasing the basicity of the nucleophile

Question 6

Which of the following best explains why bromoalkanes generally have higher boiling points than chloroalkanes of similar structure?

Accepted Answer

Bromoalkanes have greater molecular mass and surface area, resulting in stronger van der Waals forces.

Question 7

Which of the following is a geminal dihalide?

Accepted Answer

$$\mathrm{CH_2Cl_2}$$

Question 8

A solution of 1-bromobutane is mixed with sodium iodide in acetone. Which of the following best describes the expected reaction and its mechanism?

Accepted Answer

An SN2 reaction will occur, with inversion of configuration at the reacting carbon.

Question 9

Which of the following statements about the SN1 reaction mechanism is correct?

Accepted Answer

The reaction rate depends only on the concentration of the alkyl halide.

Question 10

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

Accepted Answer

$$\mathrm{I^-}$$

Question 11

Which of the following best explains why polar aprotic solvents increase the rate of SN2 reactions?

Accepted Answer

They solvate cations but not anions, leaving nucleophiles more reactive.

Question 12

Which of the following statements about carbocation rearrangements in SN1 reactions is correct?

Accepted Answer

Carbocation rearrangements can involve hydride or methyl shifts to form more stable carbocations.

Question 13

Which of the following is the correct order of reactivity for alkyl halides in SN2 reactions?

Accepted Answer

methyl \u003e 1° \u003e 2° \u003e 3°

Question 14

Which of the following real-world compounds is a halogenated hydrocarbon used as a refrigerant and is linked to ozone layer depletion?

Accepted Answer

Freon-22 ($$\mathrm{$$CHClF_2$$})$$

Question 15

Which of the following best describes the effect of branching on the boiling point of haloalkanes?

Accepted Answer

Branching decreases boiling point due to a more spherical shape and less efficient van der Waals interactions.

Question 16

Which of the following is a correct statement about the difference between nucleophilicity and basicity?

Accepted Answer

Nucleophilicity refers to the rate of attack on an electrophilic carbon, while basicity refers to the equilibrium constant for proton abstraction.

Question 17

Which of the following best explains why DDT is considered a persistent organic pollutant?

Accepted Answer

It is hydrophobic, accumulates in the food chain, and is toxic to predatory birds.

Question 18

Which of the following best describes the transition state of an SN2 reaction?

Accepted Answer

A planar, pentavalent carbon with partial bonds to both the nucleophile and the leaving group.

Question 19

Which of the following is the correct product of the reaction between 1-bromopropane and sodium cyanide in DMSO?

Accepted Answer

$$\mathrm{CH_3CH_2CH_2CN}$$

chap 6 handouts Alkyl Halides and Nucleophilic Substitution: Structure, Properties, and Mechanisms

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