Q: Which of the following is the correct rate law for an SN2 reaction between 1-bromopropane and hydroxide ion?

$$\text{Rate} = k[\text{1-bromopropane}][\text{OH}^-]$$

Question 1

Which of the following statements best explains why alkyl halides undergo nucleophilic substitution and elimination reactions?

Accepted Answer

The halogen is electron-withdrawing, creating a partial positive charge on the α-carbon and serving as a good leaving group.

Question 2

Which of the following is the correct rate law for an SN2 reaction between 1-bromopropane and hydroxide ion?

Accepted Answer

$$	ext{Rate} = k[	ext{1-bromopropane}][	ext{OH}^-]$$

Question 3

A student treats 2-bromopentane with sodium ethoxide in ethanol. Which is the major product, and why?

Accepted Answer

The Zaitsev alkene, because ethoxide is a small, unhindered base favoring the more substituted alkene.

Question 4

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

Accepted Answer

The configuration at the chiral center is inverted due to backside attack.

Question 5

Which of the following alkyl halides will react fastest in an SN1 reaction?

Accepted Answer

tert-butyl bromide

Question 6

A chemist wants to synthesize an ether using an SN2 reaction. Which combination of reactants and solvent would be most effective?

Accepted Answer

A primary alkyl halide and a strong nucleophile in a polar aprotic solvent

Question 7

Which of the following statements about E2 elimination reactions is correct?

Accepted Answer

E2 reactions are concerted and require the base to remove a β-hydrogen anti-periplanar to the leaving group.

Question 8

Which of the following best explains why a bulky base favors the Hofmann product in E2 eliminations?

Accepted Answer

Bulky bases cannot easily access the more substituted β-hydrogen, so they abstract the less hindered β-hydrogen, leading to the less substituted alkene.

Question 9

Which of the following solvents would most effectively increase the rate of an SN2 reaction?

Accepted Answer

Dimethyl sulfoxide (DMSO)

Question 10

A student reacts 2-bromobutane with methanol. Which mechanism(s) and product(s) are most likely?

Accepted Answer

SN1 and E1, forming a mixture of substitution and elimination products.

Question 11

Which of the following statements about the stereochemistry of E2 eliminations is correct?

Accepted Answer

E2 eliminations require the β-hydrogen and leaving group to be anti-periplanar for the reaction to occur.

Question 12

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

Accepted Answer

$$	ext{OTf}^- ($$triflate)

Question 13

A primary alcohol is converted to an alkyl bromide using HBr. What is the most likely mechanism?

Accepted Answer

SN2, because primary carbocations are too unstable to form.

Question 14

Which of the following statements about SN1 and E1 reactions is correct?

Accepted Answer

Both SN1 and E1 reactions proceed through a carbocation intermediate and have the same rate-determining step.

Question 15

Which of the following best describes the product distribution in an SN1 reaction at a chiral center?

Accepted Answer

A racemic mixture is formed, but more inversion product is typically observed.

Question 16

Which of the following statements about the regioselectivity of E1 and E2 reactions is correct?

Accepted Answer

E1 reactions always give the most substituted (Zaitsev) alkene as the major product.

Question 17

Which of the following is a correct statement about the effect of solvent on nucleophilicity in SN2 reactions?

Accepted Answer

Polar aprotic solvents increase nucleophilicity by destabilizing the nucleophile, making it more reactive.

Question 18

A chemist wants to synthesize an alkene from a secondary alcohol. Which reagent and mechanism should be used?

Accepted Answer

H2SO4, E1 mechanism

Question 19

Which of the following best describes why cyclohexyl bromide must have the bromine in the axial position to undergo E2 elimination?

Accepted Answer

Only the axial position allows the β-hydrogen and leaving group to be anti-periplanar.

Question 20

Which of the following is a correct application of retrosynthetic analysis for synthesizing an ether via SN2?

Accepted Answer

Identify a bond that can be formed by nucleophilic substitution, then select a primary alkyl halide and an alkoxide as reactants.

Alkyl Halides: Nucleophilic Substitution and Elimination Reactions (Chapter 7 Study Guide)

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