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 tertiary alkyl halides do not undergo SN2 reactions?

Accepted Answer

Tertiary alkyl halides are too sterically hindered for the nucleophile to perform a backside attack.

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-bromobutane with sodium ethoxide in ethanol. Which is the major product, and why?

Accepted Answer

2-butene (trans isomer), because E2 elimination favors the more substituted, more stable alkene (Zaitsev product).

Question 4

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

Accepted Answer

Inversion of configuration at the reactive carbon.

Question 5

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

Accepted Answer

Acetone (a polar aprotic solvent)

Question 6

A chemist wants to synthesize an ether using an SN2 reaction. Which combination of reactants and conditions is most appropriate?

Accepted Answer

A primary alkyl halide and a strong alkoxide in a polar aprotic solvent.

Question 7

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

Accepted Answer

E2 reactions require the β-hydrogen and leaving group to be anti-periplanar.

Question 8

When 3-bromo-3-methylpentane is treated with methanol, which mechanism is most likely to occur and why?

Accepted Answer

SN1, because the substrate is tertiary and methanol is a weak nucleophile in a polar protic solvent.

Question 9

Which of the following best explains why E1 reactions are regioselective?

Accepted Answer

The most stable (most substituted) alkene is formed as the major product due to carbocation stability.

Question 10

Which of the following is a good leaving group for nucleophilic substitution and elimination reactions?

Accepted Answer

Tosylate (OTs)

Question 11

A student reacts 1-bromopentane with sodium cyanide in DMSO. What is the expected major product and mechanism?

Accepted Answer

Pentanenitrile via SN2 mechanism.

Question 12

Which of the following statements about the effect of solvent on reaction mechanisms is correct?

Accepted Answer

Polar protic solvents increase the rate of SN1 reactions by stabilizing the carbocation intermediate.

Question 13

Which of the following best describes the stereochemical outcome of an SN1 reaction at a chiral center?

Accepted Answer

A racemic mixture is formed, but with a slight preference for inversion due to ion-pair effects.

Question 14

Which of the following bases would favor the formation of the Hofmann product in an E2 elimination?

Accepted Answer

Potassium tert-butoxide ($$	ext{KO}t	ext{Bu})$$

Question 15

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

Accepted Answer

Carbocation rearrangements can occur to form more stable carbocations, leading to unexpected products.

Question 16

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

Accepted Answer

The major product is usually the more substituted alkene (Zaitsev product), unless a bulky base is used.

Question 17

Which of the following is the best explanation for why alcohols require acidic conditions to undergo substitution or elimination reactions?

Accepted Answer

The hydroxyl group is a poor leaving group, but protonation converts it to water, a good leaving group.

Question 18

Which of the following statements about the difference between stereoselective and stereospecific E2 reactions is correct?

Accepted Answer

Stereospecific E2 reactions give a single stereoisomer depending on the substrate's stereochemistry, while stereoselective E2 reactions give a mixture with one major product.

Question 19

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

Accepted Answer

Tert-butyl bromide

Question 20

A chemist wants to convert 2-butanol to 2-bromobutane. Which reagent and mechanism should be used?

Accepted Answer

HBr, via an SN1 mechanism

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

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