Question 1

Which of the following statements best explains why tertiary alkyl halides favor the $$S_N1$$ mechanism over the $$S_N2$$ mechanism?

Accepted Answer

Tertiary alkyl halides form more stable carbocations due to hyperconjugation and inductive effects.

Question 2

Which of the following solvents would most likely increase the rate of an $$S_N2$$ reaction?

Accepted Answer

Acetone

Question 3

A reaction between 2-bromopropane and sodium ethoxide in ethanol produces which major product?

Accepted Answer

$$\mathrm{CH_3CH=CH_2$} ($$propene) via E2 elimination

Question 4

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

Accepted Answer

$$\mathrm{H_2O}$$

Question 5

In an $$E2$$ elimination reaction, which geometric relationship between the leaving group and the $$\beta-$$hydrogen is required for the reaction to proceed efficiently?

Accepted Answer

Anti-coplanar (anti-periplanar)

Question 6

Which of the following statements about $$S_N2$$ reactions is correct?

Accepted Answer

The reaction rate is second order and depends on both the substrate and nucleophile concentrations.

Question 7

A primary alkyl halide reacts with a strong, bulky base such as tert-butoxide. What is the major product and mechanism?

Accepted Answer

Alkene via $$E2$$ elimination (Hofmann product)

Question 8

Which of the following best describes the Zaitsev rule in elimination reactions?

Accepted Answer

The most substituted alkene is the major product.

Question 9

Which of the following nucleophiles would react fastest in an $$S_N2$$ reaction with methyl bromide in acetone?

Accepted Answer

$$\mathrm{CH_3O^-}$$

Question 10

Which of the following statements about $$E1$$ and $$E2$$ mechanisms is correct?

Accepted Answer

$$E1$$ reactions are favored by weak bases and highly substituted substrates.

Question 11

Which of the following is true regarding the stereochemistry of $$E2$$ eliminations?

Accepted Answer

The leaving group and $$\beta-$$hydrogen must be anti-periplanar for the reaction to occur.

Question 12

Which of the following best explains why polar aprotic solvents increase the rate of $$S_N2$$ reactions?

Accepted Answer

They do not solvate anions well, leaving the nucleophile more reactive.

Question 13

Which of the following is the correct order of leaving group ability for the halides in nucleophilic substitution reactions?

Accepted Answer

$$\mathrm{I^-} \u003e \mathrm{Br^-} \u003e \mathrm{Cl^-} \u003e \mathrm{F^-}$$

Question 14

A secondary alkyl halide reacts with sodium methoxide in methanol. Which mechanism and product are most likely?

Accepted Answer

$$E2$$ elimination, alkene product

Question 15

Which of the following statements about carbocation rearrangements is correct?

Accepted Answer

Carbocation rearrangements can occur in $$S_N1$$ and $$E1$$ reactions.

Question 16

Which of the following best describes the effect of a bulky base in an $$E2$$ elimination?

Accepted Answer

It favors the formation of the Hofmann product.

Question 17

Which of the following is a requirement for a molecule to undergo an $$E2$$ elimination on a cyclohexane ring?

Accepted Answer

The leaving group and $$\beta-$$hydrogen must be axial and anti to each other.

Question 18

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

Accepted Answer

A strong nucleophile is not always a strong base, especially in polar protic solvents.

Question 19

Which of the following is the best explanation for why $$S_N1$$ reactions are faster in polar protic solvents?

Accepted Answer

Polar protic solvents stabilize the carbocation intermediate and the leaving group.

Substitution and Elimination Reactions, Alkenes, and Alkynes: Mechanisms and Applications

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