Question 1

Which of the following statements best describes the stereochemical outcome of an $\mathrm{S_N2}$ reaction?

Accepted Answer

The product undergoes inversion of configuration at the reactive center.

Question 2

In an $\mathrm{E2}$ elimination reaction, which of the following is required for the reaction to proceed efficiently?

Accepted Answer

The leaving group and the hydrogen to be abstracted must be anti-periplanar.

Question 3

Which of the following best explains why tertiary alkyl halides favor $\mathrm{E2}$ over $\mathrm{S_N2}$ mechanisms?

Accepted Answer

Steric hindrance prevents nucleophilic attack in $\mathrm{S_N2}$ reactions.

Question 4

A chemist wants to synthesize an ether using the Williamson ether synthesis. Which combination of reagents would be most effective?

Accepted Answer

A primary alkyl halide and an alkoxide ion.

Question 5

Which of the following statements about the rate law for an $\mathrm{S_N1}$ reaction is correct?

Accepted Answer

Rate = $k[	ext{substrate}]$

Question 6

Which of the following alcohols will react fastest with $\mathrm{HBr}$ to form an alkyl bromide via an $\mathrm{S_N1}$ mechanism?

Accepted Answer

tert-butanol

Question 7

A student treats 2-bromobutane with a strong base. Which major product is expected?

Accepted Answer

2-butene via $\mathrm{E2}$ elimination

Question 8

Which of the following is a correct statement about the activation of alcohols using $\mathrm{HBr}$?

Accepted Answer

The alcohol is first protonated to form a better leaving group.

Question 9

Which of the following best describes the role of Lewis acids in the activation of alcohols for substitution reactions?

Accepted Answer

Lewis acids coordinate to the oxygen, making the leaving group more stable.

Question 10

In the preparation of ethers via acid-catalyzed $\mathrm{S_N2}$ reactions, which of the following is a common side product?

Accepted Answer

Water

Question 11

Which of the following statements about the regioselectivity of $\mathrm{E2}$ reactions is correct?

Accepted Answer

The more substituted alkene is usually the major product (Zaitsev's rule).

Question 12

A chemist is trying to distinguish between $\mathrm{S_N1}$ and $\mathrm{S_N2}$ mechanisms. Which experimental observation would support an $\mathrm{S_N1}$ mechanism?

Accepted Answer

Formation of a racemic mixture of products.

Question 13

Which of the following is a possible consequence of using a bulky base in an $\mathrm{E2}$ elimination reaction?

Accepted Answer

The less substituted alkene (Hofmann product) becomes the major product.

Question 14

Which of the following reagents can be used to activate an alcohol for nucleophilic substitution via formation of a good leaving group?

Accepted Answer

$\mathrm{PBr_3}$

Question 15

A student mixes 1-bromopropane with sodium ethoxide in ethanol. Which type of reaction is most likely to occur?

Accepted Answer

$\mathrm{S_N2}$ substitution

Question 16

Which of the following is true regarding the preparation of ethers via the Williamson ether synthesis?

Accepted Answer

A strong base is used to generate the alkoxide ion.

Question 17

Which of the following statements about the mechanism of $\mathrm{E1}$ elimination is correct?

Accepted Answer

The leaving group departs first, forming a carbocation intermediate.

Question 18

A chemist wants to convert an alcohol to an alkyl chloride. Which reagent would be most suitable?

Accepted Answer

$\mathrm{SOCl_2}$

Question 19

Which of the following is a correct statement about the use of calcium carbide in organic synthesis?

Accepted Answer

It reacts with water to produce acetylene, which can be used in further reactions.

Question 20

Which of the following is a possible side reaction when activating alcohols with brominated acids for substitution?

Accepted Answer

Elimination to form an alkene

CHEM230 Exam 4 Study Guide: Substitution, Elimination, Alcohols, and Ethers

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