$$\text{Rate} = k[\text{CH}_3\text{Br}][\text{OH}^-]$$

Question 1

Which of the following statements best explains why alkyl iodides react faster than alkyl chlorides in both $$S_N1$$ and $$S_N2$$ reactions?

Accepted Answer

Iodide is a weaker base and a more stable leaving group than chloride, so the C–I bond breaks more readily.

Question 2

Which of the following best describes the rate law for an $$S_N2$$ reaction between methyl bromide and hydroxide ion?

Accepted Answer

$$	ext{Rate} = k[	ext{CH}_3	ext{Br}][	ext{OH}^-]$$

Question 3

A student attempts to carry out an $$S_N2$$ reaction using tert-butyl bromide and sodium ethoxide in ethanol. What is the most likely major product?

Accepted Answer

2-Methylpropene via E2 elimination

Question 4

Which of the following factors most strongly favors an $$S_N1$$ mechanism over an $$S_N2$$ mechanism?

Accepted Answer

A tertiary alkyl halide substrate

Question 5

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

Accepted Answer

They result in inversion of configuration at the stereocenter.

Question 6

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

Accepted Answer

$$	ext{I}^-$$

Question 7

In a polar protic solvent, which of the following anions is the most nucleophilic?

Accepted Answer

$$	ext{I}^-$$

Question 8

Which of the following best explains why $$S_N1$$ reactions often lead to racemization at a stereocenter?

Accepted Answer

The carbocation intermediate is planar, allowing attack from either side.

Question 9

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

Accepted Answer

Polar aprotic solvents increase the rate of $$S_N2$$ reactions.

Question 10

Which of the following best describes the order of carbocation stability?

Accepted Answer

Tertiary \u003e secondary \u003e primary \u003e methyl

Question 11

A chemist wants to synthesize an alkene from 2-bromopropane using sodium ethoxide in ethanol. Which mechanism and product are most likely?

Accepted Answer

E2 elimination, yielding propene

Question 12

Which of the following is a common feature of both $$S_N1$$ and E1 mechanisms?

Accepted Answer

Both involve a carbocation intermediate.

Question 13

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

Accepted Answer

Increasing the concentration of the nucleophile

Question 14

Which of the following best explains why bulky bases favor E2 elimination over $$S_N2$$ substitution?

Accepted Answer

Bulky bases are poor nucleophiles due to steric hindrance, but can still abstract protons.

Question 15

Which of the following statements about the effect of nucleophile strength on $$S_N1$$ and $$S_N2$$ reactions is correct?

Accepted Answer

A strong nucleophile increases the rate of $$S_N2$$ reactions.

Question 16

A solution of 2-bromopropane in ethanol is heated with sodium ethoxide. Which of the following is the major product?

Accepted Answer

Propene

Question 17

Which of the following best describes the transition state of an $$S_N2$$ reaction?

Accepted Answer

The carbon is planar and the nucleophile and leaving group are both partially bonded.

Question 18

Which of the following would most likely undergo solvolysis via an $$S_N1$$ mechanism in water?

Accepted Answer

tert-Butyl bromide

Question 19

Which of the following statements about the effect of temperature on substitution and elimination reactions is correct?

Accepted Answer

Increasing temperature favors elimination over substitution.

Ionic Reactions: Nucleophilic Substitution and Elimination Reactions of Alkyl Halides

Study Guide - Practice Questions