$$\text{rate} = k[\mathrm{CH_3Br}][\mathrm{OH^-}]$$

Question 1

Which of the following statements best explains why SN2 reactions proceed with inversion of configuration at the chiral center?

Accepted Answer

The nucleophile attacks from the opposite side of the leaving group, resulting in inversion of configuration.

Question 2

A reaction between 2-bromo-2-methylpropane and water in a polar protic solvent primarily follows which mechanism, and what is the major product?

Accepted Answer

SN1 mechanism; 2-methyl-2-propanol

Question 3

Which of the following is the best leaving group in nucleophilic substitution reactions?

Accepted Answer

$$\mathrm{I^-}$$

Question 4

In the reaction of 1-bromopentane with sodium ethoxide in ethanol, which product is favored and by which mechanism?

Accepted Answer

2-pentene via E2

Question 5

Which factor most strongly influences the rate of an SN1 reaction?

Accepted Answer

Stability of the carbocation intermediate

Question 6

What is the effect of doubling the concentration of the nucleophile in an SN1 reaction?

Accepted Answer

The reaction rate remains unchanged.

Question 7

Which of the following solvents would most greatly increase the rate of an SN2 reaction involving a negatively charged nucleophile?

Accepted Answer

Acetonitrile

Question 8

A secondary alkyl halide reacts with sodium methoxide in methanol. Which of the following best describes the likely outcome?

Accepted Answer

Both SN2 and E2 reactions will compete, with E2 favored at higher temperatures.

Question 9

Which of the following best explains why tertiary alkyl halides do not undergo SN2 reactions?

Accepted Answer

Steric hindrance prevents backside attack by the nucleophile.

Question 10

According to Zaitsev’s rule, which product will predominate in a β-elimination reaction?

Accepted Answer

The most substituted alkene

Question 11

Which of the following nucleophiles is classified as 'moderate' in nucleophilicity for nucleophilic substitution reactions?

Accepted Answer

$$\mathrm{CH_3CO_2^-}$$

Question 12

Which of the following statements about the stereochemistry of SN1 reactions is correct?

Accepted Answer

SN1 reactions give racemization, but often with a slight preference for inversion.

Question 13

Which of the following best describes the rate law for an SN2 reaction between $$\mathrm{CH_3Br}$$ and $$\mathrm{OH^-}$$?

Accepted Answer

$$	ext{rate} = k[\mathrm{CH_3Br}][\mathrm{OH^-}]$$

Question 14

Which of the following carbocations is the most stable?

Accepted Answer

Tertiary benzylic carbocation

Question 15

Which of the following statements about E2 reactions is correct?

Accepted Answer

E2 reactions require a strong base and occur in a single concerted step.

Question 16

Which of the following best explains why polar aprotic solvents increase the rate of SN2 reactions?

Accepted Answer

They solvate cations but not anions, leaving nucleophiles more reactive.

Question 17

A reaction of 2-chloropropane with sodium ethoxide in ethanol at high temperature gives which major product and by what mechanism?

Accepted Answer

Propene via E2

Question 18

Which of the following is a key difference between SN1 and SN2 mechanisms?

Accepted Answer

SN1 reactions involve carbocation intermediates, while SN2 reactions do not.

Question 19

Which of the following conditions would most favor an E2 elimination over an SN2 substitution?

Accepted Answer

A secondary alkyl halide with a strong, bulky base

Question 20

Which of the following best describes the effect of increasing temperature on the competition between substitution and elimination reactions?

Accepted Answer

Increasing temperature favors elimination over substitution.

Nucleophilic Substitution and β-Elimination: Mechanisms, Factors, and Competition

Study Guide - Practice Questions