Q: Which of the following is true regarding the rate law for an $$S_N2$$ reaction?

$$\text{Rate} = k[\text{alkyl halide}][\text{nucleophile}]$$

Question 1

Which of the following statements best describes the mechanism illustrated in the image showing a nucleophile attacking a carbon bonded to a leaving group (LG)?

Accepted Answer

It is a concerted, one-step process where the nucleophile attacks from the opposite side of the leaving group, resulting in inversion of configuration.

Question 2

Which type of alkyl halide reacts fastest in an $$S_N2$$ reaction?

Accepted Answer

Methyl halide

Question 3

What is the effect of a polar aprotic solvent on the rate of an $$S_N2$$ reaction?

Accepted Answer

It increases the rate by not solvating the nucleophile, making it more reactive.

Question 4

Which of the following is the best leaving group for an $$S_N2$$ reaction?

Accepted Answer

$$\mathrm{I^-}$$

Question 5

What is the stereochemical outcome when $$(R)-2-$$bromooctane undergoes an $$S_N2$$ reaction with $$\mathrm{HS^-}$$?

Accepted Answer

Only $$(S)-2-$$octanethiol

Question 6

Which of the following best explains why tertiary alkyl halides do not undergo $$S_N2$$ reactions?

Accepted Answer

Steric hindrance prevents the nucleophile from attacking the electrophilic carbon.

Question 7

Which of the following is true regarding the rate law for an $$S_N2$$ reaction?

Accepted Answer

$$	ext{Rate} = k[	ext{alkyl halide}][	ext{nucleophile}]$$

Question 8

Which of the following nucleophiles is the strongest in a polar aprotic solvent?

Accepted Answer

$$\mathrm{I^-}$$

Question 9

Which of the following statements about the $$S_N1$$ reaction is correct?

Accepted Answer

It involves a carbocation intermediate and leads to racemization.

Question 10

Which of the following best describes the effect of branching at the reacting carbon on the rate of $$S_N2$$ reactions?

Accepted Answer

Branching decreases the rate due to increased steric hindrance.

Question 11

Which of the following is a real-world application of alkyl halides?

Accepted Answer

They are used as anesthetics, such as halothane.

Question 12

Which of the following best explains why $$S_N2$$ reactions do not occur with aryl or vinyl halides?

Accepted Answer

The carbon is sp2 hybridized, making backside attack difficult.

Question 13

Which of the following is the correct order of leaving group ability for halides in $$S_N2$$ reactions?

Accepted Answer

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

Question 14

Which of the following best describes the effect of a polar protic solvent on nucleophilicity in $$S_N2$$ reactions?

Accepted Answer

It decreases nucleophilicity by solvating the nucleophile.

Question 15

Which of the following is a consequence of the Walden inversion in $$S_N2$$ reactions?

Accepted Answer

The configuration at the reacting carbon is inverted.

Question 16

Which of the following is the best description of the transition state in an $$S_N2$$ reaction?

Accepted Answer

The nucleophile and leaving group are both partially bonded to the central carbon.

Question 17

Which of the following is a common misconception about nucleophilicity and basicity?

Accepted Answer

Nucleophilicity and basicity always correlate for all atoms.

Question 18

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

Accepted Answer

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

Question 19

Which of the following is a correct statement about the use of $$S_N2$$ reactions in synthesis?

Accepted Answer

They can be used to synthesize a specific enantiomer from a chiral starting material.

Ch 6: Nucleophilic Substitution Reactions of Alkyl Halides: SN2 and SN1 Mechanisms

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