Question 1

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

Accepted Answer

Tertiary alkyl halides are too sterically hindered for the nucleophile to perform a backside attack.

Question 2

Given the following rate law for a reaction: $$	ext{Rate} = k[	ext{Nu}][	ext{R-LG}]$$, which mechanism does this correspond to?

Accepted Answer

SN2

Question 3

Which of the following alkyl halides will react fastest in an SN1 reaction?

Accepted Answer

tert-butyl bromide ($$\mathrm{(CH_3$)_3CBr})$$

Question 4

Which of the following is the correct order of leaving group ability for the halides in SN2 reactions?

Accepted Answer

$$I^- \u003e Br^- \u003e Cl^- \u003e F^-$$

Question 5

A chiral alkyl halide undergoes an SN2 reaction. What is the expected stereochemical outcome?

Accepted Answer

Inversion of configuration at the reacting carbon

Question 6

Which of the following best describes the rate-determining step in an SN1 reaction?

Accepted Answer

The departure of the leaving group to form a carbocation

Question 7

Which of the following factors does NOT affect the rate of an SN1 reaction?

Accepted Answer

Strength of the nucleophile

Question 8

A student mixes 1-bromopropane with sodium cyanide in DMSO. Which mechanism is most likely and what is the major product?

Accepted Answer

SN2; $$\mathrm{CH_3CH_2CH_2CN}$$

Question 9

Which of the following best explains why SN1 reactions often produce racemic mixtures when the reacting carbon is chiral?

Accepted Answer

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

Question 10

Which of the following statements about the energy profile of an SN2 reaction is correct?

Accepted Answer

There is a single transition state and no intermediate.

Question 11

Which of the following is the correct order of reactivity for alkyl halides in SN2 reactions?

Accepted Answer

methyl halide \u003e 1° alkyl halide \u003e 2° alkyl halide \u003e 3° alkyl halide

Question 12

Which of the following best explains why $$HO^- is a $$better nucleophile than $$H_2O in SN2 $$reactions?

Accepted Answer

$$HO^- is $$negatively charged and more basic, making it more willing to donate electrons.

Question 13

In a biological methylation reaction, S-adenosylmethionine (SAM) acts as a methyl donor. Which statement is true about the leaving group in this reaction?

Accepted Answer

The leaving group is a neutral sulfur species, not a halide.

Question 14

Which of the following would increase the rate of an SN1 reaction for a given alkyl halide?

Accepted Answer

Using a more stable leaving group

Question 15

A student observes that the reaction of $$HO^-$$ with $$RCH_2I is $$much faster than with $$RCH_2F. $$What is the best explanation for this observation?

Accepted Answer

$$I^- is a $$much better leaving group than $$F^-.$$

Question 16

Which of the following best describes the stereochemical outcome when a chiral center undergoes an SN1 reaction?

Accepted Answer

A racemic mixture of enantiomers is formed.

Question 17

Which of the following is a real-life example of a biological SN2 reaction?

Accepted Answer

The methylation of norepinephrine to form epinephrine using S-adenosylmethionine.

Question 18

Which of the following statements is true regarding the effect of steric hindrance on SN2 and SN1 reactions?

Accepted Answer

Steric hindrance greatly slows SN2 reactions but has less effect on SN1 reactions.

Question 19

Which of the following best describes the energy profile of an SN1 reaction?

Accepted Answer

There are two transition states and a carbocation intermediate.

Substitution and Elimination Reactions of Alkyl Halides (SN1 and SN2 Mechanisms)

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