Question 1

Which of the following statements best describes the stereochemical outcome of an SN2 reaction at a chiral center?

Accepted Answer

The product will have complete inversion of configuration (Walden inversion).

Question 2

Which of the following alkyl halides will react fastest in an SN2 reaction with $$\mathrm{HO^-} as $$the nucleophile?

Accepted Answer

$$\mathrm{CH_3Br} ($$methyl bromide)

Question 3

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

Accepted Answer

$$\mathrm{I^-}$$

Question 4

A reaction of 2-bromobutane with $$\mathrm{HO^-} in $$aqueous solution produces (R)-butan-2-ol from (S)-2-bromobutane. What mechanism is most consistent with this transformation?

Accepted Answer

SN2, because it results in inversion of configuration.

Question 5

Which of the following statements about nucleophilicity and basicity is correct?

Accepted Answer

Nucleophilicity is defined by the rate of attack on an electrophilic carbon atom.

Question 6

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

Accepted Answer

A tertiary alkyl halide and a strong, bulky base.

Question 7

What is the rate law for an SN2 reaction?

Accepted Answer

$$\mathrm{rate = k_r[RX][Nuc]}$$

Question 8

Which of the following is NOT a factor that makes a good leaving group in nucleophilic substitution reactions?

Accepted Answer

Being a strong base after leaving.

Question 9

A secondary alkyl halide reacts with a strong, non-bulky nucleophile in a polar aprotic solvent. Which mechanism is most likely?

Accepted Answer

SN2

Question 10

Which of the following statements about carbocation rearrangements is TRUE?

Accepted Answer

A hydride or methyl shift can occur to form a more stable carbocation.

Question 11

How many elements of unsaturation are present in a molecule with the formula $$\mathrm{C_5H_8}$$?

Accepted Answer

2

Question 12

Which of the following best describes the E1 elimination mechanism?

Accepted Answer

It involves formation of a carbocation intermediate followed by loss of a proton.

Question 13

Which of the following statements about the Zaitsev and Hofmann products is correct?

Accepted Answer

The Hofmann product is favored when a bulky base is used.

Question 14

Which of the following is the correct IUPAC name for the compound shown below?

$$\mathrm{CH_2$=CHCH_2CH_3}$$

Accepted Answer

1-butene

Question 15

Which of the following nucleophiles is the strongest in polar protic solvents?

Accepted Answer

$$\mathrm{I^-}$$

Question 16

A tertiary alkyl halide reacts with methanol at room temperature. Which mechanism is most likely to occur?

Accepted Answer

SN1

Question 17

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

Accepted Answer

They are too sterically hindered for backside attack.

Question 18

Which of the following is the correct formula for calculating the number of elements of unsaturation in a hydrocarbon containing carbon, hydrogen, and nitrogen?

Accepted Answer

$$\mathrm{(2C + 2 + N - H)/2}$$

Question 19

Which of the following statements about the E2 elimination mechanism is TRUE?

Accepted Answer

It is a concerted reaction requiring a strong base.

Question 20

Which of the following best describes the product distribution when 2-bromobutane is treated with sodium ethoxide in ethanol?

Accepted Answer

The major product is 2-butene (Zaitsev product).

Substitution and Elimination Reactions of Alkyl Halides: SN1, SN2, E1, and E2 Mechanisms

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