Question 1

Which of the following statements best describes Zaitsev’s Rule as it applies to E2 elimination reactions?

Accepted Answer

The more substituted alkene is obtained when a hydrogen is removed from the β-position bonded to the fewest hydrogens.

Question 2

Which leaving group would most likely result in the highest percentage of the more stable alkene in an E2 reaction of 2-halohexane with $$\mathrm{CH_3O^-}$$?

Accepted Answer

$$\mathrm{I^-}$$

Question 3

A bulky base such as tert-butoxide reacts with 2-bromopropane. Which product is favored and why?

Accepted Answer

The less substituted alkene because bulky bases abstract the least hindered proton.

Question 4

Which of the following carbanions is the most stable?

Accepted Answer

Methyl anion

Question 5

Why does a higher temperature favor elimination (E2) over substitution (SN2) reactions?

Accepted Answer

Because elimination reactions have a greater $$\Delta S^\circ ($$entropy change).

Question 6

Which of the following best explains why alkyl fluorides do not follow Zaitsev’s rule in E2 reactions?

Accepted Answer

Fluoride is a poor leaving group, so the less stable alkene is favored.

Question 7

A secondary alkyl halide reacts with a strong, bulky base. Which product is most likely to predominate?

Accepted Answer

The less substituted alkene due to steric hindrance.

Question 8

Which of the following is true regarding the E2 elimination of cyclohexyl halides?

Accepted Answer

E2 elimination requires the leaving group and the β-hydrogen to be anti-periplanar.

Question 9

Which of the following statements about SN1 and E1 reactions is correct?

Accepted Answer

Both reactions proceed through a carbocation intermediate.

Question 10

A benzylic halide is treated with a weak base. Which reaction pathway is most likely?

Accepted Answer

SN1

Question 11

Which of the following best describes the difference between syn and anti elimination in E2 reactions?

Accepted Answer

Anti elimination occurs via a staggered conformation, while syn elimination occurs via an eclipsed conformation.

Question 12

Which of the following bases would most likely favor elimination over substitution in a reaction with a secondary alkyl halide?

Accepted Answer

$$\mathrm{t-BuO^-}$$

Question 13

Which product is favored when 2-bromopropane is treated with $$\mathrm{CH_3CH_2O^-} at 100$$°C?

Accepted Answer

Propene

Question 14

Which of the following statements is true regarding the reactivity of alkyl halides in SN2 and E2 reactions?

Accepted Answer

Primary alkyl halides favor substitution under SN2/E2 conditions.

Question 15

Which of the following is a correct statement about the effect of base strength and bulk on product distribution in elimination reactions?

Accepted Answer

A stronger, bulkier base increases the proportion of the less substituted alkene.

Question 16

Which of the following is a characteristic reaction of alkyl halides?

Accepted Answer

Nucleophilic substitution and elimination

Question 17

Which of the following best explains why benzylic and allylic halides are more reactive in SN1 and E1 reactions?

Accepted Answer

The carbocation intermediate is stabilized by resonance.

Question 18

Which of the following is the major product when propyl bromide reacts with $$\mathrm{CH_3O^-} in$$ $$\mathrm{CH_3OH}$$?

Accepted Answer

Methyl propyl ether

Question 19

Which of the following is a correct statement about the use of DBN and DBU in elimination reactions?

Accepted Answer

They are strong, non-nucleophilic bases that favor elimination.

Substitution and Elimination Reactions of Alkyl Halides

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