Question 1

Which of the following statements best explains why trans-2-butene is more stable than cis-2-butene?

Accepted Answer

Trans-2-butene has less steric hindrance between alkyl groups compared to cis-2-butene.

Question 2

According to Zaitsev's Rule, which product will predominate in the E2 elimination of 2-bromo-2-methylbutane with sodium ethoxide?

Accepted Answer

$$\mathrm{CH_3C(CH_3$)=$$CHCH_3$$} (2-$$methyl-2-butene)

Question 3

Which of the following best describes the stereochemical requirement for an E2 elimination reaction?

Accepted Answer

The leaving group and the hydrogen being eliminated must be anti-coplanar.

Question 4

A chemist wants to synthesize the least substituted alkene from a primary alkyl halide. Which base should they use to favor this product?

Accepted Answer

Potassium tert-butoxide

Question 5

Which of the following statements about the heat of hydrogenation of alkenes is correct?

Accepted Answer

A lower heat of hydrogenation indicates a more stable alkene.

Question 6

Which of the following is the correct order of increasing stability for alkenes based on substitution?

Accepted Answer

Monosubstituted \u003c Disubstituted \u003c Trisubstituted \u003c Tetrasubstituted

Question 7

In the dehydration of 2-butanol using sulfuric acid, which step is rate-determining?

Accepted Answer

Formation of the carbocation from the protonated alcohol

Question 8

Which of the following best explains why tertiary alcohols dehydrate more easily than secondary or primary alcohols?

Accepted Answer

Tertiary carbocations formed during dehydration are more stable due to greater alkyl substitution.

Question 9

A student treats 2-bromo-2-methylbutane with potassium tert-butoxide. Which major product is expected?

Accepted Answer

$$\mathrm{CH_3C(CH_3$)=CH_2$} (2-$$methyl-1-butene)

Question 10

Which of the following statements about carbocation rearrangements during E1 eliminations is correct?

Accepted Answer

A less stable carbocation can rearrange to a more stable carbocation via a hydride or alkyl shift.

Question 11

Which of the following best describes the product distribution when 2-bromo-2-methylbutane is treated with sodium ethoxide?

Accepted Answer

The major product is the more substituted alkene due to Zaitsev's rule.

Question 12

Which of the following is a correct statement about the (E)-(Z) system for alkene diastereomers?

Accepted Answer

If the highest priority groups are on opposite sides of the double bond, the alkene is E.

Question 13

A chemist wants to synthesize 1-cyclohexyl-1-butyne. Which of the following retrosynthetic disconnections is most appropriate?

Accepted Answer

$$\mathrm{Cyclohexylbromide + 1-butyne}$$

Question 14

Which of the following statements about the use of bulky bases in E2 eliminations is correct?

Accepted Answer

Bulky bases favor the formation of the less substituted (Hofmann) alkene.

Question 15

Which of the following is the best explanation for why the heat of hydrogenation for tetrasubstituted alkenes is lower than for monosubstituted alkenes?

Accepted Answer

Tetrasubstituted alkenes are more stable, so less energy is released upon hydrogenation.

Question 16

Which of the following is a correct statement about the mechanism of alcohol dehydration using acid?

Accepted Answer

The first step is protonation of the alcohol to form a good leaving group.

Question 17

A student is asked to predict the major product of the E2 elimination of 1-bromo-2-methylcyclohexane with sodium ethoxide. Which conformation must the molecule adopt for the reaction to proceed?

Accepted Answer

The bromine and the hydrogen to be eliminated must both be axial and anti to each other.

Question 18

Which of the following is a real-world application of catalytic hydrogenation of alkenes?

Accepted Answer

Synthesis of margarine from vegetable oils by hydrogenation of double bonds.

Question 19

Which of the following best describes the product of partial hydrogenation of an alkyne using Lindlar's catalyst?

Accepted Answer

A cis-alkene is formed via syn addition of hydrogen.

Alkenes and Alkynes I: Properties and Synthesis – Elimination Reactions of Alkyl Halides

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