Question 1

Which statement best describes Markovnikov's rule in the addition of hydrogen halides to alkenes?

Accepted Answer

The halide adds to the more substituted carbon, and the hydrogen adds to the carbon with the most hydrogens.

Question 2

During the catalytic hydrogenation of alkenes, which type of stereochemistry is observed for the addition of hydrogen atoms?

Accepted Answer

Syn addition

Question 3

Which alkene would have the lowest heat of hydrogenation, indicating the highest stability?

Accepted Answer

trans-2-Butene

Question 4

What is the correct order of reactivity of hydrogen halides in addition to alkenes?

Accepted Answer

$$\mathrm{HF} \u003c \mathrm{HCl} \u003c \mathrm{HBr} \u003c \mathrm{HI}$$

Question 5

In the presence of peroxides (ROOR), the addition of HBr to an alkene proceeds via which mechanism and gives which product?

Accepted Answer

Anti-Markovnikov addition, Br on least substituted carbon

Question 6

Which intermediate is NOT formed during the halogenation (Br$$_2$$ addition) of cyclopentene?

Accepted Answer

Carbocation

Question 7

Why does water attack the more substituted carbon during halohydrin formation from alkenes?

Accepted Answer

The more substituted carbon is more electrophilic due to partial positive charge.

Question 8

Which reagent is used for the anti-Markovnikov hydration of alkenes to alcohols?

Accepted Answer

$$\mathrm{BH_3$}$$ followed by $$\mathrm{H_2O_2}/\mathrm{NaOH}$$

Question 9

Which statement about the mechanism of hydroboration-oxidation is correct?

Accepted Answer

It is a concerted syn addition with no carbocation intermediate.

Question 10

What is the product of ozonolysis of 2,4,4-trimethyl-2-pentene followed by reductive work-up?

Accepted Answer

A ketone and an aldehyde

Question 11

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

Accepted Answer

Trans-2-butene has less steric hindrance between methyl groups.

Question 12

Which of the following is true about the stereochemistry of halogen addition to alkenes?

Accepted Answer

Halogen addition is always anti.

Question 13

In the acid-catalyzed hydration of alkenes, which step determines the regioselectivity of the reaction?

Accepted Answer

Protonation of the alkene to form the most stable carbocation

Question 14

Which of the following is the correct sequence for the retro-synthetic analysis of 2,3-epoxy-2-methylhexane from 2-methylhexane?

Accepted Answer

Alkene formation, then epoxidation

Question 15

Which of the following is NOT a possible fate of a carbocation intermediate formed during alkene addition reactions?

Accepted Answer

Formation of a bromonium ion

Question 16

Which solvent is commonly used in the halogenation of alkenes to produce vicinal dihalides?

Accepted Answer

$$\mathrm{$$CCl_4$$}$$

Question 17

What is the nucleophile in the epoxidation of alkenes using peroxy acids?

Accepted Answer

Alkene

Question 18

Which of the following best describes the product of the reaction of cyclopentene with Br$$_2 in $$CCl$$_4$$?

Accepted Answer

trans-1,2-dibromocyclopentane

Question 19

Which of the following is true about the formation of epoxides from alkenes?

Accepted Answer

Cis alkenes give cis epoxides.

Question 20

During ozonolysis, what is the fate of aldehydes in the presence of hydrogen peroxide ($$\mathrm{H_2O_2}$$)?

Accepted Answer

They are oxidized to carboxylic acids.

Addition Reactions of Alkenes: Mechanisms, Stereochemistry, and Synthetic Applications

Study Guide - Practice Questions