Question 1

Which of the following statements best describes the regioselectivity of Markovnikov addition of HBr to an alkene?

Accepted Answer

The Br atom adds to the more substituted carbon of the double bond.

Question 2

During free radical halogenation of methane, which step is responsible for chain propagation?

Accepted Answer

Reaction of a methyl radical with a halogen molecule to form methyl halide and a new halogen radical.

Question 3

Which reagent would you use to convert an alkene to a vicinal diol via syn addition?

Accepted Answer

OsO$$_4$$ followed by NaHSO$$_3$$

Question 4

A student wants to synthesize an ether using the Williamson Ether Synthesis. Which combination of reactants is most appropriate?

Accepted Answer

An alkoxide ion and a primary alkyl halide

Question 5

Which of the following best explains why anti-Markovnikov addition of HBr to an alkene occurs in the presence of peroxides?

Accepted Answer

Peroxides initiate a free radical mechanism, causing Br to add to the less substituted carbon.

Question 6

Which reaction mechanism is involved in the acid-catalyzed hydration of alkenes?

Accepted Answer

Electrophilic addition via carbocation intermediate

Question 7

What is the major organic product when 2-methylpropene reacts with HBr in the presence of peroxides?

Accepted Answer

1-bromo-2-methylpropane

Question 8

Which of the following is a key step in the mechanism of alkene hydration by oxymercuration-demercuration?

Accepted Answer

Formation of a mercurinium ion intermediate

Question 9

A chemist wants to convert an alkene to a halohydrin. Which reagents should be used?

Accepted Answer

Br$$_2 in $$water

Question 10

Which of the following reactions is used to prepare alcohols from alkenes without carbocation rearrangement?

Accepted Answer

Oxymercuration-demercuration

Question 11

In the hydroboration-oxidation of alkenes, what is the stereochemistry of the addition?

Accepted Answer

Syn addition

Question 12

Which of the following best describes the product of catalytic hydrogenation of an alkene?

Accepted Answer

An alkane formed by syn addition of H$$_2$$

Question 13

A student is attempting to synthesize a vicinal dibromide from an alkene. Which reagent should be used?

Accepted Answer

Br$$_2 in $$CCl$$_4$$

Question 14

Which of the following reactions is most likely to result in carbocation rearrangement?

Accepted Answer

Acid-catalyzed hydration

Question 15

Which reagent is used for the oxidative cleavage of alkenes to form aldehydes and ketones?

Accepted Answer

O$$_3$$ followed by Zn/H$$_2O$$

Question 16

What is the major product when 1-butene is treated with BH$$_3$$ followed by H$$_2O$_2/$$NaOH?

Accepted Answer

1-butanol

Question 17

Which of the following is true about the mechanism of alkene halogenation with Br$$_2$$?

Accepted Answer

It involves formation of a bromonium ion intermediate.

Question 18

A chemist wants to prepare a tertiary alcohol from an alkene. Which reaction would be most suitable?

Accepted Answer

Acid-catalyzed hydration of a highly substituted alkene

Question 19

Which of the following best describes the outcome of the Simmons-Smith reaction?

Accepted Answer

Formation of a cyclopropane ring from an alkene

Key Reactions and Mechanisms from Organic Chemistry Chapter 8: Alkenes and Alkynes

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