Question 1

Which of the following statements best describes the stereochemistry of the halogenation of cycloalkenes with $$X_2 ($$where $$X is Cl or Br$$)?

Accepted Answer

The reaction produces a trans-dihalide via anti addition.

Question 2

What is the major product when 2-methyl-2-pentene is treated with $$BH_3$$, followed by $$H_2O_2$$, $$OH^-$$?

Accepted Answer

2-methyl-3-pentanol

Question 3

Which reagent would you use to convert an alkene to a vicinal diol with syn stereochemistry, without forming a carbocation intermediate?

Accepted Answer

$$OsO_4 ($$osmium tetroxide)

Question 4

During the acid-catalyzed hydration of ethylene to ethanol, which intermediate is formed after protonation of the alkene?

Accepted Answer

A carbocation intermediate

Question 5

Which of the following best explains why oxymercuration-demercuration is preferred over acid-catalyzed hydration for some alkene hydrations?

Accepted Answer

Oxymercuration-demercuration avoids carbocation rearrangement.

Question 6

What is the expected product when cyclohexene is treated with $$m-$$chloroperoxybenzoic acid (mCPBA)?

Accepted Answer

1,2-epoxycyclohexane

Question 7

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

Accepted Answer

Hydrogenation occurs with syn stereochemistry.

Question 8

When 1-butene reacts with HBr in the presence of peroxides, what is the major product?

Accepted Answer

1-bromobutane

Question 9

Which of the following is true about the mechanism of halohydrin formation from alkenes?

Accepted Answer

The halonium ion intermediate is attacked by water, leading to anti addition.

Question 10

What is the major organic product when 1-methylcyclohexene is treated with aqueous acidic $$KMnO_4$$?

Accepted Answer

A mixture of carboxylic acids and/or ketones, depending on the position of the double bond.

Question 11

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

Accepted Answer

It converts alkenes to cyclopropanes using a carbenoid generated from $$CH_2I_2$$ and $$Zn(Cu).$$

Question 12

Which of the following is a correct statement about the reactivity of alkenes in halogenation reactions?

Accepted Answer

More substituted alkenes react more rapidly due to stabilization of the halonium ion intermediate.

Question 13

Which of the following is the correct product of ozonolysis of 1-octene followed by reduction with zinc?

Accepted Answer

Octanal and formaldehyde

Question 14

What is the expected stereochemical outcome when dichlorocarbene is added to cis-2-pentene?

Accepted Answer

A single stereoisomer of the cyclopropane product is formed.

Question 15

Which of the following statements about epoxidation of alkenes is correct?

Accepted Answer

Epoxidation occurs with syn addition, preserving the relative stereochemistry of the alkene.

Question 16

Which of the following is a correct retrosynthetic pathway to prepare 1,2-epoxycyclohexane from cyclohexanol?

Accepted Answer

Dehydrate cyclohexanol to cyclohexene, then treat with a peroxyacid.

Question 17

Which of the following best describes the role of peroxides in the addition of HBr to alkenes?

Accepted Answer

Peroxides initiate a radical mechanism, leading to anti-Markovnikov addition.

Question 18

Which of the following is true about the addition of water to an achiral alkene under acid catalysis?

Accepted Answer

A racemic mixture of enantiomers is formed due to planar carbocation intermediate.

Alkene Reactions and Synthesis: Addition, Oxidation, Reduction, and Stereochemistry

Study Guide - Practice Questions