Deck 8: Alkenes: Reactions and Synthesis

Question 1

Exhibit 8-3
Consider the reaction below to answer the following question(s).
​
Alkenes may be hydrated by the hydroboration/oxidation procedure shown.
​
Refer to Exhibit 8-3.Hydroboration/oxidation of alkenes occurs with:

A)anti stereochemistry.
B)trans stereochemistry.
C)syn stereochemistry.
D)unpredictable stereochemistry.

Answer 1

syn stereochemistry.

Question 2

Exhibit 8-5
The sequence of (1) alkene hydroxylation followed by (2) diol cleavage is often an excellent alternative to direct alkene cleavage with ozone.For this sequence below,answer the following question(s).
​
Refer to Exhibit 8-5.Give the formula for reagent B.

Answer 2

HIO₄

Question 3

Exhibit 8-4
Consider the reaction below to answer the following question(s).
​
When dichlorocarbene is generated in the presence of an alkene,a dichlorocyclopropane is formed.
​
Refer to Exhibit 8-4.In the reaction of an alkene with dichlorocarbene,the dichlorocarbene is the:

A)electrophile.
B)Lewis base.
C)nucleophile.
D)both b and c

Answer 3

electrophile.

Question 4

Exhibit 8-4
Consider the reaction below to answer the following question(s).
​
When dichlorocarbene is generated in the presence of an alkene,a dichlorocyclopropane is formed.
​
Refer to Exhibit 8-4.Write the complete stepwise mechanism for the formation of dichlorocarbene,CCl₂.Show all intermediate structures and show all electron flow with arrows.

Question 5

Exhibit 8-3
Consider the reaction below to answer the following question(s).
​
Alkenes may be hydrated by the hydroboration/oxidation procedure shown.
​
Refer to Exhibit 8-3.The regiochemistry of hydroboration/oxidation of alkenes is:

A)Markovnikov.
B)non-Markovnikov
C)subject to solvent effects.
D)unrelated to alkene structure.

Question 6

Exhibit 8-2
Consider the reaction sequence below to answer the following question(s):
​
Refer to Exhibit 8-2.The intermediate in the first step of this reaction sequence is called a:

A)carbocation
B)cyclonium ion
C)mercurinium ion
D)mercapto species.

Question 7

Exhibit 8-9
To answer the question(s) below consider the following information:
​
In an abandoned laboratory has been found a flammable liquid,A,in a bottle bearing only the label "Compound A: C₇H₁₂." Government agents have offered you a considerable sum to determine the structure of this compound.After verifying the molecular formula by elemental analysis,you find that Compound A reacts with 1 mol equiv of hydrogen;and,after treatment with acidic KMnO₄,Compound A gives the dicarboxylic acid C (see below).Another bottle from the same laboratory is labeled "Compound B (isomer of A)." Compound B also reacts with 1 mol equiv of hydrogen,but yields cyclohexanone after treatment with acidic KMnO₄.
​
Refer to Exhibit 8-9.How many degrees of unsaturation does Compound A possess?

Question 8

Exhibit 8-4
Consider the reaction below to answer the following question(s).
​
When dichlorocarbene is generated in the presence of an alkene,a dichlorocyclopropane is formed.
​
Refer to Exhibit 8-4.The reaction of an alkene with dichlorocarbene is:

A)regiospecific.
B)Markovnikov.
C)stereospecific.
D)non-Markovnikov.

Question 9

Exhibit 8-2
Consider the reaction sequence below to answer the following question(s):
​
Refer to Exhibit 8-2.In the second step of this reaction sequence,the organomercury compound is treated with sodium borohydride,NaBH₄,to yield the alcohol product.This replacement of a carbon-mercury bond with a carbon-hydrogen bond is termed:

A)an oxidation
B)a reduction
C)a hydroxylation
D)a cycloaddition

Question 10

Draw both chair conformations of trans-1,2-dichlorocyclohexane on the templates provided below.Circle the least stable conformation.

Question 11

Exhibit 8-3
Consider the reaction below to answer the following question(s).
​
Alkenes may be hydrated by the hydroboration/oxidation procedure shown.
​
Refer to Exhibit 8-3.Hydroboration of alkenes is an example of:

A)a rearrangement reaction.
B)a substitution reaction.
C)an elimination reaction.
D)an addition reaction.

Question 12

Exhibit 8-1
To answer the question(s) below consider the following reaction:
​
When cyclohexene reacts with chlorine in carbon tetrachloride the trans-dihalide is formed.
​
Refer to Exhibit 8-1.Since the two chlorine atoms add to opposite faces of the cyclohexene double bond,we say that the reaction occurs with:

A)syn stereochemistry
B)cis stereochemistry
C)anti stereochemistry
D)retention of stereochemistry

Question 13

Exhibit 8-2
Consider the reaction sequence below to answer the following question(s):
​
Refer to Exhibit 8-2.Write the complete reaction mechanism for the first step of this reaction sequence.Show all electron flow with arrows and show all intermediate structures.

Question 14

Exhibit 8-3
Consider the reaction below to answer the following question(s).
​
Alkenes may be hydrated by the hydroboration/oxidation procedure shown.
​
Refer to Exhibit 8-3.The intermediate formed in the first step of this reaction is:

A)
B)
C)
D)

Question 15

Exhibit 8-1
To answer the question(s) below consider the following reaction:
​
When cyclohexene reacts with chlorine in carbon tetrachloride the trans-dihalide is formed.
​
Refer to Exhibit 8-1.Write the complete stepwise mechanism for this reaction.Be sure to show all intermediate structures and all electron flow using arrows.

Question 16

Exhibit 8-9
To answer the question(s) below consider the following information:
​
In an abandoned laboratory has been found a flammable liquid,A,in a bottle bearing only the label "Compound A: C₇H₁₂." Government agents have offered you a considerable sum to determine the structure of this compound.After verifying the molecular formula by elemental analysis,you find that Compound A reacts with 1 mol equiv of hydrogen;and,after treatment with acidic KMnO₄,Compound A gives the dicarboxylic acid C (see below).Another bottle from the same laboratory is labeled "Compound B (isomer of A)." Compound B also reacts with 1 mol equiv of hydrogen,but yields cyclohexanone after treatment with acidic KMnO₄.
​
Refer to Exhibit 8-9.Suggest structures for A and B.

Question 17

Exhibit 8-1
To answer the question(s) below consider the following reaction:
​
When cyclohexene reacts with chlorine in carbon tetrachloride the trans-dihalide is formed.
​
Refer to Exhibit 8-1.The observed stereochemistry of addition of chlorine to cyclohexene is explained by the intermediacy of a:

A)cyclonium ion
B)carbocation
C)carbene
D)chloronium ion

Question 18

Exhibit 8-5
The sequence of (1) alkene hydroxylation followed by (2) diol cleavage is often an excellent alternative to direct alkene cleavage with ozone.For this sequence below,answer the following question(s).
​
Refer to Exhibit 8-5.Draw the structure of A.

Question 19

Exhibit 8-1
To answer the question(s) below consider the following reaction:
​
When cyclohexene reacts with chlorine in carbon tetrachloride the trans-dihalide is formed.
​
Provide the IUPAC name for the product of the reaction of cyclohexene with chlorine.

Question 20

Exhibit 8-4
Consider the reaction below to answer the following question(s).
​
When dichlorocarbene is generated in the presence of an alkene,a dichlorocyclopropane is formed.
​
Refer to Exhibit 8-4.Draw the complete Lewis electron dot structure for dichlorocarbene,CCl₂.

Question 21

Draw the product(s) of the reaction of (R)-3-chlorobutene with HBr.Indicate stereochemistry.

Question 22

Draw a condensed formula for a polymer containing five repeating units derived from the following monomer.Name the polymer.

Question 23

Which of the following is a difference between hydroboration/oxidation and oxymercuration?

A)conversion of an alkene to an alcohol
B)Markovnikov regiochemistry
C)hydration
D)heteroatom-containing intermediate

Question 24

Draw the skeletal structure(s) and name the product(s) of the reaction when the following substance is treated with ethanoic KOH.Atoms other than hydrogen and carbon are labeled.

Question 25

Consider partial hydrogenation of the following substance. Which of the following describes this reaction?

A)4 moles of hydrogen would required.
B)The product would contain trans double bond(s).
C)The product would be saturated.
D)The product would lower blood cholesterol.
E)All of the above would occur.

Question 26

Consider the polymeric structure below for amylose (a type of starch).Draw a box around the monomer of amylose.Extra: Propose a structure for the monomer.Hint: This polymer is formed in a dehydration reaction.

Question 27

Consider the following polymer. Draw the condensed formula for its monomer.

Question 28

Exhibit 8-9
To answer the question(s) below consider the following information:
​
In an abandoned laboratory has been found a flammable liquid,A,in a bottle bearing only the label "Compound A: C₇H₁₂." Government agents have offered you a considerable sum to determine the structure of this compound.After verifying the molecular formula by elemental analysis,you find that Compound A reacts with 1 mol equiv of hydrogen;and,after treatment with acidic KMnO₄,Compound A gives the dicarboxylic acid C (see below).Another bottle from the same laboratory is labeled "Compound B (isomer of A)." Compound B also reacts with 1 mol equiv of hydrogen,but yields cyclohexanone after treatment with acidic KMnO₄.
​
Refer to Exhibit 8-9.What was the other product formed in the KMnO₄ oxidation of B?

Question 29

​Draw the mechanism of the bromination of 3-hexene in the presence of water via bromohydrin formation.

Question 30

Consider the following intermediate. Which is applicable to this structure?

A)results in a product which has anti stereochemistry
B)produces only the cis isomer
C)is called a bromohydrin
D)occurs during the addition of HBr

Question 31

Draw the skeletal structure(s) and name the product(s) of the reaction when the following substance is treated with sulfuric acid and warmed to approximately 50 °C.Atoms other than hydrogen and carbon are labeled.

Question 32

Which of the following will not undergo catalytic reduction in the presence of H₂ and metal catalyst?

A)​

B)​

C)​

D)​

Question 33

In the formation of an addition polymer such as polyvinylchloride,

A)the monomers must have at least one degree of unsaturation.
B)the formation occurs via a polar reaction.
C)the products have the same degree of complexity as biopolymers.
D)the resulting polymer generally contains two types of monomer.

Question 34

Hydration of an alkene during enzyme catalysis in a biological system produces an optically active product even through there is a potential to form a racemic mixture.Explain why this occurs.

Question 35

What product forms when the following substance is treated with chloroform in the presence of KOH?

A)
B)
C)
D)

Question 36

Povidone is produced commercially as a series of products having mean molecular weights ranging from about 10,000 to 700,000.Complexed with iodine,povidone yields an iodophor,marketed under the tradename Betadine,which is used as a topical anti-infective. Identify the monomer unit(s) in povidone.

Question 37

Hydration of 4-methyl-1-pentene in the presence of an acid catalyst produces a product that is optically inactive.Briefly explain why.

Question 38

Hydrogenation reactions use a metal catalyst as depicted below. Which of the following does not occur during such a reaction?

A)The metal provides a surface upon molecules can adsorb.
B)π bonds are involved in the interaction between the metal and the unsaturated hydrocarbon.
C)Molecular hydrogen attacks the topside of the adsorbed hydrocarbon.
D)Hydrogen atoms are transferred to the carbon atoms of the multiple bond one at a time.

Question 39

Which of the following is a carbene?

A)R₃C⁺
B)R:^-
C)R₂:
D)R.

Question 40

Lyapolate Sodium,whose structure is shown below,is used as an anticoagulant.Identify the monomer unit(s) in lyapolate sodium.

Question 41

​Draw the mechanism of the epoxidation of 2-butene using a halohydrin.

Question 42

​Draw the mechanism of the hydration of 2-methyl-propene.