Question 1

Steroids are naturally occurring polycyclic compounds classified as lipids.The Diels-
Alder reaction has been widely used in their preparation.Shown below is a precursor
molecule used in a total steroid synthesis.What combination of diene and dieneophile can
be used to prepare this compound through the use of a Diels-Alder cycloaddition reaction.

Accepted Answer

The answer of Steroids are naturally occurring polycyclic compounds classified...

Question 2

A reaction under kinetic (or rate) control will yield predominantly:

Accepted Answer

A)   the most stable product.
B)   the product that can be formed in the fewest steps.
C)   the product whose formation requires the smallest free energy of activation.
D)   the product with the greatest potential energy.
E)   the product with the least potential energy.F) None of the above
G) A) and E)

Question 3

Which set of conditions does not result in allylic halogenation of an alkene?

Accepted Answer

A)   Cl2 at 400 °\degree° C
B)   Cl2 in CCl4 at 25 °\degree° C
C)   Cl2,ROOR,h ν
uν 
D)   Br2 at low concentration in CCl4
E)   N-Bromosuccinimide in CCl4,ROOR F) A) and C)
G) A) and B)

Question 4

Which pair does not represent a pair of resonance structures?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   All of these represent pairs of resonance structures.F) None of the above
G) A) and C)

Question 5

Which of the following dienes is a cumulated diene?

Accepted Answer

A)   CH2=CHCH2CH2CH=CH2
B)   CH2=CHCH=CHCH2CH3
C)   CH3CH=C=CHCH2CH3
D)   CH3CH=CHCH=CHCH3
E)   CH3CH=CHCH2CH=CH2F) B) and E)
G) B) and D)

Question 6

Which alkene would you expect to have the highest heat of hydrogenation?

Accepted Answer

A)  
B)  
C)  
D)  
E)  F) D) and E)
G) A) and E)

Question 7

Which of these dienes is the most reactive in the Diels-Alder reaction?

Accepted Answer

A)   1,3-Butadiene
B)   1,4-Pentadiene
C)   2,3,-Dimethyl-1,3-butadiene
D)   1,2-Butadiene
E)   1,4-CyclohexadieneF) C) and D)
G) B) and C)

Question 8

UV-vis spectroscopy can be used to indicate whether _________________ is present.

Accepted Answer

The answer of UV-vis spectroscopy can be used to indicate...

Question 9

Which of the following dienes would you expect to be the most stable?

Accepted Answer

A)   CH3CH2CH=CHCH2CH=CHCH3
B)   CH3CH=CHCH=CHCH2CH3
C)   CH2=CHCH2CH2CH2CH=CH2
D)   CH2=CHCH=CHCH2CH2CH3
E)   CH3CH2CH=C=CHCH2CH3F) All of the above
G) A) and E)

Question 10

Treatment of 2-butene (cis or trans) with Cl2 at 400   °\degree° C would yield mainly:

Accepted Answer

A)   CH2ClCHClCH2CH3
B)   CH3CHClCH2CH3
C)   CH3CH=CClCH3 
D)   CH3CH=CHCH2Cl and  CH3CHClCH=CH2 
E)   CH3CHClCHClCH3 F) A) and C)
G) D) and E)

Question 11

Which is the major product of the following reaction?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   None of theseF) A) and B)
G) All of the above

Question 12

An equilibrium-controlled reaction will yield predominantly:

Accepted Answer

A)   the more/most stable product.
B)   the product whose formation requires the smallest free energy of activation.
C)   the product that can be formed in the fewest steps.
D)   the product that is formed at the fastest rate.
E)   the product which possesses the greatest potential energy.F) A) and B)
G) A) and D)

Question 13

The LUMO of 1,3-pentadiene has how many electrons in its ground state?

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   0F) A) and D)
G) D) and E)

Question 14

Which carbon-carbon bond in the following compound would you expect to be longest?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   VF) A) and C)
G) A) and B)

Question 15

Ignoring stereochemistry,the 1:1 reaction of bromine with 1,3-cyclohexadiene at 25 °\degree° C in the dark and in the absence of peroxide forms which of these?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   Both I and II F) A) and E)
G) B) and D)

Question 16

Treatment of 4-methylcyclohexene with N-bromosuccinimide in CCl4 would yield mainly: 4 would yield mainly:   A)  I B)  II C)  III D)  IV E)  All of the above" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   All of the aboveF) C) and E)
G) B) and C)

Question 17

Estimate the stabilization energy for 1,3-butadiene using the heats of hydrogenation in Table 1. Table 1.
Heats of Hydrogenation for Selected Compounds
Compound
Moles H2
 Δ\DeltaΔ H(kJ mol-1) 
1-Butene
1
-127
1-Pentene
1
-126
1,3-Butadiene
2
-239
Trans-1,3-Pentadiene
2
-226

Accepted Answer

A)   13 kJ mol-1
B)   15 kJ mol-1
C)   28 kJ mol-1
D)   239 kJ mol-1
E)   112 kJ mol-1 F) All of the above
G) A) and B)

Question 18

Which diene and dienophile would you choose to synthesize the following compound?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   None of theseF) B) and E)
G) C) and E)

Question 19

How could the following synthesis be carried out? 2/CCl4; (2) CH3CH2MgCl,ether; (3) CH3ONa/CH3OH B)  (1) HBr,80 \degree C; (2) (CH3CH2) 2CuLi,ether C)  (1) HBr,80 \degree C; (2) Mg,ether; (3) CH3CH2OH,then H3O+ D)  More than one of the above E)  All of the above " class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   (1) Br2/CCl4; (2) CH3CH2MgCl,ether; (3) CH3ONa/CH3OH
B)   (1) HBr,80 °\degree° C; (2) (CH3CH2) 2CuLi,ether
C)   (1) HBr,80 °\degree° C; (2) Mg,ether; (3) CH3CH2OH,then H3O+
D)   More than one of the above
E)   All of the above F) A) and C)
G) A) and E)

Question 20

The first step in the total synthesis of synthetic cholesterol involves production of the
intermediate structure shown.Which combination of diene and dieneophile will result in
its preparation?

Accepted Answer

The answer of The first step in the total synthesis...

Exam 13: Conjugated Unsaturated Systems

Which of the following dienes would you expect to be the most stable?

Correct Answer
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Treatment of 4-methylcyclohexene with N-bromosuccinimide in CCl₄ would yield mainly:

Correct Answer
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The first step in the total synthesis of synthetic cholesterol involves production of the intermediate structure shown.Which combination of diene and dieneophile will result in its preparation?

Correct Answer
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The LUMO of 1,3-pentadiene has how many electrons in its ground state?

Correct Answer
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Which of these dienes is the most reactive in the Diels-Alder reaction?

Correct Answer
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Which diene and dienophile would you choose to synthesize the following compound?

Correct Answer
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Which is the major product of the following reaction?

Correct Answer
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Treatment of 2-butene (cis or trans) with Cl₂ at 400 $\degree$ C would yield mainly:

Correct Answer
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Which pair does not represent a pair of resonance structures?

Correct Answer
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Estimate the stabilization energy for 1,3-butadiene using the heats of hydrogenation in Table 1. Table 1. Heats of Hydrogenation for Selected Compounds Compound Moles H₂ $\Delta$ H(kJ mol^-1) 1-Butene 1 -127 1-Pentene 1 -126 1,3-Butadiene 2 -239 Trans-1,3-Pentadiene 2 -226

Correct Answer
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Correct Answer
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Which alkene would you expect to have the highest heat of hydrogenation?

Correct Answer
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Which set of conditions does not result in allylic halogenation of an alkene?

Correct Answer
verified

UV-vis spectroscopy can be used to indicate whether _________________ is present.

Correct Answer
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Which of the following dienes is a cumulated diene?

Correct Answer
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A reaction under kinetic (or rate) control will yield predominantly:

Correct Answer
verified

An equilibrium-controlled reaction will yield predominantly:

Correct Answer
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Correct Answer
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Which carbon-carbon bond in the following compound would you expect to be longest?

Correct Answer
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Exam 13: Conjugated Unsaturated Systems

Which of the following dienes would you expect to be the most stable?

Correct AnswerverifiedShow Answer

Treatment of 4-methylcyclohexene with N-bromosuccinimide in CCl4 would yield mainly:

Correct AnswerverifiedShow Answer

The first step in the total synthesis of synthetic cholesterol involves production of the intermediate structure shown.Which combination of diene and dieneophile will result in its preparation?

Correct AnswerverifiedShow Answer

The LUMO of 1,3-pentadiene has how many electrons in its ground state?

Correct AnswerverifiedShow Answer

How could the following synthesis be carried out?

Correct AnswerverifiedShow Answer

Which of these dienes is the most reactive in the Diels-Alder reaction?

Correct AnswerverifiedShow Answer

Which diene and dienophile would you choose to synthesize the following compound?

Correct AnswerverifiedShow Answer

Which is the major product of the following reaction?

Correct AnswerverifiedShow Answer

Treatment of 2-butene (cis or trans) with Cl2 at 400 °\degree° C would yield mainly:

Correct AnswerverifiedShow Answer

Which pair does not represent a pair of resonance structures?

Correct AnswerverifiedShow Answer

Estimate the stabilization energy for 1,3-butadiene using the heats of hydrogenation in Table 1. Table 1. Heats of Hydrogenation for Selected Compounds Compound Moles H2 Δ\DeltaΔ H(kJ mol-1) 1-Butene 1 -127 1-Pentene 1 -126 1,3-Butadiene 2 -239 Trans-1,3-Pentadiene 2 -226

Correct AnswerverifiedShow Answer

Ignoring stereochemistry,the 1:1 reaction of bromine with 1,3-cyclohexadiene at 25 °\degree° C in the dark and in the absence of peroxide forms which of these?

Correct AnswerverifiedShow Answer

Which alkene would you expect to have the highest heat of hydrogenation?

Correct AnswerverifiedShow Answer

Which set of conditions does not result in allylic halogenation of an alkene?

Correct AnswerverifiedShow Answer

UV-vis spectroscopy can be used to indicate whether _________________ is present.

Correct AnswerverifiedShow Answer

Which of the following dienes is a cumulated diene?

Correct AnswerverifiedShow Answer

A reaction under kinetic (or rate) control will yield predominantly:

Correct AnswerverifiedShow Answer

An equilibrium-controlled reaction will yield predominantly:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which carbon-carbon bond in the following compound would you expect to be longest?

Correct AnswerverifiedShow Answer

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Treatment of 4-methylcyclohexene with N-bromosuccinimide in CCl₄ would yield mainly:

Correct Answer
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Treatment of 2-butene (cis or trans) with Cl₂ at 400 $\degree$ C would yield mainly:

Correct Answer
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Estimate the stabilization energy for 1,3-butadiene using the heats of hydrogenation in Table 1. Table 1. Heats of Hydrogenation for Selected Compounds Compound Moles H₂ $\Delta$ H(kJ mol^-1) 1-Butene 1 -127 1-Pentene 1 -126 1,3-Butadiene 2 -239 Trans-1,3-Pentadiene 2 -226

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