Question 1

Which of the following would afford a synthesis of the following compound?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   None of these

Question 2

Which diene and dienophile would you use to prepare the following molecule using a Diels-
Alder cycloaddition reaction:

Accepted Answer

The answer of Which diene and dienophile would you use...

Question 3

What would be the product of the following reaction?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   All of these

Question 4

A thermodynamically-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.

Question 5

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.

Question 6

Which of these dienes can undergo the Diels-Alder reaction?

Accepted Answer

A)  
B)  
C)  
D)  
E)

Question 7

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

Accepted Answer

A)   CH3CH2CH=CHCH2CH=CHCH3
B)   CH3CH=CHCH=CHCH2CH3
C)   CH2=CHCH2CH2CH2CH=CH2
D)   CH2=CHCH=CHCH2CH2CH3
E)   CH3CH=C(CH3) CH=CHCH2CH3

Question 8

Which carbocation would be most stable?

Accepted Answer

A)  
B)  
C)  
D)  
E)

Question 9

What product(s) would you expect from the following substitution reaction of 14C-labeled propene? 14C-labeled propene?   A)   14CH2=CH-CH2Cl alone  B)   14CH2=CH-CH2Cl and CH2=CH-14CH2Cl,in equal amounts C)  CH2=CH-14CH2Cl alone  D)   more 14CH2=CHCH2Cl,but a little CH2=CH-14CH2Cl  E)   more CH2=CH-14CH2Cl,but a little 14CH2=CHCH2Cl " class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   "14CH2=CH-CH2Cl alone"
B)   "14CH2=CH-CH2Cl and CH2=CH-14CH2Cl,in equal amounts
C)   CH2=CH-14CH2Cl alone"
D)   "more 14CH2=CHCH2Cl,but a little CH2=CH-14CH2Cl"
E)   "more CH2=CH-14CH2Cl,but a little 14CH2=CHCH2Cl"

Question 10

Estimate the stabilization energy for 1,3-cyclohhexadiene 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) 
Cyclohexene
1
-120
1,4-Cyclohexadiene
2
-240
1,3-Cyclohexadiene
2
-232
1,5-Hexadiene
2
-253

Accepted Answer

A)   13 kJ mol-1
B)   21 kJ mol-1
C)   8 kJ mol-1
D)   120 kJ mol-1
E)   112 kJ mol-1

Question 11

Which carbocation would be most stable?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   V

Question 12

Draw arrows to indicate the electron flow for the following intramolecular Diels-Alder
cycloaddition reaction:

Accepted Answer

The answer of Draw arrows to indicate the electron flow...

Question 13

Which of the following dienes is a cumulated diene?

Accepted Answer

A)   CH2=CHCH2CH2CH2CH=CH2
B)   CH2=CHCH=CHCH2CH2CH3
C)   CH3CH=C=CHCH2CH2CH3
D)   CH3CH=CHCH=CHCH2CH3
E)   CH3CH2CH=CHCH2CH=CH2

Question 14

Which hydrogen atom(s) of  is/are most susceptible to abstraction by free radicals?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   V

Question 15

Which diene would you expect to react most rapidly with maleic anhydride?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   V

Question 16

Arrange these carbocations in order of expected increasing stability.

Accepted Answer

A)   V < II < I < IV < III
B)   V<I<II<IV<III
C)   IV <I< II <V< III
D)   IV < III < I < II < V
E)   I < II < IV < III < V

Question 17

What reagents would be needed to synthesize the following substance via the Diels-Alder reaction? Give stereochemical details,as relevant.

Accepted Answer

The answer of What reagents would be needed to synthesize...

Question 18

Predict the product of the following Diels-Alder cycloaddition reaction:

Accepted Answer

<img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30"> Topic Die...

Question 19

Draw the structural formula for (2E,4Z,6E)-3,4,7,8-tetramethyl-2,4,6-nonatriene,clearly indicating stereochemical details.

Accepted Answer

The answer of Draw the structural formula for (2E,4Z,6E)-3,4,7,8-tetramethyl-2,4,6-nonatriene,clearly indicating...

Question 20

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

Accepted Answer

A)  
B)  
C)  
D)  
E)

Exam 13: Conjugated Unsaturated Systems

Which diene and dienophile would you use to prepare the following molecule using a Diels- Alder cycloaddition reaction:

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Which hydrogen atom(s) of is/are most susceptible to abstraction by free radicals?

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Which carbocation would be most stable?

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Which of these dienes can undergo the Diels-Alder reaction?

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Estimate the stabilization energy for 1,3-cyclohhexadiene 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) Cyclohexene 1 -120 1,4-Cyclohexadiene 2 -240 1,3-Cyclohexadiene 2 -232 1,5-Hexadiene 2 -253

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A thermodynamically-controlled reaction will yield predominantly:

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Draw the structural formula for (2E,4Z,6E)-3,4,7,8-tetramethyl-2,4,6-nonatriene,clearly indicating stereochemical details.

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What reagents would be needed to synthesize the following substance via the Diels-Alder reaction? Give stereochemical details,as relevant.

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Which carbocation would be most stable?

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Predict the product of the following Diels-Alder cycloaddition reaction:

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What product(s) would you expect from the following substitution reaction of 14C-labeled propene?

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Which of the following would afford a synthesis of the following compound?

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

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Draw arrows to indicate the electron flow for the following intramolecular Diels-Alder cycloaddition reaction:

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What would be the product of the following reaction?

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Which pair does not represent a pair of resonance structures?

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

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Which of the following dienes is a cumulated diene?

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Arrange these carbocations in order of expected increasing stability.

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Which diene would you expect to react most rapidly with maleic anhydride?

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Estimate the stabilization energy for 1,3-cyclohhexadiene using the heats of hydrogenation in Table 1. Table 1. Heats of Hydrogenation for Selected Compounds Compound Moles H₂ $\Delta$ H(kJ mol^-1) Cyclohexene 1 -120 1,4-Cyclohexadiene 2 -240 1,3-Cyclohexadiene 2 -232 1,5-Hexadiene 2 -253

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What product(s) would you expect from the following substitution reaction of ¹⁴C-labeled propene?

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