Question 1

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 2

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 3

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 4

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

Accepted Answer

A)  
B)  
C)  
D)  
E)

Question 5

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 6

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 7

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 8

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 9

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 10

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 11

Which carbocation would be most stable?

Accepted Answer

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

Question 12

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

Accepted Answer

A)  
B)  
C)  
D)  
E)

Question 13

What would be the product of the following reaction?

Accepted Answer

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

Question 14

Which carbocation would be most stable?

Accepted Answer

A)  
B)  
C)  
D)  
E)

Question 15

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 16

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 17

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 18

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 19

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 20

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

Accepted Answer

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

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

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A thermodynamically-controlled reaction will yield predominantly:

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

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

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Arrange these carbocations in order of expected increasing stability.

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

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

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Which carbocation would be most stable?

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Which of the following dienes is a cumulated diene?

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What would be the product of the following reaction?

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

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

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

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

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Which carbocation would be most stable?

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Which pair does not represent a pair of resonance structures?

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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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