Question 1

What is the hybridization around the indicated oxygen atom in the following anion?

Accepted Answer

A)  sp3 
B)  sp2 
C)  sp 
D)  p 
A)  sp3 
B)  sp2 
C)  sp 
D)  p B

Question 2

Which of the following is (are) conjugated dienes?

Accepted Answer

A)  Only I 
B)  Only II 
C)  Only I and II 
D)  I, II and III 
A)  Only I 
B)  Only II 
C)  Only I and II 
D)  I, II and III B

Question 3

Which of the following dienes contain isolated double bonds?

Accepted Answer

A)  Only I and II 
B)  Only II and III 
C)  Only I and III 
D)  Only II and IV 
A)  Only I and II 
B)  Only II and III 
C)  Only I and III 
D)  Only II and IV D

Question 4

Which of the following compounds is the most reactive dienophile in a Diels-Alder reaction?

Accepted Answer

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

Question 5

Which of the following statements about the Diels-Alder reaction is true?

Accepted Answer

A)  The diene can react only when it adopts the s-trans conformation. 
B)  Electron-withdrawing substituents in the diene increase reaction rate. 
C)  Electron-donating substituents in the dienophile increase the reaction rate. 
D)  The stereochemistry of the dienophile is retained in the product. 
A)  The diene can react only when it adopts the s-trans conformation. 
B)  Electron-withdrawing substituents in the diene increase reaction rate. 
C)  Electron-donating substituents in the dienophile increase the reaction rate. 
D)  The stereochemistry of the dienophile is retained in the product.

Question 6

Which of the following conjugated dienes represent two conformations?

Accepted Answer

A)  Only I and II 
B)  Only I and III 
C)  Only II and III 
D)  None of the choices 
A)  Only I and II 
B)  Only I and III 
C)  Only II and III 
D)  None of the choices

Question 7

Which of the following statements about resonance structures is true?

Accepted Answer

A)  The placement of atoms is different. 
B)  The placement of F1F1F1S1F1F1F10 bonds is different. 
C)  The placement of F1F1F1S1F1F1F10 bonds is different. 
D)  The placement of nonbonded electrons is the same. 
A)  The placement of atoms is different. 
B)  The placement of F1F1F1S1F1F1F10 bonds is different. 
C)  The placement of F1F1F1S1F1F1F10 bonds is different. 
D)  The placement of nonbonded electrons is the same.

Question 8

What is (are) the major product(s) of the following reaction?

Accepted Answer

A)  Only I 
B)  Only I and III 
C)  Only II and IV 
D)  Only I, II, and III 
A)  Only I 
B)  Only I and III 
C)  Only II and IV 
D)  Only I, II, and III

Question 9

Rank the following dienophile in order of increasing reactivity in a Diels-Alder reaction, listing the least reactive first.

Accepted Answer

A)  I < II < III 
B)  III < I < II 
C)  II < I < III 
D)  III < II < I 
A)  I < II < III 
B)  III < I < II 
C)  II < I < III 
D)  III < II < I

Question 10

What is (are) the major product(s) of the following reaction?

Accepted Answer

A)  Only I 
B)  Only II and IV 
C)  Only I and III 
D)  Only I, II and III 
A)  Only I 
B)  Only II and IV 
C)  Only I and III 
D)  Only I, II and III

Question 11

Which of the following compounds is conjugated?

Accepted Answer

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

Question 12

Rank the following dienes in order of increasing reactivity in a Diels-Alder reaction, listing the least reactive first.

Accepted Answer

A)  I < II < III 
B)  III < I < II 
C)  II < I < III 
D)  I < III < II 
A)  I < II < III 
B)  III < I < II 
C)  II < I < III 
D)  I < III < II

Question 13

Rank the following compounds in order of increasing stability, putting the least stable first.

Accepted Answer

A)  I < II < III 
B)  III < II < I 
C)  II < I < III 
D)  III < I < II 
A)  I < II < III 
B)  III < II < I 
C)  II < I < III 
D)  III < I < II

Question 14

Which of the following compounds is the least reactive dienophile in a Diels-Alder reaction?

Accepted Answer

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

Question 15

Rank the following dienes in order of decreasing heat of hydrogenation, putting the diene with the highest heat of hydrogenation first.

Accepted Answer

A)  I > II > III 
B)  III > II > I 
C)  II > I > III 
D)  III > I > II 
A)  I > II > III 
B)  III > II > I 
C)  II > I > III 
D)  III > I > II

Question 16

Which of the following statements about the mechanism of the Diels-Alder reaction is true?

Accepted Answer

A)  Three pi bonds break; two sigma bonds and one pi bond form. 
B)  Three pi bonds break; one sigma bond and two pi bonds form. 
C)  Two pi bonds break; one sigma bond and one pi bond form. 
D)  Two pi bonds break; two sigma bonds and one pi bond form. 
A)  Three pi bonds break; two sigma bonds and one pi bond form. 
B)  Three pi bonds break; one sigma bond and two pi bonds form. 
C)  Two pi bonds break; one sigma bond and one pi bond form. 
D)  Two pi bonds break; two sigma bonds and one pi bond form.

Question 17

Which of the following electronic transitions is common in the UV spectrum of 1,3-butadiene?

Accepted Answer

A)  "F1F1F1S1F1F1F10 F1F1F1S1F1F1F10 F1F1F1S1F1F1F10" 
B)  "F1F1F1S1F1F1F10 F1F1F1S1F1F1F10 F1F1F1S1F1F1F10*" 
C)  "n F1F1F1S1F1F1F10 F1F1F1S1F1F1F10*" 
D)  "F1F1F1S1F1F1F10 F1F1F1S1F1F1F10 F1F1F1S1F1F1F10*" 
A)  "F1F1F1S1F1F1F10 F1F1F1S1F1F1F10 F1F1F1S1F1F1F10" 
B)  "F1F1F1S1F1F1F10 F1F1F1S1F1F1F10 F1F1F1S1F1F1F10*" 
C)  "n F1F1F1S1F1F1F10 F1F1F1S1F1F1F10*" 
D)  "F1F1F1S1F1F1F10 F1F1F1S1F1F1F10 F1F1F1S1F1F1F10*"

Question 18

What is the major organic product of the following reaction?

Accepted Answer

A)  Only I 
B)  Only II 
C)  Only III 
D)  Only I and II 
A)  Only I 
B)  Only II 
C)  Only III 
D)  Only I and II

Question 19

What is the thermodynamic product obtained from the addition of 1 equivalent of HBr to 1,3-butadiene?

Accepted Answer

A)  3-Bromo-1-butene 
B)  1-Bromo-2-butene 
C)  2-Bromo-2-butene 
D)  2-Bromo-1-butene 
A)  3-Bromo-1-butene 
B)  1-Bromo-2-butene 
C)  2-Bromo-2-butene 
D)  2-Bromo-1-butene

Question 20

Which of the following is the least reactive diene in a Diels-Alder reaction?

Accepted Answer

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

Exam 16: Conjugation, Resonance, and Dienes

What is the hybridization around the indicated oxygen atom in the following anion?

Which of the following is (are) conjugated dienes?

Which of the following dienes contain isolated double bonds?

Which of the following compounds is the most reactive dienophile in a Diels-Alder reaction?

Which of the following statements about the Diels-Alder reaction is true?

Which of the following conjugated dienes represent two conformations?

Which of the following statements about resonance structures is true?

What is (are) the major product(s) of the following reaction?

Rank the following dienophile in order of increasing reactivity in a Diels-Alder reaction, listing the least reactive first.

What is (are) the major product(s) of the following reaction?

Which of the following compounds is conjugated?

Rank the following dienes in order of increasing reactivity in a Diels-Alder reaction, listing the least reactive first.

Rank the following compounds in order of increasing stability, putting the least stable first.

Which of the following compounds is the least reactive dienophile in a Diels-Alder reaction?

Rank the following dienes in order of decreasing heat of hydrogenation, putting the diene with the highest heat of hydrogenation first.

Which of the following statements about the mechanism of the Diels-Alder reaction is true?

Which of the following electronic transitions is common in the UV spectrum of 1,3-butadiene?

What is the major organic product of the following reaction?

What is the thermodynamic product obtained from the addition of 1 equivalent of HBr to 1,3-butadiene?

Which of the following is the least reactive diene in a Diels-Alder reaction?

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