Question 1

Which of the following is a type of pericyclic reaction?

Accepted Answer

A)  electrocyclic reactions
B)  acyclic reactions
C)  cycloelimination reactions
D)  electrophilic reactionsE) None of the above
F) B) and C)

Question 2

Which of the following statements about porbitals is true?

Accepted Answer

A)  p orbitals are formed by the linear combination of two sp3 orbitals.
B)  p orbitals are formed by the linear combination of two sp2 orbitals.
C)  p orbitals are formed by the linear combination of two sp orbitals.
D)  p orbitals are formed by the linear combination of two p orbitals.E) B) and C)
F) A) and D)

Question 3

How many pi electrons are in the ground state LUMO for hexa-1,3,5-triene?

Accepted Answer

A)  0
B)  2
C)  4
D)  6E) A) and D)
F) C) and D)

Question 4

Which of the following statements about the Cope rearrangement is not true?

Accepted Answer

A)  The Cope rearrangement involves the rearrangement of a 1,5-diene to an isomeric 1,5-diene.
B)  The Cope rearrangement takes place readily in a suprafacial pathway under photochemical conditions.
C)  The Cope rearrangement involves three electron pairs; two in p bonds and one in a s bond.
D)  The Cope rearrangement takes place readily in a suprafacial pathway,when heated.E) None of the above
F) All of the above

Question 5

How many pi electrons are in the ground state HOMO for hexa-1,3,5-triene?

Accepted Answer

A)  0
B)  2
C)  4
D)  6E) None of the above
F) A) and C)

Question 6

What is the major organic product of the following oxy-Cope rearrangement?

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) A) and B)
F) A) and C)

Question 7

How many bonding molecular orbitals are present in 1,3,5,7,9-decapentaene?

Accepted Answer

A)  4
B)  5
C)  10
D)  12E) A) and B)
F) A) and C)

Question 8

What type of sigmatropic rearrangement is illustrated below?

Accepted Answer

A)  [1,3]
B)  [1,4]
C)  [3,3]
D)  [1,5]E) None of the above
F) A) and C)

Question 9

Which of the following statements about molecular orbitals is true?

Accepted Answer

A)  The number of molecular orbitals formed is different from the number of atomic orbitals used.
B)  The number of molecular orbitals formed is equal to the number of atomic orbitals used.
C)  The number of molecular orbitals formed is equal to twice the number of atomic orbitals used.
D)  The number of molecular orbitals formed is equal to half the number of atomic orbitals used.E) B) and D)
F) A) and D)

Question 10

Which of the following statements about cycloaddition reactions is true?

Accepted Answer

A)  Cycloaddition reactions occur only intermolecularly.
B)  Cycloaddition reactions occur only intramolecularly.
C)  Cycloaddition reactions form a cyclic product with two new p bonds.
D)  Cycloaddition reactions can be intramolecular or intermolecular.E) All of the above
F) A) and C)

Question 11

Which of the following statements about orbital symmetry and cycloaddition reactions is true?

Accepted Answer

A)  Thermal cycloadditions involving an even number of p bonds proceed by a suprafacial pathway.
B)  Thermal cycloadditions involving an odd number of p bonds proceed by a suprafacial pathway.
C)  Photochemical cycloadditions involving an odd number of p bonds proceed by a suprafacial pathway.
D)  Photochemical sycloadditions involving an even number of p bonds proceed by an antarafacial pathway.E) All of the above
F) B) and D)

Question 12

What is the correct classification of the following reaction?

Accepted Answer

A)  Cycloaddition reaction
B)  Electrocyclic reaction
C)  Electrophilic reaction
D)  Sigmatropic reactionE) A) and B)
F) All of the above

Question 13

Which of the following statements about electrocyclic ring closure is not true?

Accepted Answer

A)  It is an intramolecular reaction.
B)  It requires heat or light.
C)  The cyclic product contains one more s bond and one fewer p bond than the reactants.
D)  The cyclic product contains one more p bond and one fewer s bond than the reactants.E) B) and C)
F) B) and D)

Question 14

Which of the following statements about pericyclic reactions is not true?

Accepted Answer

A)  Pericyclic reactions are concerted reactions.
B)  Pericyclic reactions proceed through a cyclic transition state.
C)  Pericyclic reactions are not stereospecific.
D)  Pericyclic reactions require light or heat.E) A) and D)
F) B) and C)

Question 15

Which of the following statements about electrocyclic reactions is true?

Accepted Answer

A)  An electrocyclic reaction is generally irreversible.
B)  Generally,an acyclic triene is favored over a six-membered ring at equilibrium.
C)  Generally,a four-membered ring is favored over an acyclic diene at equilibrium.
D)  An electrocyclic reaction is generally reversible.E) A) and D)
F) C) and D)

Question 16

How many pi electrons are in the excited state HOMO for buta-1,3-diene?

Accepted Answer

A)  0
B)  1
C)  2
D)  3E) None of the above
F) A) and C)

Question 17

Which of the following statements about an electrocyclic ring-opening reaction is not true?

Accepted Answer

A)  An electrocyclic ring-opening reaction is an intramolecular reaction.
B)  An electrocyclic ring-opening reaction requires a source of energy (heat or light) .
C)  The product of an electrocyclic ring-opening reaction contains one fewer p bond than the reactant.
D)  The product of an electrocyclic ring-opening reaction contains one more p bond than the reactant.E) A) and C)
F) A) and B)

Question 18

Which of the following statements about sigmatropic reactions is true?

Accepted Answer

A)  The reactants contain one more p bond than the product.
B)  The product contains one more p bond than the reactant.
C)  A p bond is broken in the reactant.
D)  A s bond is broken in the reactant.E) A) and C)
F) A) and D)

Question 19

What is the correct classification of the following reaction?

Accepted Answer

A)  Cycloaddition reaction
B)  Electrocyclic reaction
C)  Electrophilic reaction
D)  Sigmatropic reactionE) B) and D)
F) B) and C)

Question 20

How many nodes are present in Y5 of 1,3,5,7,9-decapentaene?

Accepted Answer

A)  2
B)  3
C)  4
D)  5E) A) and C)
F) A) and B)

Exam 25: Pericyclic Reactions

Which of the following statements about electrocyclic reactions is true?

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How many pi electrons are in the excited state HOMO for buta-1,3-diene?

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Which of the following is a type of pericyclic reaction?

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Which of the following statements about electrocyclic ring closure is not true?

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What is the major organic product of the following oxy-Cope rearrangement?

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Which of the following statements about sigmatropic reactions is true?

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What is the correct classification of the following reaction?

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Which of the following statements about molecular orbitals is true?

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How many nodes are present in Y5 of 1,3,5,7,9-decapentaene?

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Which of the following statements about the Cope rearrangement is not true?

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What is the correct classification of the following reaction?

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How many pi electrons are in the ground state HOMO for hexa-1,3,5-triene?

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Which of the following statements about an electrocyclic ring-opening reaction is not true?

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How many pi electrons are in the ground state LUMO for hexa-1,3,5-triene?

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Which of the following statements about porbitals is true?

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What type of sigmatropic rearrangement is illustrated below?

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How many bonding molecular orbitals are present in 1,3,5,7,9-decapentaene?

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Which of the following statements about pericyclic reactions is not true?

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Which of the following statements about cycloaddition reactions is true?

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Which of the following statements about orbital symmetry and cycloaddition reactions is true?

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How many nodes are present in Y₅ of 1,3,5,7,9-decapentaene?

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