Question 1

Which of the following statements about F1F1F1S1F1F1F10 orbitals is true?

Accepted Answer

A)  "F1F1F1S1F1F1F10 orbitals are formed by the linear combination of two sp3 orbitals." 
B)  "F1F1F1S1F1F1F10 orbitals are formed by the linear combination of two sp2 orbitals." 
C)  "F1F1F1S1F1F1F10 orbitals are formed by the linear combination of two sp orbitals." 
D)  "F1F1F1S1F1F1F10 orbitals are formed by the linear combination of two p orbitals." 
A)  "F1F1F1S1F1F1F10 orbitals are formed by the linear combination of two sp3 orbitals." 
B)  "F1F1F1S1F1F1F10 orbitals are formed by the linear combination of two sp2 orbitals." 
C)  "F1F1F1S1F1F1F10 orbitals are formed by the linear combination of two sp orbitals." 
D)  "F1F1F1S1F1F1F10 orbitals are formed by the linear combination of two p orbitals." D

Question 2

What is the major organic product of the following Claisen rearrangement?

Accepted Answer

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

Question 3

Predict the major organic product(s) of the following electrocyclic 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 B

Question 4

What type of cycloaddition reaction is shown in the following equation?

Accepted Answer

A)  [2+2] 
B)  [4+2] 
C)  [4+4] 
D)  [0+2] 
A)  [2+2] 
B)  [4+2] 
C)  [4+4] 
D)  [0+2]

Question 5

What is the correct classification of the following reaction?

Accepted Answer

A)  cycloaddition reaction 
B)  electrophilic reaction 
C)  electrocyclic reaction 
D)  sigmatropic reaction 
A)  cycloaddition reaction 
B)  electrophilic reaction 
C)  electrocyclic reaction 
D)  sigmatropic reaction

Question 6

Which of the following statements about cycloaddition reactions is true?

Accepted Answer

A)  Cycloaddition reactions can be initiated by heat only. 
B)  Cycloaddition reactions can be initiated by light only. 
C)  Cycloaddition reactions can be initiated by heat or light. 
D)  Cycloaddition reactions are identified by the number of F1F1F1S1F1F1F10 electrons in the two products. 
A)  Cycloaddition reactions can be initiated by heat only. 
B)  Cycloaddition reactions can be initiated by light only. 
C)  Cycloaddition reactions can be initiated by heat or light. 
D)  Cycloaddition reactions are identified by the number of F1F1F1S1F1F1F10 electrons in the two products.

Question 7

What type of sigmatropic rearrangement is illustrated below?

Accepted Answer

A)  [1,3] 
B)  [1,4] 
C)  [3,3] 
D)  [1,5] 
A)  [1,3] 
B)  [1,4] 
C)  [3,3] 
D)  [1,5]

Question 8

How many F1F1F1S1F1F1F10 molecular orbitals are present in 1,3,5-hexatriene?

Accepted Answer

A)  3 
B)  4 
C)  5 
D)  6 
A)  3 
B)  4 
C)  5 
D)  6

Question 9

Why is the Diels-Alder reaction called a thermal [4+2] cycloaddition?

Accepted Answer

A)  Because the reaction is initiated by heat; the diene has four F1F1F1S1F1F1F10 electrons and the dienophile has two F1F1F1S1F1F1F10 electrons. 
B)  Because the reaction is initiated by light; the diene has four F1F1F1S1F1F1F10 electrons and the dienophile has two F1F1F1S1F1F1F10 electrons. 
C)  Because the reaction is initiated by heat; the dienophile has four F1F1F1S1F1F1F10 electrons and the diene has two F1F1F1S1F1F1F10 electrons. 
D)  Because the reaction is initiated by light; the dienophile has four F1F1F1S1F1F1F10 electrons and the diene has two F1F1F1S1F1F1F10 electrons. 
A)  Because the reaction is initiated by heat; the diene has four F1F1F1S1F1F1F10 electrons and the dienophile has two F1F1F1S1F1F1F10 electrons. 
B)  Because the reaction is initiated by light; the diene has four F1F1F1S1F1F1F10 electrons and the dienophile has two F1F1F1S1F1F1F10 electrons. 
C)  Because the reaction is initiated by heat; the dienophile has four F1F1F1S1F1F1F10 electrons and the diene has two F1F1F1S1F1F1F10 electrons. 
D)  Because the reaction is initiated by light; the dienophile has four F1F1F1S1F1F1F10 electrons and the diene has two F1F1F1S1F1F1F10 electrons.

Question 10

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. 
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.

Question 11

What is the correct classification of the following reaction?

Accepted Answer

A)  cycloaddition reaction 
B)  electrophilic reaction 
C)  electrocyclic reaction 
D)  sigmatropic reaction 
A)  cycloaddition reaction 
B)  electrophilic reaction 
C)  electrocyclic reaction 
D)  sigmatropic reaction

Question 12

Which of the following statements about sigmatropic reactions is true?

Accepted Answer

A)  The reactants contain one more F1F1F1S1F1F1F10 bond than the product. 
B)  The product contains one more F1F1F1S1F1F1F10 bond than the reactant. 
C)  A F1F1F1S1F1F1F10 bond is broken in the reactant. 
D)  A F1F1F1S1F1F1F10 bond is broken in the reactant. 
A)  The reactants contain one more F1F1F1S1F1F1F10 bond than the product. 
B)  The product contains one more F1F1F1S1F1F1F10 bond than the reactant. 
C)  A F1F1F1S1F1F1F10 bond is broken in the reactant. 
D)  A F1F1F1S1F1F1F10 bond is broken in the reactant.

Question 13

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

Accepted Answer

A)  Thermal cycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
B)  Thermal cycloaddition involving an odd number of F1F1F1S1F1F1F10 bonds proceed by an antarafacial pathway. 
C)  Photochemical cycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by an antarafacial pathway. 
D)  Photochemical cycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
A)  Thermal cycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
B)  Thermal cycloaddition involving an odd number of F1F1F1S1F1F1F10 bonds proceed by an antarafacial pathway. 
C)  Photochemical cycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by an antarafacial pathway. 
D)  Photochemical cycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway.

Question 14

Which of the following statements about thermal electrocyclic reactions is not true?

Accepted Answer

A)  The number of F1F1F1S1F1F1F10 bonds in the conjugated polyene determines whether rotation is conrotatory or disrotatory. 
B)  Thermal electrocyclic reactions occur in a disrotatory fashion for a conjugated polyene with an odd number of F1F1F1S1F1F1F10 bonds. 
C)  Thermal electrocyclic reactions occur in a conrotatory fashion for a conjugated polyene with an even number of F1F1F1S1F1F1F10 bonds. 
D)  In thermal reactions, we consider the orbitals of the HOMO of the ground state electronic configuration to determine the course of the reaction. 
A)  The number of F1F1F1S1F1F1F10 bonds in the conjugated polyene determines whether rotation is conrotatory or disrotatory. 
B)  Thermal electrocyclic reactions occur in a disrotatory fashion for a conjugated polyene with an odd number of F1F1F1S1F1F1F10 bonds. 
C)  Thermal electrocyclic reactions occur in a conrotatory fashion for a conjugated polyene with an even number of F1F1F1S1F1F1F10 bonds. 
D)  In thermal reactions, we consider the orbitals of the HOMO of the ground state electronic configuration to determine the course of the reaction.

Question 15

Which of the following statements about a F1F1F1S1F1F1F10-bonding molecular orbital is true?

Accepted Answer

A)  A F1F1F1S1F1F1F10-bonding molecular orbital is formed when two p orbitals of similar phase overlap. 
B)  A F1F1F1S1F1F1F10-bonding molecular orbital is lower in energy than a F1F1F1S1F1F1F10-bonding molecular orbital. 
C)  A F1F1F1S1F1F1F10-bonding molecular orbital is formed when two p orbitals of opposite phase overlap. 
D)  Both the statements "a F1F1F1S1F1F1F10-bonding molecular orbital is formed when two p orbitals of similar phase overlap" and a F1F1F1S1F1F1F10-bonding molecular orbital is lower in energy than a F1F1F1S1F1F1F10-bonding molecular orbital" are true. 
A)  A F1F1F1S1F1F1F10-bonding molecular orbital is formed when two p orbitals of similar phase overlap. 
B)  A F1F1F1S1F1F1F10-bonding molecular orbital is lower in energy than a F1F1F1S1F1F1F10-bonding molecular orbital. 
C)  A F1F1F1S1F1F1F10-bonding molecular orbital is formed when two p orbitals of opposite phase overlap. 
D)  Both the statements "a F1F1F1S1F1F1F10-bonding molecular orbital is formed when two p orbitals of similar phase overlap" and a F1F1F1S1F1F1F10-bonding molecular orbital is lower in energy than a F1F1F1S1F1F1F10-bonding molecular orbital" are true.

Question 16

Which of the following is not a type of pericyclic reactions?

Accepted Answer

A)  cycloadditions 
B)  nucleophilic reactions 
C)  electrocyclic reactions 
D)  sigmatropic rearrangements 
A)  cycloadditions 
B)  nucleophilic reactions 
C)  electrocyclic reactions 
D)  sigmatropic rearrangements

Question 17

What is the correct classification of the following reaction?

Accepted Answer

A)  cycloaddition reaction 
B)  electrocyclic reaction 
C)  electrophilic reaction 
D)  sigmatropic reaction 
A)  cycloaddition reaction 
B)  electrocyclic reaction 
C)  electrophilic reaction 
D)  sigmatropic reaction

Question 18

Which of the following is a type of pericyclic reaction?

Accepted Answer

A)  electrocyclic reactions 
B)  acyclic reactions 
C)  cycloelimination reactions 
D)  electrophilic reactions 
A)  electrocyclic reactions 
B)  acyclic reactions 
C)  cycloelimination reactions 
D)  electrophilic reactions

Question 19

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

Accepted Answer

A)  A sigmatropic reaction is an intramolecular pericyclic reaction. 
B)  In a sigmatropic reaction, F1F1F1S1F1F1F10 bond is broken in one of the reactants. 
C)  The F1F1F1S1F1F1F10 bonds rearrange in a sigmatropic reaction. 
D)  The number of F1F1F1S1F1F1F10 bonds in the reactants and product differs in a sigmatropic reaction. 
A)  A sigmatropic reaction is an intramolecular pericyclic reaction. 
B)  In a sigmatropic reaction, F1F1F1S1F1F1F10 bond is broken in one of the reactants. 
C)  The F1F1F1S1F1F1F10 bonds rearrange in a sigmatropic reaction. 
D)  The number of F1F1F1S1F1F1F10 bonds in the reactants and product differs in a sigmatropic reaction.

Question 20

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

Accepted Answer

A)  Thermal cycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
B)  Thermal cycloadditions involving an odd number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
C)  Photochemical cycloadditions involving an odd number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
D)  Photochemical sycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by an antarafacial pathway. 
A)  Thermal cycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
B)  Thermal cycloadditions involving an odd number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
C)  Photochemical cycloadditions involving an odd number of F1F1F1S1F1F1F10 bonds proceed by a suprafacial pathway. 
D)  Photochemical sycloadditions involving an even number of F1F1F1S1F1F1F10 bonds proceed by an antarafacial pathway.

Exam 27: Pericyclic Reactions

Which of the following statements about  orbitals is true?

What is the major organic product of the following Claisen rearrangement?

Predict the major organic product(s) of the following electrocyclic reaction.

What type of cycloaddition reaction is shown in the following equation?

What is the correct classification of the following reaction?

Which of the following statements about cycloaddition reactions is true?

What type of sigmatropic rearrangement is illustrated below?

How many  molecular orbitals are present in 1,3,5-hexatriene?

Why is the Diels-Alder reaction called a thermal [4+2] cycloaddition?

Which of the following statements about molecular orbitals is true?

What is the correct classification of the following reaction?

Which of the following statements about sigmatropic reactions is true?

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

Which of the following statements about thermal electrocyclic reactions is not true?

Which of the following statements about a -bonding molecular orbital is true?

Which of the following is not a type of pericyclic reactions?

What is the correct classification of the following reaction?

Which of the following is a type of pericyclic reaction?

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

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

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