Question 1

What is the product obtained from the following [1,5] sigmatropic rearrangement?

Accepted Answer

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

Question 2

What is the major product of the following [3,3] sigmatropic rearrangement?

Accepted Answer

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

Question 3

What are the three most common pericyclic reactions? Give examples.

Accepted Answer

The answer of What are the three most common pericyclic...

Question 4

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

Accepted Answer

A) CH2     CHOCH3 
B) CH2     CHCHO 
C) CH3CH   CHCH3 
D) (CH3)2C   CH2 
E) CH2     CH2 
A) CH2     CHOCH3 
B) CH2     CHCHO 
C) CH3CH   CHCH3 
D) (CH3)2C   CH2 
E) CH2     CH2

Question 5

Give the conditions for 1,3-hydrogen shifts.

Accepted Answer

A) suprafacial rearrangement 
B) antarafacial rearrangement 
C) thermal conditions 
D) photochemical conditions 
E) all of the above 
A) suprafacial rearrangement 
B) antarafacial rearrangement 
C) thermal conditions 
D) photochemical conditions 
E) all of the above

Question 6

Electrocyclic reactions are reversible. The cyclic compound is favored for electrocyclic reactions that form six-membered rings, whereas the open-chain compound is favored for reactions that form four-membered rings. Explain thoroughly in terms of the enthalpy changes that are occurring.

Accepted Answer

In general, the cyclic compound is favor

Question 7

Give the 2 + 2 cycloaddition reaction of thymine.

Accepted Answer

The answer of Give the 2 + 2 cycloaddition reaction...

Question 8

Explain what a node is and how it is formed.

Accepted Answer

A node is a plane in which the

Question 9

Consider the π molecular orbitals of pentadienyl cation and answer the following questions. Please refer to the lowest π MO as ψ1.
a) How many π molecular orbitals of pentadienyl cation are bonding?
b) Which π molecular orbital is the HOMO?
c) Which π molecular orbitals are asymmetric with respect to a mirror plane perpendicular to the molecular plane?

Accepted Answer

a) ψ₁ and ψ

Question 10

Give the product for the following reaction.

Accepted Answer

A)    
B)    
C)    
D)    
E) no reaction 
A)    
B)    
C)    
D)    
E) no reaction

Question 11

Which of the following statements about carbon migrations is (are)correct?

Accepted Answer

A) Carbon migrations never occur by a sigmatropic rearrangement. 
B) Under thermal conditions, a [1,3] carbon migration that occurs suprafacially must also occur with inversion of configuration at the migrating carbon. 
C) Under thermal conditions, a [1,5] carbon migration that occurs suprafacially must also occur with inversion of configuration at the migrating carbon. 
D) Under thermal conditions, a carbon migration that occurs suprafacially must occur with inversion no matter the system's symmetry. 
E) B, C, and D 
A) Carbon migrations never occur by a sigmatropic rearrangement. 
B) Under thermal conditions, a [1,3] carbon migration that occurs suprafacially must also occur with inversion of configuration at the migrating carbon. 
C) Under thermal conditions, a [1,5] carbon migration that occurs suprafacially must also occur with inversion of configuration at the migrating carbon. 
D) Under thermal conditions, a carbon migration that occurs suprafacially must occur with inversion no matter the system's symmetry. 
E) B, C, and D

Question 12

What pericyclic photochemical reaction can lead to skin cancer in humans? Draw the structure of the compounds involved in the reaction, and explain how this reaction leads to skin cancer.

Accepted Answer

Thymine dimerization.
At any point in DN

Question 13

Which of the following pericyclic reactions best describes the following reaction?

Accepted Answer

A) nucleophilic 
B) electrocyclic 
C) radical 
D) sigmatropic 
E) cycloaddition 
A) nucleophilic 
B) electrocyclic 
C) radical 
D) sigmatropic 
E) cycloaddition

Question 14

Which of the following sets of atomic orbitals form an asymmetric molecular orbital?

Accepted Answer

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

Question 15

How many π molecular orbitals does 1,3,5,7-octatetraene have?

Accepted Answer

A) 2 
B) 4 
C) 6 
D) 8 
E) 10 
A) 2 
B) 4 
C) 6 
D) 8 
E) 10

Question 16

Give the product for the following thermal reaction.

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 17

Explain why the following (2+2)cycloaddition reaction would work under photochemical conditions but not under thermal conditions.

Accepted Answer

Under thermal conditions, suprafacial ov

Question 18

Show the mechanism for the following 1,3-hydrogen shift.

Accepted Answer

The answer of Show the mechanism for the following 1,3-hydrogen...

Question 19

What is the product of the following 1,7-hydrogen shift?

Accepted Answer

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

Question 20

Give the product(s)for the following reaction.

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Exam 28: Pericyclic Reactions

What is the product obtained from the following [1,5] sigmatropic rearrangement?

What is the major product of the following [3,3] sigmatropic rearrangement?

What are the three most common pericyclic reactions? Give examples.

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

Give the conditions for 1,3-hydrogen shifts.

Electrocyclic reactions are reversible. The cyclic compound is favored for electrocyclic reactions that form six-membered rings, whereas the open-chain compound is favored for reactions that form four-membered rings. Explain thoroughly in terms of the enthalpy changes that are occurring.

Give the 2 + 2 cycloaddition reaction of thymine.

Explain what a node is and how it is formed.

Give the product for the following reaction.

Which of the following statements about carbon migrations is (are)correct?

What pericyclic photochemical reaction can lead to skin cancer in humans? Draw the structure of the compounds involved in the reaction, and explain how this reaction leads to skin cancer.

Which of the following pericyclic reactions best describes the following reaction?

Which of the following sets of atomic orbitals form an asymmetric molecular orbital?

How many π molecular orbitals does 1,3,5,7-octatetraene have?

Give the product for the following thermal reaction.

Explain why the following (2+2)cycloaddition reaction would work under photochemical conditions but not under thermal conditions.

Show the mechanism for the following 1,3-hydrogen shift.

What is the product of the following 1,7-hydrogen shift?

Give the product(s)for the following reaction.

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds

Isomers: the Arrangement of Atoms in Space

Alkenes Thermodynamics and Kinetics

Reactions of Alkenes

Reactions of Alkynes Introduction to Multistep Synthesis

Electron Delocalization, Resonance, and Aromaticity More About Molecular Orbital Theory

Substitution Reactions of Alkyl Halides

Elimination Reactions of Alkyl Halides Competition Between Substitution and Elimination

Reactions of Alcohols, Ethers, Epoxides, and Sulfur-Containing Compounds

Organometallic Compounds

Reactions of Alkanes, Radicals

Mass Spectrometry, Infrared Spectroscopy, and Uvvis Spectroscopy

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Alpha Carbon of Carbonyl Compounds

Reactions of Benzene and Substituted Benzenes

More About Amines Heterocylic Compounds

Carbohydrates

Amino Acids, Peptides, and Proteins

Catalysis

The Organic Mechanisms of the Coenzymes

The Chemistry of Metabolism

Nucleosides, Nucleotides, and Nucleic Acids

Synthetic Polymers

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