Question 1

What characterizes a pericyclic reaction?

Accepted Answer

Pericyclic reactions involve concerted breaking and formation of bonds within a closed ring of interacting orbitals.

Question 2

Explain what a node is and how it is formed.

Accepted Answer

A node is a plane in which there is no probability of finding an electron.It is formed between overlapping out-of-phase orbitals or through the center of p orbitals.

Question 3

Give a representation of the antibonding π molecular orbital of the allyl anion.

Accepted Answer

The answer of Give a representation of the antibonding π...

Question 4

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

Accepted Answer

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

Question 5

Which of the following statements concerning electrocyclic reactions is correct?

Accepted Answer

A) The ground state HOMO of a compound with an even number of conjugated double bonds is asymmetric. 
B) The allowed mode of ring closure under thermal conditions for a molecule containing an even number of conjugated double bonds is disrotatory. 
C) The allowed mode of ring closure under photochemical conditions for a molecule containing an odd number of conjugated double bonds is disrotatory. 
D) both B and C 
E) none of the above 
A) The ground state HOMO of a compound with an even number of conjugated double bonds is asymmetric. 
B) The allowed mode of ring closure under thermal conditions for a molecule containing an even number of conjugated double bonds is disrotatory. 
C) The allowed mode of ring closure under photochemical conditions for a molecule containing an odd number of conjugated double bonds is disrotatory. 
D) both B and C 
E) none of the above

Question 6

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 7

Describe an electrocyclic reaction.

Accepted Answer

A) The reactant has lost a sigma bond,the product has a new sigma bond,and the pi bonds have rearranged. 
B) The product contains a new ring,with two less sigma bonds,and two more pi bonds than the starting material. 
C) The product contains a new ring,with two more sigma bonds,and two less pi bonds than the starting material. 
D) The product contains a new ring,with one less sigma bond,and one more pi bond than the starting material. 
E) The product contains a new ring,with one more sigma bond,and one less pi bond than the starting material. 
A) The reactant has lost a sigma bond,the product has a new sigma bond,and the pi bonds have rearranged. 
B) The product contains a new ring,with two less sigma bonds,and two more pi bonds than the starting material. 
C) The product contains a new ring,with two more sigma bonds,and two less pi bonds than the starting material. 
D) The product contains a new ring,with one less sigma bond,and one more pi bond than the starting material. 
E) The product contains a new ring,with one more sigma bond,and one less pi bond than the starting material.

Question 8

Give the product for the following [3,3] sigmatropic rearrangement.

Accepted Answer

The answer of Give the product for the following [3,3]...

Question 9

What is the product from the following 1,3-carbon shift reaction?

Accepted Answer

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

Question 10

In the allyl radical,which π molecular orbital is singly occupied?

Accepted Answer

A) the bonding π molecular orbital 
B) the nonbonding π molecular orbital 
C) the antibonding π molecular orbital 
D) none of the above 
A) the bonding π molecular orbital 
B) the nonbonding π molecular orbital 
C) the antibonding π molecular orbital 
D) none of the above

Question 11

(a)Under thermal conditions,will ring closure of (2E,4Z,6Z,8E)-decatetraene be conrotatory or disrotatory? Explain.
(b)Will the product be cis or trans? Explain

Accepted Answer

(a)Since the number of conjugated pi bon

Question 12

How many nodes would you expect from the following atomic orbital overlap?

Accepted Answer

The molecular orbital is an ou

Question 13

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

Question 14

How would you synthesize the following compound from butadiene and ethylene?

Accepted Answer

Diels-Alde

Question 15

What is the major product of the following reaction?

Accepted Answer

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

Question 16

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

Accepted Answer

Under thermal conditions,supra

Question 17

Provide the structure of the major organic product in the following reaction.

Accepted Answer

The answer of Provide the structure of the major organic...

Question 18

Provide the structure of the diene and dienophile for the preparation of the following compound.

Accepted Answer

The answer of Provide the structure of the diene and...

Question 19

Which of the following compounds is the most reactive dienophile in a Diels-Alder reaction with 1,3-butadiene?

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 20

What are the structures of A,B,and C?

Accepted Answer

The answer of What are the structures of A,B,and C?...

Exam 28: Pericyclic Reactions

What characterizes a pericyclic reaction?

Explain what a node is and how it is formed.

Give a representation of the antibonding π molecular orbital of the allyl anion.

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

Which of the following statements concerning electrocyclic reactions is correct?

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

Describe an electrocyclic reaction.

Give the product for the following [3,3] sigmatropic rearrangement.

What is the product from the following 1,3-carbon shift reaction?

In the allyl radical,which π molecular orbital is singly occupied?

(a)Under thermal conditions,will ring closure of (2E,4Z,6Z,8E)-decatetraene be conrotatory or disrotatory? Explain. (b)Will the product be cis or trans? Explain

How many nodes would you expect from the following atomic orbital overlap?

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

How would you synthesize the following compound from butadiene and ethylene?

What is the major product of the following reaction?

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

Provide the structure of the major organic product in the following reaction.

Provide the structure of the diene and dienophile for the preparation of the following compound.

Which of the following compounds is the most reactive dienophile in a Diels-Alder reaction with 1,3-butadiene?

What are the structures of A,B,and C?

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds: Nomenclature, physical Properties, and Structure

Isomers: the Arrangement of Atoms in Space

Alkenes: Structure,nomenclature,and an Introduction to Reactivity - Thermodynamics and Kinetics

The Reactions of Alkenes - the Stereochemistry of Addition Reactions

The Reactions of Alkynes - Introduction to Multistep Synthesis

Delocalized Electrons: Their Effect on Stability, pka, and the Products of a Reaction - Aromaticity and Electronic Effects: an Introduction to the Reactions of Benzene

Substitution and Elimination Reactions of Alkyl Halides

Reactions of Alcohols, ethers, epoxides, amines and Sulfur-Containing Compounds

Organometallic Compounds

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 Α-Carbon

Reactions of Benzene and Substituted Benzenes

More About Amines - Reactions of Heterocylic Compounds

The Organic Chemistry of Carbohydrates

Amino Acids,peptides,and Proteins

Catalysis in Organic Reactions and in Enzymatic Reactions

The Organic Chemistry of the Coenzymes, compounds Derived From Vitamins

The Organic Chemistry of the Metabolic Pathways

The Organic Chemistry of Lipids

The Chemistry of the Nucleic Acids

Synthetic Polymers

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