Question 1

The following [3+2] cycloaddition was reported in Organic Letters, 2011, 402. Predict whether the reaction would be thermally or photochemically promoted. Justify your answer by showing overlap of the correct molecular orbitals. Assume the alkene is the electrophile.

Accepted Answer

The answer of The following [3+2] cycloaddition was reported in...

Question 2

Dicylopentadiene results when cyclopentadiene reacts with itself in a Diels-Alder reaction. Provide the structure of dicyclopentadiene. Pay particular attention to stereochemical detail.

Accepted Answer

The answer of Dicylopentadiene results when cyclopentadiene reacts with itself...

Question 3

Which has a λmax in its UV spectrum at a longer wavelength, 2,4-hexadiene, 1,4-hexadiene, or 1,5-hexadiene?

Accepted Answer

Question 4

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

Accepted Answer

A)   CH2  2     CHOCH3 
B)   CH2     CHCHO 
C)   CH3CH   CHCH3 
D)   (CH3) 2C   CH2 
E)   CH2     CH2" class="answers-bank-image d-inline" rel="preload" >CHOCH3
B)   CH2  2     CHOCH3 
B)   CH2     CHCHO 
C)   CH3CH   CHCH3 
D)   (CH3) 2C   CH2 
E)   CH2     CH2" class="answers-bank-image d-inline" rel="preload" >CHCHO
C)   CH3CH 2     CHOCH3 
B)   CH2     CHCHO 
C)   CH3CH   CHCH3 
D)   (CH3) 2C   CH2 
E)   CH2     CH2" class="answers-bank-image d-inline" rel="preload" > CHCH3
D)   (CH3) 2C 2     CHOCH3 
B)   CH2     CHCHO 
C)   CH3CH   CHCH3 
D)   (CH3) 2C   CH2 
E)   CH2     CH2" class="answers-bank-image d-inline" rel="preload" > CH2
E)   CH2  2     CHOCH3 
B)   CH2     CHCHO 
C)   CH3CH   CHCH3 
D)   (CH3) 2C   CH2 
E)   CH2     CH2" class="answers-bank-image d-inline" rel="preload" >CH2F) A) and B)
G) B) and D)

Question 5

What characterizes a pericyclic reaction?

Accepted Answer

Pericyclic reactions involve c...

Question 6

For what does the acronym HOMO stand?

Accepted Answer

highest oc...

Question 7

Which of the following terms best describes a Diels-Alder reaction?

Accepted Answer

A)   a [4+2] cycloaddition
B)   a [2+2] cycloaddition
C)   a sigmatropic rearrangement
D)   a 1,3-dipolar cycloaddition
E)   a substitution reactionF) A) and C)
G) C) and E)

Question 8

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

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

Question 9

When 3-bromo-1-methylcyclohexene is heated in a good ionizing solvent, reactions occur through a carbocation intermediate. Draw all reasonable resonance contributors of this cation and indicate which is the major contributor.

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The answer of When 3-bromo-1-methylcyclohexene is heated in a good...

Question 10

Draw the major organic product that results from the intramolecular Diels-Alder reaction.

Accepted Answer

The answer of Draw the major organic product that results...

Question 11

Which sequence correctly ranks the following conjugated systems in order of increasing UV λmax absorption values? max absorption values?   A)  1

Accepted Answer

A)   1 
B)   2 
C)   2 
D)   3 
E)   3 < 2 < 1F) A) and B)
G) A) and C)

Question 12

Assuming kinetic conditions, draw the major product of the reaction below. Include correct stereochemistry.

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The answer of Assuming kinetic conditions, draw the major product...

Question 13

Draw the most stable conformation of (2Z,4E)-2,4-hexadiene.

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The answer of Draw the most stable conformation of (2Z,4E)-2,4-hexadiene....

Question 14

Using resonance structures, explain the regiochemistry observed in this reaction:

Accepted Answer

The answer of Using resonance structures, explain the regiochemistry observed...

Question 15

What descriptive term is applied to the type of diene represented by 1,5-octadiene?

Accepted Answer

A)   conjugated diene
B)   cumulated diene
C)   isolated diene
D)   alkynyl diene
E)   none of the aboveF) C) and E)
G) A) and E)

Question 16

Give a representation of the highest occupied π MO of 1,3-butadiene in its ground state.

Accepted Answer

The answer of Give a representation of the highest occupied...

Question 17

How many nodes, other than the node coincident with the molecular plane, are present in the HOMO of 1,3,5-hexatriene?

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   5F) A) and B)
G) A) and C)

Question 18

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 19

How many nodes, other than the node coincident with the molecular plane, are present in the LUMO of 1,3,5-hexatriene?

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   5F) A) and B)
G) A) and C)

Question 20

What is the major organic product which results when cycloheptene is irradiated in the presence of N-bromosuccinimide?

Accepted Answer

A)   1-bromocycloheptene
B)   2-bromocycloheptene
C)   1,2-dibromocycloheptane
D)   3-bromocycloheptene
E)   4-bromocyclohepteneF) A) and D)
G) A) and E)

Exam 15: Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

The following [3+2] cycloaddition was reported in Organic Letters, 2011, 402. Predict whether the reaction would be thermally or photochemically promoted. Justify your answer by showing overlap of the correct molecular orbitals. Assume the alkene is the electrophile.

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When 3-bromo-1-methylcyclohexene is heated in a good ionizing solvent, reactions occur through a carbocation intermediate. Draw all reasonable resonance contributors of this cation and indicate which is the major contributor.

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Draw the most stable conformation of (2Z,4E)-2,4-hexadiene.

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

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What is the major organic product which results when cycloheptene is irradiated in the presence of N-bromosuccinimide?

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Draw the major organic product that results from the intramolecular Diels-Alder reaction.

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What descriptive term is applied to the type of diene represented by 1,5-octadiene?

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Dicylopentadiene results when cyclopentadiene reacts with itself in a Diels-Alder reaction. Provide the structure of dicyclopentadiene. Pay particular attention to stereochemical detail.

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Assuming kinetic conditions, draw the major product of the reaction below. Include correct stereochemistry.

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How many nodes, other than the node coincident with the molecular plane, are present in the HOMO of 1,3,5-hexatriene?

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

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What characterizes a pericyclic reaction?

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Which has a λmax in its UV spectrum at a longer wavelength, 2,4-hexadiene, 1,4-hexadiene, or 1,5-hexadiene?

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Give a representation of the highest occupied π MO of 1,3-butadiene in its ground state.

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For what does the acronym HOMO stand?

Correct Answerverifiedhighest oc...View AnswerShow Answer

Which sequence correctly ranks the following conjugated systems in order of increasing UV λmax absorption values?

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

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How many nodes, other than the node coincident with the molecular plane, are present in the LUMO of 1,3,5-hexatriene?

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Using resonance structures, explain the regiochemistry observed in this reaction:

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Which of the following terms best describes a Diels-Alder reaction?

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Pericyclic reactions involve c...
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Which has a λ_max in its UV spectrum at a longer wavelength, 2,4-hexadiene, 1,4-hexadiene, or 1,5-hexadiene?

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highest oc...
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Which sequence correctly ranks the following conjugated systems in order of increasing UV λ_max absorption values?

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