Question 1

Would you expect the following compound to absorb visible light? Why or why not?

Accepted Answer

Yes, you would expec

Question 2

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 3

Draw the structure of the major product which results when the diene shown is treated with HBr at 40°C.

Accepted Answer

The answer of Draw the structure of the major product...

Question 4

According to the 1,3-butadiene structure below, which positions would be best to place methoxy groups to yield the most reactive dimethoxy-1,3-butadiene isomer in the Diels-Alder reaction?

Accepted Answer

A)  c and d 
B)  a and c 
C)  b and c 
D)  a and d 
E)  a and f 
A)  c and d 
B)  a and c 
C)  b and c 
D)  a and d 
E)  a and f

Question 5

Draw structures for the two major products of the following reaction.

Accepted Answer

The answer of Draw structures for the two major products...

Question 6

Draw the resonance structures of the intermediate and then predict the two major products in the following reaction.

Accepted Answer

Resonance structures

Question 7

Which of the following compounds is the most stable?

Accepted Answer

A)  (
E) -2-methyl-1,3-pentadiene 
B)  2-methyl-1,2-pentadiene 
C)  (Z)-2-methyl-1,3-pentadiene 
D)  2-methyl-2,3-pentadiene 
E)  2-methyl-1,4-pentadiene 
A)  (
E) -2-methyl-1,3-pentadiene 
B)  2-methyl-1,2-pentadiene 
C)  (Z)-2-methyl-1,3-pentadiene 
D)  2-methyl-2,3-pentadiene 
E)  2-methyl-1,4-pentadiene

Question 8

Indicate whether the following cyclization, conducted under thermal conditions, is symmetry allowed. Justify your answer by showing whether the overlapping orbitals in the transition state generate a symmetry-allowed or symmetry-forbidden scenario. Treat ethylene as the nucleophile.

Accepted Answer

The answer of Indicate whether the following cyclization, conducted under...

Question 9

Show how the carbon p orbitals overlap to form the lowest energy π molecular orbital of 1,3-butadiene.

Accepted Answer

The answer of Show how the carbon p orbitals overlap...

Question 10

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 11

When the relative energies of the s-cis and s-trans conformers of 1,3-butadiene are compared, one finds that ________.

Accepted Answer

A)  the s-cis conformer is lower in energy than the s-trans 
B)  the s-trans conformer is lower in energy than the s-cis 
C)  the two conformers are of equal energy 
A)  the s-cis conformer is lower in energy than the s-trans 
B)  the s-trans conformer is lower in energy than the s-cis 
C)  the two conformers are of equal energy

Question 12

Provide the major organic product of the following reaction.

Accepted Answer

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

Question 13

The Diels-Alder reaction is a concerted reaction; this means ________.

Accepted Answer

A)  a mixture of endo and exo products are formed 
B)  all bond making and bond breaking occurs simultaneously 
C)  the products contain rings 
D)  the reaction follows Markovnikov's rule 
E)  the reaction is highly endothermic 
A)  a mixture of endo and exo products are formed 
B)  all bond making and bond breaking occurs simultaneously 
C)  the products contain rings 
D)  the reaction follows Markovnikov's rule 
E)  the reaction is highly endothermic

Question 14

How many nodes, other than the node coincident with the molecular plane, are found in the highest energy π MO of

Accepted Answer

A)  0 
B)  1 
C)  2 
D)  3 
E)  none of the above 
A)  0 
B)  1 
C)  2 
D)  3 
E)  none of the above

Question 15

Which substrate would react most rapidly in an SN2 reaction?

Accepted Answer

A)  CH3CH2CH=CHCH2Br 
B)  BrCH2CH2CH=CHCH3 
C)  CH3CHBrCH=CH2CH3 
D)  CH3CH2CH2CH=CHBr 
A)  CH3CH2CH=CHCH2Br 
B)  BrCH2CH2CH=CHCH3 
C)  CH3CHBrCH=CH2CH3 
D)  CH3CH2CH2CH=CHBr

Question 16

How many electrons are present in the nonbonding π molecular orbital of the allyl anion?

Accepted Answer

A)  0 
B)  1 
C)  2 
D)  3 
E)  4 
A)  0 
B)  1 
C)  2 
D)  3 
E)  4

Question 17

Provide the necessary synthetic sequence for preparing 1,3-cyclopentadiene from cyclopentane.

Accepted Answer

1) Br₂, hν

Question 18

What name is given to the type of "control" which arises in a reaction which does not achieve equilibrium and in which the product distribution is determined by the relative activation energies of the pathways which produced them?

Accepted Answer

The answer of What name is given to the type...

Question 19

Why does the diene shown below fail to undergo a Diels-Alder reaction with even the most reactive dienophiles?

Accepted Answer

The diene cannot ach

Question 20

Including all possible stereoisomeric forms, how many distinct allylic bromides could be produced when 2-methylpent-1-ene is treated with NBS under irradiation by a sunlamp?

Accepted Answer

A)  2 
B)  3 
C)  4 
D)  5 
E)  6 
A)  2 
B)  3 
C)  4 
D)  5 
E)  6

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

Would you expect the following compound to absorb visible light? Why or why not?

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

Draw the structure of the major product which results when the diene shown is treated with HBr at 40°C.

According to the 1,3-butadiene structure below, which positions would be best to place methoxy groups to yield the most reactive dimethoxy-1,3-butadiene isomer in the Diels-Alder reaction?

Draw structures for the two major products of the following reaction.

Draw the resonance structures of the intermediate and then predict the two major products in the following reaction.

Which of the following compounds is the most stable?

Indicate whether the following cyclization, conducted under thermal conditions, is symmetry allowed. Justify your answer by showing whether the overlapping orbitals in the transition state generate a symmetry-allowed or symmetry-forbidden scenario. Treat ethylene as the nucleophile.

Show how the carbon p orbitals overlap to form the lowest energy π molecular orbital of 1,3-butadiene.

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

When the relative energies of the s-cis and s-trans conformers of 1,3-butadiene are compared, one finds that ________.

Provide the major organic product of the following reaction.

The Diels-Alder reaction is a concerted reaction; this means ________.

How many nodes, other than the node coincident with the molecular plane, are found in the highest energy π MO of

Which substrate would react most rapidly in an SN2 reaction?

How many electrons are present in the nonbonding π molecular orbital of the allyl anion?

Provide the necessary synthetic sequence for preparing 1,3-cyclopentadiene from cyclopentane.

What name is given to the type of "control" which arises in a reaction which does not achieve equilibrium and in which the product distribution is determined by the relative activation energies of the pathways which produced them?

Why does the diene shown below fail to undergo a Diels-Alder reaction with even the most reactive dienophiles?

Including all possible stereoisomeric forms, how many distinct allylic bromides could be produced when 2-methylpent-1-ene is treated with NBS under irradiation by a sunlamp?

Structure and Bonding

Acids and Bases; Functional Groups

Structure and Stereochemistry of Alkanes

The Study of Chemical Reactions

Stereochemistry

Alkyl Halides; Nucleophilic Substitution

Structure and Synthesis of Alkenes; Elimination

Reactions of Alkenes

Structure and Synthesis of Alcohols

Reactions of Alcohols

Infrared Spectroscopy and Mass Spectrometry

Nuclear Magnetic Resonance Spectroscopy

Ethers, Epoxides, and Thioethers

Aromatic Compounds

Reactions of Aromatic Compounds

Ketones and Aldehydes

Amines

Carboxylic Acids

Carboxylic Acid Derivatives

Condensations and Alpha Substitutions of Carboxyl Compounds

Carbohydrates and Nucleic Acids

Amino Acids, Peptides, and Proteins

Lipids

Synthetic Polymers

Filters

Which substrate would react most rapidly in an S_N2 reaction?