Question 1

Identify the isoprene units in this structure.

Accepted Answer

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Question 2

Draw the product of 1,4 addition of Cl2 to the molecule shown here.

Accepted Answer

Question 3

Draw the products of the addition reaction under each of the conditions shown; indicate the major and minor product isomers in each case:

Accepted Answer

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Question 4

Devise a multistep synthesis for the following transformation.You may use any organic or inorganic reagents of your choice.Include the reagents necessary for each step and the product of each step.

Accepted Answer

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Question 5

Which of these orbitals is the HOMO in the allyl anion?

Accepted Answer

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

Question 6

When 1,3 -butadiene reacts with chlorine, a  50/50  mixture of 3,4 -dichloro-1-butene and (E)-1,4-dichloro-2-butene is generated. When the same diene is reacted with bromine, the 3,4 -dibromo-1-butene is the predominant product.. What could explain the difference in regioselectivity?

Accepted Answer

A)  The more stable intermediate bromonium ion favors 1,2 -addition. 
B)  The more reactive bromide anion favors the kinetic product. 
C)  The more reactive chloride anion favors the thermodynamic product. 
D)  The more stable intermediate chloronium ion favors the 1,4 -addition product. 
E)  The electronegative bromine destabilizes the positive charge on the β-carbon. 
A)  The more stable intermediate bromonium ion favors 1,2 -addition. 
B)  The more reactive bromide anion favors the kinetic product. 
C)  The more reactive chloride anion favors the thermodynamic product. 
D)  The more stable intermediate chloronium ion favors the 1,4 -addition product. 
E)  The electronegative bromine destabilizes the positive charge on the β-carbon.

Question 7

Draw a mechanism for the transformation shown here.Include all lone pairs of electrons, curved arrows, and formal charges.

Accepted Answer

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Question 8

Which of the following molecules contains the most acidic hydrogen?

Accepted Answer

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

Question 9

Draw the product of 1,2 addition of Br2 to the molecule shown here.

Accepted Answer

Question 10

The molecule shown here can undergo an intramolecular Diels-Alder reaction.Draw the product of this reaction.

Accepted Answer

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Question 11

Draw the structure of the product formed when cyclopentadiene dimerizes in a Diels-Alder
reaction.

Accepted Answer

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Question 12

Which of these statements about thermodynamic and kinetic control is true?

Accepted Answer

A) The thermodynamic product is always different from the kinetic product. 
B) Reactions under equilibrium conditions will favor the thermodynamic product. 
C) A higher-energy transition state will favor the thermodynamic product. 
D) The kinetic product will generally be favored at higher temperatures. 
E) 1,4-Addition gives the thermodynamic product because the intermediate cation is more stable. 
A) The thermodynamic product is always different from the kinetic product. 
B) Reactions under equilibrium conditions will favor the thermodynamic product. 
C) A higher-energy transition state will favor the thermodynamic product. 
D) The kinetic product will generally be favored at higher temperatures. 
E) 1,4-Addition gives the thermodynamic product because the intermediate cation is more stable.

Question 13

Which pairing of diene and dienophile would lead to the product shown here?

Accepted Answer

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

Question 14

Rank the following   isomers in order of increasing heats of formation.

Accepted Answer

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Question 15

Which molecular orbitals are involved in each reactant in the Diels-Alder reaction?

Accepted Answer

The molecular orbitals involve

Question 16

Which of the following compounds could be classified as terpenes?

Accepted Answer

A)  I and II 
B)  II and III 
C)  II and IV 
D)  III and IV 
E)  All can be classified as terpenes. 
A)  I and II 
B)  II and III 
C)  II and IV 
D)  III and IV 
E)  All can be classified as terpenes.

Question 17

Draw a mechanism for the isomerization of the starting material to the product shown using the reagents given.

Accepted Answer

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Question 18

Draw a mechanism for the reverse Diels-Alder reaction that occurs when the following molecule
is heated.

Accepted Answer

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Question 19

Which structure contains the longest C-C bond?

Accepted Answer

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

Question 20

Which of these structures is the product of 1,4 addition of HBr to the molecule shown here?

Accepted Answer

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

Exam 13: Dienes and the Allyl System: 2p Orbitals in Conjugation

Identify the isoprene units in this structure.

Draw the product of 1,4 addition of Cl2 to the molecule shown here.

Draw the products of the addition reaction under each of the conditions shown; indicate the major and minor product isomers in each case:

Devise a multistep synthesis for the following transformation.You may use any organic or inorganic reagents of your choice.Include the reagents necessary for each step and the product of each step.

Which of these orbitals is the HOMO in the allyl anion?

When 1,3 -butadiene reacts with chlorine, a 50/50 mixture of 3,4 -dichloro-1-butene and (E)-1,4-dichloro-2-butene is generated. When the same diene is reacted with bromine, the 3,4 -dibromo-1-butene is the predominant product.. What could explain the difference in regioselectivity?

Draw a mechanism for the transformation shown here.Include all lone pairs of electrons, curved arrows, and formal charges.

Which of the following molecules contains the most acidic hydrogen?

Draw the product of 1,2 addition of Br2 to the molecule shown here.

The molecule shown here can undergo an intramolecular Diels-Alder reaction.Draw the product of this reaction.

Draw the structure of the product formed when cyclopentadiene dimerizes in a Diels-Alder reaction.

Which of these statements about thermodynamic and kinetic control is true?

Which pairing of diene and dienophile would lead to the product shown here?

Rank the following isomers in order of increasing heats of formation.

Which molecular orbitals are involved in each reactant in the Diels-Alder reaction?

Which of the following compounds could be classified as terpenes?

Draw a mechanism for the isomerization of the starting material to the product shown using the reagents given.

Draw a mechanism for the reverse Diels-Alder reaction that occurs when the following molecule is heated.

Which structure contains the longest C-C bond?

Which of these structures is the product of 1,4 addition of HBr to the molecule shown here?

Atoms and Molecules; Orbitals and Bonding

Alkanes

Alkenes and Alkynes

Stereochemistry

Rings

Substituted Alkanes: Alkyl Halides, Alcohols, Amines, Ethers,thiols, and Thioethers

Substitution Reactions: the Sn2 and Sn1 Reactions

Elimination Reactions: the E1 and E2 Reactions

Analytical Chemistry: Spectroscopy

Electrophilic Additions to Alkenes

More Additions to Bonds

Radical Reactions

Aromaticity

Substitution Reactions of Aromatic Compounds

Carbonyl Chemistry 1: Addition Reactions

Carboxylic Acids

Derivatives of Carboxylic Acids: Acyl Compounds

Carbonyl Chemistry 2: Reactions at the Α Position

Special Topic: Carbohydrates

Special Topic: Bio-Organic Chemistry

Special Topic: Amino Acids and Polyamino Acids Peptides and Proteins

Special Topic: Reactions Controlled by Orbital Symmetry

Special Topic: Intramolecular Reactions and Neighboring Group Participation

Filters

Draw the product of 1,4 addition of Cl₂ to the molecule shown here.

Draw the product of 1,2 addition of Br₂ to the molecule shown here.