Deck 20: Reactions Controlled by Orbital Interactions

Question 1

What number of ð electrons is possible in a thermal cycloaddition?

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

Answer 1

6

Question 2

Which of the following best describes the Cope rearrangement?

A)cycloaddition
B)sigmatropic rearrangement
C)electrocyclic reaction
D)dipolar cycloaddition

Answer 2

sigmatropic rearrangement

Question 3

What is the product of a Claisen rearrangement?

A)a carbonyl
B)an ether
C)a vinylic ether
D)a 1,3-unsaturated carbonyl

Answer 3

a carbonyl

Question 4

What are the reactants of the following reaction?

A)
B)
C)
D)

Question 5

What is the product of the following reaction?

A)
B)
C)
D)

Question 6

Which of the following best describes a Diels-Alder cycloaddition?

A)loss of one ð bond and gain of one á bond
B)loss of one ð bond and gain of two á bonds
C)loss of two ð bonds and gain of one á bond
D)loss of two ð bonds and gain of two á bonds

Question 7

What is the product of the following reaction?

A)
B)
C)
D)

Question 8

Which of the following best describes the reaction shown below?

A)cycloaddition
B)sigmatropic rearrangement
C)electrocyclic reaction
D)substitution

Question 9

Which of the following best describes the product of the reaction shown below?

A)conrotatory movement of orbitals and a trans product
B)conrotatory movement of orbitals and a cis product
C)disrotatory movement of orbitals and a trans product
D)disrotatory movement of orbitals and a cis product

Question 10

Which of the following best describes the diene shown below?

A)cis
B)trans
C)s-cis
D)s-trans

Question 11

Which of the following best describes the reaction of a [2+2] cycloaddition of two alkenes?

A)thermally and photochemically forbidden
B)thermally and photochemically allowed
C)thermally allowed and photochemically forbidden
D)thermally forbidden and photochemically allowed

Question 12

Which of the following best describes A and B in the following Diels-Alder reaction?

A)A and B are both electron withdrawing.
B)A and B are both electron donating.
C)A is electron withdrawing,and B is electron donating.
D)A is electron donating,and B is electron withdrawing.

Question 13

Which of the following represents the product of the reaction shown below?

A)
B)
C)
D)

Question 14

Which of the following reactants are involved in a [4+2] cycloaddition?

A)an alkene and a diene
B)an alkene and a carbonyl
C)two alkenes
D)two dienes

Question 15

Which of the following orbitals are involved a thermal [4+2] cycloaddition?

A)the dienophile HOMO and the diene HOMO
B)the dienophile HOMO and the diene LUMO
C)the dienophile LUMO and the diene HOMO
D)the dienophile LUMO and the diene LUMO

Question 16

Which of the following reactions involves the breaking of a sigma bond?

A)cycloaddition
B)sigmatropic rearrangement
C)electrocyclic reaction
D)dipolar cycloaddition

Question 17

Which of the following contains a SOMO?

A)diene
B)dienophile
C)radical
D)carbocation

Question 18

Which of the following is a reactant for the Cope rearrangement?

A)1,3-hexadiene
B)1,4-hexadiene
C)1,5-hexadiene
D)1-hexene

Question 19

Which of the following represents the most reactive diene in a Diels-Alder cycloaddition?

A)
B)
C)
D)

Question 20

What is the product of the following reaction?

A)
B)
C)
D)

Question 21

What is the product of the following reaction?

A)
B)
C)
D)

Question 22

Which of the following best describes the reaction shown below?

A)loss of one ð bond and gain of one á bond
B)loss of one ð bond and gain of two á bonds
C)loss of two ð bonds and gain of one á bond
D)loss of two ð bonds and gain of two á bonds

Question 23

What product is favoured in the following reaction and why?

A)I because of aromaticity
B)I because of hyperconjugation
C)II because of aromaticity
D)II because of hyperconjugation

Question 24

Which of the following best describes the electrocyclic rearrangement shown below?

A)thermally and photochemically forbidden
B)thermally and photochemically allowed
C)thermally allowed and photochemically forbidden
D)thermally forbidden and photochemically allowed

Question 25

What is the product of the following reaction?

A)
B)
C)
D)

Question 26

Which of the following best describes a [4+2] cycloaddition?

A)thermally and photochemically forbidden
B)thermally and photochemically allowed
C)thermally allowed and photochemically forbidden
D)thermally forbidden and photochemically allowed

Question 27

Which of the following cycloadditions is photochemically controlled?

A)[4+2]
B)[4+4]
C)[4+6]
D)[6+4]

Question 28

What is the name of the following intermediate formed in the ozonolysis of an alkene?

A)ozonide
B)molozonide
C)ozonate
D)molozonate

Question 29

What conditions will generate the following product,and what best describes the rotation of orbitals in the electrocyclic reaction shown below?

A)Heat is required to generate the product,and it is formed through a conrotatory movement of orbitals.
B)Hv is required to generate the product,and it is formed through a conrotatory movement of orbitals.
C)Heat is required to generate the product,and it is formed through a disrotatory movement of orbitals.
D)Hv is required to generate the product and it is formed through a disrotatory movement of orbitals.

Question 30

Which of the following is the favoured product in the reversible sigmatropic rearrangement shown below,and why?

A)I because of conjugation
B)I because of hyperconjugation
C)II because of conjugation
D)II because of hyperconjugation

Question 31

Which orbital is considered the HOMO in a diene?

A)Ø₁
B)Ø₂
C)Ø₃
D)Ø₄

Question 32

Which of the following terms involves opposing rotation of orbitals in electrocyclic reactions?

A)rotatory
B)counterrotatory
C)conrotatory
D)disrotatory

Question 33

[2+2] cycloadditions occur under thermal conditions.

Question 34

What is the product of the reaction shown below?

A)
B)
C)
D)

Question 35

What is the intermediate of the following reaction?

A)
B)
C)
D)

Question 36

A [4+2] cycloaddition is thermally allowed.

Question 37

s-trans dienes are in equilibrium with s-cis dienes.

Question 38

What conditions will generate the following product?

A)heat
B)hv
C)acid
D)both heat and hv

Question 39

Which of the following best describes the sigmatropic rearrangement shown below?

A)thermally and photochemically forbidden
B)thermally and photochemically allowed
C)thermally allowed and photochemically forbidden
D)thermally forbidden and photochemically allowed

Question 40

Which orbital is considered the LUMO in a diene?

A)Ø₁
B)Ø₂
C)Ø₃
D)Ø₄

Question 41

SUMO orbitals are formed by heating

Question 42

Dipolar cycloadditions requires a zwitterionic compounds.

Question 43

A sigmatropic rearrangement involves the loss and gain of one sigma bond.

Question 44

Photochemical electrocyclic reactions always involve disrotatory movement of orbitals.

Question 45

The Hoffman rearrangement transforms an amide into amines.

Question 46

Sigmatropic rearrangements are photochemically forbidden.

Question 47

OsO₄ transforms an alkene into a trans-diol.

Question 48

Ketenes are capable of [2+2] thermal cycloadditions

Question 49

Ozone transforms an alkene into carbonyls.

Question 50

A dieneophile is activated with electron withdrawing groups.

Question 51

A reaction of an alkyne and an azide is termed a [3+2] cycloaddition.

Question 52

[6+4] cycloadditions are thermally forbidden.

Question 53

Electrocyclic ring closures involve the loss of a ð bond.

Question 54

A diene is activated with electron withdrawing groups.

Question 55

A [2+2] cycloaddition is thermally allowed.

Question 56

SUMO orbitals are involved in photochemical cycloadditions.

Question 57

The sigmatropic rearrangement involves the overlap of two LUMO orbitals.

Question 58

[4+2] cycloadditions are photochemically forbidden.

Question 59

Electrocyclic rearrangements are photochemically forbidden.

Question 60

The Baeyer-Villiger oxidation converts ketones into esters.

Question 61

Propose a mechanism for the following transformation.

Question 62

Predict the reactants of the following cycloaddition reaction.

Question 63

A [2+2] cycloaddition occurs under _______________ conditions.

Question 64

Draw the product of the following reaction under both thermal and photochemical conditions.

Question 65

The Claisen rearrangement is an example of a(n)_______________ rearrangement.

Question 66

Electron _______________ groups activate dienophiles in the Diels-Alder reaction.

Question 67

Diels-Alder cycloadditions are irreversible.

Question 68

Draw the product and mechanism of the following transformation.Show using molecular orbitals.

Question 69

Two orbitals rotating in the same direction are referred to as _______________ .

Question 70

The conversion of a ketone to an ester involves the use of a(n)_______________ .

Question 71

Two orbitals rotating in opposite directions are referred to as _______________ .

Question 72

Determine the product and show the mechanism of the following transformation.

Question 73

A [2+2] cycloaddition is thermally_______________.

Question 74

Predict the product of the following reaction and show the transition state.

Question 75

The _______________ orbital of a diene is the reactive orbital in the Diels-Alder reaction.

Question 76

A [4+2] cycloaddition is _______________ forbidden.

Question 77

Draw the product and the mechanism of the following reaction.

Question 78

Draw the product and mechanism of the following transformation.Show using molecular orbitals.

Question 79

Bromine is a reagent in the Baeyer-Villiger oxidation.

Question 80

A [4+2] cycloaddition occurs under _______________ conditions.