Deck 14: Delocalized Pi Systems: Investigation by Ultraviolet and Visible Spectroscopy Interlude

Question 1

The LUMO of 1,3,5-hexatriene is:

A)( $\Psi$ )10
B) ( $\Psi$ 2)
C) ( $\Psi$ 3)
D) ( $\Psi$ 4)
E) ( $\Psi$ 5)

Answer 1

( $\Psi$ 4)

Question 2

What would be the expected major product of the following reaction?

A)

B)

C)

D)

E)

Answer 2

Question 3

What would be the product of the following reaction?

A)

B)

C)

D)

E) No reaction occurs

Answer 3

Question 4

UV-visible spectroscopy involves what type of phenomenon?

A) Binding of chemical bonds
B) Electron transitions between orbitals
C) Molecular rotations
D) Nuclear spin transitions
E) Stretching of chemical bonds

Question 5

A typical Diels-Alder reaction involves

A) an electron-rich diene and an electron-rich dienophile.
B) an electron-poor diene and an electron-rich dienophile.
C) an electron-rich diene and an electron-poor dienophile.
D) an electron-poor diene and an electron-poor dienophile.
E) a non-substituted diene and a non-substituted dienophile.

Question 6

What product would you expect from the following reaction?

A)

B)

C)

D)

E)

Question 7

What would be the expected major product of the following reaction sequence?

A)

B)

C)

D)

E)

Question 8

What product(s)would NOT be formed from the reaction of 1,3-butadiene with HCl?

A)

B)

C)

D) neither A nor C
E) neither B nor C

Question 9

What product(s)would you expect the following radical reaction to provide in reasonable yields?

A)

B)

C)

D) both B and C
E) both A and C

Question 10

What would be the final product(s)of the following reactions?

A)

B)

C)

D) both A and B
E) both A and C

Question 11

What would be the major product of the following reaction?

A)

B)

C)

D)

E) None of these products are formed.

Question 12

What would be the major product from the following reaction?

A)

B)

C)

D)

E)

Question 13

What major product would result from the following sequence of reactions?

A)

B)

C)

D)

E)

Question 14

The reaction of butadiene with acrolien would yield what product?

A)

B)

C)

D)

E) None of these products are formed.

Question 15

The presence of a bromine WHERE in the following carbon chain would give the most reactive material for an S_N2 reaction with a nucleophile (all other bonds would be to hydrogen)?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 16

What product(s)would you expect from the following reaction?

A)

B)

C)

D) both A and B
E) both A and C

Question 17

Which of the following dienes would you expect to be the most reactive in Diels-Alder reactions?

A)

B)

C)

D)

E)

Question 18

In order of decreasing reactivity,how would the bromides below rank in the following reaction?

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

Question 19

What would be the major product of the following reaction?

A)

B)

C)

D)

E)

Question 20

Which one of the following dienes would you expect to be the most stable?

A)

B)

C)

D)

E)

Question 21

What is the IUPAC name for the following compound?

A) (3E,5E)-7-Bromo-4,6-nonadiene
B) (3E,5E)-3-Bromo-3,5-nonadiene
C) (3E,5Z)-7-Bromo-4,6-nonadiene
D) (3Z,5E)-3-Bromo-3,5-nonadiene
E) (3Z,5Z)-3-Bromo-3,5-nonadiene

Question 22

Which of the structures below do not benefit from resonance stabilization?

A)

B)

C)

D)

E) None of the above.

Question 23

What is the proper IUPAC name for the following molecule:

A) (2E,4Z)-2,4-heptadiene
B) (2E,3Z)-2,3-heptadiene
C) (2Z,4E)-2,4-heptadiene
D) (2E,4Z)-2,4-hexadiene
E) (2Z,3E)-2,3-hexadiene

Question 24

The reaction shown below is expected to produce which product(s)?

A)

B)

C)

D)

E) more than one of these

Question 25

Which of the following alkylbromides cannot be a product of the allylic bromination of 1-methylcyclopentene with NBS?

A)

B)

C)

D)

E) All of the above can be a product from the reaction.

Question 26

The UV spectrum of the following molecule is useful for determining _______.

A) coupling constants between hydrogen atoms
B) molecular weight
C) conjugation resulting in electronic transitions
D) molecular formula
E) two of these are correct

Question 27

The pi electrons in 1,3-butadiene are distributed as follows:

A) One in each of 4 bonding orbitals
B) Two in bonding orbitals,two in non-bonding orbitals
C) Two in each of 2 bonding orbitals
D) One in each of 4 non-bonding orbitals
E) None of these.

Question 28

Predict the product of the following reaction:

A)

B)

C)

D)

E) No reaction

Question 29

Which of the following electrocyclic reactions occurs via a conrotatory process?

A)

B)

C)

D)

E) Both B and C

Question 30

Predict the MAJOR product of the following reaction:

A)

B)

C)

D)

E) No reaction

Question 31

When reacted with Br₂ and light,which C-H bond 2-pentene will preferentially dissociate to give a radical?

A) The C-H_a bond
B) The C-H_b bond
C) The C-H_c bond
D) The C-H_d bond
E) The C-H_e bond

Question 32

Which is the MAJOR product of combining 1,3-butadiene with HBr at 25 ^oC?

A) 1-bromo-2-butene
B) 3-bromo-1-butene
C) 1,3-dibromobutadiene
D) 2,3-dibromobutene
E) 3,3-dibromobutene

Question 33

Which of the following are most favored thermodynamically?

A)

B)

C)

D) All of these.
E) None of these.

Question 34

Predict the product of the hydrolysis of (S)-4-bromo-2-pentene.

A) (R)-2-pentene-4-ol
B) Racemic 3-pentene-2-ol
C) (R)-2-hydroxy-3-pentene
D) Racemic-3-hydroxy-3-pentene
E) (S)-2-hydroxy-3-pentene