Deck 10: Alkenes

Question 1

Which of the following statements about alkenes is not true?

A) They are less reactive than alkanes.
B) They can exist as cis/trans isomers.
C) The bond angle around the C-C double bond is approximately 120°.
D) The carbon of the C-C double bond is sp² hybridized.

Answer 1

They are less reactive than alkanes.

Question 2

Which of the statements about the properties of the carbon-carbon double bond is not true?

A) There is restricted rotation around the carbon-carbon double bond.
B) Whenever the two groups on each end of a carbon-carbon double bond are the same, two diastereomers are possible.
C) Trans alkenes are generally more stable than cis alkenes.
D) The stability of the carbon-carbon double bond increases as the number of substituent groups increases.

Answer 2

Whenever the two groups on each end of a carbon-carbon double bond are the same, two diastereomers are possible.

Question 3

What is the common name of the following compound?

A) 2-Vinylcyclohexene
B) 2-Allylcyclohexene
C) 1-Allylcyclohexene
D) 1-Vinylcyclohexene

Answer 3

1-Vinylcyclohexene

Question 4

What is the IUPAC name for the following compound?

A) 1,2-Dimethylcyclohexene
B) 2,3-Dimethylcyclohexene
C) 1,6-Dimethylcyclohexene
D) 1,2-Dimethyl-3-cyclohexene

Question 5

What is the IUPAC name for the following compound?

A) 6-Ethyl-1-heptene
B) 2-Ethyl-1-heptene
C) 2-Ethyl-1-octene
D) 6-Ethyl-6-heptene

Question 6

What is the IUPAC name for the following compound?

A) 4-Ethyl-3-methyl-1-octen-5-ol
B) 3-Ethyl-4-methyl-2-octen-5-ol
C) 5-Ethyl-6-methyl-7-octen-4-ol
D) 4-Ethyl-6-methyl-1-octen-5-ol

Question 7

Which of the following alkenes are terminal alkenes?

A) I and II
B) II and III
C) I and IV
D) I and III

Question 8

Rank the following compounds in order of decreasing stability, putting the most stable first.

A) I > II > III
B) II > I > III
C) III > II > I
D) III > I > II

Question 9

Calculate the degree of unsaturation for a molecule with molecular formula C₆H₁₁Cl.

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

Question 10

What is the IUPAC name for the following compound?

A) 1-Methylcyclopentene
B) 2-Methyl-1-cyclopentene
C) 1-Methylene-1-methylcyclopentane
D) 1-Methylcyclohexene

Question 11

Which of the following reaction conditions would result in anti-Markovnikov addition to an alkene?

A) H₂O/H₃O⁺
B) HBr
C) HCl
D) [1] BH₃; [2] H₂O₂/HO^-

Question 12

Rank the following isomers in order of increasing boiling point, putting the least first.

A) I < II < III
B) I < III < II
C) II < III < I
D) II < I < III

Question 13

Which of the following statements about alkenes is true?

A) Alkenes react with nucleophiles and bases.
B) Alkenes contain double bonds from two sp-hybridized carbon atoms.
C) In the reactions of alkenes, the  bond is not always broken.
D) Alkenes react with electrophiles.

Question 14

Which of the following compounds has the highest boiling point?

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

Question 15

Calculate the degree of unsaturation for a molecule with molecular formula C₈H₉N.

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

Question 16

What is the IUPAC name for the following compound?

A) 5-Methyl-5-hexen-2-ol
B) 6-Methyl-6-hepten-2-ol
C) 6-Hydroxy-2-methylheptene
D) 6-Hydroxy-2-methyl-1-heptene

Question 17

Which of the following alkenes are internal alkenes?

A) I and II
B) II and III
C) I and III
D) II and IV

Question 18

Label each C-C double bond in Kavain, a naturally occurring relaxant, as E or Z.

A) I = Z and II = Z
B) I = Z and II = E
C) I = E and II = E
D) I = E and II = Z

Question 19

What is the major product of the following reaction?

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

Question 20

Which of the following is a terpene?

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

Question 21

Predict the product(s) of the following reaction.

A) Only I and II
B) Only I and III
C) Only II and III
D) Only III and IV

Question 22

What is the major product obtained from the following reaction?

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

Question 23

Which of the following alkenes will undergo a carbocation rearrangement when reacting with H₂O in the presence of a small amount of H₂SO₄?

A) Only I and II
B) Only I and III
C) Only II and III
D) I, II and III

Question 24

Predict the major product of the following reaction.

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

Question 25

In which of the following alkene addition reactions will carbocation rearrangements occur?

A) Addition of Br₂ and H₂O
B) Addition of Br₂
C) Addition of Cl₂ and H₂O
D) Addition of H₂O in the presence of H₂SO₄

Question 26

Predict the major product of the following reaction.

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

Question 27

What is the best choice of reagent to accomplish the following transformation?

A) H₂O, Br₂
B) [1] BH₃; [2] H₂O₂/HO^-
C) H₂O, H₂SO₄
D) [1] BH₃; [2] H₂O

Question 28

What is the major product obtained from the following reaction (assume enantiomer is also formed)?

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

Question 29

Predict the major product(s) of the following reaction.

A) Only I and II
B) Only II and III
C) Only III and IV
D) Only I and IV

Question 30

Predict the major product of the following reaction.

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

Question 31

What is the best choice of reagent to accomplish the following transformation?

A) HBr
B) Br₂, H₂O
C) Br₂
D) H₂O₂/Br₂

Question 32

Markovnikov addition of HBr to CH₃CH=CH₂ involves which of the following?

A) Initial attack by bromide anion (Br^-).
B) Initial attack by bromine radical (Br•).
C) Formation of a primary carbocation.
D) Formation of a secondary carbocation.

Question 33

What is (are) the major product(s) obtained from the following reaction?

A) Only I
B) Only II
C) Only III
D) Only I and II

Question 34

What type of reactive intermediate is formed in the reaction of an alkene with HI to give an iodoalkane?

A) Carbanion
B) Carbocation
C) Cyclic bromonium ion
D) Radical

Question 35

Predict the product of the following reaction.

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

Question 36

Predict the major product(s) of the following reaction.

A) Only I and II
B) Only II and IV
C) Only II and III
D) Only I and IV

Question 37

What is (are) the major product(s) obtained from the following reaction?

A) Only I
B) Only II
C) Only III
D) Only I and II

Question 38

What type of reactive intermediate is formed in the reaction of an alkene with Br₂ and H₂O to give a bromohydrin?

A) Carbanion
B) Radical
C) Carbocation
D) Cyclic bromonium ion

Question 39

Rearrangements can occur in which of the following reactions?

A) Addition of Cl₂ to an alkene.
B) Addition of HOBr to an alkene.
C) Addition of H₂O/H₃O⁺ to an alkene.
D) None of the above.

Question 40

Which of the following alkenes reacts fastest with HCl?

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

Question 41

Rank the carbocation in order of increasing stability, putting the least stable first.

A) III < I < II
B) III < II < I
C) I < II < III
D) I < III < II

Question 42

What is (are) the missing reagent(s) in the following reaction?

A) Br₂/CCl₄
B) NBS, DMSO/H₂O
C) [1] Br₂; [2] H₂O
D) [1] BH₃; [2] H₂O₂/HO^-

Question 43

Which of the following statements about the stereochemistry of electrophilic addition of HX to alkenes is true?

A) Achiral starting materials yield an unequal mixture of two enantiomers.
B) Hydrohalogenation occurs with syn stereochemistry only.
C) Hydrohalogenation occurs with anti stereochemistry only.
D) Hydrohalogenation occurs with syn and anti addition of HX.

Question 44

What is the starting material in the following reaction?

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

Question 45

Which of the following statements about hydroboration/oxidation of alkenes is true?

A) In hydroboration, the boron atom bonds to the more substituted carbon.
B) Hydroboration occurs with anti addition.
C) Oxidation occurs with retention of configuration.
D) 9-BBN does not undergo hydroboration in the same manner as BH₃.

Question 46

Which of the following reactions of alkenes takes place with anti stereochemistry only?

A) Addition of HBr
B) Addition of H₂O in the presence of H₂SO₄
C) Addition of BH₃ followed by H₂O₂/HO^-
D) Addition of Br₂

Question 47

Predict the product of the following reaction, ignoring stereochemistry.

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