Deck 7: Structure and Synthesis of Alkenes; Elimination

Question 1

The steroid testosterone has the molecular formula C₁₉H₂₈O₂. Given that there are two π bonds in a molecule of testosterone, how many rings are present in each molecule?

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

Answer 1

4

Question 2

Which of the following statements best describes the relative bond dissociation energies of the sigma and pi bonds present in the carbon-carbon double bond of an alkene?

A) sigma > pi
B) pi > sigma
C) sigma = pi
D) cannot be estimated

Answer 2

sigma > pi

Question 3

Which of the following best approximates the CCC bond angle of propene?

A) 90°
B) 109°
C) 120°
D) 150°
E) 180°

Answer 3

120°

Question 4

What two atomic orbitals or hybrid atomic orbitals overlap to form the C-C σ bond in ethylene?

A) C sp³ + C sp³
B) C sp³ + C sp²
C) C sp² + C sp²
D) C sp³ + C p
E) C sp² + C p

Question 5

Consider molecules with the formula C₁₀H₁₆. Which of the following structural features are not possible within this set of molecules?

A) 2 triple bonds
B) 1 ring and 1 triple bond
C) 2 rings and 1 double bond
D) 2 double bonds and 1 ring
E) 3 double bonds

Question 6

How many elements of unsaturation do molecules with a molecular formula of C₆H₆Cl₆ have?

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

Question 7

The prostaglandin precursor arachidonic acid has the molecular formula C₂₀H₃₂O₂. Given that arachidonic acid is an acyclic carboxylic acid that contains no carbon-carbon triple bonds, how many carbon-carbon double bonds are present?

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

Question 8

How many elements of unsaturation are implied by the molecular formula ?

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

Question 9

Carbon-carbon single bonds tend to be ________ and ________ than carbon-carbon double bonds.

A) shorter; stronger
B) longer; stronger
C) shorter; weaker
D) longer; weaker

Question 10

Why is rotation about the carbon-carbon double bond in alkenes prohibited while relatively free rotation can occur about the carbon-carbon single bond in alkanes?

Question 11

Circle all atoms that are coplanar in the molecule below.

Question 12

How many elements of unsaturation are implied by the molecular formula

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

Question 13

Give the structures of three examples of molecules that have a molecular formula of C₆H₈. One of the structures should have only one ring and one of the structures should have no rings.

Question 14

What two atomic orbitals or hybrid atomic orbitals overlap to form the C-H bond in ethylene?

A) C sp³ + H s
B) C sp² + H s
C) C sp + H s
D) C p + H s

Question 15

What two atomic orbitals or hybrid atomic orbitals overlap to form the C-C π bond in ethylene?

A) C sp³ + C sp³
B) C sp³ + C sp²
C) C sp² + C sp²
D) C sp² + C p
E) C p + C p

Question 16

Which of the indicated carbon-carbon bonds is shorter?

Question 17

A newly isolated natural product was found to have the molecular formula C₁₅H₂₈O₂. By hydrogenating a sample of the compound, it was determined to possess one π bond. How many rings are present in the compound?

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

Question 18

Which of the following molecular formulas corresponds to a monocyclic saturated compound?

A) C₆H₆
B) C₃H₇Br
C) C₃H₇N
D) C₃H₈O

Question 19

How many elements of unsaturation do molecules with a molecular formula of C₈H₄N₂ have?

A) 2
B) 4
C) 6
D) 8
E) 10

Question 20

The carbon-carbon bond length in ethylene is ________ than the carbon-carbon bond length in ethane, and the HCH bond angle in ethylene is ________ the HCH bond angle in ethane.

A) shorter; smaller than
B) shorter; larger than
C) longer; smaller than
D) longer; larger than
E) longer; the same as

Question 21

Draw an acceptable structure for 4-phenylbut-1-ene.

Question 22

Provide the proper IUPAC name for the alkene shown below.

Question 23

Which of the following alkenes can show geometric isomerism: 2,3-dichloro-2-pentene, 4-chloro-3-ethyl-3-hexene, 3-chloro-2-methyl-2-butene, and 3-chloro-2-methyl-1-butene?

Question 24

Draw an acceptable structure for 4-ethylhept-1-ene.

Question 25

Provide the proper IUPAC name for the alkene shown below.

Question 26

Name the alkene shown. Be sure to include the appropriate E or Z label necessary.

Question 27

If a certain hydrocarbon molecule has 10 carbons atoms, one ring and two triple bonds, how many hydrogens does it have?

A) 10
B) 12
C) 14
D) 16
E) 18

Question 28

Identify the correct name for the following structure.

A) 3-methoxy-5-methylcyclohepta-1,5-diene
B) 6-methoxy-1-methylcyclohepta-1,4-diene
C) 7-methoxy-5-methylcyclohepta-1,4-diene
D) 4-methoxy-2-methylcyclohepta-1,5-diene

Question 29

Name the compound shown below.

Question 30

Draw and name the six alkenes which have the molecular formula C₅H₁₀.

Question 31

Provide an acceptable name for (CH₃)₂CHCH=C(CH₃)CH₂CH₃.

Question 32

Provide the proper IUPAC name for the alkene shown below.
CH₂

CHCH₂CH₂CH₂CH₃

Question 33

Draw and name all alkenes which have the molecular formula C₄H₈.

Question 34

Provide a correct IUPAC name for the structure below.

Question 35

A chemist has isolated a new natural product and determined its molecular formula to be C₂₄H₄₀O₄. In hydrogenation experiments the chemist found that each mole of the natural product reacted with two moles of H₂. How many rings are present in the structure of the new natural product?

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

Question 36

Provide the proper IUPAC name for the alkene shown below.

Question 37

For which of the following alkenes will cis- and trans- isomers not exist?

A) a) only
B) b) only
C) both a) and c)
D) d) only
E) both c) and d)

Question 38

Provide an acceptable name for (CH₃CH₂)₂CHCH₂CH=CH₂.

Question 39

Draw an acceptable structure for 1,2-dimethylcyclohexene.

Question 40

How many elements of unsaturation are implied by the molecular formula

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

Question 41

Which of the following best describes the geometry about the carbon-carbon double bond in the alkene below?

A) E
B) Z
C) neither E nor Z

Question 42

Draw an acceptable structure for (Z)-2-chloro-4-ethylhex-2-ene.

Question 43

Provide the structure of (Z)-1-chloro-1-fluoro-1-butene.

Question 44

Which of the following best describes the geometry about the carbon-carbon double bond in the alkene below?

A) E
B) Z
C) neither E nor Z

Question 45

Draw the structure of poly(tetrafluoroethylene) or Teflon.

Question 46

Provide a structure for (Z)-4-bromo-3-heptene.

Question 47

Provide the proper IUPAC name for the alkene shown below.

Question 48

Provide the proper IUPAC name for the alkene shown below.

Question 49

Which has the smaller heat of hydrogenation, (E)-2-pentene or (Z)-2-pentene? What is the structural origin of this difference?

Question 50

Which of the following best describes the geometry about the carbon-carbon double bond in the alkene below?

A) E
B) Z
C) neither E nor Z

Question 51

Why doesn't cyclohexene have cis/trans isomers?

Question 52

Provide the proper IUPAC name for the alkene shown below.

Question 53

Which of the following best describes the geometry about the carbon-carbon double bond in the alkene below?

A) E
B) Z
C) neither E nor Z

Question 54

The compound produced when 3-methylpent-2-ene undergoes hydrogenation in the presence of a platinum catalyst is ________.

Question 55

Provide the structure of the monomer from which PVC or poly(vinyl chloride) is made.

Question 56

Draw the structure of polyethylene.

Question 57

Which of the following best describes the geometry about the carbon-carbon double bond in the alkene below?

A) E
B) Z
C) neither E nor Z

Question 58

Circle the alkene below which has the smallest heat of hydrogenation.

Question 59

Provide the proper IUPAC name for the alkene shown below.

Question 60

Name the alkene shown. Be sure to include the appropriate E or Z label necessary.

Question 61

Which of the following alkenes has the largest molar heat of hydrogenation (ie, releases the most heat upon hydrogenation)?

A) 2,3-dimethyl-2-butene
B) 2-methyl-2-butene
C) trans-2-butene
D) cis-2-butene
E) 1-hexene

Question 62

Does the alkene shown below violate Bredt's rule?

Question 63

The industrial method of making alkenes is via catalytic cracking. If decane is subjected to these conditions, hexane and 1-butene are one set of possible products. Draw the products in line-angle structures.

Question 64

Which of the following alkenes has the smallest molar heat of hydrogenation (ie, releases the least heat upon hydrogenation)?

A) 2,3-dimethyl-2-butene
B) 2-methyl-2-butene
C) trans-2-butene
D) cis-2-butene
E) 1-hexene

Question 65

Compare the relative heats of hydrogenation of cyclobutene and cyclopentene and explain the difference in magnitude.

Question 66

Does the alkene shown below violate Bredt's rule?

Question 67

Which is the more stable diene shown below? Briefly explain your answer.

Question 68

The trans isomers of cycloalkenes with rings containing fewer than ________ atoms are unstable at room temperature.

Question 69

Using Zaitsev's rule, choose the most stable alkene among the following.

A) hex-1-ene
B) (E)-hex-2-ene
C) (Z)-hex-2-ene
D) They are all of equal stability according to Zaitsev's rule.

Question 70

Rank the following compounds in order of increasing heat of hydrogenation, ΔH_hyd.

A) AB) AC) BD) C

Question 71

Using Zaitsev's rule, choose the most stable alkene among the following.

A) 1-methylcyclohexene
B) 3-methylcyclohexene
C) 4-methylcyclohexene
D) They are all of equal stability according to Zaitsev's rule.

Question 72

Using Zaitsev's rule, choose the most stable alkene among the following.

A) 1,2-dimethylcyclohexene
B) 1,6-dimethylcyclohexene
C) cis-3,4-dimethylcyclohexene
D) They are all of equal stability according to Zaitsev's rule.

Question 73

Which sequence ranks the following compounds in order of increasing heat of hydrogenation, ΔH_hyd?
1 cis-2-butene 2 1-butene 3 cyclohexene

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

Question 74

Consider the constitutional isomers 2-methylbut-1-ene, 2-methylbut-2-ene, and 3-methylbut-1-ene. When each of these alkenes is subjected to catalytic hydrogenation (H₂, Pt), a single product results. Which of the following best describes the structural relationship among these products?

A) The products are cis-trans isomers.
B) The products are identical.
C) The products are constitutional isomers.
D) The products are enantiomers.
E) The products are diastereomers.

Question 75

Draw the alkene of formula C₅H₁₀ which evolves the most heat per mole upon hydrogenation.

Question 76

Circle the most stable alkene in the set of isomers below.

Question 77

Circle the most stable alkene in the set of isomers below.

Question 78

3-Methylpentane can be dehydrogenated to form an alkene with molecular formula of C₆H₁₂. What is the most stable alkene that could be formed? Name it with the appropriate stereochemical designator.

Question 79

There are three isomeric methylbutene structures. Draw each of them and then circle the isomer with the highest heat of hydrogenation.

Question 80

Does the alkene shown below violate Bredt's rule?