University of New England

CHEM 1020

Chapter 3 -- Alkenes and Alkynes

MULTIPLE CHOICE

1)Which of the following dienes can be classified as conjugated?

1. 1. CH₃CH=C=CH₂
   2. CH₃CH=CHCH=CH₂
   3. CH₂=CHCH₂CH=CH₂
   4. CH₃CH=CHCH₂CH₂CH=CH₂
   5. CH₂=C=CH₂

                                

 

2. Which of the following molecular formulas could not represent an alkene?
   1. C5H10
   2. C7H14
   3. C10H20
   4. C27H56
   5. C31H62

                                

 

3. 
   What is the correct name for the following molecule?

 

1. 1. 1-ethylcyclohexene
   2. 2-ethylcyclohexene
   3. 3-ethylcyclohexene
   4. cyclohexylethane
   5. 1-ethyl-3-cyclohexene

                                

 

4. Which of the following compounds can exhibit cis/trans isomerism?
   1. 1-heptene
   2. 2-heptene
   3. 2-methyl-2-hexene
   4. 3-methyl-1-hexene
   5. 3-ethyl-2-pentene

                                

 

5. 
   The correct IUPAC name for the following molecule is:

1. 1. trans-2,3-dichloro-5-methyl-2-hexene
   2. trans-2,3-dichloro-5-methyl-3-hexene
   3. cis-2,3-dichloro-5-methyl-3-hexene
   4. trans-4,5-dichloro-2-methyl-4-hexene
   5. cis-4,5-dichloro-2-methyl-4-hexene

                                

 

6. What is the correct structure for 2,3-dimethyl-2-pentene?

 

A)

 

 

 

 

B)

 

 

 

 

 

C)

 

 

 

 

 

D)

 

 

 

 

 

E)

 

 

 

 

 

                                

 

7. The correct structure for allyl bromide is:

 

A)

 

 

 

B)

 

 

C)

 

 

D)

 

 

 

E)

 

 

                                

 

8. Which of the following molecules is 4-methyl-2-hexyne?

 

A)

 

 

 

B)

 

 

 

C)

 

 

 

 

D)

 

 

 

 

E)

 

 

 

 

                                

 

9. The correct name of the molecule below is:

 

 

 

 

1. 1. 5-methyl-7-octen-1-yne
   2. 4-methyl-1-octen-7-yne
   3. 4-methyl-1-octyn-7-ene
   4. 5-methyl-1-octen-7-yne
   5. none of these is correct

                                

 

10. The multiple bonds in the following compounds are conjugated:

 

 

 

 

1. 1. 2, 3, and 5
   2. 4 and 6
   3. only 1
   4. 2 and 3
   5. 2 and 5

                                

 

11. The structure of (Z)-3-methyl-2-pentene is

 

A)

 

 

 

 

B)

 

 

 

 

 

C)

 

 

 

 

 

D)

 

 

 

 

E)

 

 

 

 

 

 

 

                                

 

12. Which compound contains a carbon-carbon double bond with (Z) stereochemistry?

 

A)

 

B)

 

 

 

C)

 

D)

 

 

 

E)

 

 

                                

 

 

 

 

 

13. The correct name for                                                         is:

 

1. 1. 2-methyl-4-isopropyl-3-hexene.
   2. 3-ethyl-2,5-dimethyl-3-hexene.
   3. 2,5-dimethyl-4-ethyl-3-hexene.
   4. 1-ethyl-1,2-diisopropylethene.
   5. 1,2-diisopropyl-1-butene.

                                

 

14. The double bond in ethene is made up of
    1. a pi bond and a sigma bond formed by lateral overlap of two p orbitals.
    2. a sigma bond formed by overlap of two s orbitals and a pi bond formed by lateral overlap of two p orbitals.
    3. a pi bond formed by end-on overlap of two sp² orbitals and a sigma bond formed by overlap of two s orbitals.
    4. a sigma bond formed by end-on overlap of two sp² orbitals and a pi bond formed by lateral overlap of two p orbitals.
    5. a pi bond formed by lateral overlap of two sp² orbitals and a sigma bond formed by end-on overlap of two sp² orbitals.

                                

 

15. The triple bond in ethyne is made up of
    1. two pi bonds and a sigma bond, each formed by a lateral overlap of two p orbitals.
    2. a sigma bond formed by overlap of two s orbitals and two pi bonds, each formed by lateral overlap of two p orbitals.
    3. a sigma bond formed by end-on overlap of two sp² orbitals and a pi bond formed by lateral overlap of two p orbitals.
    4. two pi bonds, each formed by lateral overlap of two p orbitals, and a sigma bond formed by end-on overlap of two sp orbitals.
    5. two pi bonds, each formed by end-on overlap of two p orbitals, and a sigma bond formed by lateral overlap of two sp orbitals.

                                

 

16. Which of the following statements is false relative to alkenes?
    1. the C of the carbon-carbon double bond is sp² hybridized
    2. the bond angles are approximately 120° around the carbon-carbon double bond
    3. there is the possibility of cis/trans isomerism
    4. they are more reactive than alkanes
    5. the bond length of the carbon-carbon double bond is longer than that of the carbon- carbon single bond

                                

17. Which of the following hydrocarbons will be the most acidic?
    1. pentane
    2. ethene
    3. acetylene
    4. isobutane
    5. propylene

                                

 

18. Which of the following statements are true about acetylene (ethyne)?
    1. It is more acidic than ethane and ethene.
    2. The bond angle around the carbon-carbon triple bond is 180°.
    3. The carbon-carbon triple bond is shorter than the carbon-carbon double bond.
    4. All of the above are true.
    5. None of the above are true.

                                

 

19. What is the percent s character in an sp² hybrid orbital?

A) 25%

B) 33%

C) 50%

D) 67%

E)   75%

                                

 

20. What is the percent s character in an sp hybrid orbital?

A) 25%

B) 33%

C) 50%

D) 67%

E)   75%

                                

 

21. What would be the major product of the following reaction?

 

 

 

 

 

 

1. 1. I
   2. II
   3. III
   4. IV
   5. V

                                

 

22. Select the necessary reagent(s) to convert cycloheptene to cycloheptane.

 

1. 1. H₂ and Ni
   2. H₂O
   3. H₂SO₄ and heat
   4. Zn and H⁺
   5. KOH in alcohol and heat

                                

 

23. Select the necessary reagents to convert 1-methylcyclopentene to 1-methylcyclopentanol.

 

1. 1. H₂O and H₂SO₄
   2. Zn, H₂O
   3. BH₃, then H₂O₂ and ^–OH
   4. O₃, then Zn, H⁺
   5. KOH in alcohol and heat

                                

 

24. What is the product for the reaction below?

 

 

 

 

 

 

A)

 

 

 

 

 

 

B)

 

 

 

 

 

C)

 

 

 

 

 

D)

 

 

 

 

 

E) none of these

                                

 

25. What is the product for the reaction below?

 

 

 

 

 

A)

 

B)

 

 

 

C)

 

D)

 

 

 

E)

 

                                

 

26. Upon ozonolysis and treatment with Zn in water, compound A yielded two moles of formaldehyde, HCHO, and 1 mole of the following molecule:

 

 

 

 

What is the structure of A?

 

 

 

 

 

1. 1. I
   2. II
   3. III
   4. IV
   5. V

                                

 

27. What is observed when water, in the presence of sulfuric acid, is added to 2-methyl-2- pentene?

A)

 

 

B)

 

 

 

 

C)

 

 

 

 

 

 

D)

 

E)

 

 

 

 

 

                                

 

28. The products obtained by the acid-catalyzed hydration of 1-methylcyclohexene and methylenecyclohexene are
    1. identical.
    2. regioisomers.
    3. cis-trans isomers.
    4. constitutional isomers.
    5. none of the above.

                                

 

29. The product of the reaction sequence

 

 

 

is

 

A)

 

B)

 

 

C)

 

 

 

D)

 

 

 

E) none of the above

                                

 

30. The product of the reaction

 

 

 

is

 

A)

 

 

 

 

B)

 

 

 

 

C)

 

 

 

 

D)

 

 

 

 

E)

 

 

 

 

 

                                

 

31. The products of the following reaction sequence

 

 

 

 

are

A)

 

 

 

B)

 

 

 

 

 

C)

 

 

 

 

 

D)

 

 

 

 

 

E)

 

 

 

 

 

                                

 

32. What product(s) will be observed by the addition of one molar equivalent of Br₂ to

                                 1,3-cyclohexadiene?

1. 1. 1,2-dibromocyclohexene
   2. 3,4-dibromocyclohexene
   3. 1,3-dibromocyclohexene
   4. 3,6-dibromocyclohexene
   5. both b and d

                                

 

33. The Diels-Alder reaction is very important in the synthesis of six-membered rings. What six- membered ring is produced with the following reaction?

 

 

 

 

1. 1. 

      

      D)

 

 

 

 

 

 

 

1. 2. E)

 

                                               

 

 

C)

 

 

 

 

 

 

 

 

                                

 

34. The product of addition of two moles of HBr to 1,4-pentadiene is
    1. 2,2-dibromopentane.
    2. 2,4-dibromopentane.
    3. 1,5-dibromopentane.
    4. 3,3-dibromopentane.
    5. 1,4-dibromopentane.

                                

 

35. The products obtained by adding 1 mole of HBr to 2,4-hexadiene are
    1. 4-bromo-2-hexene and 5-bromo-2-hexene.
    2. 3-bromo-2-hexene and 4-bromo-2-hexene.
    3. 4-bromo-2-hexene and 2-bromo-4-hexene.
    4. 2-bromo-3-hexene and 3-bromo-2-hexene.
    5. 2-bromo-3-hexene and 4-bromo-2-hexene.

                                

 

36. 

    The product of the reaction                                                                         is:

 

 

A)

 

 

 

 

 

B)

 

C)

 

D)

 

 

 

 

 

E)

 

                                

 

37. What type of compound is prepared by adding water to propyne in the presence of sulfuric acid and mercuric sulfate?
    1. aldehyde
    2. ketone
    3. carboxylic acid
    4. ester
    5. ether

 

                                

 

 

 

38. The product of the reaction                                                                       is:

 

 

A)

 

 

 

B)   

 

C)

 

 

 

D)

 

 

 

E)

 

 

 

 

                                

 

39. What is the name of the product formed from the following reaction?

 

 

 

 

1. 1. bromocyclopentane
   2. 1,1-dibromocyclopentane
   3. cis-1,2-dibromocyclopentane
   4. trans-1,2-dibromocyclopentane
   5. 1,1-dibromocyclopentene

                                

 

40. Addition of H₂ to 2-pentyne in the presence of the Lindlar's catalyst will produce:
    1. pentane
    2. 1-pentene
    3. cis-2-pentene
    4. trans-2-pentene

                                

 

41. What alkene is required to make 3-methyl-1-butanol using the hydroboration-oxidation reaction?
    1. 1-butene
    2. 2-butene
    3. 3-methyl-1-butene
    4. 2-methyl-2-butene
    5. 2-methyl-1-butene

                                

 

42. What is the final product of adding 1 mole of each reactant in the following sequence?

 

 

 

 

1. 1. propyl chloride
   2. propyl bromide
   3. 1-bromo-2-chloropropane
   4. 2-bromo-2-chloropropane
   5. 2,2-dibromopropane

                                

 

43. Which of the following alkenes is needed to prepare 3-cyclohexyl-1-propanol via a hydroboration-oxidation reaction?

 

 

 

3-cyclohexyl-1-propanol

1. 1. cyclohexene
   2. vinyl cyclohexane
   3. allyl cyclohexane
   4. propyl cyclohexene
   5. 1- octene

                                

 

44. Upon ozonolysis which alkene will give only acetone, (CH₃)₂C=O?
    1. 2,3-dimethyl-2-butene
    2. 2,2-dimethyl-2-butene
    3. 3-hexene
    4. 2-methyl-2-pentene
    5. 2-methyl-3-hexene

                                

 

45. What is the name of the alkene produced by treating 1-butyne with 1 mole of Br₂?

1. 1. (E)-1,2-dibromo-1-butene
   2. 1,1-dibromo-1-butene
   3. (Z)-1,2-dibromo-1-butene
   4. 1,2-dibromo-1-butene
   5. none of the above

                                

 

46. Examine the following reaction energy diagram for the reaction

 

 

Which of the following statements are true?

1. The reaction is exothermic.
2. The reaction occurs in one step.
3. The first step is the rate-determining step.
4. The reaction is endothermic.
5. If the reaction is heated, the reaction rate will increase.

 

1. 1. 1, 2, and 5
   2. 1, 3, and 5
   3. 2 and 4
   4. 3, 4, and 5
   5. 3 and 4

                                

 

47. Which of the following statements about chemical reactions are true?

 

1. Exothermic reactions occur at a rapid rate.
2. The products of exothermic reactions are lower in energy than the reactants.
3. Exothermic reactions give off heat.
4. The products of endothermic reactions are lower in energy than the reactants.

 

1. 3
2. 1, 2, and 3
3. 1, 3, and 4
4. 2 and 3
5. 2

                                

 

48. Markovnikov addition of HCl to propene involves:
    1. initial attack by the chloride ion
    2. initial attack by the chlorine atom
    3. isomerization of 1-chloropropane
    4. formation of a propyl cation
    5. formation of an isopropyl cation

                                

 

49. What type of carbocation will form from the addition of a H⁺ to 2-methylpropene?
    1. H₃C+
    2. 1°
    3. 2°
    4. 3°
    5. allyl

                                

 

50. Cyclohexene is treated with cold dilute KMnO₄. What is the spatial arrangement of the hydroxyls on the resulting cyclohexane ring?
    1. 1,2-cis
    2. 1,2-trans
    3. 1,4-cis
    4. 1,4-trans
    5. a mixture of 1,2-cis and 1,2-trans

                                

 

51. The first step in the free radical mechanism for the preparation of polyethylene is:
    1. formation of a stable carbocation
    2. formation of a stable carbanion
    3. heating an organic peroxide to break the O–O bond
    4. decoupling of the free radicals
    5. propagation of the free radicals

                                

 

52. Polyethylene is usually produced by
    1. an ionic electrophilic addition reaction
    2. heating ethylene to 1000^oC.
    3. cationic polymerization.
    4. a free-radical chain reaction.
    5. epoxidation.

                                

 

53. Which of the following reagents can be used to distinguish cyclohexene from cyclohexane?
    1. Zn, H⁺
    2. H₂O
    3. Cl₂, h?