Homework answers / question archive / The College at Old Westbury ORGANIC 12 Chapter 12: Reactions of Arenes - Electrophilic Aromatic Substitution 1)What is the product of the following reaction? isobutylbenzene                                                 C)         sec-butylbenzene 2-methyl-1-phenylpropene                           D)        tert-butylbenzene   The major product(s) in the nitration of benzoic acid is(are) mixture of ortho and para-nitrobenzoic acid

The College at Old Westbury ORGANIC 12 Chapter 12: Reactions of Arenes - Electrophilic Aromatic Substitution 1)What is the product of the following reaction? isobutylbenzene                                                 C)         sec-butylbenzene 2-methyl-1-phenylpropene                           D)        tert-butylbenzene   The major product(s) in the nitration of benzoic acid is(are) mixture of ortho and para-nitrobenzoic acid

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The College at Old Westbury

ORGANIC 12

Chapter 12: Reactions of Arenes - Electrophilic Aromatic Substitution

1)What is the product of the following reaction?

1. 1. isobutylbenzene                                                 C)         sec-butylbenzene
   2. 2-methyl-1-phenylpropene                           D)        tert-butylbenzene

 

2. The major product(s) in the nitration of benzoic acid is(are)
   1. mixture of ortho and para-nitrobenzoic acid.
   2. nitrobenzene.
   3. meta-nitrobenzoic acid.
   4. nitrobenzene and para-nitrobenzoic acid.

 

3. Which of the following aromatic compounds reacts faster than benzene in electrophilic aromatic bromination?

1. 1. A      B) B       C) C        D) D

 

4. Nitration of benzoic acid has a reaction rate which is      than the nitration rate of benzene and gives primarily the                                                                                    product(s).
   1. slower, meta                                                        C)         faster, ortho,para
   2. slower, ortho,para                                             D)        faster, meta

 

 

 

 

 

 

5. Which one of the following is the electrophile in the reaction shown below?

1. 1. benzene     B) NO₃¯         C) NO₂⁺        D) H₂SO₄

 

6. What is the electrophile in the Friedel-Crafts alkylation reaction below?

1. 1. AlCl₃        B) Cl¯         C) benzene      D) (CH₃)₃C⁺

 

7. Which point on the potential energy diagram corresponds to the species shown to the right for the electrophilic bromination of benzene with Br₂/FeBr₃?

1. 1. A      B) B       C) C        D) D

 

8. Which species below best depicts the electrophile in the FeBr₃-catalyzed bromination of benzene?
   1. Br₂      B) FeBr₄^-        C)     D) FeBr₃

 

 

 

 

 

9. Which one of the following reactions does not give tert-butylbenzene?
   1. benzene + (CH₃)₃CCl/AlCl₃                              C)         benzene + (CH₃)₃CH/AlCl₃
   2. benzene + (CH₃)₂C=CH₂/H₂SO₄                     D)        benzene + (CH₃)₃COH/H₂SO₄

 

10. Which point on the potential energy diagram corresponds to the species shown to the right for the electrophilic nitration of benzene with HNO₃/H₂SO₄?

1. 1. A      B) B       C) C        D) D

 

11. What is(are) the product(s) of the following reaction?

1. 1. C₆H₅CH₂CH₂CH₃
   2. C₆H₅CH(CH₃)₂
   3. C₆H₅CH₂CH₂CH₂C1
   4. a mixture of C₆H₅CH₂CH₂CH₃ and C₆H₅CH(CH₃)₂

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

12. Which one of the following is not a resonance form of the cyclohexadienyl cation intermediate in the bromination of benzene?

1. 1. A      B) B       C) C        D) D

 

13. How many mononitration products are possible in the nitration of naphthalene, shown below?

 

 

 

1. 1. only 1       B) 2       C) 3       D) 4

 

14. Rank the following compounds in order of decreasing reactivity to aromatic electrophilic bromination.

I. benzene      II. toluene      III. benzoic acid         IV. phenol

1. IV > II > I > III                                                         C)         II > I > IV > III
2. IV > III > II > I                                                         D)        II > III > IV > I

 

15. Which of the following groups are ortho/para directors?

I. –NO₂       II. –OCH₃         III. –CO₂CH₃          IV. –CH₃

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

 

 

 

 

 

 

 

 

 

 

16. Predict the effect the substituent attached to the benzene ring below would have on electrophilic aromatic substitution reactions?

 

 

 

1. 1. ortho/para director, activator                        C)         meta director, activator
   2. ortho/para director, deactivator                  D)        meta director, deactivator

 

17. In the Friedel-Crafts alkylation of benzene, dialkylation is often a significant by- product. In the Friedel-Crafts acylation of benzene, diacylation is not a significant by- product. Which of the following is the primary reason for this difference?
    1. Alkyl groups activate the ring to further substitution, acyl groups deactivate it.
    2. Alkyl groups are less sterically hindered than acyl groups.
    3. Acyl cations are more difficult to make with Lewis acids.
    4. Unlike acyl cations, carbocations can undergo rearrangements.

 

18. Which of the following is the best method to make n-butylbenzene?

1. 1. A      B) B       C) C        D) D

 

 

 

 

 

19. What is the major product of the following reaction?

 

 

 

1. 1. 4-ethyl-2-nitrophenol                                       C)         1-ethyl-4-nitrobenzene
   2. 4-ethyl-3-nitrophneol                                       D)        4-nitrophenol

 

20. Based on resonance theory, what is the approximate charge on the indicated carbon?

 

 

 

A) +1       B) +0.50        C) +0.33        D) +0.20

 

 

21. Which isomer of dichlorobenzene gives a single mononitration product?
    1. ortho     B) meta      C) para       D) none of them

 

22. Arrange the following compounds in order of increasing reaction rate with HNO₃/H₂SO₄.

I. C₆H₅CH=O           II. C₆H₅OCH₃           III. C₆H₅Br          IV. C₆H₅CH₃

1. I < III < IV < II                                                         C)         III < I < II < IV
2. I < IV < III < II                                                         D)        III < I < IV < II

 

 

 

 

 

 

 

 

 

 

23. Salicylic acid reacts with two equivalents of ICl to give one of the products below. Which one is it? (Hint: Cl is more electronegative than I.)

1. 1. A      B) B       C) C        D) D

 

24. Identify the preferred site(s) of electrophilic attack on the following compound.

1. 1. ortho/para positions on ring 1                       C)         ortho/para positions on ring 2
   2. meta position on ring 1                                     D)        meta position on ring 2

 

25. Which of the following is the best method to make meta-bromoethylbenzene from benzene?

1. 1. A      B) B       C) C        D) D

 

 

 

 

26. Which one of the following compounds undergoes electrophilic aromatic sulfonation at the fastest rate?

1. 1. A      B) B       C) C        D) D

 

27. What is the product of the following series of reactions?

1. 1. A      B) B       C) C        D) D

 

 

 

28. Nitration of chlorobenzene has a reaction rate which is         than        the        nitration rate of benzene and gives primarily the                                                                          product(s).
    1. faster, ortho/para     B) faster, meta       C) slower, ortho/para       D) slower, meta

 

29. What is the major product of the Friedel-Crafts alkylation of benzene with (CH₃)₂CHCH₂Cl and AlCl₃?
    1. isobutylbenzene                                                 C)         sec-butylbenzene
    2. tert-butylbenzene                                              D)        butylbenzene

 

30. Where would the compound shown below undergo bromination with Br₂/FeBr₃?

1. 1. ortho/para position on ring 1                         C)         ortho/para position on ring 2
   2. meta position on ring 1                                     D)        meta position on ring 2

 

31. Where would the compound shown below undergo bromination with NBS and benzoyl peroxide?

1. 1. ortho/para position on ring 1                         C)         C(2) position on ring 2
   2. meta position on ring 1                                     D)        methyl group on ring 2

 

 

 

 

 

 

 

 

 

 

 

32. Based on directing effects in electrophilic aromatic substitution reactions, predict the major addition product of the following reaction.

1. 1. A      B) B       C) C        D) D

 

33. Which one of the following substituents is deactivating and ortho-para directing in electrophilic aromatic substitution reactions?
    1. –Cl       B) –N(CH₃)₂         C) –CO₂H         D) –CH=CH₂

 

34. Consider the partial rate factors for electrophilic aromatic substitution at the indicated position of anisole and nitrobenzene. Which of the following correlates to these partial rate factors?

1. 1. A      B) B       C) C        D) D

 

 

 

 

35. Starting with toluene, which of the following is the best synthesis of meta- bromobenzoic acid?

1. 1. A      B) B       C) C        D) D

 

36. Predict which position of the naphthalene compound below is the most reactive with electrophiles in electrophilic aromatic substitution?

1. 1. A      B) B       C) C        D) D

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

37. Starting with toluene, which of the following is the best method to make the ether shown below? (Assume you can separate ortho and para isomers.)

1. 1. A      B) B       C) C        D) D

 

38. Identify the major product(s) of the reaction sequence shown below.

1. 1. ortho and para-chloroacetophenone        C)         ortho and para-chlorobenzaldehyde
   2. meta-chloroacetophenone                            D)        meta-chlorobenzaldehyde

 

 

 

 

 

 

 

 

 

39. Which of the following is not a valid resonance form of the intermediate species in the reaction shown below?

1. 1. A      B) B       C) C        D) D

 

40. How many mononitration products are possible in the nitration of the compound shown below?

1. 1. only 1       B) 2       C) 3       D) 4

 

 

 

 

 

41. What is the product of the following reaction?

 

 

 

1. 1. A      B) B       C) C        D) D

 

42. What is the product of the following reaction?

1. 1. benzene     B) ortho-chloroaniline         C) meta-chloroaniline         D) aniline

 

 

 

 

 

 

 

 

43. Which one of the following has the weakest carbon-chlorine bond?

1. 1. I      B) II        C) III        D) IV

 

44. Which compound in each of the following pairs is the most reactive to the conditions indicated?

1. 1. I and III        B) I and IV         C) II and III         D) II and IV

 

45. Which of the following reacts at the fastest rate with potassium methoxide (KOCH₃) in methanol?
    1. fluorobenzene                                                     C)         2,4-dinitrofluorobenzene
    2. 4-nitrofluorobenzene                                       D)        2,4,6-trinitrofluorobenzene

 

46. Which of the following reacts at the fastest rate with potassium methoxide (KOCH₃) in methanol?
    1. fluorobenzene                                                     C)         p-fluorotoluene
    2. p-nitrofluorobenzene                                       D)        p-bromofluorobenzene

 

 

 

47. Which of the following is the kinetic rate equation for the addition-elimination mechanism of nucleophilic aromatic substitution?
    1. rate = k[aryl halide]                                            C)         rate = k[aryl halide][nucleophile]
    2. rate = k[nucleophile]                                         D)        rate = k[aryl halide][nucleophile]²

 

48. Which of the following is not a resonance form of the intermediate in the nucleophilic addition of hydroxide ion to para-fluoronitrobenzene?

1. 1. I      B) II        C) III        D) IV

 

49. Which chlorine is most susceptible to nucleophilic substitution with NaOCH₃ in methanol?

1. 1. #1                                                                              C)         #1 and #2 are equally susceptible.
   2. #2                                                                              D)        No substitution is possible.

 

50. What is the product of the following reaction?

1. 1. N,N-dimethylaniline                                          C)         phenyllithium (C₆H₅Li)
   2. para-chloro-N,N-dimethylaniline                D)        meta-chloro-N,N-dimethylaniline

 

 

 

51. Which one of the reagents readily reacts with bromobenzene without heating?
    1. NaOCH₂CH₃          B) NaCN/DMSO           C) NaNH₂/NH₃          D) (CH₃)₂NH

 

52. Which of the following would work best for the synthesis of the ether shown below?

1. 1. A      B) B       C) C        D) D

 

 

 

 

 

 

 

 

 

 

 

 

 

 

53. Carbon-14 labelled chlorobenzene is reacted with sodium amide in ammonia as shown below. Which of the following depicts the carbon-14 labeled in the product(s)?

1. 1. A      B) B       C) C        D) D

 

 

 

 

 

 

 

 

 

 

 

 

 

54. Identify the product(s) of the following reaction.

1. 1. only ortho-methylaniline
   2. ortho-methylaniline and meta-methyaniline
   3. meta-methylaniline and para-methyaniline
   4. ortho-methylaniline and para-methyaniline

 

55. Which of the following best estimates the percentages of the three isomeric methylanilines from the reaction shown below?

1. 1. A      B) B       C) C        D) D

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

56. Which of the following is a key intermediate in the reaction shown below?

1. 1. I      B) II        C) III        D) IV

 

 

 

 

 

57. Identify the diene required for the synthesis shown below.

1. 1. A      B) B       C) C        D) D

 

58. Assume that the following reaction goes by the elimination-addition mechanism for nucleophilic aromatic substitution. Based on that, how many isomeric naphthylamines are expected in the following reaction?

1. 1. only a single product         B) two       C) three      D) four

 

 

 

 

 

 

 

59. Which of the following best estimates the percentages of the three isomeric deuterated anilines from the reaction shown below?

1. 1. A      B) B       C) C        D) D

 

60. Which of the following is(are) true concerning the intermediate benzyne?

1. Benzyne is aromatic.
2. All the hydrogens of benzyne are equivalent and indistinguishable.
3. The benzyne molecule has strain energy.

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

 

 

 

 

 

 

 

61. Which of the following is(are) true concerning the intermediate in the addition- elimination mechanism of the reaction below?

1. The intermediate is aromatic.
2. The intermediate is a resonance stabilized anion.
3. Electron withdrawing groups on the benzene ring stabilize the intermediate.

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

 

62. Which one of the following has the fastest rate of reaction with sodium ethoxide, NaOCH₂CH₃, at 25^°C?
    1. para-fluoronitrobenzene                                C)         para-bromonitrobenzene
    2. para-chloronitrobenzene                               D)        para-iodonitrobenzene

 

63. Arrange the following compounds in order of increasing reactivity with sodium methoxide, NaOCH₃?

1. 1. I < II < III          B) I < III < II           C) II < I < III           D) III < II < I

 

 

 

 

 

 

 

64. Which position on the potential energy diagram corresponds to the species shown for the reaction of para-fluoro (trifluoromethyl) benzene with sodium methoxide?

 

 

 

1. 1. A      B) B       C) C        D) D

 

 

 

 

 

 

 

 

 

65. Which of the following is the product from the reaction sequence shown below?

1. 1. A      B) B       C) C        D) D

 

 

 

 

66. Identify the likely mechanism in the reaction shown below.

1. 1. S_N2                                                                            C)         electrophilic addition-elimination
   2. S_N1                                                                            D)        nucleophilic addition-elimination

 

67. Which of the following is NOT a common electrophile in electrophilic aromatic substitution reactions?

A) ⁺SO₃H         B) ⁺Br        C) ⁺CN         D) ⁺NO₂

 

 

68. Ranked in order of decreasing reactivity in electrophilic aromatic substitution reactions, the order would be (more reactive > less reactive)
    1. chlorobenzene > toluene > acetophenone
    2. chlorobenzene > acetophenone > toluene
    3. toluene > chlorobenzene > acetophenone
    4. toluene > acetophenone > chlorobenzene

 

69. Which statement is true in electrophilic aromatic substitution?
    1. no meta directors have a nitrogen atom directly attached to the ring
    2. all ortho/para directors make the ring more reactive than benzene
    3. no meta directors have non-bonding electrons on the atom directly attached to the ring
    4. all ortho/para directors have non-bonding electrons on the atom directly attached to the ring

 

 

 

 

 

 

 

70. What would be the most efficient way to make meta-nitrobromobenzene?

1. 1. bromobenzene + HNO₃/H₂SO₄
   2. nitrobenzene + Br₂/FeBr₃
   3. either of these approaches would work
   4. neither of these approaches would work

 

71. Which one of the common electrophilic aromatic substitution reactions puts an electron donating group on a benzene ring?
    1. Br₂, FeBr₃        B) SO₃ + H₂SO₄           C) RCOCl + AlCl₃              D) RCl + AlCl₃

 

72. What major product do you expect?

1. 1. A      B) B       C) C        D) D

 

 

 

 

 

 

 

73. How many TOTAL resonance structures can be drawn for this intermediate? (incl. this one)

1. 1. one     B) two       C) three      D) four

 

74. Of the choices given, where would an aromatic substitution occur on this molecule?

1. 1. A      B) B       C) C        D) D

 

75. What major product(s) would you expect from this reaction?

1. 1. A      B) B       C) C        D) D

 

 

 

76. How would you best accomplish this?

1. 1. 1. SO₃, H₂SO₄, heat; 2. K₂Cr₂O₇, H₂SO₄
   2. 1. K₂Cr₂O₇, H₂SO₄, heat; 2. SO₃, H₂SO₄
   3. either of these would work.
   4. neither of these would work.