CHEM 242 REACTIONS OF ARENES: CHAP 12 ASSIGN ELECTROPHILIC AROMATIC SUBSTITUTION 1. Consider carefully the mechanism of the following electrophilic aromatic substitution reaction and indicate which of the following is NOT formed as a product or intermediate during the course of the reaction. 2. The ring in an aromatic compound typically undergoes what type of reaction? A. addition B. substitution C. elimination D. oxidation E. reduction 3. What is the major product of the following reaction? 4. Rank the following functional groups in order of decreasing reactivity in electrophilic aromatic substitution (i.e., decreasing electron-donating ability to an aromatic ring). Rank them as most reactive > least reactive. A. B > D > A > E > C B. C > A > E > B > D C. D > A > E > C > B D. E > C > A > B > D E. D > B > E > A > C 1
5. What combination of reagents would be required to produce 3-bromoethylbenzene from benzene? A. B. C. D. E. None of these would work. 6. Which of the following statements most accurately describes why the halogens are deactivating yet are ortho /para directors in terms of electrophilic aromatic substitution reactions on halobenzenes? A. Halogens are electron withdrawing in an inductive sense. B. Halogens are electron donating in a resonance sense. C. Halogens are electron donating in an inductive sense. D. Halogens are electron withdrawing in a resonance sense. E. Two of these responses are correct. Which ones? 7. Why do electron withdrawing groups on a benzene ring direct substitution to mostly the meta positions? A. The meta positions are always more reactive. B. The intermediate from meta attack has 3 reasonably stable resonance structures while ortho or para attack yields one especially unstable resonance structure. C. The intermediate from meta attack has one especially stable and two reasonably stable resonance structures, while ortho/para attack yields three reasonably stable resonance structures. D. The intermediate from meta attack has two especially stable and one reasonably stable resonance structures, while ortho/para attack yields three reasonably stable resonance structures. E. The intermediate from meta attack has two especially stable and one reasonably stable resonance structures, while ortho/para attack yields two reasonably stable and one especially unstable resonance structures. 8. What would be the major product(s) expected from the following reaction? Both B. and D. 2
9. Consider carefully the mechanism of the reaction shown below. Which of the following intermediates or products will not be formed during the course of the reaction? 10. What would be the major product of the following reaction? More than one of these. Which ones? 11. What set of reaction conditions is necessary to effect the following transformation? A. B. C. D. E. Two of these are correct. Which ones? 3
12. Predict the major product of the following reaction. Two of these are correct. Which ones? 13. Predict the major product of the following reaction. A. B. C. D. Two of these are correct. Which ones? E. This reaction will not proceed as written. 14. Predict which position of the naphthalene compound below is the most reactive with electrophiles in electrophilic aromatic substitution? 15. Which of the following combinations of reagents is appropriate to brominate the ring of benzene as shown below? A. Br 2, light B. Br 2, H 2O C. Br 2, NaOH D. Br 2, H 2SO 4 E. Br 2, FeBr 3 4
16. 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.) 17. The electrophile in the nitration reaction of benzene is: A. HNO 3 B. HNO 3/H 2SO 4 C. NO 2 d. NO 2 + 18. The electrophile in the sulfonation reaction of benzene is most probably: A. SO 3 + B. SO 3 C. H 2SO 4 D. H 3O + 19. Which of the following can serve as a catalyst in Friedel-Crafts reactions? A. FeCl 3 B. AlCl 3 C. SnCl 4 D. all of the above 20. The function of FeBr 3 in Friedel-Crafts alkylations is A. to form a complex with benzene, thus increasing its reactivity. B. to complex with the carbocation, thus stabilizing it. C. to abstract the halide from the alkyl halide, thus forming a carbocation. D. to abstract the proton from the -complex and regenerate the aromatic ring. 21. The reaction of isobutyl bromide with benzene in the presence of AlCl 3, yields as the major product. A. 2-phenylbutane B. n-butylbromide C. isobutylbenzene D. t-butylbenzene 22. Which of the following reactions can be used to alkylate benzene? A. (CH 3) 2C=CH 2/H + B. (CH 3) 3COH/H + C. (CH 3) 2CH 2Cl/AlCl 3 D. only (a) and (b) E. all of the above 5
23. The reagent(s) in the synthesis of -bromomethylbenzene from toluene is/are A. Br 2/UV B. HBr C. Br 2/Fe D. Br 2/CCl 4 24. The major mononitration product(s) of the following compounds is(are) A. o-/p- m- o-/p- m- m- B. m- o-/p- o-/p- m- m- C. o-/p- o-/p- m- m- m- D. m- m- o-/p- o-/p- o-/p- 25. The common name for is A. aniline B. toluene C. anisole D. acetophenone E. phenol 26. The presence of chlorine on the benzene ring the ring and directs the electrophile. A. activates; o-/p- B. deactivates; o-/p- C. activates; m- D. deactivates; m- 27. Which of the following is not a meta-directing substituent in electrophilic aromatic substitutions? A. -N(CH3)3 + B. -NO2 C. -C N D. -NHCOCH3 28. The most reactive and the least reactive compound towards nitration are benzene acetophenone toluene chloromethyl benzene chlorobenzene phenol I II III IV V VI A. VI/II B. I/II C. III/V D. VI/IV 29. The sequence of reactions below yields A B C D 30. Which of the following is an incorrect contributing structure in the nitration of anisole? A B C D 6
NAME DATE ANSWER SHEET CHEM 242 CHAP 12 ASSIGN 1. 11. 21. 31. 2. 12. 22. 32. 3. 13. 23. 33. 4. 14. 24. 34. 5. 15. 25. 35. 6. 16. 26. 36. 7. 17. 27. 37. 8. 18. 28. 38. 9. 19. 29. 39. 10. 20. 30. 40. SP 2014 7