Practice Multiple-Choice Questions for Ending Chem 21 and/or Starting Chem 22

Transcription

1 Practice Multiple-Choice Questions for Ending Chem 21 and/or Starting Chem 22 Includes information from chapters 5-10 of the third edition of Klein s Organic Chemistry text. 1. Which of the following compounds is most acidic? a) I b) II c) III d) IV e) All of these 2. Which of the following compounds is most basic? a) I b) II c) III d) IV e) All of these 3. What is the correct order of hybridization state for the numbered carbon atoms in the following compound? = sp 3, II = sp 2, III = sp B) I = sp 2, II = sp, III = sp 2 C) I = sp, II = sp 2, III = sp 3 D) I = sp, II = sp 2, III = sp E) I = sp 2, II = sp 3, III = sp 2 4. Which of the following is/are correct resonance structure(s) for compound A? a) I & II b) II & III

2 c) III & IV d) I, II & III e) I & IV 5. How many s sp 2 sigma bonds are in the following compound? A) 2 B) 3 C) 4 D) 5 E) 0 6. Which of the following choices is a diastereomer of the first structure shown? 7. Assign the absolute configuration of the chirality center as R or S. 8. Which of the following is a correct Fischer projection of the following compound? 9. Predict the sign of Δ G for an endothermic reaction with a decrease in entropy. A. positive B. negative C. no change D. cannot predict without additional information 10. Which of the following energy diagrams shows a concerted endothermic reaction? 11. Which of the following cannot be a nucleophile?

3 12. Of following reactions, which one(s) would you expect to have a negative Δ S? 13. What is wrong with the following mechanism? A. There is no leaving group, so there should be no arrows. B. The arrow should be removing a proton from the H 2 O group. C. An arrow is also needed to indicate the loss of the leaving group. D. The arrow is backwards. 14. Identify the sequence of curved arrows (electron movement) in the steps of the following reaction. A. Proton transfer, proton transfer, nucleophilic attack B. Proton transfer, loss of leaving group, nucleophilic attack, proton transfer C. Nucleophilic attack, proton transfer, loss of leaving group D. Proton transfer, loss of leaving group, proton transfer, nucleophilic attack 15. What is the IUPAC name for the following compound? A) 2-Bromo-4-pentylhexane B) (2S,4S)-2-Bromo-4,5-diethylheptane C) 3,4-Diethyl-6-bromoheptane D) 2-Bromo-4-methylhexane E) (2R,4R)-2-Bromo-4,5-diethylheptane 16. Consider the following S N 2 reaction,

4 Assuming no other changes, what is the effect on the rate, if the concentration of NaN 3 is tripled? A) No effect B) It would double the rate C) It would triple the rate D) It would increase four times E) It would increase the rate six times 17. Predict the product for the following reaction. E) None of these 18. Rank the following compounds from most to least reactive in an S N 2 reaction. >IV>II>III >I>IV>III >IV>I>II >I>II>III E) IV>III>I>II 19. Draw the transition state for the following reaction. 20. Which of the following compounds will undergo the fastest S N 1 reaction?

5 E) Both I & IV 21. Which of the following is true about the stereochemistry of S N 1 reaction? A) retention of configuration at the electrophilic center B) inversion of configuration at the electrophilic center C) 50:50 mixture of retention and inversion of configuration at the electrophilic center D) slightly more inversion than retention at the electrophilic center E) slightly more retention than inversion at the electrophilic center 22. Rank the following from most to least stable. A) C>B>A B) A>B>C C) B>C>A D) None of the above 23. Which of the following is the major product of the following elimination? 24. Which of the following alkyl halides would be more reactive in an E2 elimination? 25. Which of the following is the energy diagram for the following reaction? 26. Which of the following is the structure of the rearranged carbocation intermediate in the following dehydration? 27. In the addition reaction of HI to 2-methyl-2-butene, the Markovnikov addition mechanism involves:

6 A) Attack of 2-methyl-2-butene initiated by an iodide ion. B) Attack of 2-methyl-2-butene initiated by an iodine atom. C) Isomerization of 2-iodo-2-methylbutene. D) Formation of a carbocation at carbon two (C-2). E) Formation of carbocation at carbon three (C-3). 28. The expected major product of the following reaction is: A) B) C) D) E) 29. The reaction shown below would be expected to produce as major products which of the following compounds? A) B) C) D) E) 30. What is the expected major product for the following reaction?

7 31. What is the expected major product for the following reaction? A) B) C) D) 32. What is the expected major product for the following reaction sequence? 33. Identify the major organic product generated from the reaction shown. 34. What is the expected major product for the following reaction?

8 35. Which of the statements is most correct regarding the products expected from the halogenation reaction shown below? A) Equal amounts of I and II are produced. B) Equal amounts of III and IV are produced. C) Equal amounts of I and IV are produced. D) Equal amounts of II and III are produced. E) Equal amounts of I and III are produced. 36. For the reaction sequence below, identify the expected major product(s). D) I and III E) II and III 37. Treatment of 1,2-dimethylcyclopentene with OsO 4, followed by aqueous NaHSO 3, produces which of the following: 38. Provide the expected major organic product of the reaction sequence shown.

9 and II B) IV and V C) I only D) II only E) III only 39. Which reaction is not stereospecific? 40. For the following reaction sequence, identify the expected major organic products and provide their stereochemical relationship. and II; enantiomers I and IV; enantiomers C) I and II; diastereomers D) II and III; diastereomers E) III; diastereomers 41. What is the IUPAC name for the molecule shown below? A) (E) -5-methyl-5-hepten-1-yne B) (Z) -5-methyl-5-hepten-1-yne C) (E) -3-methyl-2-hepten-6-yne D) (Z) -3-methyl-2-hepten-6-yne

10 E) (E) -2-butynyl-2-butene 42. For the reaction shown, select the expected major organic product. 43. Select the reagent(s) expected to accomplish the transformation shown below. A) H 2, Ni B) H 2, Ni 2 B C) H 2, Lindlar s catalyst D) A and B E) B and C 44. For the reaction shown, select the expected major organic product. 45. For the reaction shown, which of the compounds listed would be the expected major, and final, organic product?

11 46. For the reaction shown, which of the compounds below would be the expected enol intermediate? 47. Select the expected major product(s) from the treatment of 1-pentyne with 1 equivalent of Br 2. A) 1,1-dibromo-1-pentene B) ( E )-1,2-dibromo-1-pentene C) ( Z )-1-bromo-1-pentene D) A and B E) B and C 48. Which alkyne would produce the products below upon ozonolysis? A) HC CC CCH 2 C CH B) HC CCH 2 CH 2 CH 2 C CH C) CH 3 C CCH 2 C CCH 3 D) HC CCH 2 CH 2 C CCH 3 E) CH 3 C CC CC CH 49. What is the final major product expected for the following reaction sequence?

12 50. Which of the compounds listed would be one of the final major products for the following reaction sequence? 51. Which sequence of reactions is expected to produce the product below as the final, and major, organic product? A) 1) Na, NH 3 ( l ); 2) OsO 4 ; 3) NaHSO 3 /H 2 O B) 1) H 2, Lindlar s cat.; 2) MCPBA; 3) H 3 O + C) 1) H 2, Ni 2 B (P-2); 2) KMnO 4, NaOH (cold) D) Both A and B E) Both A and C 52. Predict the major product(s) of the following reaction. B) I and II C) I, II, and III D) I, II, III E) IV 53. Which of the following are major products of the reaction shown?

13 B) I, II C) I, IV D) I, III E) I, II, III, IV 54. A compound with the formula C 8 H 16 reacts with bromine to give a pair of enantiomers. Reaction of the same compound with hydrogen in the presence of a platinum catalyst gives 3,4-dimethylhexane. What is the structure of C 8 H 16? a. b. c. d. e. None of these. 55. Which is expected to react the fastest in a solvolysis reaction with methanol? a. b. c. d. e. The compounds in choices a and c react at the same rate and are the fastest Chapter 15, 16 second edition of David Klein IR, MS and NMR 1. Which of the following bonds has the weakest absorption? A. C=C B. O H C. C=O D. sp 3 C H E. A & D 2. Which of the following compounds will show a broad absorption around 3300 cm -1 and a sharp absorption at 1650 cm -1? A. I B. II C. III D. IV E. V

14 3. Which of the following compounds will show absorptions at 1640 cm -1, 2950 cm -1 and 3050 cm-1 on the IR spectrum? A. I B. II C. III D. IV E. V 4. Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology A. I B. II C. III D. IV E. V 5. How many signals would you expect in the 1 H NMR spectrum of the following compound? 6. a) 2 b) 3 c) 4 d) 5 e) 6

15 7. How many signals would you expect to find in the 13 C NMR spectrum of the following compound? A. 2 B. 3 C. 4 D. 5 E. none of these 8. Which of the following carbon atoms will display the signal most downfield in the 13 C NMR spectrum? A. I B. II C. III D. IV E. none of these 9. Which of the following compounds is consistent with the proton NMR spectrum below?

16 a. b. c. d. e. none