Departmental Final Examination. Organic Chemistry I Caffein

Transcription

1 Departmental Final Examination rganic Chemistry I 2423 Caffein

2 Name CEMISTRY 2423 FINAL EXAM FALL, 2005 DIRECTINS: A periodic table is attached at the end of this exam. Please answer all questions as completely and clearly as possible, showing all your work. Part I. Nomenclature and Structures (2 pts each) 1. Give the correct IUPAC name for the following structures (2 pts each): - C 2 - C - C 2 -C - C 2 (a) (b) (c) (a) (b) (c) 2. Draw the structure that corresponds to the following name (2 pts each): (a) (R)- 3-bromohexane (b) Trans-3 chloro 4-methyl-cyclpentene (c) 4,5-diethyl-2- heptyne Part II. Multiple choice. Circle the one best answer. (2 pts each) 3. For the molecule, shown, what are the hybridization of the oxygen atom and the approximate C-C- bond angle, respectively? C 2 CC 2 C C A. sp 3, B. sp 3, 120 C. sp 2, 120 D. sp 2, 180 2

3 4. What functional group is present in the molecule shown? A. alcohol B. ester C. amide D. ether 5. The most stable conformation of cis-2-tert-butylcyclohexanol is a chair with the group: A. equatorial and tert-butyl group equatorial B. axial and the tert -butyl group axial C. equatorial and the tert -butyl group axial D.axial and the tert -butyl group equatorial 6. What are the configurations of carbons 1 and 2 in the compound, 2-methylcyclohexanol, shown below? C A. 1R, 2S B. 1S, 2R C. 1R, 2R D. 1S, 2S 7. What is the conjugate Acid for -? (A) - (B) C 2 - (C) (D) Which of the following alkyl halides gives only one alkene as the product in the elimination reaction? C 2 C C 2 C A B C D 9. Which one of the following groups has the highest priority? - C - -CC 2 -CC 2 (A) (B) (C) (D) 3

4 10. Which of the following is the best synthesis of cyclohexene from cyclohexane? A. K, alcohol B. 2 S 4 C. 2, light; then K, alcohol D. 2, light; then 2 S 4, heat 11. Which of the following is the most stable conformation of 1,3-dimethylcyclohexane? 3 C A. B. C. D. 12. What is the major organic product of the following reaction? C C + Li liquid N 3 3 C 3 C 3 CC C - Na + 3 CC CC 2 - Na + C C C C A B C D 13. Which of the statements about the molecule shown is TRUE? _ N _ A. The geometry of N is trigonal planar. B. The formal charge on is -1. C. The hybridization of N is sp 2. D. The formal charge on the N is Which of the following free radicals is the MST stable?. A. B. C. D. 15. What is the IUPAC name for the molecule shown? 4

5 Cl A. cis-1,2-diethyl-1-chloro-2-methylene B. (E)-3-chloro-4-methyl-3-hexene C. (E)-1-chloro-1-ethyl-1-pentene D. (Z)-1-chloro-1-ethyl-1-pentene 16. What is the degree of unsaturation in DDT, C 14 9 Cl 5? A. 5 B. 6 C. 7 D What is the direction of the dipole moment in the molecule shown? C Cl A. B. C. D. 18. Which of the following statements is true about the reaction shown? C 2 C 2 Cl C - A. The product will have R configuration. B. A meso compound is produced. C. The product will have S configuration. D. The reaction will happen with recemization. 19. Which of the following compounds has the IGEST boiling point? A B C D 20. Which of the step(s) of a free radical chain reaction is deactivation step with an activation energy equal to zero? A. initiation only B. propagation only C. termination only D. both termination and initiation 21. Molecule A is the enantiomer of molecule B. Molecule B is a stereoisomer of the molecule C but NT its 5

6 mirror image. What is the relationship between A and C? A. Same compound. C. Diastereomers B. Enantiomers. D. Constitutional isomers 22. Which of the following statements about the relative stabilities of the structures shown is TRUE? A II is more stable than I B. II represents a gauch conformation. C. I is more stable that II D. Two of these are true 23. The following process demonstrates: (A) resonance (B) conjugation (C) racemization (D) tautomerism 24. Which of the following will give the transformation shown? +? A. Cl 2, 2 B. P 3 followed by 3 + C. g(ac) 2 / 2 S 4, water D. B 3, TF followed by 2 2, In mass spectroscopy, (A) the sample is irradiated with infrared radiation (B) the heat of combustion of the sample is measured (C) the sample is bombarded with a stream of high energy electrons (D) the sample is irradiated with ultraviolet radiation 26. Which of the following fragment shows a peak at m/e = 29 in the mass spectrum. (A) C 2 + (B) C 2 (D) ( ) 2 C + D. all of these Part III. Reactions 6

7 Give the major product(s) of each of the following reactions. Show all relevant stereochemistry. (2 pts each) 27. ( 3 C) 2 CC 2 C 2 S 4 3 heat C C 2 mol C C gs 4, 2 2 S CCl C- ether ( ) 2 C = C 1) B 3, TF 2) 2 2, - 1) 3 2) Zn/ C 2 I 2 / Zn(Cu) 36. KMn

8 Part IV. Synthesis ( 3 points each) Show by a series of reactions how you could prepare the following compounds (major) from the indicated starting compound. Be sure to clearly indicate the reagent used in each step Acetylene - C - C 2 - C 2-8

9 Part V. Mechanisms Write a complete mechanism for the following reactions. Show all intermediate structures, formal charges, and electron flow using the curved arrow convention. (3 pts each) / S 4 heat 9

10 Part VI. Spectra ( 5 points) Use the mass spectrum for a cyclicalkene shown below to answer questions What is the base peak (1 pt)? 43. What is the parent ion peak (1 pt)? 44. What is the structure of the compound (3 pts)? 10

11 RGANIC CEM 2423 FINAL EXAM (FALL 2005) Answers PART I Nomenclature and structures (2 points each) 1. (a) 3-isobutyl-1-methylcyclohexene (b) 3-bromo-4-methyl-1-pentyne (c) 2-ethyl-4-methyl-1-pentene 2. C 2 C 2 Cl C 2 a) b) c) C C - C - C - C 2 - C 2 C 2 PART II Multiple Choice (2 points each) 3. C 4. D 5. D 6. A 7. C 8. B 9. B 10. C 11. A 12. D 13. D 14. B 15. B 16. D 17. C 18. C 19. A 20. C 21. C 22.D 23. D 24. D 25. C 26. A PART III. Reactions (2 points each) 27. C = C C C C 2 PART IV. Synthesis (3 points each) S 4 heat C 2 I 2 Zn(Cu) 2 S S 4 heat 11

12 S S Acetylene - C - C 2 - C 2 - NaN 2 - C C : - Na + C 2 C 2 gs 4 / 2 2 S 4 - C C - C 2 C 2 Part V. Mechanisms (2 pts each) : 2 : S 3 Part VI. Spectra (5 points) 42. base peak, m/e = parent peak, m/e = Structure: 4-Methyl-1-cyclopenten 12