Ochem exam help
Michelle E CHEM 2321-001/002 FINAL (Form A) DEPARTMENTAL Organic Chemistry I05/10/2017 LAST NAME:__________________ FIRST NAME:______________________ ID: 100_ _ _ -_ _ _ _ Carefully read all instructions. Look over the exam; make sure you have 30 multiple-choice questions, 3 write-up questions, and enough space to write your synthesis/mechanism answers. Multiple-choice questions should be answered on a Scantron 882-E form. Please write a large letter A for your test form on the scantron. Select the best answer and darken the space corresponding to that answer completely with pencil. For the remaining questions, answer them in the spaces provided. Please write clearly; you will not get credit for illegible answers. You only have 2.5 hours, so use your time wisely. Any form of academic dishonesty will not be tolerated. This exam has a total of 110 points. ____________________________________________________________________________________________________________ 2 Fill in the answers in your Scantron (1-30) (2.5 points each) 1. Which of the following reactions proceeds by a halonium ion intermediate? a)CH3CH3 + Cl2/h b)CH3CH3 + Br2/h c)CH2=CH2 + Cl2/H2O d)CH2=CH2 + HBr/ether e)(a), (b), and (c) 2. Which of the following pairs of structures are NOT valid resonance structures? 3. What is the relationship between the two compounds? a) Constitutional isomers b) Diastereomers c) Enantiomers d) Identical and meso e) Identical and not meso 4. Select the best name for the following molecule based on the IUPAC nomenclature of organic compounds. A) (6R,2E)-6-chloro-2-methylhept-2-ene B) (2R,5E)-2-chloro-5-methylhept-5-ene C) (6R,2Z)-6-chloro-3-methylhept-2-ene D) (2S,5Z)-2-chloro-6-methylhept-5-ene E) (6S,2Z)-6-chloro-3-methylhept-2-ene 5. Which of the following alkenes is the most stable? 6. Consider the reaction of (Z)-3-hexene with OsO4 in pyridine, followed by treatment with sodium bisulfite in water. Which statement concerning this reaction is correct? a)The product is optically inactive because it contains no chirality centers. b)The product is optically inactive because it is a racemic mixture of enantiomers. c)The product is optically inactive because it is meso. d)The product is optically inactive because it is a racemic mixture of diastereomers. e)The product is optically active. 7. What is the expected major organic product from treatment of 4-methyl-2-pentyne with Lindlar´s catalyst and hydrogen gas? A) (E)-2-methyl-2-pentene B) (E)-4-methyl-2-pentene C) (Z)-2-methyl-2-pentene D)(Z)-4-methyl-2-pentene E)2-methylpentane 8. Which of the following alcohols could be selectively prepared by hydroboration/oxidation of an alkene? a)I only b)III only c)I and III d)I and II e)I, II, and III 9. Which of the compounds below is/are chiral? I.1-butanol II.2-butanol III.2,3-pentanediol IV.3-pentanol a)I, II, and IV b)III only c)II and III d)II, III, and IV e)I, II, III, and IV 10. Which Newman projection represents the conformation shown? a) b) c) d) e) 11. Which of the following is the reaction diagram for an exothermic, E1 reaction? 12. What would be the major product of the reaction below? 13. Identify the product from the sequence depicted below. a)d) b)e) c) 14. Which of the following is the product of the reaction? 15. Consider the reaction below: What is the mechanism for the formation of the major product? a)E1 d)SN1 b)E2 e)SN2 c)free-radical 16. What is the major product of the following reaction? A. B. C. D. E. No reaction 17. What is the relationship of the two structures drawn below? a)constitutional isomers b)enantiomers c)diastereomers d)identical and meso e)identical, but not meso 18. Which of the compounds below should be designated with an (R) configuration? a)I b)II c)I and II d)neither 19. What is the expected stereochemical outcome of the following reaction? (R)-3-bromo-3-methylhexane 3-methyl-3-hexanol a)complete inversion at the center undergoing substitution. b)complete retention at the center undergoing substitution. c)equal amounts of inversion and retention at the center undergoing substitution. d)slightly more inversion than retention at the center undergoing substitution. e)slightly more retention than inversion at the center undergoing substitution. 20. What is the product from the oxymercuration of the indicated alkyne? 21. Which of the bases below would quantitatively deprotonate a terminal alkyne? A)NaOCH2CH3 B)NH3 C)t-BuOK D)NaH E)NaOH 22. How many sp, sp2, and sp3 carbon atoms are present in the estrogen analogue ethinyl estradiol? a) 2 sp, 4 sp2, and 16 sp3 b) 2 sp, 3 sp2, and 16 sp3 c) 2 sp, 5 sp2, and 14 sp3 d) 2 sp, 2 sp2, and 17 sp3 e) 2 sp, 3 sp2, and 15 sp3 23. How many lone pairs of electrons are present in ethinyl estradiol (seen in problem 22)? a) 2 b) 3 c) 4 d) 6 e) 8 24. What is the correct molecular formula for the following structure? A) C7H11ClO B) C7H13ClO C) C8H15ClO D) C9H17ClO E) C10H19ClO 25. Which of the following is not one of the products of the reaction shown? a)d) b)e) c) 26. Identify the major product from the sequence depicted below. 27. What would be the major product of the reaction sequence below? 28. Consider the two stereoisomers of 1-bromo-4-tert-butylcyclohexane. Which statement concerning the E2 elimination reaction involving these two compounds is true? a) The trans stereoisomer undergoes E2 elimination faster than the cis stereoisomer. b) The cis stereoisomer undergoes E2 elimination faster than the trans stereoisomer. c) Both stereoisomers undergo E2 elimination at the same rate. d) Neither compound undergoes E2 elimination. 29. Consider the two compounds below. Which is expected to be more stable? I II a)I b)II c)They are equally stable. 30. Why can’t the following alkene be converted into an alkyne by reaction with bromine followed by excess sodium amide and then with water? A) Because it has a bulky substituent (tertbutyl) B) Because it doesn’t have enough protons for the E2 C) Because it is a terminal alkene D) Because it is an alkane not an alkene E) Because it is not a symmetrical alkene Answer the remaining questions in the space provided 1. (a) Order the following compounds from more acidic to least acidic. (Most acidic 1, least acidic 4) (5 points) (b). In the next box, draw the bond-line structure of trans 1,2-dibromocyclohexane. Then, on the right, draw both chair conformations and depict the equilibrium of the equation with the correct arrow. (5 points) (c)Suggest reagents to be used to complete the following three transformations. Then, name all the compounds. (5 points) 2.Draw the complete mechanism for the reaction below, using curved arrows to represent every bond broken and every bond formed. (5 points) 3. Show step-by-step (include reagents and solvents/conditions where crucial) how you would convert the compound given to the product shown. You can use any stable organic molecules in addition to the starting compound, any inorganic reagents and any solvents. Write clearly and THINK!!! Remember not to use reactions that give multiple products. (Each synthesis is worth 5 points for a total of 15 points.) Pick three syntheses out of the four and answer your picks, in the space below, as required on the narrative of question 3. If you give answers for all four syntheses, only syntheses questions A to C will be graded. Scantron Points:/ 75 Open Questions Points:/ 35 Total Points:/ 110 H O OH OHA B DC ? ? ? ? O OH CH 2 CH 3 H 3 C OHH 3 C CH 2 CH 3 CH 3 OHH 3 CH 2 C OHH 3 CH 2 C CH 3 Cl a. b. c. d. e. O H I . O H O H H 3 C I I . I I I . OH Br OH H H Br HOH H Br HOH H Br HO Br H H OH H Br H C C H 3 C P h C l H H C H 3 N a + - O C H 3 C H 3 O H P h a ) P h b ) P h c ) P h d ) P h e ) H O 1.CH 3 CH 2 MgBr 2.H 2 O OH OH O OH OH excess Br 2 CCl 4 Br Br BrBr Br Br Br Br Br Br Br Br Br Br Br Br a) b) c) d) e) OTs NaBr DMSO Me major product Br t-BuOK Me Ot-Bu Me Me Cl CH 3 H H H 3 C Cl Cl Cl C H CH 2 CH 3 CH 3 Cl C CH=CH 2 C(CH 3 ) 3 CH 3 H I II HgSO 4 , H 2 SO 4 , H 2 O O H O OH OH OH OH a.b.c. d.e. O H H H O H H O Cl NBS h Br Br Br Br Br 1. HBr, ROOR 2. PhS - , DMF SPh PhS SPh SPh OH a. b. c. d. e. B r 2 C H 2 C l 2 2 N a N H 2 N H 3 H 2 S O 4 , H 2 O H g S O 4 O H a ) O H b ) O H O H c ) O H d ) O e ) H 2 C C H CH 2 CH 2 C H H 2 C H 2 C C OH H H 3 C C O H H 3 C N O O H 3 C N O O H 2 C C O H H 2 C C O H a. b. c. d. e. O H F O H H O H H O O O F F Cl Cl IUPAC namereagents reagents reagents Cl Cl IUPAC name IUPAC name IUPAC name dil. HBr Br