1NAME _______________________ ID # _______________________ ORGANIC CHEMISTRY I (2301) 9:30 – 11:30 am, August 4, 2011 Final Exam Form A There will be two ways that you can pick up your graded final exam: - You can pick up your graded exam from Andy at office hours that he will hold on Friday, August 5th (9:30-10:30 am) at Coffman Union Starbucks. - Alternately, you will be able to pick up your graded exam from Chemistry department staff in 115 Smith beginning Friday, August 5th at noon. Exams that are not picked up within two weeks will be disposed of. A periodic table, a chart of reaction conditions, and tables of typical NMR chemical shifts, coupling constants, IR stretching frequencies, and isotopic abundances are attached to the back of this exam as aides. Otherwise, you are not permitted to use any other materials (including notes, books, or electronic devices of any kind). Right now, write your name at the top of this page, and fill in the bubbles on the multiple-choice answer sheet for your name and your 7-digit student ID number. When the exam begins, also write your name at the top of page 5. You may use pen or pencil. However, re-grades will be considered only for exams completed in pen. Please write your answers in the bubble sheet for the multiple choice portion of the exam, and in the boxes/spaces provided for the written portion. If your answer is not in the appropriate space in the written portion (say, for example, it’s on the back of the page), draw us an arrow and/or note telling us where to look.2Multiple-Choice Problems Please answer these problems on the bubble sheet. (2 pts each) For ethylformamidinium cation, drawn at right: - For each atom marked “hybridization”, indicate whether the atom is hybridized(a) sp, (b) sp2, (c) sp3, or (d) none of these. - For each bond angle marked “angle”, indicate whether the angle is closest to (a) 109.5°, (b) 120°, or (c) 180°. 7. (3 pts) Of the resonance structures on the right, which contributes least to the overall electronics in ethylformamidinium cation? 8. (3 pts) Which of the structures below represents the most stable 3-dimensional conformation of ethylformamidinium cation? HN CHNHCHCHHHHHhybridization #3 hybridization#2 hybridization #1 hybridization#4 angle #5 angle #6 HN CHNHCHCHHHHHa. HN CHNHCHCHHHHHHN CHNHCHCHHHHHc. b. NCNHH CCHHHH HHa. NCNHH CCHHHH HHb. NCNHHH CCHHHH Hc. d. NCNHHHCCHHHH H3(2 pts each) Does the proton-transfer equilibrium for each acid-base pair shown below favor products, or starting materials? (Is the acid strong enough to protonate the base?) 9. 10. 11. (2 pts each) For each of the molecules drawn on the right: - For each atom marked “chirality”, indicate whether the atom would be labeled as (a) an (R)-chiral center, (b) an (S)-chiral center, or (c) not a chiral center, according to the Cahn-Ingold-Prelog classification system. - Indicate whether the molecule would be chiral or achiral. 17. (2 pts) Are the methyl-group hydrogens in the structure on the right a. enantiotopic, b. diastereotopic, or c. neither of the above? Does the equilibrium favor: NH2H3C HOHOCH3H3CHBrBrHchirality#15 chirality#12 chirality#13 16. Is this molecule a. chiral, or b. achiral? 14. Is this molecule a. chiral, or b. achiral? NHH HOHH H+ a. products, or b. starting materials? conjugate acid-base products CH3OOF3COOH+ conjugate acid-base products a. products, or b. starting materials? H HH H H HH HHHHHH+ conjugate acid-base products a. products, or b. starting materials?4(4 pts each) Each of the reactions below is drawn with two possible reaction conditions. If only one of the two reaction conditions would generate the given molecule as the major product, answer with the corresponding letter. If both sets of conditions would accomplish the reaction, answer (c) “BOTH”. If neither set of reaction conditions would succeed, answer (d) “NEITHER”. 18. 19. 20. 21. BOTH would work NEITHER would work HBr HBr, benzoyl peroxide Bra. b. c. d. BOTH would work NEITHER would work H2SO4, H2O 1. Hg(OAc)2, H2O 2. NaBH4 OHa. b. c. d. BOTH would work NEITHER would work mCPBA, H2O KMnO4 (cold, dilute in H2O/OH-) H3CHCH3HH3CCH3OHOHa. b. c. d. BOTH would work NEITHER would work Na, NH3 Pt, H2 H3CC C CH3a. b. c. d.522. (4 pts each) Each of the reactions below is drawn with two possible products, marked (a) and (b). If one of the two products predominates, answer with the letter corresponding to the correct product. If the two products are produced equally, answer (c) BOTH. If neither product would result from the reaction, answer (d) NEITHER. 23. 24. 25. Multiple-choice problems 26-31 are found later in the exam, on pages 6-7. BOTH would work NEITHER would work 1. CH3Li (1 equiv) 2. H3O+ 1. CH3MgBr (1 equiv) 2. H3O+ H3COHOH3COHHO CH3a. b. c. d. + FOClH3C HOHNa2Cr2O7 H2SO4 a. b. HOOHO BOTH (equally) c. NEITHER d. Br2 h BrBra. b. BOTH (equally) c. NEITHER d. pyridine HOHCH3H3COOCH3HF HH3COOHH3CF Ha. b. BOTH (equally) c. NEITHER d.6NAME _______________________ Scoring: 32. _________ / 29 35. _________ / 14 33. _________ / 25 36. _________ / 26 34. _________ / 32 Total Score: _________ / 126 32. (29 pts) For the reactions shown below, draw a mechanism that explains how the product is generated from the starting material. In your answer, make sure that you: - Draw each step of the mechanism separately; - Use “electron pushing” to show where the electrons in each step go; - Use only the molecules that you are given; do not invoke reactants or solvents that aren’t in the problem. Mechanism: HBr CH3OHCH3Br7 33. (25 pts) Draw the missing reactant or product in the empty boxes. For products, give the predominant, most favored product. Illustrate stereochemistry in your answer where appropriate. For reactions that yield multiple enantiomers, draw only one enantiomer in the box, and include the note “+ enantiomer”. HOOHOCl SOOCH3NMechanism: OH3CHH3CC C Na8 Br2 H2O CH3NaBH4 CH3OH OOOCH3ONaH3COCH3BrCH3HClH3COOH934. (32 pts) 1,5-dibromo-2,2-dimethylpentane can react with one equivalent of OH- by SN2 substitution at either end on the molecule, to give products in which one of the bromines has been