exam_answers_Midterm_2%20KEY

exam_answers_Midterm_2%20KEY - Chemistry 2388 Midterm 2...

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Unformatted text preview: Chemistry 2388 Midterm 2 February 25th 2009 instructions: You will have 75 minutes to complete as many problems as possible. Where provided, write your answers in the boxes. Your answers will not be graded unless they are in the proper box. Points will be deducted for incorrect structures or answers that are drawn in the box but you cannot receive a score of less than zero for any particular problem. Write your name on the top right corner of every page. Name Circle Your TA: Brock Fitch Maki Quiz section 1. For a lH-NMR, assign the multiplicity of the circled proton in each molecule shown below. (9 points) \ P o O ‘\ \\ Br Br H \\H\| H H | ~‘ \ ‘ O H \\H\‘\ O \ H I \ H :H‘- 2. The molecule shown below contains four sets of non-equivalent protons (a-d). Assign the signals observed in the 1H-NMR to the appropriate protons in the molecule. (8 points) H Hc ‘3 Hd chm 0 d Ha Ha Hb Hb CI triplet, 3H E doublet, dOUblet. quartet, 2H 2H 2 l .U 3. Suggest three possible combinations of Grignard Reagent (RMgBr) and Carbonyl (aldehyde, ketone, ester or carboxylic acid) that could be used to generate the alcohol shown. Assume a dilute aqueous acid workup after each reaction. (12 points) Combination 1 carbonyl 1 of 0H Kz© 22> carbonyl 2 Me Combination 2 Combination 3 Grignard 3 4. Fill in the box with the appropriate starting material or product. Draw only the major organic product. (20 points) i r \ H30 0’0 @w g1eguiv) 0 (1 equiv) o 'o—gr-CI +/ 9 OH 0 Ch) (5 (FCC) (no water) O OH I) O/k 1. LiA|D4 (1 equiv) O/k 2. H20 (4 equiv) 5. Starting with ketone A, develop an efficient synthesis of product B. You must use A in the first step but you may use any additional reagents that are necessary after the first step. Show all reagents and the product that is formed after each step. (12 points) 6. Provide a detailed electron-pushing mechanism for the reaction shown below. Be sure to include any intermediates and relevant resonance structures. (12 points) 7. The 1H-NMR and the 13C-NMR of compound X [CIOHI 1C102] are shown below. Draw the structure of X in the box. An IR spectrum reveals that compound X has a sharp absOrption peak at 1725 cm]. (10 points) Hl-NMR doublet, doublet, ggublet, 2H 2H triplet, \ / 2H / triplet, \ 1H C13-NMR 2&0 ' 260 ' 1éo ' 1é0 1—1210 ' 1§oPPM160 ' 8'0 [—60 ' 71'0—' 2'0 8. Fill in the box with the appropriate starting material or product. For products, draw only the major organic product (unless otherwise specified). Please specify the correct stereochemistry where appropriate. Note: H3OJr = dilute aqueous acid work—up. (20 points) cm H 1- (1 equiv) O 3. FCC (no water) HI 0 heat bit 1. H SO t “War ; 4 “’a) . Ho 0 2_ MgBr (2 equw) HO 3. H30+ O H )ko \ d 1)_ H30 0 \ or. (1 equiv) O:>_PH 2). H2804 O (catalytic) 9. Propose an efficient synthesis of product Z using methanol and 2-bromopropane as your only sources of carbon. You may use any additional reagents that are necessary. Show all reagents and the product that is formed after each step. (12 points) 10. The 1H—NMR and the 13C-NMR of compound T [C14H200] are shown below. Dihydroxylation of compound T with 0504 followed by exposure to H104 generates two products U and V. The 1H-NMR and 13C-NMR of compound U [C6H1202] are shown below. The 1H-NMR and 13C-NMR of compound V [CgHgO] are also shown. IR spectra of compounds U and V both show sharp absorption peaks at 1730 cm'l. Draw the structure of T in the box. (10 points) 0304 (cat), NaOH 1. _ 6 HO O C6H1202 + C8H80 2. H|O4 ProductU ProductV H1-NMR (compound T) gigglet, \ singlet, 3H d bl t, doublet, 1%” e l 2“ gfiublet, quartet, \ / dfiublet, 2H / l l I | l E 4 93 C13-NMR (compound T) H1-NMR (compound U) singlet, 6H \ singlet, 1 H PPM C13-NMR (compound U) 250 250'1é0 1éo ' 1310 130 150 80 60 4o 20 0 PPM H1-NMR (compound V) ginglet, H \ C13-NMR (compound V) ...
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This note was uploaded on 03/03/2010 for the course CHEM 237 taught by Professor Andersen during the Spring '08 term at University of Washington.

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exam_answers_Midterm_2%20KEY - Chemistry 2388 Midterm 2...

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