Final Exam Fall 2009 - Vannoya Valana 810205001...

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Unformatted text preview: Vannoya Valana 810205001 lllillllllllllllllllll m r” W \lllllllllllllllllllll Final Exam SCORE December 10, 2009 1 7}) Be sure to read each question carefully. Partial credit will be assigned where appropriate. Relax and good luck!! 2 g’ a J 3‘ 1. (20 points) Bromination of bromocyclohexane gives nine isomeric products of formula C6H10Bl'2, including stereoisomers. Draw structures for the products in the boxes. In 3_ the smaller boxes, answer with “yes” or “no” as to whether or not the product contains chiral carbons and “yes” or “no” as to whether or not the product is optically active. 4 Brz ' ""—“— Br fl—h'—"' CaHmBrz (9 isomeric products) 5 L, v , : Chiral carbons? Optically active? I is" Chiral carbons? 1 f , Optically active? '1' _r / Chiral carbons? ‘r f- E . . 9 Optically active. J. Chiral carbons? Optically active? Chiral carbons? Optically active? Chiral carbons? I w Optically active? 2. (18 points) Reaction of (S)-(1-bromoallyl)benzene (shown) with hydroxide ion produces an 0}Ai_cal_lymactive alcohol iii-£116 onlyfiprtfiugt. Heating of (S)-(I-bromoallyl)benzene in water produces a different, optically inactive alcohol as the only product. Predict the structures of the products and write mechanisms of both reactions. In chiral products, use R, S notations to label the chirality center. / H20, heat I‘d last, first 810# 3. (9 points) Treatment of (S)-4-bromohex-1-ene with NBS/hv followed by reduction using H2 over Pd/C yields three isomeric products with molecular formula C6H|2Br2. Draw structures for the products. Label all chiral carbons using R or S notations. Answer with “yes” or “no” to indicate if the product is optically active. H4 i l -. ’I i I' 4‘ ‘ ’1 fl CfiHnBrz (3 isomeric f \ CCl4 products) Optically active? a 4. (20 points) Outline a synthesis for each of the following compounds starting from acetylene and any other reagents or carbon compounds containing five or fewer carbons. "3 (CH3)2CHCH'2‘CH2CH2COOH HCECH 4. (continued) minor product 5. (9 points) Predict the major product (or products) resulting form reaction of (lR,3R)—l- bromo-3-methylcyclohexane with a) iodide ion DMSO; b) water; c) acetlylide ion in THF. In chiral products use R, S notations to label all Cniglitx centers. Hint: DMSO and THF are solvents. — _ ufi / «7 lag, first 810# 6. (12 points) Consider conformational equilibria in alkanes and cycloalkanes. a) Using the template below, write a Newman projection along C2-C3 bond of the most stable 7 conformation of (R)-2-bromorbutane. C 1 of CH; is shown. ’t 1' _ \ . ; “,1 ' ' r _..3L 2 ‘. . : ‘ /r_ t /' 1CH3 b) Using template below (position 1,2, and 3 are labeled) write: 0 the dash-and-wedge projection of meso-isomer of 1,3-dimethylcyclohe ane; 0 most stable conformation of this compound. 1 1' l l , 7-, \"'- .3 \{.‘ '5: . 7. (20 points) Addition of HBr to a double bond with an ether substituent occurs regiospecifically to give a product in which the —Br and the —OR are bonded to the same carbon. Write a stepwise, detailed mechanism to account for the formation of the product using resonance to explain why the observed product is formed. OCH3 HBT Br 7. (continued) Write a stepwise, detailed mechanism to account for the formation of the following reaction. Draw structures for all intermediates. H H“, H20 __..__—*. 8. (10 points) Complete the following reactions by providing the starting material, necessary reagent(s), or major product. _PB’3__..___.. er EtZO ~<L0103m first 9. (12 points) Consider the reaction shown below. Heating of 1,2-dibromo-l-phenylpropane could produce two isomeric bromoethers A and B (ignoring stereochemistry). However, one is formed much faster. OMe 3' Br MeOH. heat _——- Bf 0M8 Br a) In the box labeled A1 write the structure of reaction intermediate leading to products A. In the box BI - intermediate for B. b) Energy levels corresponding to intermediates A1 and BI are shown on the energy diagram. Which one has a higher energy? Answer this question by labeling the energy levels corresponding to A1 and BI on the diagram. (1) Plot an energy diagram for the formation of both A and B. c) Which product is formed faster A or B? Hint: mind Hammond Postulate! e) Use an arrow to mark the transition state corresponding to the rate-limiting step in the formation of bromoether B. .- Hr" 31" . .J_\,\ __.\"\"\(“ 3 v Intermediates tort?" Reaction progress 7 Bonus (12 points) Compound X is optically active and has the formula CMHBBr. On treatment with strong base, X gives optically inactive hydrocarbon Y, CHI-112~ 0n catalytic hydrogenation (H2) over Pd/C, Y produces compound W, CMHM. Ozonolysis of Y produces a single product, an aldehyde C7H60. Write the reactions involved and identify W, X, Y, and Z. /' / /, ’4. J r/ 3/ 255E535.qu mafia: 3. 53.; SEE; Ekazguiéum 33.3 3.“ 3:5 8.553 2: EF 2: am am no as a. mm 5 em a. a an a. Na 5 am 3 22 E”. m. 5 LE Eu mE< ti m z a van. E. .82 .33 :3 5.... T :2. m. 5”. n. 5”. m. 3:. n. 53 n. «3.5 a. $2.: I 832 1 3:3 E a an ca S nu ma 5 no No 5 an mm mm =._ L; PE. m. 2.. E a... .5 a. 3 "En En. n. 33.: N. 1:”: 7 an? u. 22...— ? 8.1: a. 3.3. a. main. n. 929 N. 5;: N. 2.8. 2 .935. 3 $52 33E .0 .9653 2.. EE 38 3 =3. Iwa a 85mg 2. 3350: m9. o>ona EgEac HEBu B EcmEEm 3.. £0953 ucm mmEmc uszEmiw 9:... gm, 2...: cm; as a s. E. E: .33 i. 9.5 .3: :8. a. 333—. 233.. . . . 375.2: E— 2. pp p _= a 332:. E. «n 26% 9.5 mu mEmEQm .E mun—Qua a up" .3202 coEEou 5 RAM.» “3E m5 3 EBEac mam:— Em mammcEEmn :_ BEES. was: "202 VIN ll :ozflzuecoo 5:35 0 A1 5252 2.5:. 83— u 02 co 263 2a mamme 3:53 ozfiom 82% Ema saunas 8628 :1 vi :93 .T was: 9:52 25.2mm 2: B 2an 28:2. ...
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This note was uploaded on 07/18/2011 for the course CHEM 1212 taught by Professor Suggs during the Spring '08 term at University of Georgia Athens.

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Final Exam Fall 2009 - Vannoya Valana 810205001...

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