final - Lieu, Nyla 810204450...

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Unformatted text preview: Lieu, Nyla 810204450 lllllllllIllIlllllllllllllllIlllllllllllllllllll last, _ first 810# CHEMISTRY 2211 ‘ Final Exam SCORE December 10, 2009 2b I. Be sure to read each question carefully. Partial credit will be assigned where appropriate. — Relax and good luck!! f K 2. 1. (20 points) Bromination of bromocyclohexane gives nine isomeric products of formula C6H10Br2, 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 VII chiral carbons and “yes” or “no” as to whether or not the product is optically active. ; 4. ' Brz . . Br ———"* CsHmBrz (9 Isomenc products) h V 5. . I r‘\—.——'J; 7 V4 7. Chiral carbons? Chiral carbons? Chiral carbons? % Optically active? Optically active? Optically active? 8' W Chiral carbons? Optically active? 1.. l5 Chiral carbons? Optically active? Chiral carbons? Optically active? I’ V‘ s {I Chiral carbons? Optically active? 5r an” Chiral carbons? Chiral carbons? Optically active? Optically active? 2. (18 points) Reaction of (S)-(1-bromoallyl)benzene (shown) with hydroxide ion produces an optically active alcohol as the only product. Heating of (S)-(1-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. NAME last, llI‘St 3. (9 points) Treatment of -4-br0m0hex-1-ene with NBS/lav followed by reduction using H2 over Pd/C yields three isomeric products with molecular formula CfileBrz. 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. H2, Pd/C —"—"' -—._-'—," ClezBrz (3 isomeric products) 5! ll x2 ‘5’ "" O ticall active? t, LL 0 ticall active? PO p y 5 p y 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. ' ,J . 7“ ‘ ' ,..--7 (ember/rcrfisnzcnzcoon L’H‘ ‘- ,I .J [I .. 4. (continued) 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 chirality centers. Hint: DMSO and THF are solvents. NAME last, first 810# 6. (12 oints) Consider conformational equilibria in alkanes and cycloalkanes. 21) Using the template below, write a Newman projection along C2-C3 bond of the most stable conformation of (R)-2-bromorbutane. C1 of CH3 is shown. g a ( AE- ti’ “*4 1CH3 ( H23. b) Using template below (position 1,2, and 3 are labeled) write: . 7-7" ' o the dash—and-wedge projection of meso-isomer of 1,3-dimethylcyclohehane; /' ” 0 most stable conformation of this compound. (H5 ~ 13.! (IL-1‘3 >( X 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 OCH3 HBI‘ B'- ——P— .. 7. (continued) Write a stepwise, detailed mechanism to acc0unt for the formation of the following reaction. Draw structures for all intermediates. OH 8. (10 points) Complete the following reactions by providing the starting material, necessary reagent(s), or major product. OB, NaOCHZCHg. heat <Lo1m3m NAME first 9. (12 points) Consider the reaction shown below. Heating of 1,Z-dibromo-l-phenylpropane could produce two isomeric bromoethers A and B (ignoring stereochemistry). However, one is formed much faster. Br MeOH. heat OMB Br _.._..___-. + Br Br OMe A B a) In the box labeled A1 write the structure of reaction intermediate leading to products A. In the box Bl - intermediate for B. b) Energy levels corresponding to intermediates A1 and BI are shown on the energy diagr . Which one has a higher energy? Answer this question by labeling the energy levels corresponding to A1 and BI on the diagram. e) Use an arrow to mark the transition state corresnding to the rate-limiting step in the formation of bromoether B. Reaction progress 7 Nx k5 C‘ 6-", 1"". LL'. ’ '| Bonus (12 points) Compound X is optically active and has the formula C14H13Br. On treatment with strong base, X gives optically inactive hydrocarbon Y, C14H12, 0n catalytic hydrogenation (H2) over Pd/C, Y produces compound W, CMHH. Ozonolysis of Y produces a single product, an aldehyde C7H60. Write the reactions involved and identify W, X, Y, and Z. .C_.~.w.:2.m PA 11.13.: :_._ CZE- ,:_r:u__.:_H >2Fn2nw—ZU Zn 137.33 .3. fiazah P5333: :: 2:. mm mm 3 mm w. mm 22 E”. mm LE :5 EE .3: ,n an“. EN. .3“. m. :3 2 Eu m. 55 m. Ea. n. EN. m. $53 m. E 3 mm mm B > mm mm 3 no mm =._ L; E... ._m_ a: a a... we a. 3 En n. 5.3: 1 3n: n. :35 2 SE n. 232 T on NE E R3: 7 mmng N. 933 N. :3. .o<n_:_ 3 3E? Ea: .6 365% m5 :3: “am: an =5 mm; 9.6% Ema—5.... 252m B mEmEEu .2 235% ucm maEm: oszmfi>m 9;. ....................................... 1 NE. 5;. 2:. 2:. 2:. 25.25 55 =2 5 3 Eu :3. a an“: .5“. fix. 3 I: R : mmu‘nnw a; unq—mm a. m: w.m_.wm.m7 FATanM. “Tn—.Nmé? N‘mem.mT N.~Twm.m_.. an mm :2 ._n_ : m f a 3.— m. mad: 9. e 8». a E a 2.2 w 3 an; E. unqwmw can .mneofl :oEEou 5 £52m EOE us. he E353: mmmE Em w— m_. 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This note was uploaded on 09/21/2011 for the course CHEM 2211 taught by Professor Hubbard during the Spring '07 term at UGA.

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final - Lieu, Nyla 810204450...

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