CH151Exam1KeySS06

CH151Exam1KeySS06 - E‘Mm l K57 Chis—l L 831mg D a) (5...

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Unformatted text preview: E‘Mm l K57 Chis—l L 831mg D a) (5 oi !| - ‘ cis-Z-butene. Do you expect this molecule to act like a w. ELECTROPHILE? (circle your answer) LQIS-‘I- 172.5” / \ ‘5 .- . # "x L Lu W 1mm ) b) (5 points) Provide the complete IUPAC name for the compound shown below. lCH .(ZDH 2H 44a \ , a 2'245—H c 3 d) \c=c’ Na ‘7‘ / \tt’ “\5 H tl>HCH20H3 _ man“ i a CH3CHC-H GH3 \ N‘3Wan) " ‘1 1 5 2°] ,w (0 c) (5 points) Draw the skeletal line structure for 3-isopropyl—2~methylhexane. 2) Acidibase chemistry \ a) (5 points) Predict the products of the following acidibase reaction. ( 915" it’d-1L») b) (5 points) Show the electron movement (mechanism) that leads to the expected products. Be sure to include formal charges where ap - - WI? 0) (10 points) PTedict whether the equilibrium lies to th r LEFT and BRIEFLY EXPLAIN your reasoning (structures are wor ' ousand words). -—| mpg 5/}: + Na't'OH , H. * CH3 0 11” \‘rc‘fi ' ' I I I ' j 0 \d—aJ-L loam fie Q‘s—Misfit?) ' _ ' arrow} 9W“ Hfium resonance shblllzeflfifimhr Lax '“ 1 I t (HMO glad?) 02’? fit $ r In “on J animlocalizea \B W 3) COIlSI er penicillin G shown below: a) (4 points) Praw in all lone pairs of elec rons. $7; ti {b “[2. {TQM-e b) (8 points) D termine the hybridization and geometry of the indicated carbon atoms. Write your answers on the lines provided. 0) (3"points) Circle one electrophilic atom and label E+. d) (.3 points) Circle one nucleophilic atom and label NUC. / .435“ V Geometry _ Hybridization a \ i’Izu r3” a-i'r'u )— S P— \ 1/ {edema 41* \ \zu‘rtvt‘fi; l :5 CH3 b MM " §P3 L i: a?“ a ’V r NQ< \ii‘ (“{3} \% 9cm»)? 'iDboL b.\ \‘x CH3 vie-Awe?“ 1’ J"? vr WW: "5 F5 .. (x ‘ o 'ZMuLw I'afi__,i"”kb dyletigfl) (15 points) The naturally occurring molecule a-terpineol is biosynthesized by a route r ‘(I‘Qvafill including the following steps. Suggest a structure of the intermediate carbocation ‘44 $3} and provide the curved arrows to indicate the electron flow required for each step of W the pathway (1 have given you all of the intermediates except the first one.) CH3 H 0+ + HacXO/ *Df'w'l r5 {2er :-‘-_ 3 H'0 CH3 unterpineol 5) Consider n-hexane. I 2. 3 4- 5" l’ a) (10 points) Draw Newman Projections of n-hexane citing down the C2-C3 bond depicting the highest and lowest energy conformational isomers. C LC”; Emma 05 w ‘5 A ll H u 3 "'3— D’ ll “u ll ‘4 ” Ed x {)5sz cuLcuLC _ a?” HIGHEST ENERGY LOWEST EJNERGY b) (5 points) List ONE kind of repulsion present in the higher energy isomer. Sigrid rcPtdsauw E— Van (1,6r [Denis repulsifi ® e," I C" Tc pubic“. or msimd t c) (5 points) DrawElN'Elconstitutional isomer of n—hexane. 6) (10 points) Based on the pKa values provided, label the strongest base. Also, circle the two species that will be present in highest concentration at equilibrium. OH 0+ 16 573 >157 budflne 5 outtake: I 65+ {lot A "than finial/icy}.th has 5% , wmmb 7) Draw a complete orbital picture of the methyl cation, +CH3 L a) (3 points) Show all orbitals for the carbon and hydrogens. ' Cm N (k [360mg b) (3 points) Clearly identify each orbital as s, p, Sp, sp2, or sp3. c) (3 points) Indicate angles between all orbitals on carbon. é . a Sp —P 90 sfl—sp'l I'MI d) (8 points) Circle the most stable carbocation shown below. Give ONE reason for your choice. +C HQCHQC H2O H3 n-butyl cation 3Ps~lm1brucltzea C '2 mu Shblhw Pos.+l'v~€ Charge (WW)? mks—i . H’k‘l‘wfflgkfi (3f Cups C.\c: drum dew.er 36C} Wagesfab,/,-gpa b. j J HYPrCOUEja‘HM .' acclaim; 1}) C'H £00615 five/MP w‘t‘l’k 6h?4-y P whl'l’ql .‘.€.‘+‘ll3l'lilt Pom-lulu . (‘2me PM.“ (“36 Cliktl Ci/au-pj(3>hflm 00(3) 8) (20 points) Below is an energy diagram for formation of product A. Based on your knowledge of the mechanism of the addition of HBr to an alkene: a) complete the energy diagram of the formation of product 3. Pay close attention to the relative energies of the carbocation intermediates and the transition states (715.) leading to the carbocations. Label clearly the energy of activation of the rate determining step. b) Use the diagrams to explain the observed regioselectivity (invoke Hammond’s postulate). CaF’DOCOL‘i'iDn icadij =C w. Br Br 4» Product 8= + HBr { + \—C aunCJudC 4: on product A product B 4" a. ‘ r am only product not observed Energy Diafl ram $Dr fPdeAxc+ A Reqci'i on Coordi no: le c [arcs-l- lntfi'WIq-k 4 Ham 4“ WM“: ‘ TS. ene‘HY OPP’W’WW 5‘1 L-{ THIS {flStfi RDS a PFDM‘FXM: +A€m T-S ‘9 C1” 3° 0* +0 Mel- A more Tina/w lo C+ 1:451:33 ' TS.“3%°C+ loaf anti-3y ‘im TS --> IOU" 1: '1 lower energy Ts. C‘s/responds torts smily A6: LIL 3W\\6’ [36* Curegpond; rcac+o~_ --_ P(9¢LLLQ\~ A 9) You may choose ONE pathway (a or b). Only one pathway will be graded. a) (10 points) Fill in the boxes with the major product for each transformation. You will either complete al and 32 OR b1 and b2. Please do not Show mechanisms. ("7H W {95‘ y“: b on Hg{OAc)2 Ox H20 pathway b NaBl—h NaOH b) (5 points) Show the TWO major products you would expect to isolate upon hydration with water and catalytic H2804 i OH“ 0:533: on U\ C>_\\ H20 m "" V10. diaboa ...
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This note was uploaded on 05/13/2010 for the course CHEM 151L taught by Professor Roy,christopher during the Summer '08 term at Duke.

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CH151Exam1KeySS06 - E‘Mm l K57 Chis—l L 831mg D a) (5...

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