322bsu09_final_key

322bsu09_final_key - F ‘ 9‘” M7 Chemistry 322hL Name...

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Unformatted text preview: F ‘ 9‘” M7 Chemistry 322hL Name ,7?!“ H56. Basic Organic Chemistry August 10, 2009 FINAL EXAMINATION Answer the following questions in the space provided. Please organize your though d attempt to make your answer as legible as possible. If we cannot read your answer, it ca given credit. Please remember that C-C-C-C without hydrogens and “stick” structural representations will be given N0 credit (except for rings only). You may use the backs of pages for scratch paper. I. (22) II. (10) III. (30) IV. (32) V. (30) v1. (08) VII. (20) VIII. (32) IX. (22) TOTAL (206) Chemistry 32sz Final Examination August 10, 2009 page 2 I. (22 pts) Provide names for the following structures, or stru as appropriate. Either IUPAC or common names are (a) (Ml/00“ v ' o v: ctures for the following names, acceptable. (b) E ll-l ~-— WE”: ‘M ~ « ) \ C /CH2 H’ (EH/ Q? ‘CH3 MM CH3’NH H , anomenc configuration, absolute configuration, etc HO ,0 Dz H ~ ~ ~. n n o - HO Chemistry 322m. Finn] Examination August 10, 2009 II. (10 pts) (a) The guam'dino group (shown below) of arginine is one of the most basic of all page 3 uncharged organic groups (pK. = 12.5). Using any needed structural representations, concisely explain this fact. Ll NH + A??? '31 “.5, 69/3 W" H ’ f; < > HZNANH-R —--> N”; / \ M H R M”; ‘Q \w; 1/ (egowcmce s’vabmzec MHZ mhén . .1. 53m: /‘§ «--—-— bmw ml 83% /’ “’ “2 .fl CH2 CH2 CH2 <37 F Fm ‘ F l F t a; H a W +9 CH30 CH30 CH30 (3 CH30 NHAc / NHAc / :NHAc NHAc m CH2 CH2 ‘ t CH {0? F\ ' F F CHSO CH30 CH3O N V c NHAc GD NHAc NHAc I «4% u (a III. (30 pts) Fill in the blanks or the best answer for each ofthe following. Cass u med (a) Give the pK. of the following acids (:1 units). 0” O (+)NH3 c H ‘Cm 0‘” (5 <7“ <3 (5 S” v2 '2 25' 2 57 H <‘ OH 0 H (+)NH3 o ' (+) coza / l H20 \ ~—’ to 20 s 5 M» H Chemlury 322bL Final Examination page 4 August 10, 2009 CH3 (EH3 \ ,C -Cl CH3 (c) Which of the following molecules is most acidic? Which is least acidic? (Fill in IE9 blanks.) CH C 3 / H3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 NH (+) \ / x / \ / \ / CH3 CH3 NH(+) NH (+) NH (+) NH (+) OCH3 N02 oer-:3 Cl letzg'i’ VlA0$+ ._______ (d) Which molecule reacts most rapidly Wlth NaCN m DMF? OCH3 Cl 1 Br : CN OZN N02 I N02 OCH3 (FillinlflleanksJ cozH O’COZH C02H OCOZH COZH COZH C CH3 WK} F WK} $ CH Jud: mi; __ (f) Nucleophilic addition to the acyl carbon occurs fastest and slowest for which of the following? (Fill in TWQ blanks.) 2 O o o o < > do CHa/lLOCH3 CH3/U\NH2 CHs/U\C| ° Simost in yile m Chemistry 32251. Final Examination page 5 August 10, 2009 (g) Label each of the following molecules as W gag-aromatic or (gm-aromatic. For simplicity, assume that all of these molecules are m as written for your assignment. (file (it's <0®©©t351 Qmm. row. mm Qnfl mom Q"er (h) Circle 311 of the structures below that do NOT represent valid 1: molecular orbitals (bonding, nonbonding, or antibonding) for 1,3,5-hexa orbitals. Light and dark lobes represent the wave functions. triene. Ignore the relative size of the contributing atomic “+” and “-—” algebraic sign (not charge) of the atomic 3. 9;. H, m “(mg/o Chemistry 322bL Final Examination page 6 Aumut 10, 2009 IV. (32 pts) Give the main organic product(s) for the following reactions, or provide reagents and conditions to carry out the indicated transformations, as requested. More than one step may be large CH3 we“ 0% Chemistry 32sz A t 10 2009 m“ E‘m'm" pm 7 ugul , No,~ N02 F zc/ifi o mg“) g 0.2 + b M-l I Ha "33:33 NH N02 ' CH @901“ 914m 79%” 3 “(Pr 0 (f) (3 O H /’ H / O 1) KCN, HOAc \C OH 2) Ba(OH)2. H2011 H OH JG H ‘ W. H o H + (q > OH 4) NZ/Hg, H20, pH ~4 H OH H 0 u C -OH (show both pmducts) A H» O H W3” Gulon 1) NaNOz, H20 (3) ‘ NHz C© (E). N 2) CuBr, 100°C /S 1) H 0, pH ~ 9 N / O UWC/ “bow/W (+) 2)Hé‘(o)~ CH3N02 $=( " + Me O M 3) H30“) “2 52‘ + C+> 9” 9 Chemistry 322”. August 10, 2009 Final Examination ( PhNHNH2 C: N—MHfg (excess) ' H O ‘ H G” (k) 1)NaBH4,MeOH 2 rk [ m "" /cH cu5 Ho fl \CH3 page 8 Chant-try 322bL August 10, 2009 (m) o 61”" - + O (n) / CH30HzC/ OH (0) Final Examination o cata C H r5 8\ NaOIyEfltc b. CHz=CH/ CH3 HOEt \\/\ O (5 r 1 OQUiV Bf2 \ C L) P (catalytic) CH3CH B; (dark) M90 page 9 Chemistry 322hL Final Examination page 10 August 10, 2009 V. (30 pts) Provide reasonable syntheses (i. e., minimum number of steps, good yields, good stereoselectivity, good regiochemistry, etc. .) for the molecules shown below starting with the / Q indicated starting materials and using other needed organic or inorganic reagents of any kind except N as specified. Be as specific as you can regarding reagents and conditions. Show the product formed \ from each important step of your syntheses. Be sure to indicate if a step results in formation of an oxtho-para isomer mixture, but assume that such mixtures are readily separated. Do not show mechanisms. H A gel—A . ___________ u, 2 g Q “O‘CQ (+3 ‘ ' We“ F \,M - 0 R01an i H 2 ( A\C\3 /\,/°“% mun JQ/ H554 A slug) l “2.5 H of / rate ‘5 “RN09- Lg} 5 ") 141.904 UNDg W“: KEV ‘1 “*0 G) 130 x l /\ 2 l \¢,HC|)A “M A + ‘ ‘ H a D 2) Hal) (b) N ’ 9H 9H3 OCH, CH and CHaQHOH ------------- --> C—CHCHa CH3 1 éHz as the guacamon sources \ £00; 6» (-3 / so 0143 B30 Chemistry 322bL Final Examination pnge 11 August 10,2009 (c) o o C02Et ” CHICHZCOzH C0023 and CH2=CH-C-OEt ........... H, b“ .y .0 6 ' gleggllwdioate J‘OO C (. a) ‘ “0.054 (st (C‘s bfmc - / V [:\Q 20” H4420” Hm G CGHL J, 1 0L ) warm + .+ + E H30 A H o . ) l 3 [flaking G 6 . CH1 culmzéi i a 05i- ‘ Amie} (d) Show hOW to use the W953 to prepare leucine using 2-methyiallyl chloride. 0 “’M—b—CH—cozi—> I) “40 C . cna , CH2=é-CHzCI - ’ ' ‘ ' ‘ ‘ ‘ ‘ ' ’ "> (" a?) 6. god” H3 2) Nauirdvza cu? 44 u —- 044152” lefuiu NaOEf ‘ SON i w A c NH’ C (rota); {ulcqu 6 0 Nail! ins I U G + l //\/ H; I 3) H30 ACNH" C ((02 41+): M A CNN“? ((0.1%); ‘ A” iod/Carkah Q1410” CH} 2 1 C” r u/i‘ CH 3 9 Chemistry 322bL Final Examination page 12 August 10, 2009 (e) Provide a good synthesis for the dipeptide NAla-Valc from the individual amino acids. Show the molecular structure of any group or reagent at least once. Thereafier you may use an abbreviation if you wish. Be as specific as you can regarding reagents and conditions. Show the product fi-om each it11130113!“ Step of your synthesis 6 (+) _ (+) __ Ala = Nib-oH—coé’ Val = NHs—(IzH—coé) $0430}, (+\ " CHa CH—CHa ~——a— NHS‘CH~C-OC’H2 t c'3H3 \4“ / Xle/QW/ o O S +o—E—NH-—g:— com m m0 5 Q 6 N 01; (0M ’ Boo-MH~W~£vNH—$NCOQH(¢ 1M mac»; i“: M 6 “Dr (“h v NH5~C‘(4-—~ 3 *NH -Cu -— (Crocuch CH3 0 HA/FA/Car‘oeh 02.: H'fir/HQAC NA’Q‘VMC Chemistry 32sz . Final Examination page 13 August 10, 2009 VI. (8 pts) (a) Using structural formulae, (i) show the product of the first step (no mechanism), and (ii) show the mechanism of the second step. 02H 1)NaNO, ‘ (CH3): NHz “23024 Zwitter 2) HOC(CH3)3 + 00(CH3)3 H20, 5°C '°" Q N02 1 {‘7 N02 N02 / ’ W1 ,9 .5 1 H\ {84: u 6. ~ 0 “(R-3 / :54 BM aqueous NaOH. Hydrolysis of this product in dilute aqueous acid gives 2,3,4,6-tetra-0-methyl-D- galactose and 2,3,4-tri-0-methyl-D-mannonic acid. (Monosaccharide structures on last page.) mformation.) < 00 cud)“ (4 (am/0 0H (9 m ou 07%)4) (.- wéen‘m 13"“ Chemistry 322M. Final Examination page 14 August 10, 2009 (b) A graduate student isolated a monosaccharide that mass spectrometry showed to have a molecular weight of 150. To her surprise, the compound turned out to be optically inactive. o What is the structure of this monosaccharide? 0 _ g 0 a .. _ J ’ CH Em CH \90 v--=> (0410),; <C> guzl ’~ t ‘2 cu cu ; mu on im'xrrer (3km VIII .‘ (32 pts) (a) What is the 1° structure of a protein? (L) AA gegwuc What is the 2° structure of a protein? . (>4 —— l4 :2\ l X SiVUC/‘l' WV fi~€\emw I I What is the 3° structure of a protein? ) \\ (a, M d O "1 <1) TM 34) struc‘ilme Oé Sigh protein What is the 4° structure of a protein? <1) CNsiersog/(Jroiam flat-9i OC‘FWH‘A ’ (b) To what must an enzyme bind most strongly to catalyze its reaction? iran Lon SHE (0) Very briefly, what is specific acid-base catalysis? fiat W m H. 92,— EDS <37Pr0‘t0h3hm or degfisg‘iohéhgm §ouowecp ‘09 Wvde‘wcmMM} fzorgan'lzcfimn % “ hwvAl/JI’M bond'kj. Chemistry 322hL Final Examination page 15 August 10, 2099 (d) Very briefly, what is general acid-base catalysis? Pr6‘\0 “ * Va "3 Se ( dur‘m; (it). ' ' wi+a <37 bowl recrgan‘fz‘w“ \ 'mub g2 (e) Why do enzymes often use general rather than specific acid—base catalysis to speed up their catalytic reactions? , , . ,ol’ 9 ion {ransgexs dun-MA bondm &/fl‘njfla (Twit (KM ¥Orm gig/gingevgg (hqh‘qhg or among (1) The pH-rate profile for lysozyme catalyzed cleavage of (glucNAc-murNAch oligomers is shown in Figure l at the right. What is the significance of the pHs corresponding to the two points of 50% activity (3.8 and 6.7)? l We Qm'fim 6V“ é‘fifl’“ ‘\’ we Cwiai girl C groum d flu. . t (g) Figure 2 at the right shows the proposed arrangement of the substrate (structurally simplified) and the principal lysozyme catalytic functional groups in the active site of the enzyme- substrate complex. Can you say anything specific about the relationship of the answer to part (t) above and the proposed structure of Figure 2? Ta jail Sigma is (tweet, (,ka % flu CAM“) W M) (9-7 w T1944 55°52) W lac 3.8, 6'] , Figure 1. Lysozyme pH-rate profile Figure 2. Proposed catalytic functional groups of lysozyme and the cleaveg of the (simplified) bound eubetrae. Chemistry 322bL Final Examination page 16 August 10, 2009 (h) Lysozyme catalysis is believed to occur in two distinct steps. Show the generally proposed first step in the mechanism of polysaccharide chain cleavage by completing the partial diagram below. Draw curved arrows on the lefi side of the equation to show the “flow of electrons," and complete the structures on the right side of the equation to show the outcome of the step. (Don’t forget to draw in any missing atoms, bonds and charges on the product side of this equation.) Briefly comment on how this would be a good example of general acid catalysis. equation to show the “flow of electrons,” and complete the structures on the right side of the equation to show the outcome of the step. (Don’t forget to draw in any missing atoms, molecules, bonds and charges on the reactant side of this equation.) Briefly comment on how this Would be a gémeemple of general base cateyis ‘ ‘v “(3S> an I 0 n lu(35) Chemistry 322bL Augult 10, 2009 Final Examination CHaO OCH3 {y + Tl , ’ Chemistry 322M. Final Examination page 18 ‘ August 10, 2009 (b) The basic hydrolysis of an ester (saponification) is a paradigm for nucleophilic acyl substitution reactions. We discussed in lecture an experiment that was of considerable importance in establishing the currently accepted mechanism. This experiment, shown below, involves the partial hydrolysis of an acyl-oxygen-labelled ester: :0- * No //0 H20, heat 0 0% x / lbel! CH3-C\ + 0H“) CH3-C\/ + CH3-C: “ m 0% 0% (it = no label) completion *0 0 // // + CH3-Cé‘(-) + CH3‘CK'K (-) O 0 Give a detailed mechanism ONLY of that part of the mechanism that firms unlabeled starting material. In just a few words state exactly what this implies about the mechanism of saponification. (Remember that the solution is basic in this experiment, not acidic.) ‘ OH UL;— C “GU-lg 94/34 0W CHg‘C”OCH5 + hue) « a ...
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322bsu09_final_key - F ‘ 9‘” M7 Chemistry 322hL Name...

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