322af07_final_key

322af07_final_key - Chemistry 322a f 325a —2— Name:...

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Unformatted text preview: Chemistry 322a f 325a —2— Name: Final Exam 1. (6 pt) In each pair of compounds, circle the stronger acid. In the event of a tie, circle both (2 pt each). 2. (12 pt) For the indicated hydrogen atom, estimate the water-referenced pKal (2 pt each). .. @300 .thi flag; 01%!) 01—91%— Ci—9 5: d.®°' e.®OH ’ f,®o/“CH3 43.7 41L 2!; «a I? If?“ “it 3. (6 pt) Assign the Cahn—Ingold-Prelog designation (R or S) for the indicated stereocenters below. Assign the alkene as E or Z (2 pt each). OH . Ho N(H}Me n < Br bl b. HO (adrenaline) (limonene) a. 4. (12 pt) In each pair of comp0unds (or conformers), circle the one that is more stable, that is, the one with the most negative heat of formation. In the event of a tie, circle both (2 pt each). Chemistry 322a f 325a -3- Name: Final Exam 5. (12 pt) For each pair of reactions, circle the faster reaction. In the event of a tie, circle both (2 pt each). _‘__‘__.":..r...A.-. - -- - .. :_mfi__wm_ 9H3 mCPBA mCPBA . O 00 0/ ()0 NaHCO3 * NaHCOa Kw—fim mum...— ._... -_‘W_‘_;_____.; 3";- KM Air/F5 Lb? rM—Abrf’ 0T5 tBuOK _,.. (+;-) Q {Bu "'9 {Bu a. CI OH HOMe HOMe o” A o” U A oU f. K m _ w and”. .4..._. MJW=WMM - 6. (8 pt) Predict the Km] and AG" for this reaction using your knowledge of pKa values and thermochemisz (4 pt each). 6) NH3 + H3C-CEC Fiat 515— p’éo, 3 3 I NH2 + H3C-CECH (__ / .t '4) v 223: 3 — {)1 (3’7 ‘” )6 ‘3 iéf M; -= {K as I 2 " H ’5 WW!) 10:5“ Chemistry 3223 f 325a -4- Name: Final Exam 7. (8 pt) Draw a complete Lewis dot structure for the molecules below. Be sure to draw all bonds, lone pairs, and formal charges. If multiple resonance forms are possible, draw the most important (major) resonance form. The first one is done for you (4 pt each). a. Ammonia, NI-I3 b. Sulfur Dioxide, 802 c. Ozone, 03 8. (12 pt) Draw two important resonance forms for each of the molecules (or molecular ions) below. Be sure to indicate all bonds and formal charges. It is not necessary to use curved arrows to illustrate the relationship between the resonance forms (3 pt each). { it) ban". 5 1’qu3; . u , _f, a. Diazomethane, CHEN? 9. (12 pt) Draw a product (2 pt each) and transition state (4 pt each) for each of the reactions below. Each proceeds in high yield in a single concerted step. Be sure to include partial bonds, full and partial charges, and all key stereoelectronic details. Isms u ‘_ {g} pf,¢.'-"§'.“sz fpmr) ' A" {gut Mam—f- Chemistry 3223 I 3253 -5- Name: Final Exam 10. (55 pt) Fill in the missing starting material, product or reagent from the synthetic schemes below. Be sure to include any stereochemical details that you are able to describe. Although it is not important to indicate the inorganic side products, indicate all major organic products. Where applicable, indicate whether there is a major product or if materials are formed in a 1:1 ratio. Upon completion, each reaction is worked up with water (5 pt per box). (2) Commem- “7A + 3 l % g CH} a. CI _( O! (3) WMg-hmqui e I 7 _ l 1' LE 0 + N —‘"_" “‘ CZ) Mohair O‘§*CH3 -§ 5%} i b. O (1 equivalent) - ( 3 ) éohl-fl‘fg.[¢-g MeS\/:\ Br + NaSMe -—-—-———n (“g ’3 b-mfiéggf C. 0/ + Br2 in H20 —.. MOH + H30+ —-- ( {OM adrf Mal-1:7 NaOMe (353 :3” *3 (1 equivalent) MS: 194 glmol Chemistry 3223 1’ 325a -6— Name: Final Exam 3-) {guns-tutu. a; f 7 0 H2304 “3 W PM it) magmas. 1m Hf + EtOH )‘" L) . (catalyst) lira {A} i may g. M (Me602)2 Me ~—...-/ 602 Me 5! heat 002Me 602Me n h. Pory(methylmemacrylate), pMMA, plexiglass® _ {L} amt} “23¢; g” g) {05" £55514 / f,” r .- /X If! F Chemistry 322a / 325a -7- Name: Final Exam 11. (11 pt) A compound of formula CgHwO2 has the 1H NMR and IR spectra (KBr disk) below. Propose its structure. Partial credit will be given for partial structures, 3 pt per correct spin system. [DD TIflN5HETTflNE El 5“ an U 1666*“ “1606 “1261 4000 3000 EDGE LEHEI lDDD EEO IIFI'I'ENUI'II Efil -1l Chemistry 3223 f 3253 -8- Name: Final Exam 12. (11 pt) A compound of formula C5Hm02 has the 1H (21ines) and 13C NMR (3 lines) spectra below. Propose its structure. Partial credit will be given for partial structures, 3 pt per correct Spin system. WT—T—fi—Twfifir—T—W—lfi—lfi—l—‘fi—‘_r 200 180 160 140 120 100 80 60 40 20 0 ppm Chemistry 322a 2’ 325a -9- Name: Final Exam 13. (10 pt) Cycloheptane is approximately 6 kcal/ mol more highly strained than cyclohexene, thus ring contraction rearrangements from seven to six are driven by ~ 6 kcal/ mol of strain release. Write a reasonable curved-arrow mechanism for the ring contraction of A to give alkene B. Show each bond-forming and bond-breaking step distinctly. m . .r H+ 0H __.. Chemistry 322a f 3253 -10— Name: Final Exam 14. (10 pt) Isoprene (A) is a readily available, naturally occurring diene. It can be converted to racemic cycloporpyloxiranes B through a two-step epoxidation/ cyclopropanation sequence. Treatment of B with concentrated I-l'Br in water results in a remarkably selective rearrangement to give C. This is an example of a highly diastereoselective synthesis of a trisubstituted alkene, a synthetic problem that is usually difficult to solve. Write a reasonable curved-arrow mechanism for the conversion of B to C. Show each bond- forming and bond-breaking step distinctly. 1. epoxidation H CH3 48% HBr, H2O / // \: 2. Simmons-Smith 31%,>20:1 E Br OH A B LIT-fir c //7 / H 21;”? ’35"”"’{ gfi/fii’é’? A > / 22:“- r’“ Low r“ H W 1 'L- ('{JJ'QAzT/fl H J; {7 'v'lfl 3“ 14,: {K ,, . c”; c', cit-"39:?! i! Chemistry 322a I 325a -11- Name: Final Exam 15. (15 pt) Toprol XL is a beta blocker marketed by Novartis for treatment of hypertension and angina. The commercial roduct is a racemate. In 2006 Novartis sold $1.47 billion of Toprol XL, which puts it at #21 on e list of highest grossing pharmaceturicals of last year, just ahead of #22 Vytorin, a combination therapy used for similar indications. Propose a synthesis of T0prol XL from the three indicated starting materials and any reagent that you think is appropriate. OH r-(_ \ NH2 foo ~H Wm + at MeO )— HO l, 796,? 3 Toprol XL Wot h, i 9?; r. i / A Z M's-L o l 4: aft/01,3751 Watt) A/ V A 3 «I —w' 1’;- $11,: A, “ J r '— x” / OH ’5/V /’ a .s-«-' ‘3 “r £F5J;4' / i“ O . 2“ 1 y, \ lay—- ' L41: ‘} #1], Ef'flr r '” H O . , x ,- /u I” 3P1) P“ f r W323i» 3 : U L21 ? i o 1' '3” \_ g; a r M 0m ml, q v H / / O_'_t.._ ma”; A: \ 4/13“? Oil/«tr 886 must; goo; ‘6. L0? “‘Li'} “ J“ { g1 :19 it“? / ...
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322af07_final_key - Chemistry 322a f 325a —2— Name:...

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