322bs07_e3_key

322bs07_e3_key - E \( CHEMISTRY 322bL/325bL Please K “...

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Unformatted text preview: E \( CHEMISTRY 322bL/325bL Please K “ EXAM NO. 3 Print Last Name MARCH 21, 2007 First Name First four digits of USC ID ~ _ _ _ -XXXX-XX TA's Name Grader (1) (15) _ (2) (15) __ _ (3) (15) _ _ (4) (20) _ .— (5) (10) __ _ (6) (10) _ (7) (15) _ __ (100) Lab Day 8: Time first letter of last name I will observe all the rules of Academic Integrity while taking this exam. Chemistry 322bL, 325bL Exam No. 2 -2— Name (1) (15) Complete the reactions below by providing the missing products inside the boxes. Be careful to give all the important organic products, as requested. It is not necessary to give the byproducts or minor products of the reactions. "Workup" means treatment with water and bringing the reaction mixture to neutral pH. 3H 1-1+ (A) CH3OH C9H1202 3313 + _ CH3COZ‘Na” + CfiHSNI‘I-NHB, H+ (C) CH3QHCH23CH3 + HOCHQCHZOH CGHE 1 Law? - H3 H3 H+ ([3) H20 CSHIOOZ + (i) BuLi/ ether 1 Bl" (ii) cyclohexanone Chemistry 322bL, 325bL Exam No. 2 3 M C Lj- (2) (15) Complete the reactions below by providing the missing products inside the boxes. Be careful to give all the important organic products, as requested. It is not necessary to give the byproducts or minor products of the reactions. "Workup" means treatment with water and bringing the reaction mixture to neutral pH. Name + Brz + H o THF CH3 2 I 100% ee (5) 0 M7 0 [9 (0 m 0 fit/1,0 CH (3) + CHEECHE‘ + KOH H20, THF slowa d' ion OCH3 1 16’ m grad c/O ( CW fli mama/a. WCUHHOZ H+ ‘ + HCECCH2CH20H (C) o 1-1 H c L' (D) + (C 3C 2h L1 1 THF workup (E) CH3CH2CH2CH2L1 (i)1-Oqu(CH3)2CH]2NH/THF -78 c (ii) 1.0 eq é /THF '780C Chemistry 322bL, 325bL —4— Name Exam N0. 2 (3) (15) Answer the questions below. (A) (4) When 5-methyl—1,3-cyclohexadi0ne is reacted with 1.0 equivalent of lithium diisopropylamide (LDA) in dimethoxyethane (DME),and then benzylbromide, two isomeric products are formed. Provide their detailed structures in the boxes. (i) LDA in DME, 0°C ‘3 (ii) C6H5CHZBr H3C 0 5-methyl-1,3-cyclohexadzr:1e / I 1% 11 two isome product eifl-n N w 0522!" 20K (B) (5) Provide a plausible mechanism that explains the formation of the two isomeric products. Carefully draw and circle the key intermediate. Be sure to show important stereochemical details in all structures. Part (C) of (3) is on next page Chemistry 322bL, 325bL -5- Name Exam No. 2 (3) Contd. (C) (6) Reaction of 5-hydroxypentanal with excess ethanol in tetrahydrofuran with a small amount of concentrated sulfuric acid produces III. Provide a plausible mechanism that explains the formation of III. CHZCH3 34 small amount of H2804 HOCHQCHZCHZCHZ + CH3CH2OH —"——‘—‘—"—’ excess THF ‘O:/\H ' 111 © HOCH CH CH CH &-H (“£9 :Q’H L L z Z + CHSCHZQ H if Recalcugqguzh 1Ath 9119 + h—0 93—‘7‘ ,9. ChiLBoM‘tL u .- u HQQHLCHLCHZCH C—H "5 WC: GD—H fl", F.) $6 9 + CHSCHEch-l «a: r. Cqu-lagrfi He m Ace 14: L "——l+ H- it‘d—w tats <9 l® ___.:> / -. - 4— (HQ . -—~ \ . d 3 7-H C l ' <‘ + HLD V + E+°l+ mammal) m w __ cm“ Q U 3 ‘0‘"H ®._ +~ QHscHJQf'H g; 36’? file +— mad-5944 Chemistry 322bL, 325bL -6- Name Exam No. 2 (4) (20) Circle the correct answer for each statement or question below. (A) Among the carbonyl compounds below, the hydrate will be the most favored in the following equilibrium with (circle answer below) (33R HQ pH 9 l H - _ ' R + 20 R c R CH3?“ @ (5 CH3CCI-I3 (B) The rate of hydration of any single aldehyde or ketone will be slowest near pH (circle anSWer) 2.5 4.5 10.0 (C) In each pair of carbonyl compounds below, the rate of nucleophilic addition under identical conditions will be faster with 9 g (circle answer below) (3 & @013 @013 ALBI ALB II CH3CCH3 CH3 AILBi ‘ I II , I 11 \_fl.__/ pair A pair B (D) An isomer of C5H30 gives a red precipitate with the 2,4-DNP reagent, a positive test with the Tollen's reagent, 3 negative iodoform test, and shows a strong band in the infrared near 1685 cm'l. The structure consistent with these observations among those below is (circle answer below) emu/w (E) Which of the following structures are acetals or "ketals?" HZCH3 1—13 ‘ O>$ H (Circle answer below) H3 3 on] I [0 CH3 CH3CH2CH(OCH2CH3)2 Ian W I [I III IV all oi tlem Chemistry 322bL, 325bL -7— Name Exam No. 2 (4) Contd. (F) The order of acidity (strongest acid to weakest acid), among the labeled H in the structure below, is Hc HC (circle answer below) 0 CECE—HA A>B>C B>A>C C>A>B (G) The product of the reaction sequence below is (i) lithium diisopropylarnide in ether solvent, 0°C CHsCHfiCHa aggregates; """""""""""""""""""" (circle answer below) é? QCHzceHs CHzcéH5 CH3 CH3CH2 =CH2 CH3 CH3CH2CCH2CH2C6H5 (I-I) Which of the following compounds cannot undergo an aldol self-condensation reaction? (circle answer below) (CH3)3C§H CH3CH2CH2§H CH2=CH3H C6H5gi III and IV I, II and III 1 11 111 IV 1 and IV (I) The alcohol protected in I may be deprotected by deprotect H3 cI—I3 ------ “’C6H5 HCHZOH O OCH2CHC6H5 I (circle answer below) LiAlH 4 / ether conc. KOH in H20 /THF (CHa>aSiClinTHF (1) Which statement below is not true about the following condensation reaction? a C6H5 + ‘ ' ' ‘ ' ' ' ' ' ' ’ ' ' ‘ ‘ ‘ ‘ ' ' ’ HZO/THF (circle answer below) -The carbonyl in benzaldehyde is activated towards nucleophilic addition by protonation. -The acid catal zes formation of the enol of acetone. -This directed crossed aldol reaction is best carried out by slow addition of benzaldehyde to a solution of acetone in a ueous H O/THF. -The B—hydroxylketone product rapidly o e y rates to an a,B—unsaturated ketone. Chemistry 322bL, 325bL —8— Name Exam No. 2 (5) (10) Answer the following questions about propanal (I) and 2—butenal (I!) which have comparable acidities (A) (2) Circle the most acidic H in each of the above structures of I and II. (B) (4) Use resonance theory to explain the acidities of] and 11. Draw appropriate resonance structures in the boxes below, and explain in one or two sentences how they account for the acidities in the shadow comment box. .. (—3) .. ._ u H ‘ HILC- -—C.H : CH —-q-—H <—> HZC: QH—«QU. -<:-n €~>R§:Q-l—-Q4_c comment box arm é¢KOg¢Lilq (Mimi +lv-rL-‘GDFKMOI'L smut-L. MC ’oI\.'—t 0C +l~L (ho-Hung bun. Wk em“ Limp. lg OSLULd' o-F +l-a\ «\éeL. (C) (4) When 11 is dissolved in a dilute solution of NaOD in D20 and then quickly recovered and analyzed, it has incorporated some D in place of H. Provide a mechanistic scheme below that shows how and where the D is incorporated into 11. We hammer-net. s+r~uc+u r43 shot—.9 +\r\1\ sfiua, o-C {KLSCLHUL CKOLPSL CkTL ‘9" _S_‘_J?6\— ¥us+1v H; -—CH HQH -——c~H O maZ—cs+:u+—~E H 3 HiCZCH héH—tim m on sin»th “lessee o o D smut. BE P—oLLNQ HT quq Ql—C): (LL—Cfl—L Chemistry 322bL, 325bL -9- Name Exam No. 2 gel; (6) (10) With benzaldehyde as a starting material and using any other needed organic compounds or reagents, propose short syntheses for two of the three compounds below. Only (A) and (B) will be graded, if you work all three parts, and don't indicate which two to grade. From C6H531 and any other organic compound or reagent: (A) C6H5CH2CI-I2COOH o c) C” t N ck _ C‘HSEH + CHSEokth _.i____> CbuSCfi_Q\-\QQOH Hear \/H1\?+ GLY- H‘U‘wfi C QRSCH£HLQ9°R (B) C6H5CI-I2QHNH2 CH3 ‘3 NCLOSHr C H.Q\i:Q—-N‘O (sHScH + “35%sz 54, c. s \ 7— CH; C c 6 4—4 “I’M “HS%(HN A Q‘qab CG_j‘. . QH (C) C6H5CI-ICOOH O {:3 SGML HQ 94 __ («HSCH + NRC—N "-F'h’ CQHSIKQZU ® H o H 3 OlH H10) Hui—b (Gus—C\COOH RYANKYS‘S Chemistry 322bL, 325bL -10- Exam No.2 3 M( (9/60 (7) (15) Provide the missing structures (starting material, reagent or products) inside the boxes in the following synthetic scheme. Name (i) 03, CH2C12,-78°C g g 3 —» CH3 CHZCI-IZCI-IZCHZ CH3 (ii) Zn, H20 CH . (i) dill-10', HZO/THF (ii) acid, heat ether (ii) workup reagent A fit. MAL C161—122 synthesis of reagent A (i) C6H5CHgBr/diethyl ether (C H ) P F. 6 5 3 (ii) n-BuLi in diethyl ether (QH "‘ a“ 53:5 reagent A ...
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This note was uploaded on 07/13/2008 for the course CHEM 322AL taught by Professor Jung during the Spring '07 term at USC.

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322bs07_e3_key - E \( CHEMISTRY 322bL/325bL Please K “...

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