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322bf07_e3_key - L CHEMISTRY 322bL Please 2 EXAM NO. 3...

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Unformatted text preview: L CHEMISTRY 322bL Please 2 EXAM NO. 3 Print Last Name OCTOBER 29, 2007 First Name First four digits of USC ID _ _ _ _ —XXXX—XX TA's Name Grader (1) (15) Lab Day & Time (2) (15) __ ____.. (3) (10) ___ ____ (4) (20) __ __ (5) (15) .4 __ (6) (10) __ __ (7) (15) __ .___. (100) _ firs letr 01st nam I will observe all the rules of Academic Integrity while taking this exam. Chemistry 322bL —2— Name Exam NO- 3 3 “c L #2 (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. H+ C6H5 CH3C02- Na“ + CCHQCHZCH3 + Cl‘ H3NOH (B) W @923] : + ————~ (C) O O HOCHZCI-IZOH (H20) OCH2CH3 HO+ HQO/THF C6H5 //O (E) l l + (C6H5)3P= 'CsHs M 2H3 ether + (C6H5)3PO Chemistry 322bL -3- N me Exam No. 3 3 at: (2) (15) Complete the reactions below by providing the missing product(s) or starting material inside each box. 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. i (A) / I EL NaOD " 1320, THF 25°C CH3 H 100% ee (S) strong band in ir near 1700 cm‘ (3 l KOH 1% Q 0” pa H20,THF, Lula-t ——-_ (B) CH3 (i) 12,NaOH,H20 (C) excess (ii) r130+ OCH3 (i) 1.0 eq [(CH3)2CH]2NLi/DME,0°C (D) (ii) (CHahSiCl EN COO H (E) (i) NaOI-I, H20, THF, heat (ii) Hgo+ O CH 3 CH I. x l Chemistry 322bL -4- Name Exam No.3 (3) (10) Isotope substitution experiments often give valuable clues about the mechanisms of reactions as illustrated in the problem below. Benzaldehyde with a deuterium in the aldehydic-H position and enriched with 1% 180 in the carbonyl oxygen is dissolved in a mixed solvent of HZO/THF (no isotope enrichment in the solvent), in the presence of a catalytic amount of acid. (The tetrahydrofuran helps dissolve the organic compound.) After a short period of time, the benzaldehyde is recovered and analyzed by mass spectroscopy. In the shadow box below, indicate which, if any, isotopes in the starting benzaldehyde are disappearing. Sketch a mechanism below that explains your prediction. “3) cat H+ CsHs HzO/THF OH H l "9.1% t) F) (t, use-b <" Chemistry 322bL ~5- Name Exam No. 3 1 Mr /_ (4) (20) Circle the correct answer for each statement or question below. (A) For each pair of aldehydes/ketones below, hydrate formation in the equilibrium below will be more favored with H gt 3 5% R31? + Q C13C3-I H3C Hsc CH3 H3C I II 1 11 H20 afli RcR' OI-I . A , B (Circle answer) A I, B I A I, B II A II, B I A II, B II (B) Which of the following compounds will yield aldehyde or ketone products when reacted with water in the presence of acid? H3 H3 CH3CI-IZOCI-I2CI-IZOCH2CH3 (circle answer below) 111 I H GED H3 OCHQCHB, (361—15 HOCH3 111,1v 1,11,1v I 11 IV (C) Which factors inside the box increase the rate of the nucleophilic addition reaction sketched below? X is electron—withdrawing X is electron-donating 93 I II X©CU= ‘—"’ R is Changed from H R is changed from CH3 to CH3 to Phenyl III IV (circle answer) I, IV II, III,IV II only (D) Which compound in each pair e ow will show the C=O stretch at a lower -1 wavenumber (cm )? (circle anSWer below) g A I, B I A I, B II x\/» ‘ I 11 I II k‘_"\r"_‘J L—‘Waj AILBII A B (E) A compound C5H100 gives a red precipitate with the 2,4»DNP reagent, a negative test with the Tollens reagent, and a negative result with the iodoform test. The structure below consistent with these observations is (circle answer) Chemistry 322bL 6- Name Exam No. 3 1 “f k / (4) Contd. (F) In the ketone-enol equilibria described below, the dominant enol in each case will be H H H H Q0 a0 a0 I A II I B II (circle answer) ALBI AILBI AILBII (G) 1,3—Diphenyl—2—buten—1—one may be prepared by the condensation reaction of cansdl—x C6H5CH2éi-I A + B HO €6H5q=CH§<36Hs I “ £4 ("I—{20) CH3 C6H5 CH3 CfiHSCH2CH2 C III IV (mkmwafi A=I,B=IV A=II,B=II A=II,B=III A=IILB=III (H) The alkylation reaction below may be carried out with which of the bases below in step (i)? (i) B:' BuLi/ ether NaOH/HZO/THF C6H5 CHzCH2C6H5 1 11 CéHSCHzBr (26115;ng3 KOBu-t/t-BuOH LDA/ ether (circle answer) I, IV III, IV all of them III IV (I) Among the labeled H in the structure below, the order of acidity (strongest to weakest) is (\C ’\ (PH (“x A H CHCOOH D _ ’ 0 (Circle answer below) O¢\/ fl D>A>B>C (D>A>C>B ) A>D>C>B D>C>A>B ECHI, B (I) Which of the following compounds will give a positive iodoform test? 9H 3 3 CGHSCHQCHCH3 CH3 CH3 CH3CH2 C6H5 C6H5CH2CHO I II III IV (circle answer) only II II and 1v land 11‘ II, III and 1v Chemistry 322bL -7- Name Exam No. 3 (5) (15) Based on the information in the following synthetic sequence, provide the missing structures for A,B and C and the reagents I and II in the boxes below. Also indicate how reagents I and II are prepared in the appropriate boxes. Read through the entire scheme before beginning your work. Note that catalytic hydrogenation of product A yields cyclohexanol while the isomeric B and C react by the Clemrnensen reduction and catalytic hydrogenation, respectively, to give the products show below. CH33CH2CH2CH2 I-I CH3CH2CH2CHZBr (i) HO‘/H20,THF H H30+, heat Reagents I and II both produce butane when reacted with acid. (i) Reagent I (i) Reagent 11 (ii) workup (ii) workup B CioHisO C CIOHIBO ZNHS) Hz/Pt gHCl, HOAC /———— ,l/\/ H0 Chemistry 322bL -8- Name Exam N0. 3 (6) (10) You are assigned the task of preparing p—toluic acid (4—methylbenzoic acid) from p- bromotoluene by the standard synthesis shown below. (A) (4) Provide the missing reagents and structures inside the boxes below. 0 ((5% a. ‘1 Br . a aseous rea ent an organometallic g g OOH es ,d- H30+ C01 ADJ v workup C33 . H p-toluic ac1d . a salt Unfortunately, something went wrong with this textbook synthesis. After aqueous workup, spectroscoPic analysis of the product shows you have only a 45% yield of the desired p-toluic acid. The remainder of the recovered material is toluene. (B) (2) You are determined to salvage what you can from this synthesis. Propose a simple chemical method for separating the p-toluic acid from the toluene byproduct. You may not use separation methods such as crystallization, distillation, or chromatography. TLL Ger—b93117qu a_¢_£¢L Mm}? lac S¢Q¢mfid n»— +‘afl. Wu +r-&\ +b\ue_mc ln ova—Fro-u-Ho’vx. "(Le Qméug—t— M‘Lx+-v bk (-3 dtg$°\ucl TM 1* ‘1 r” Ch“ Q—F‘H—o-L‘lfieci '3ch m\ :5 .. CL U2 ad 3 'F-DH SeLv‘H’k. W G. ULOU5 “ma 0 aLLJM—mi “cw-L *‘4— cc" ‘wv‘r \ m: acid 33 Jr‘fq-LO—wé. I'd—1‘..ch Md_ (C) (I) You are asked to run the synthesis again and to get a better yield of the desired product. Briefly suggest what may have gone wrong in the first synthesis. What are two possible steps in the synthesis where improper procedures could lead to toluene? What Gag i #6 .. . 1.! I I “ 1 TL... OFCSTML\ D+Wl~ Salve“ mu/ Kat—use \mzh-vs UT‘ ‘ ‘ ugfi—tb’w ‘{\ GML +151. Grifimar—d was": “me-U fro-K4144 b3 we Chemistry 322bL -9- Name Exam N0. 3 (7) (15) Provide reasonable syntheses below, as requested. (A) 5) Work either - art (i) or (ii) be] . u If you work both parts, and do not indicate 1:: one to grae, on y part 1 W1 be graded. CH3CH2CHZQHCH20H from CH3CH2CH20H and any other needed reagents (’9 ~ 0 H O C Ho C“ Q“ “——_—~> CHBQHLE H W QHBCl-lzb-ICIIH‘! H L <H (PC—C. t": PVT" a FM'JUM CHor-ozkrchjgs) 3 3 2. _ QHJQHLCHZSH QHZOH P+ qu C Hug) CH3 .3 (u) C6H5CH2CH2NH2 from C6H5CH20H and CH3N02 and any other needed reagents O CngCHLOH pcq > C3 H O (D L I. H—a 0 (“£4th a.— CH no CtHCCACHL” 2- 3 L HLCDDTHF Chemistry 322bL -10- Name Exam No.3 (C) (10) Provide a reasonable synthesis of C from A by way of B, using any needed reagents. Partial credit will be given for completing Afl' B orB——*C. @‘3 """"" @cicmgg” 35 t W3 BM—t (OI) :3, ken—1‘ @ t—Bfuiji-i: 0V 0 ox 3611‘! H: NBS-E N J13 reamcfiuccwumt d1 \J CW 0'5 )Ofilc'b -7g°< (:fl QmJHLO ...
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322bf07_e3_key - L CHEMISTRY 322bL Please 2 EXAM NO. 3...

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