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322af01_e4_key - 4mm (:97 CHEMISTRY 322aL V Please EXAM NO....

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Unformatted text preview: 4mm (:97 CHEMISTRY 322aL V Please EXAM NO. 4 Print Last Name November 28, 2001 ' ’ First Name SSN TA's Name__ Grader (1) (30) ____ Lab Day 8: Time (2) (15) __ _____ (3) (20) __._ ._____ (4) (10) __ _ (5) (15) __ ~— (6) (10) _____ _ (100) first letter of last name I will observe all the rules of Academic Integrity While taking this exam. Chemistry 322aL/325aL -2- Name Exam No. 4 (1) (30) Complete the chemical reactions below by providing the organic product or products (as requested) within each box. You do not need to. show byproducts of the reactions or any mechanisms. Provide stereochemical details in the products wherever they are important. ' "Workup' means adding water and bringing the solution to neutral pH. (A) CH3CH2CH2CH2Br Na" ‘OCH2CH3 CH3CH20H, heat Two products. C4H3 and C6H14O Label major and minor products. 9H3 K+ 'OC(CH3)3 (B) CHsg-Br __... CH3 (CH3)3COH, heat (C) CH3CH2CHBrCHZBr + 2NaI L%\. I, 'L XI‘I’OAVZL acetone 9H3 OH (D) CH3-(liudH-CH3 CH 3 1 %, 26/3”! " Ch! :1 major product is a hydrocarbon with only a single resonance in 1H NMR Conc. H2504 heat CH3 (E) bch Brz H CH3 CCL1 Chemistry 322aL/325aL -3- Name Exam No. 4 (1) (Contd.) CH3 (F) g + HBr ML CH CH (G) 3 2:C (H + Br2 CH3 H H20 6’.» l 1% Et -c « aha/7! 4 Me (EH3 (i) KMnO4, HO', H20, heat (H) CH3Cqu=CCH2CH3 H CH3 (11) workup,H+ CH3 (1) 0504, pyridine CH3 (i) 03, CH2C12, -7s°c (1) (ii) Zn, H20 H3 Chemistry 322aL/325aL —4— Name Exam No. 4 (2) (15) Answer the questions below. (A) (3) Provide a detailed structural formula for the compound below. Place your answer inside the box. (Z)-3-bromo-2-hexene (B) (4) Indicate the number of degrees of unsaturation ("U” number) for each structure below. Place your answer on the line below each structure. CH3CH=CH-CH2<:‘ 6 i 3 (C) (6) How many different proton resonances (signals) would appear in the 1H NMR spectrum of each compound below? Ignore spin-spin interactions. 2 «£4 (4/ (fl 9H3 CHsCH2\ /H CHBCFCH2CH3 CH3CC12CHCH2CH2C1 /C=C\ CH3 r 5 1/"6 N5 «1%. Lt (D) (2) A proton resonance appears at 5 3.0 in an 1H NMR spec rum recorded using a 500 MHz spectrometer. What is the chemical shift of this resonance in Hz relative to tetramethylsilane as a reference signal? Place your answer in the box. B H [300 H chemical shift in Hz 2 “ch, Chemistry 322aL/325aL ' -5- Exam No. 4 Name (3) (20) Circle the answer that correctly completes each question or statement below. (A) Among the solvents below, the polar aprotic solvents are (circle answer below) 0 _ l 1, 111 d v H20 CH3C =N NH3 CI-I3sCH3 CH3CH20H °n1y H a“ I 11 III IV v w II, III and IV R. (B) The stability order (most stable to least stable) of the cycloalkenes below is (circle answer below) H3 H3 H3 I>III>II II>I>III H3 II>III> CH3 CH3 I H 111 (C) The order of acidity (strongest to weakest) of the compounds below is (circle answer below) CH3OI-I CHZ=CH2 HCECH CH3CH3 b I>II>III>I 1 H 111 IV III>I>II>IV III>II>I>IV (D) Compound A with the formula C6H10 reacts with excess H2 over a platinum catalyst to give a product B with the formula C6H12. Possible structures for A are CH2=CHCH2CH2CH=CH2 0 011—13 0113312? CCHZCH3 l:>=CI—l2 ' II III 1V V I (circle answer below) only II, 111, IV only 11,111,1v,v only 11 and III (E) The order of reactivity (fastest to slowest) of the alcohols below in the acid— catalyzed dehydration reaction is CH - . . OH CHZOH \OH (Circle answ - u. i O “‘ I>II>III m 11 II>I>III II>III>I I "’Cfls III (F) Which of the following reactions of 1,2-dimethylcyclopentene is not stereospecific? C D A B _ (circle answer below) Br2 H2 HBr cold KMnO4, HO ——» —» —> --—-> A B o D CH CH3 CC14 Pt H20 3 l M c As Chemistry 322aL/325aL -6- Exam No. 4 Name (3) Contd. (G) What is the structure of the hydrocarbon, C7H12, that yields the keto-aldehyde below in the ozonolysis reaction? (circle correct structure below) H m g Q (1“ 12 (ii) Zn. H20 HCCH2CH2CH2CCH2CH3 CH3CH2 3 CH3 (H) An unknown compound is soluble in concentrated sulfuric acid but does not deCOIOIiZE‘ a SOlution 0f BIZ in CC14. Which structure below is consistent with these observations? (circle answer below) 006 H‘ (1) Identify the hydrogens that are diasteriotopically related in 2-chloro-1-butene below. ~none of the H are diasteriotopic H. (I) In the compound below, A B c D 1 N l \ CH3OCH2CHZOCH2C1 the most downfield resonance (signal) in the 1H NMR spectrum will be from hydrogens labeled (circle correct answer) A B C Chemistry 322aL/325aL -7- Name ‘ Exam No. 4 (4) (10) Reaction of trans-l-bromo-Z-methylcyclohexane with sodium ethoxide in ethanol produces only 3-methylcyclohexene, while the similar reaction of cis-l- bromo-Z-methylcyclohexane gives a mixture of 1—methylcyclohexene (major) and 3- methylcyclohexene (minor). CH3 CH3 .«Br Na+ 'O~Et __.___> CHSCHZOH CH3 CH3 CH3 Br Na+ 'O-Et —-———> + CH3CH20H minor (A) (4) Draw the conformationally correct structure of the trans isomer required for this reaction in the box below. Briefly explain why only the 3-methylcyclohexene is formed. ‘ \% +NS flac‘h't‘OM’ ‘rl’xt \zmvl'tfij flmu93 Mvé'l‘ ‘04 va'ti- pzr’s P\cuv\a.f‘ HNMLk “Lawns dXCA‘MK\ \'Y\ a. (Y Q“) htxgq—p‘q , E\KK§~\«H o M («M °M\Y occucr- (m o'yuL leCHoM Uk‘lm CL VD‘l'\ TS CL‘tKTO-A. TMT$ Pu‘\"\~ “Prodxmus trans-1-bromo-2-methylcyclohexane 3‘ ML +4“! (6, CAD k LX (“Q . (B) (6) Draw the conformationally correct structure of the cis-isomer required for this reaction in the box below. Explain why two alkenes products are formed and why 1-methylcyclohexene is the major product. (DH—M Ackae ct“) “\sumzw’ “HAL rLckutrLcl CX'YV‘F1 .— gut—VT 9\,C-.’V\cq‘ COW-gar Meg-56%)“ (TC (mot/mi jmwps \5 ?Vts¢m+ \'7\ bow—M dere-‘fioms "u. $0 Wm 04x cempfifimfi EL infi—HOMS, cis—1-bromo-Z-methylcyclohexane Wm l-ML—ka/lO/Llo berLA/UL \S mafia r— Pro dues-k— \QQC (Lug H‘ \3 Mo FL $+c~lola Wm 3»MLW7(QJ<LXokem—ne . \M +'\:\4_ T3 For GIL) +\'\L““~ ‘3 AKVQAOG‘VA‘ ou\\§d_'y\¢._ Q\/\CLT‘°~¢)Y(-\" 'Hvrt‘ CLEVKV “PM: +\\&. ‘- o— ‘VL fl— ‘S 09 TWAIN Kort/\QL ‘l‘t‘m lilif/Wg vwm S’hdolg angMK \g (Omar Chemistry 322aL/325aL -8- Name Exam No. 4 (5) (15) Propose a plausible synthesis of 4-methyl-1-phenylpentane from 3-methyl-1- butene by way of 3-methy1-1-butyne using only benzyl bromide as an additional organic chemical source. You may use any other needed reagents (bases, acids, etc.). CH3CFHCH=CH2 CHscHCECH _ CHaqHCHzCHfiHzCeHs CH3 CH3 CH3 3~methyl—1-butene 3—methyl-1-butyne 4-methyl-1—phenylpentane usmg QCHzBr and any needed reagents. benzyl bromide Write out each reaction in your synthesis as a separate step showing reactants, reagents and products. Your synthesis should be a series of chemical reactions. t" ‘ 3 N ; a 1m 3:129 CH QHCHQH firm Ji? “will WW3 H L 3 \ L \‘\ (H3 1 QHB H ) Hzo H < H EC'CH * a CH \ Or 9"? 3 cagchachZQch bu g cHg Chemistry 322aL/325aL -9- Name Exam No. 4 - (6) (10) The energies of the nuclear spin states for two magnetically nonequivalent H (H A and HB ) change with increasing magnetic field strength (Bo ) as shown below. (A) (3) At a fixed value of Bo, will the resonance condition be achieved with the same frequency of electromagnetic radiation, or different frequencies of electromagnetic radiation for H A and HB? If different frequencies are required, which H requires the greater frequency? 2/ DFQ-‘Qtr‘ “gr”? tum: HS. OIL mam? PLQL. HA Nikkim‘b ex \avafl r “FD? k WMt—h o k-go m I. Ck {ewut‘ Jr-o MS‘M" Spmx i-l—k‘f‘cz , (B) (5) In general, what influences cause the spin states for H A and HB to respond different] to B ? Give an exam le of one such ‘ H e ce. y 0 p filer/25) 3 Lo «Li (\n-l-ercu\\ "‘0" "A'L'Hg‘q hm? IKLfiALC’S CowLSk. Hrs CK'KCl 1 \-lg +0 IDA MIL "AL‘HC «H mm“ u‘Oq\¢L—~,{i~——— Meat—mqu bio—tr spm s—Hc‘ms cesium/xi %mej +0 Bo. WK Q’kLrsy gap inn-hunk flux 39m fi‘h-Jk; «la PPM}; 6" 7L2 O'M fig, MkS’Kt—‘EK 744A S-l-rI-N/lk Surfikk b1 1"“ MM Mac/Luis. L004 mtme cuts cm "\«7 mumm— e “‘7’ tax—XE; 8%: “r: axtfli (3?”- “Mitts ‘ ’ "K 2 ‘L a ,__ - u (\Vw'tq Largesk {kg Q—\¢~L‘\T~OM dmm H IIL d‘ hm‘ Qikss Ska‘d—[drmfit ,fi‘QlQ—ciroms Crrgv (can; (4‘ fi‘%3 +0 ,(C) (2) In the above diagram, finch H (H A or HB) 15 more shielded? Mamie o 0 (meme; +a cwx minted field Lap/(l4 sp‘Ltdjmj tics mldF‘KS Stealer: . He (3 horn Shmfclch ...
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322af01_e4_key - 4mm (:97 CHEMISTRY 322aL V Please EXAM NO....

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