322af06_final_key

322af06_final_key - CHEMISTRY 322aL / 325aL FINAL EXAM...

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Unformatted text preview: CHEMISTRY 322aL / 325aL FINAL EXAM Please kt fl Print Last Name DECEMBER 7, 2006 (1) (15) (2) (15) (3) (15) (4) (20) (5) (20) (6) (30) (7) (20) (8) (15) (9) (15) (10)(10) _ (11)(25) _ (200) First Name First 4 digits of USC ID _ _ -XXXX-XX TA's Name Grader Lab Day & Time first letter of last name I will observe all the rules of Academic Integrity while taking this exam. Chemistry 322aL /325aL Name -2- Final Exam 3 04/ (1)-(3) (45) 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. Show or describe stereochemical details in the products wherever they are important, such as a racemic form of a chiral product. (1) (15) H3 £83 (A) CH3CH2CH2 HCHzBr + KOBu-t t_BuOH cugqulq-‘zizqrh product decolorizes cold aqueous, alkaline KMnO4 (i) NaNHZ, Liq NH3, -33°C (B) CH3CH2CECH (ii) CH3CH21 g h + NaOEt CH3 (100% ee) ma, 6 JOI‘ product only A soluble in cold, conc. H2504, but does not decolorize Brz/CC14 1 : H3 Br heat H H20 / THF (THF is tetrahydrofuran) two major products are separable and neither decolorizes Brz /CC14 solution C|H3 9H heat (E) CH‘TCE CH-CH3 conc. H2504 CH3 major product Cf,le shows only single resonance in 1H NMR Chemistry 3223L / 325aL -3- Name Final Exam (2) (15) / H3 (A) CHBCH2 :CH2 cold a ueous KMnO , KOH H3 (B) (1) hot KMnO4,KOH/HZO 5 (ii) H3O+ H‘ CH3 (100% ee) hv + Brz heat CH3 (1000/o ee) (5) C\ OH . HCl product is insoluble in come. H2504 and does not decolorize Brz/CCI4 ( CHBCH 2CH3C\ 001043 Q HS f c C7H15BI' (i) Hg(0Ac)2/THF,H20 OH CH3 ————> > ‘ H3 (ii) NaBH4,KOH,H20 CH3C‘HCH CH3 CSHIZO ir: strong bands 3200-3500 cm‘1 1/4 R643lxcél-ch/LCé/Log M W V JfAC/VW) Chemistry 322aL/ 325aL -4— Name Final Exam (3) (15) geHs (A) CH3, l‘H CH’3 g\BH2 C6H5 (as a racemic form) (PH + PBI‘3 racemic form l (H C_H:_QHCH3 3 product is insoluble in cold conc. H2504 ,... c H3 H: BH3.THF Ema ram mu {me (C) [If THF , H °€ 5"“st Amish N o , M B N V esHus * W1 than 241; I; (D) HCE C(fi\C1—120H+ (CH3)3SiC1 amine base CH3 (100% ee) H— 1—14 \\CH3 E 3H HA" -“ H an 0 0+ 0 (E) — 3 H s 2. C\ f + NaOC 3 CHsoH ‘ Chemistry 322aL / 325aL -5- Name Final Exam (4) (20) Answer the questions below. (A) (5) Add any missing formal charges to the structures below where all valence-level electrons are shown or are implied by the bonding. Add the charges immediately next to the atoms on which they reside. If there is no formal charge in the structure, write "none" on the line below the structure. (B) (10) Indicate whether each structure below is chiral or achiral on the line below each structure. Identify all stereocenters in a structure with an asterisk (*). A stereocenter is defined according to the usage in our textbook and in the lectures. oH CH3 HCHCH(CH3)2 H as ‘3; Ca.) (C) (5) Identify the pairs of structures below as constitutional isomers, enantiomers, diastereomers, or the same compound on the line below each pair. L ?Q R\-’5~\>rorno -!—Egm‘\'"0.nz L R‘ ~ 3~ bromome-J "Gong Chemistry 322aL / 325aL Final Exam Name (5)(20) Answer the questions below. (A) (3) Provide a complete IUPAC name for the structure to the right on the line below: £%x n/ovf (B) (3) Provide a complete IUPAC name for the structure to the right on the line below: kw I-MHM hue s- {m— z~o\ “l MAM/L61, (C) (3) In the box to the right, draw the most stable conformation of cis—3-ethylcyclohexanol. Wfiud) (D) (3) In the box to the right, draw a bond-line structural formula of (E)-5-methyl-2-hexene. I W (E) (8) Circle the more file isomer in each pair below and identify each pair as constitutional isomers, conformational isomers or diastereomers on the line below the pair.. 9H CH2=CHCH2CH2CCH3 CH3 0 H “$7.. \ )-2-butene dfimg‘k'it’comt S ~ chrgo NV» V S Chemistry 322aL / 325aL -7 Final Exam - 1 2 k (6) (30) Circle the correct answer to each question of statement below. Name (A) What are the molecular formula and U-number (degrees of unsaturation) of the structure below? (circle answer below) W C9H120 2U C9H120 3U C9H14O 2U < C9H14O 3U ) B enum erso va ence e ectrons e C emlca S ec1es e OW are Th b 1 1 1 h h ' 1 p ' b 1 (circle answer below) H 4(:N+ HCOZ- 1 13,1117 112,1118/) I II I 13, II 18 I 12, II 17 (C) Among the organic compounds of comparable mass below, the one with the highest boiling point is (circle answer below) H3 c CH33CH3 CH3CHCH3 CH3CH2CHZOH 3 CH3CH2C1 MW 58 58 60 / 64 (D) In the structure below, the order of acidity (strongest to weakest) of the labeled H is H (circle answer below) 1 d S? f N- III 11>111>1 l ./ H b (E) Tartaric acid has the structure HOOCCH(OH)CH(OH)COOH. Which Newman projection formula below is the meso-diastereomer of tartaric acid? e below) OOH H H H\ H HO\ H H\ H H COOH HOO H OOH OOH OOH Chemistry 322aL/ 325aL -8- Name Final Exam lag/V (6) (Contd) (F) Which of the factors below will facilitate a nucleophilic substitution reaction 5N1 R-X + Nuz- R—Nu + X” by the SN] mechanism? (circle answer below) a tertiary R group in RX a primary R group in RX H and HI I II a more polar protic solvent a higher conc. of Nu:' 1’ H and HI H and IV 111 IV (G) The dominant mechanistic pathway for the reaction below r (circle answer below) CH3CH2§CH3 + ethanol prOduCts be 5N2 @ H3 (H) The major and minor products in the acid-catalyzed dehydration of 2,3-dimethyl-2- butanol will be f? H3O+ H3 EH3 9133 CH3 H -i’l. _ _ _ _ __I__i -6--- CH22CH_ CH3 CH3 H3 CH3 eat, (' 2 ) CH3 CH3 CH3 2,3-dimethyl-2—butanol I II III II major, I and III minor C II major; III minor ) (circle answer) II major, I minor III major, I and II minor (1) The proton-decoupled 13C NMR spectrum of C6H1'4 shows two resonances at 5 19.5 and 5 34.3. The alkane below consistent with this spectrum is (circle answer) hexane 3-methylpentane 2,2-dimethylbutane 2,3-dimethylbutane (I) Which statement below is not true about mass spectroscopy? (circle statement) -A beam of electrons induces ionization of molecules producing "parent ions.". - 9-. . -.- - ratedb anelectri '_ .n n-- o-I- db ama eticfield. -The masses of both ions and neutralvfra ments a ear in the mass spectrum. - n a 1 on o " o - I . ' weig an e emental composition 1n orma ion, 3 ruc ural information is obtained by mass spectroscopy. Chemistry 322aL / 325aL Final Exam -9- 1 flow Name— (6) Contd. (K) The relative reactivities of C-H in the photochlorination reaction at 25°C are 3°-H, 5.0/20-H, 3.0/10-H, 1.0. This information indicates the monochlorination product mixture in the photochlorination of butane will be h CH3CH2CI-I2CH3 + c12 ZSZC CH3CH2CH2CH2C1 + CH3CHZCHC1CH3 I II (circle answer) I/II = 3/1 2/1 @ 1/3 (L) The stability order (most stable to least stable) of the alkyl radicals below is . (circle answer below) CH3CI'12qH—ICHCH3 CH3CI'12‘;CHzCH3 CH3CHzQHCI'12C-Hz I>II>III CH3 CH3 CH3 1 [I III I>III>II III>I>II (M) Which statement below is true about the free radical halogenation reactions of methane? CH4 + X2 CH3X + (circle correct answer below) -All the halogenation reactions (fluorination, chlorination, bromination and iodination) occur equally well. ~Only fluorination, chlorination and bromination occur because of energetically favorable initiation steps, while this step is unfavorable with iodine. . -Iodination does not occur because of the energetically unfavorable step: ~CH + 12 —> CH3I + I- ~ - odination oes no occur ecause of an energetically unfavorable step: I- + CH4 > -CH3 + H1 (N) Which reactions in the box below give anti-addition products with 1,2- dimethylcyclopentene? CH3 hydroboration oxymercuration bromination anti-addition I II III _______ ' ' I HBr / peroxides epoxidation with peroxyacids IV V (circle answer) I, II, III II, III, V only III (0) Which synthetic methods inside the box may be used for the reaction below? 93H?) (FH3 . . + CH3 CHZCHZ ........ H. CH3 _ HCH3 directhydration(H3O /HZO) II H H conc. H SO thenh dration III H3 3 CH3 hydroboration then oxidation I (circle answer) I, 11, IV I, III only I only IV oxymercuration then demercuration IV Chemistry 322aL /325aL -10— Name Final Exam (7) (20) Answer the questions below. (A)(8)There are four alkene isomers of C4H8. Provide the proper structure in each box below according to the information provided. Stereochemical details must be shown. alkene isomers of C4H8 luck number of resonances in proton—decoupled 4 3 2 2 13C NMR spectrum AHgomb (kcal /m01) -649.8 -646.1 -647.1 —648,1 (AHocomb is the heat of combustion.) (B) (12) The 1H NMR spectrum of compound A, C6H12, is shown in the Appendix. Compound A reacts rapidly at room temperature with Br2 to produce compound B, C6H1ZBr2. Compound B is an achiral compound. Compound A reacts with hot aqueous KMnO4 with added KOH to produce compound C, C5H100, and C02. The 1H NMR of C is shown in the Appendix. Provide structures of A, B and C in the boxes below. A (26H12 hot KMnO4, KOH I see Appendix for H20 1H NMR spectrum A6 ("Eff % 1% C CSHmo x4 ,‘ucofvvecf 6‘“ Z ifffififiifiélfm chm/3 V? Y“ ' Chemistry 322aL / 325aL -11- Name Final Exam (8) (15) The ionic addition (no peroxides) of HBr to 1-methyl-1-vinylcyclopentane gives 1-bromo-1,2—dimethylcyclohexane as the product. H=CH2 H3 + HBr —————-——> CH3 BI‘ CH3 (A)(10) Provide a plausible mechanism to explain this result. Use the curved arrow formalism, show all key bond making and bond breaking steps, identify the rate- determining step, and circle key intermediates in your mechanism. In the shadow box, identify the key factor that promotes for u . in of the observed product. QCHQ fl ——8 (H3 4. H r ®_CH (Q C 5 1‘2- AWmv'a-‘l H3 Sk2$+ . Q43 H e 'hv L\Lop\'\‘\l§ @CH/t F ago“; DJ; SKIS-r is E>Wrwh<L +kk New 3D’CQPBOQMH0’IH. (B) (5) The product actually is a mixture of two separable isomeric compounds. What are they? Be specific. . \ (TWO F’WdugtS O-Frgk ""\ «V Q\L°Pkk Tk¢ am deS‘l‘V-(‘Lefi/VLFS. CH a"; C4] 7 W‘— +3 B?__, "5+ / 3 @ w ' BA Will these two products necessarily be formed in equal amounts? Why? (3 'Tk N0_ +Loo (‘LQLHO’K FG-Yks \'T\ 'I\U<,\L0 flgtfio’K G-T‘L “Rafi mtrror TlV'o/ (1K drought“: MOPULK\\7 ra\a+L4\. 2 «415,, Chemistry 322aL / 325aL -12- Name Final Exam (9)(15) The oxymercuration reaction of 3,3-dimethyl—1-butene (1) yields the hydroxy mercuric acetate addition product (II). H3 Hg(OAc)2 (FHs CH3 -CH=CH2 ———> CH3 —%H-CH2-Hg-0Ac H3 H20, H3 H I II (A) (10) Provide a mechanism for this reaction. In your mechanism use the curved arrow formalism, show all key bond making and bond breaking steps, and circle the key intermediate. Carefully show the step that determines the regiochemistry of the oxymercuration reaction. Explain the regioselectivity of this reaction with resonance theory by drawing a§ries of resonance étiuctures inside the box below. HSQOAC\LT:> 3‘0AQ + CH 3 cuz‘c—cuzcuz + @3‘OAQ c243 U ——-—: i‘H + 5., r: H. \ H ‘3’ 1cm: r (We as (C93) C“ C“ " CHLHfiO‘AQ $93 Nu k\tc+ro POSV'fiék {(—_ H O M l? (‘crigsccuq-tIt???0AK + HLD: -——> (cnségCCHCX-tzkgovkq + HQ (B) (5) This icular reaction is often cited support for the generaaccepted mechanism of oxymercuration. Briefly describe an alternative mechanism and explain why the formation of II from I would seem to rule it out. A“ NLKN’X?3W\ (a: ‘QT‘MQJT'KOM 0+ qt Cor‘moCLAKfiom "C'K‘WrMLAuSE‘. Q l , ,A 7‘9 - "C— 5—) CH3 A” cH—cuiqsoaq cu 140% Chemistry 322aL / 325aL -13- Name Final Exam (10) (10) Provide the missing structures in the boxes below by completing the stereostructures. 1:1 Path A ? Path B H o V'ch C H 3 CHZCHZCH3 CH3SOZC1 NaH amine base (S)-2-pentanol (100% ee) ether solvent I;1 I; <937$Voc H: q__ L ~5- cuzo r$V CH3 CHZCHZCH3 CHZCHZCH3 11 III (100% ee) (100% ee) What term describes the overall stereochemical outcome for I ------- ——> 11 Q] by Path A? lmwfi g Q 3 “L What term describes the overall stereochemical outcome for I ----- ——> III by Path B? Sid-$3533 0 ~\ M6— 546 ‘f‘ SM {(36%}‘0'W’W M H46!“ Chemistry 322aL /325aL Final Exam (11)(25) Provide reasonable syntheses as requested below. Each synthesis should be a series of reactions with starting materials, needed reagents, and products shown for each step. Stereochemical details in structures must be shown. A table of selected reagents that were discussed this semester is provided in the Appendix. You are not limited to these reagents in designing your syntheses. (A) (15) Propose syntheses for the three transformations below. H/ H ' ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ' — - ---> SL\IA'\’I\N\ KA‘M O C H C ECC 44 LL H a. x a r w> \/ : C, MM pp Pow: o«~Lde.j\~_ (“let S— \< “HY 0r 0 H N‘ g /:r£ooH H z, n. -._) anp 3 RFC) \Coig] W92 H —N H H (ii) CH3 """""" m» CH3 H H 6 H “limo” New H ov~ Q1U\U&\o4;‘\ CN 290,52 QENH fir H (iii) CH3§CH3 ——————— -—* CH3 HCH2Br H3 H3 gch Mm 0E4 CH C __ CH 16:3" CH A ._____9 33H 3 (i-tlxumfl gq‘qg K Pare «54: g 3 lL o u I CHSE. \ o H j Qh'mz ham f 3 ath:—h;\9\ H \l Chemistry 322aL / 325aL -15- Name Final Exam (11) Contd (B) (10) Propose a reasonable synthesis for the transformation below. ................. w CH3CCH2CH2CH2CH SL\LQJ€\VL \L\9Lz\n 04'" 0 q" BY; BC NCLOE+ \ “3 l\'\}( lx<LoC\’ CH3 Q+\\Q_’V\0\ H3 Appendix Proton NMR Spectra for Problem 7 Compound A C6H12 C. Compound y C5H100 ...
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322af06_final_key - CHEMISTRY 322aL / 325aL FINAL EXAM...

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