C201HF07T2 - 1. For each of the pairs of structures,...

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Unformatted text preview: 1. For each of the pairs of structures, indicate which is more stable. If, for example, you chose the left structures for all three comparisons, your answer would be L, L, L, which corresponds to “a”. _, c. flair-{4:075 T2 _ owe}? a... a l 1 II." I ‘- \ vs.- a “5- i 1 vs. I + I (CHzlaCHa 'EI -' 1\ CH2Q_H 3 /_. a. L, L, L b. L, R, L c. R, R, L d. R, L, R @mne ofthe above 2. Which of the following mechanistic steps in the acid-catalyzed hydration of propene is the slowest? a. attack of the pi-bond of propene onto a proton to form a 1° carbocation (9 attack of the pi-bond of propene onto a proton to form a 2° carbocation c. d. e. /"7++’+ A ““5‘ +4. 2 0 attack of water onto a carbocation attack of water onto the proton of a protonated alcohol to form product (acid-base reaction) impossible to determine; it depends on the temperature at which the reaction is carried out 3. Which alkene is preferred for making the alkyl bromide shown at right? i? 4. Give the major product of addition of HBr to the following: / / ' N k a. Br ® . Br d. e. 6 Br °>H\ r S. The stereoisomers of the amino acid, isoleucine, are shown below. Indicate the relationships between the structures. w. 002' x. 002' Z. coz- Y. 002‘ «t- + + + H NH3 H NHa H3N H H3N Et 9 Me Me Et Et Me Me H H H /a’. W & X are enantiomers, Y & Z are enantiomers, and W or X are diastereomers of Y or Z . W 45'; Y are enantiomers, X a Z are enantiomers, and W or Y are diastereomers of X or Z @W & Z are enantiomers, X & Y are enantiomers, and W or Z are diastereomers of X or Y d. W 8: Z are enantiomers, X & Y are identical, and W or Z are diastereomers of X or Y e. none of the above 6. Name the following compound: H CHZCHECH3 / (E)-4—propy1—3-octen-7-yne \; g / b. (Z)-4-propyl-3-octen-7-yne /C= \ (Ej-S-propyl-S-octen- l -yne '_ , . .. __ (Z)-5-propy1—5-octen-l-yne g" %PT35¥12 9H2C _2_E..={EHD e. (Q-S-butenyl-l-octyne q 73— 7. Compounds isolated from the Australian desert plant, Eremophiin neglecra, such as that shown at right, have been shown to exhibit antibacterial activity. What is the maximum number of potential stereoisomers for this compound? (stereochemical information intentionally omitted). a. 4 or less @8 c. 16 d. 32 23 e. 64 or greater - 8. Assign R/S configurations to carbons A and B, respectively in the compound shown below. For your convenience, the molecule is shown twice so you can do your assignments separately. CHZCHg a. K R A A CHZCHa 13- R S — x P\ s a) @s, R H OH H 0H d. S, S r Ho H Ho H ' a He E Hc 7‘ — (61-367 \\ z\ 9. The specific rotation of cholesterol is -3 1 .5° at 598 um and 20°C . What is the observed specific rotation of a pure mixture of 33% cholesterol and 62% of its enantiomer under the same experimental conditions? a. (0.33 — 0.62) x 315° @062 — 0.38) at 316° c. (0.62 - 0.38) x 015* d. In (0.38 — 0.62) — e3” *2” e. not enough information is provided to answer the question ‘f-MH-l - i 13¢ 10. Includin stereoisorners, how many mono—alkenes (compounds containing one double bond) yield an 2-methylpentane on treatment with H; and Pt /C? on! CM;C.H cu, CH: 04 a.20rless b.3 6:91 d.5 6H3 a“; 7:43 I i m = an H ca 6!: CHLH DH cu cw. mam tr! . . . . 2- 311.3(3- ii“;£tfg ;' nib-r - " rm)“ 5 W‘Wm‘i‘fi' ' 319"” ll. Methyl tert-butyl ether (MTBE) 1s a gasoline additive used to improve octane rating. Which of the following yield(s) MTBE? I‘ (HECH [Hpuztt e. 6 or greater MTBE a? tert—butyl alcohol (l'UPAC: 2—methyl-2-propanol), methanol, trace acid 0/ ,h’. dimethyl ether (IUPAC: methoxymethane), excess CH3Br, trace acid 6:) l) 2-methylpropene with Hg(OAc)2 in THF I methanol 2) NaBE d. 2-methylpropene, methanol, trace acid tug H o W's c. More than one of the above yield the product & “‘5’ Egg” A 12. Use the homolytic bond dissociation enthalpies from the table provided on the last page to estimate the standard change in enthalpy (AH°) for the reaction of HCl with 2~methylpropene to produce 2-chloro~2-methylpropane. Assume it takes 63 kcalfmol to break the n-bond. We can say the reaction is by about kcaUmol. a. endothermic; 10 b. endothermic; 20 one of the above c. exothermic; 10 d. exothermic; 20 LJJED I .. \t .’ -tu Indicate whether each of the following pairs of compounds are: (3) identical, (b) constitutional isomers, (c) enantiomers, (d) diastereomers, or (e) different compounds that are not isomers Each question has a single answer, but answer choices can be repeated between questions. H '1 14. 3 CHzBr , Br CH3 5 g H CH3 H H Br - 1 Br ffH H c gar-r ——-—‘» tar-44H (Azalrtfls . . . . * 'i 16. Starting from ethyne, whrch is the preferred method of preparmg 2-pentanol? w _ Lumiwl Of} a. 1. NM; 2. CH3Br 3. NaNH; 4. CH3CH2B1' 5. H2304, H10 7' b. 1. NM; 2. CH3(CH2)‘Br 3. H2804, HgSO4, H20 W i CwC-WM'S @1. NaNHz 2. CH3(CH1);_Br 3. H2, Lindlar‘s catalyst 4. H2804, H20 . l. NaNH; 2. CHgBl' 3. NaNHz 4. CH;CH2Br 5. H2, Lindlar‘s catalyst 6. H1304, H20 e. 1. NM; 2. CHgBr 3. NaNHz 4. CH3CHzBr 5. H1, Lindlar’s catalyst 6. Hg(OAc)2, HZOITHF 7. NaBH.‘ 17. Indicate the product. .. PH 'rm .f. [r 3., r , "g P i? \\ 1_ 3H, E'I'HF : «urmOH ' 0 ‘ 0 R ‘\\\\ 2. H302, on; H10 fl 0H / -._- Plus manual-nel- plus enantiomer plus ensntiomer plus enentiomer “r on 18. For the reaction of 2-methylpropene with Hg(OAe)2 in methanol and THF, which of the following correctly depict a step in the major reaction pathway and which do not? Lu} Hui... c_.—-3--""3 :1“pr (\ * Hg—OAc H\ __ ® /—\ one " HQ—OAc 9/ / n + W k —" Hg RON: V- CH3§H 2‘ +Hg—(Mc H‘s/0A: X .3 _. g: X, H 1.2 hydride shift r’ '\ ‘ CH3:C:)H a. W, Z are correct; X, Y are incorrect b. W, Y are correct; X, Z are incorrect c. X, Z are correct; W, Y are incorrect @ W, X are correct; Y, Z are incorrect e. Y. Z are correct; X. W are incorrect C _ [In -g‘-t.;____.@ a. 1, 11, v “ I, III, w {L _f_l 19. Which of the following compounds have at least one achiral stereoisomer? 1"I (l i t Li I U. - - (—v _Q, ‘ I f if— (K: L C“C'C"C—- c. c'- Note: if a compound has no stereoisomers to begin with, it can’t by definition have any achiral Stereoisomers. {/1 2,3-dichlorobutane 1,3 -dichlorocyclopentane ‘ 2,3—dichloropentane " ,3-dichl _ -2,3—dimethylbutane ® 1.6!? gs. __ ' i/ . ' V. 1,3-dib mocylobutanéijfk - -' ' (_5 .- ___ k F, e ._._ c. 1,-1y, v? d. 11, IV, v e. I, 111,1v “e ._ El 20. Indicate ihe major product fonried by treatiné 2—bentyne with excess HCl. £1 a. 2,2-dichloropentanc only L Mu , b. 3,3-dichloropentane only CH“: C E C WW3 —-—") CH: C; CH? Elf/Fm"? (a) mixture of 2,2-dichloropentane and 3,3—dichloropentane a {Lo-‘0' _d. 2,2,3,3-tetrachloropentane only r; I. e. 2,3-dichloropentane only CH3 CHTCE (“if—H3 Cl 21. AG” for the conversion of A to B, as shown below, is -5.0 kcallmol. What is the expression for the percentage of B at equilibrium at 20°C? R = 1.987 x 10'3 kcal mol'lK'1 _ [1-5.1 '- "50 5&1 T _ RTM \Lect '1' : 7'73 Qty” 91 A B . Kag- : 8 a. 1 x 100 b. In(5.0!1.987x10'3 * 293) 96‘3""? m 5.0 r1331 10‘3 * 293 "'"fi—Z" " l + 3[ x ) H QW I21” 5.0 H.987 10-3 * 293 _ £1.98? *3 * 293 g c( x j 100 d. (ego “0 } — 1)x100 " (5.011.987 x 103 * 293) x 1 + {‘3 1 e(5.0f1.937x10‘3‘ 293) 6- + x 100 (5.0 H.987 x10‘3 * 293) 22. Indicate the major product: W011 M / Clz e (:1 Cl: :1. —-—‘i- (3:12:312 H Cl ,9! ,4 0 0 CI Cl C] 0 Cl 23. Addition of Br; to (E)-2-butenc yields: 01?; I l4 ,9, 1: It: --‘9 Pg . . . . . \x Z. a. a Single compound which 15 optically actlve H {H 3 a single compound which is optically inactive I c. aracemic mixture [5? '3, an“ A, has A a fruit, d. two compounds that are not a racemic mixture 1 ' l 24. Epoxidation of 4,4-dimethylcyclohexene yields: Note: For purposes of this question, ignore the carboxylic acid (RC02H) side product. a. a single compound which is optically active ° "W" ‘ d “ " e"? I“ i b. a single compound which is optically inactive Q “0;” I c. a racemic mixture @two compounds that are not a racemic mixture 25. Hydrogenation of which mono-aikene produces the product shown in the box? H ME : = Pr = Bu = CH3(CH2)3 {Kiri plus enantiomer Chas cum“ CHLLHE I 51-11 CHLUP'Ib Your Answer( 1- 50): EBCBCDBCBC CEAADCBDBC CDBDC Correct Answer : . . . . . . . ..D E...C.A.C. ...CB ...
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This note was uploaded on 11/05/2011 for the course CHM 201 taught by Professor Colonna during the Fall '08 term at University of Miami.

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C201HF07T2 - 1. For each of the pairs of structures,...

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