HE3Key - NAME kEY LAST FIRST CHEMISTRY 152.002 Spring 2005...

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Unformatted text preview: NAME kEY LAST FIRST CHEMISTRY 152.002 Spring, 2005 April 19, 2005 R E II I 30 II 40 III 15 IV 15 V 20 VI 30 TOTAL 150 Exam Begins Here I. (30 points). In the answer area below, darken the space of the most appropriate response to each of the following muitiple choice questions. ANSWERS TO QUESTION I a b c d e a b c d i e 1. II I II II II 4 If I U // ll 2. I! I! I! II I 5. II I II I! ll 3. I! II I II If 6. II I! If I ll Initials—kil— 1. Which of the following compounds could not have been prepared by an aide] addition/condensation reaction? . O OH W (EIGHZOH OH AN W O O O A B C D and C 2. Which of the following compounds would be the most basic? NW: 0 0 Me O 0 Me Mex )LNM A/NW /u\/\N/\ MN\ Me Me A B C D E a. A b. B c. C d. D 3. Given the ionization constants for glycine of pKall = 2.34 and pKa2 = 9.60, at which pH is glycine least soluble in water? a. 1.17 b. 2.34 @597 d. 9.60 e. 11.94 4. When the protein-related material from the newly discovered Alabama Red Neck pond frog was- isolated there was obtained a new a-amino acid with an isoelectric point of 9.23. The side chain of this amino acid was most likely: a. neutral @basic c. acidic d. zwitterionic e. amphoteric Initials j 5. When allowed react with D20 in the presence of a trace amount of NaOD, which hydrogens in the molecule below wiil be exchanged by deuterium (D)? 0 HC HC 0 Haws Hb Hbe Ht, a. H, b c. Hc d. Ha and H, e. Ha and Hc 6. Which of the following statements is (are) not true of the carbonyl group? a. Carbonyl groups can behave as Bronsted bases. b. The enols of carbonyl groups can be nucleophiles. c. Hydrogens or. to a carbonyl group can be exchanged by deuterium (D). Enolates usually react as electrophiles. e. Two of the above statements are not true. Initials k EY II. (40 points). Draw the structure of the major organic product of each of the following reactions. Be sure to indicate stereochemistry if it is an issue. If no reaction would occur write NR. Unless otherwise stated there is enough of all reagents to react completely. Reaction mechanisms are not necessary. (3021.1 1. 80012 NEH.- 2. NH3 (excess) 1. 3. BrleaOH/HEO (warm) CH3 W} CH3 1. LDAITHF. -7a° DB 2- CH30H2BI' O o CH20H3 1. Me! 20% .nNM92 2. AQZOIHZO 3. 3. heat "'CH3 .3 1. SanCI H30 N02 2. NaNOZIHC] H 4. U 3. H20, Cu20, (3110103)2 W O O 1 . NaOEt (cat)/EtOH + 5. + Hack/c023 2. H30 Iheat (C12H160) CH2 CH3 1. NaOEt (1 equiv)/EtOH; - HCOzEt 6' m0 2. 1130+ 7- we Bra, NaOH, H20 0 r O f O 1. NaOEt (cat)/EtOH \ CH0 + a. 0 + T 2.H {heat QH3 I CC“ Hmofl mumsw III. (15 points). When compound A below was treated with thiophenol (PhSH) and a mild base (K2C03) in methanol product B was formed in high yield. Provide a mechanistic explanation for this transformation. Most of the product stereochemistry has been omitted for clarity. O HMe 0 Me Me PhSHlK2003/MeOH ’H Initials KEY IV. (15 points). In the boxes below show the structures of the compounds formed by the successive treatment of the di-sodium salt of aspartic acid with three equivalents of HCl affords. The three pKa values for aspartic acid are 1.88, 3.65, and 9.60, respectively. In the last box estimate the value of the isoelectric point (p1) for aspartic acid. A COZH I + HaN 002' aspartic acid 1 equivalent HCE PI 7‘ (9mx +PEC~2 l {Lea +3.cs’)/2_ 2.4.07 aspartic acid isoelectric point V. (20 points). When pure 3-ethylcylopentenone A is treated with dilute NaOH in methanol a new compound, 2,3-dimethylcylopentenone B is formed. In fact after extended reaction time an equilibrium mixture of A and B is formed in which B is the major component. Write a detailed reaction mechanism that shows how A is converted to B. Wh es the equilibrium mixture favor B? o o NaOHIMeOH H30 H30 H C n 6—) A a a no O 9 Mao-H , a//, “‘9 Ros-x CD‘S + to “A to r. \fi -: #:"5 .... J: OH ID r9 {'1' [g H H—0 (3—) Meo- b 0—5 Ilm VI. (30 points). Show starting material and an isolable intermediates. Initia13__k_;§_L___ you would carry out the following two transformations using the indicated y other reagents (organic or inorganic) you might need. Show the structures of all Reaction mechanisms are not necessary. how O OH \ We? 3 \ 2. if: \ didrdfikbw “ Lemma/YEW“ o C : a. 635A. C0252? {If—A i _..———-p H \ / [211.0 E— O \ %V%Br L? Q5532” u. —-CD.L 3 __________D L E 2e: 2- \ No2 B ? BI'OBF CH3 . CH3 *- M0 N“; H”?— \ S 3"“ Q ‘3“ 9%?” _..—- '—-—-—--—--—-—D ————-——P m3 G) QJt m3 _ Q Ca- H2. 0.43 ...
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This test prep was uploaded on 04/01/2008 for the course CHEM 152 taught by Professor Baldwin during the Spring '08 term at Duke.

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HE3Key - NAME kEY LAST FIRST CHEMISTRY 152.002 Spring 2005...

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