Midterm 1 Key

Midterm 1 Key - Name: x.-.» page 1 1 Chemistry C3443 Fall...

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Unformatted text preview: Name: x.-.» page 1 1 Chemistry C3443 Fall 2004 X Midterm #1 {K 57 75 minutes 0 September 27, 2004 Instructions: (1) For some questions, you have a choice of which problem(s) to answer. For these, cross out (X) answers you do not want counted. (2) Notice that for each question, we have suggested how much time you spend on that question and indicated how many points it is worth. We suggest that you first go through the entire exam and answer the questions that are easier for you and then go back to the questions that are harder for you. (3) Put your name at the top of each page. (4) Unless indicated otherwise, all structures should be skeletal (line) drawings. The exam contains 10 pages (including this face page). The total number of points is 100. I. 1. 2. 3. 4. 5. II. 1. 2. 3. III. IV. V. TOTAL: / 100 Name: page 2 I. For the following compounds write the I.U.P.A.C. name or draw the compound corresponding to the given I.U.P.A.C. name. Choose 4 0f the 5 problems. (5 minutes, 10 points total) '2” 3 " Cl mall“ WWW 1. 2. 2—bromo—3—methylpentane (51" Cl M '2- (Ll/119w) ~ 2 ~ h—QX-QJ’FQ, 4. cis—1—isopr0pyl—2—methylcyclobutane Name: page 3 II. For the following compounds (3) write Lewis dot structures, (b) indicate the overall charge on the molecule, (c) write all major resonance forms, and ((1) indicate all formal charges on individual atoms. Choose 2 0f the 3 problems. - (15 minutes, 30 points total) 1' C9 ‘f‘. ‘0') 0 no” 5 ' \ H utC/ 'C'W ‘ :H H2 3‘ H W 99 c) 4 /\ 2”» ‘3‘ b7 (flea ll Q"> [I w e—» ~-/\\ O -‘.\/ D U,9 (1U “(9 Y H ' / ‘ ,fi’y M® @N 2. O : ‘ 0 JL (*3 O ‘03 HZN NH2 H' it H H CD‘- 6 0C9 ‘0‘ U A—"'7 O 3 ,— C3/\AH l k? /.\© “ > ’4 I t‘ fl Q i H ‘ N All 1’ 41 41V \M HZ MN “7’ “Z N “1 Name: I]. continued 73:29; Odom we, page 4 Name: page 5 III. For either 11 (1) or II (2) above, draw a three—dimensional diagram of the molecule, explicitly including all p—orbitals and all lone—pair orbitals and explicitly indicating the interactions of these orbitals with one another. Indicate the hybridization of all atoms, except hydrogen atoms. (7.5 minutes, 15 points total) ‘ t) /\ C i Y NHL an (315 (We 31f“ JUL {3 ’Torp, clown View Z) ll N T Spl Name: ___________.___ page 6 IV. Consider the two conformational isomers shown below. (3) Draw skeletal (line) drawings of both isomers. Use wedges and dashes to clearly represent the orientation of the substituents in three—dimensional space. (b) Indicate if each conformer is_staggered or eclipsed. (c) Assuming that the interaction energies for chloro and ethyl substituents are the same as those for methyl substituents, indicate the difference in energy between the two conformers. Clearly indicate which conformer is more stable. (7.5 minutes, 15 points) “99% Slalom. (-6633 Stem ._ .. er c1 m c1 5 .‘lOJtcu 1 Q 7' I fit? jMe *6) HQ 1C: _ O C ) "1 11—1 RAMC e *9 ‘ 3.5 (>- H /0 " I], 1",; \ l H Mt, ML Name: page 7 V. The rate of rotation about an amide bond is considerably slower than the rate of rotation about an ester bond. (a) Given this information, write a free energy diagram that describes the rotation about an amide bond, and another diagram for the rotation about an ester bond. Clearly label the axes, the reactants, the products, AG°, the ts (transition state) for the reaction, and the Ea (activation energy) for the reaction on the free energy diagrams. (b) Using resonance structures, provide an explanation for why the rate of rotation about an amide bond might be slower than that for an ester bond. (15 minutes, 30 points) 0 JOL roa1on ,H ______, ,CH Rabi, R I? 3 CH3 H m “1‘ in I, i it i‘ .‘y l ‘l\ \‘K Mm? — 'I“ 1), ‘ x" ,1— fl/k why m w m “fig , mm“ mm.” MM Wm . fixigu 3,3. 1 ‘31 a on V" \ ’V \3 J t" ‘Kfl (madam-eke (thicdaen) Wei/1 (arrow-I‘d 206146, ' ('wczaalq‘en) iéig “ ; 101(5) b) \H 1" .. an... <—-> Q. l m. \ ® 12/ \‘kf‘u K)\\N~n / < 7 fix“: R, K @ i *3 ' , f" 7 Mere, alng ices/wt anteater" m @‘rlwfl 31’) @ ‘3'ka W C“ L '4’W 13mile ‘ m. _ w . Wat's?“ ELM Awake, SCH"; hijanglfi rid/L2,) b EVIJWEQ/ "ii/WI 4 D W inn, (q.- t... an {73% in}?! f»; e, 312133111, j“! your fire; :0 Wig/mi (erHCiL‘PCxQALt/eif‘ a. 5 {SL999 ...
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Midterm 1 Key - Name: x.-.» page 1 1 Chemistry C3443 Fall...

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