F07 midterm1 key

F07 midterm1 key - Circle your TA’s name: José Ryan Amy...

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Unformatted text preview: Circle your TA’s name: José Ryan Amy Ben CHEM 30A Fall 2007 Midterm Exam #1 October 24, 2007 Please sign the following HONOR STATEMENT below before beginning. No regrade requests will be honored if the signature space is left blank. The answers in this examination booklet are entirely my own work. I neither gave nor received information or assistance in writing this examination. I understand that sharing information during this examination, or using materials not explicitly allowed by the instructor, will result in a failing grade on this exam, and possibly in additional action that may affect my ability to continue attending UCLA. SIGNATURE PLEASE READ THE FOLLOWING INSTRUCTIONS BEFORE BEGINNING. 1. Please verify that your cell-phone and/or pager are OFF. If your device rings or vibrates during the exam, 5 points will be deducted from your score. 2.The exam consists of 6 questions on 7 pages. Please verify NOW that you have all pages, and raise your hand for assistance if you do not. 3. Please write your name at the top of EVERY page NOW. 4. To receive full credit, your answers must be legible, structures readable, chemical names spelled and punctuated correctly, and numerical answers given to the correct number of significant figures. To receive partial credit on problems for which it is given, you must show your work. .Always indicate clearly if your work continues onto the back ofa page! If there is no such indication, graders will not look at the page backs. R=8.314J-K-1mor‘ R = 0.0821 L - atm - mol‘lK‘l lkcal =4.1841<J kB = 1.381 - 10‘23J-K" 1 erg = 10‘7 J 1 L‘atm = 101.325 J 1 Noggin = 142.1 cm3 . 20 -lIll AG = AG° + RTan AG° = —RTan k = Ae—Ea/RT _ i k=Ce AG /RT AG" = 2 AG;’— 2 AG: rx n products reactants NAME I; I _ Page 2 of 7 1. (20) Below is the structure of a molecule called TNP—470. Its structure is similar to that of fumagillin, a compound found in a fungus. Because it inhibits the formation of new blood vessels (a process called angiogenesis), this compound is being investigated as an anticancer agent. o o E a)(2) What is the hybridization of the carbon labeled a? S P 7. b)(2) What is the functional group b ? Q \ kCh e. (B c)(2) Is the atom to which the chlorine is bonded a 1°, 2° or 3° carbon? k QPOKQQ d)(2) What is the name of the functional group containing the atom labeled C? S QY‘ gang 3" QM e)(2) What is the absolute configuration of the stereocenter labeled d? E g G f)(2) Within 5°, what is bond angle LCCN (middle atom labeled *)? g)(2) What does the abbreviation OMe stand for? MQ'U‘OXQ 3 WP h)(2) As shown, is the OMe group axial or equatorial? +0?ij i)(2) How many stereocenters are in TNP—470? (£2 j)(2) What is the common (trivial) name of the group to the right of a? l‘SOE'O Name E I Page 3 of 7 2. (24) For each pair of structures, write their relationship in the box. Your choices are: the same molecule, enantiomers, diasteromers, constitutional isomers, or none of these. CH3 H H NH2 H2N CH3 H CH3 H CH3 CH20H3 CHZCHS A B C b. B andC(above): ‘ R$TEEES -R C. (P/ w ‘ E? " 1‘: 0| 1 d. Me Br H H H H /-\ e. fl H Br Me H iPr iPr CI f. Lb 4b “ NTloMElZ CI Name E __ Page 4 of 7 3. (25) PART 1: Drawn below is one Lewis structure for the allyl cation. H H \+ / / \ /H <—> H Q (I: A H a) (4) In the box above right, draw the best possible alternative Lewis structure. b) (3) Draw arrow(s) on the structure at left to show how you obtained the structure you drew. c) (3) What is the arrangement of bonding orbitals on the carbon labeled “A” in the given structure? (Put answer in box at right.) A. tetrahedral B. pyramidal C. trigonal planar D. insufficient information to say. (1) (2) What do we call species (such as this) in which there is a carbon atom with only six electrons in its valence shell and it bears a positive charge? Mal—Lice} PART 11 different molecule! : Consider the conceivable Lewis structures X, Y, & Z below. +3: "0" 33: _ + H3C—l=CH—8H2 H3C—C—CH=CH2 H3c—<l=CH—CH2 .1)“:sz Mxmw; #mssmu? Bani»! v‘DGESN‘T‘ n mrze 1* 125: car ' MESW‘ alumnae GHARfiE :mnm‘w A 1mm;M '8 X:o(+l Fomcuarweor’ Y: HOMB- Z:o poaggj mint-be Queue” «We? semen-ij e) (3) Select from the seven options below (A through G) to rank order these structures, based on how much they contribute to the resonance hybrid. Put your answer in the box at right. A.X>Y>Z D.Y>Z>X B. X>Z>Y E. Z>X>Y E) C. Y>X>Z F. Z>Y>X G. insufficient information to answer f) (8) In the space provided below each structure, justify your answer to (e), using short phrase(s) to indicate any deficiencies (less than optimal characteristics). If none, write “none.” g) (2) Why doesn’t the following structure contribute to the resonance hybrid? p g p mvaLem‘ c: Hem 1 5+ rammeprcfima/v) 0.0.. l + H3c—c=CH——CH2 Name I _ Page 5 of 7 4. (10) The heat of combustion of compounds D and E are given along with their structures in the boxes below. D -1164 kJ/mol O E —1264 kJ/mol /°\ HZC CH2 i H3C H a) (4) What oxidation number should be assigned to the carbon bonded to the oxygen in compound D? in compound E? E b) (2) Based on their heats of combustion, which compound is more stable, D or E? c)(2) What makes the other one less stable? New stRm N d 2 Is com oundE olar or non olar? X > P P P $01.;sz Name L Page 6 of7 — 5. (12) Below is the framework structure of menthol, a common ingredient in cough drops and mints. /%r‘.' 09; u #2. 7V OH /,u BFZ— 6’73 6)) , a) (8) Using Haworth (planar hexagon) representations, draw all possible cis,trans isomers. (If you draw something you do not want counted as one of your final structures, please draw a big X through it, so it won’t be graded.) R: [Pr = iSOPpoPa‘ : -—< R “‘3 R LL CH} H H 5‘ cu» a w a as u H R 14 H H L-\ U~|®ME {TZVCTUQESB b) (3) The following is the actual structure of menthol. Draw the most stable chair conformation in the box at right. R dw Mm masv s m aura-mm." /\ ALA EQMAmaJ-t L. c) (1) Write in the box whether menthol is CHIRAL or ACHIRAL. C Hl P R'L In Name \L". _ Page 7 of 7 6. (9) a. (3) Name the following compound according to systematic IUPAC rules, including the absolute configuration(s). (SS\—- 2 3-Dmemr' LPENTAME b. i) (3)For compound F, complete the Newman projections of the three different staggered conformations Sl, SZ, and S3. Draw them as if you are looking down the C1-C2 bond. ii) (3) Assuming that the X and Y groups have greater steric demands than hydrogen (H), state which of the conformers (SI, 82, or S3) is lowest in energy, and why. which? why? BecauSe of S‘l'cr‘v‘c. r‘ePKISton lac'l‘wcenx 4‘ Y m ‘32. 4 $3! Most- s'roxlolg corrForm‘l‘l‘cm place; X A \/ amt" ...
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This test prep was uploaded on 04/06/2008 for the course CHEM 30A taught by Professor Chatterjee during the Fall '08 term at UCLA.

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F07 midterm1 key - Circle your TA’s name: José Ryan Amy...

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