2011.Exam4 - First Three Letters of Last Name NAME <...

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Unformatted text preview: First Three Letters of Last Name NAME < (I: Network ID Section CHEMISTRY 236 SPRING 2011 EXAM IV APRIL 29, 2011 Note: The last pages of this exam are a periodic table and NMR values. (9) (9) (21) (12) (6) (12) (12) (6) (5) 100 LDOONmm-bWNi-A |_\ O 1 6 Mon— \CLUflNUJL CHEM 236 — Spring 2011 2 Exam IV 1. [9 points] a. Draw a correct structure for: 5-iodo-7-ethylcyclodecyne ‘L “SC 7 Q 3/3 #1 '5 ‘ \‘\¢. b. Provide a correct name for: q $ C5H5 1.. CeHs ll 3 - cliPV‘emgl— Ll — iso-wbpgl bun-germ (c) Draw the structure of any heteroaromatic compound which has the molecular formula C4H4N2. /N /\N / _ 3 m, Eu . or e CHEM 236 — Spring 2011 3 Exam IV 2. [8 points] a. Draw the resonance structures ofthe carbocation that would be formed by the protonation ofA at the carbon bearing the methyl group in A. Show the curved arrows for the protonation step and for contributing structures to the resonance hybrid. \m N- \ + H -. W ———» m H3CO “fro A I / com /\ " e ’ 16‘” ,P/ a + “5 “£10 “99;; “£29 “3c? b. The product from the protonation ofA is the compound B. Show how the intermediate you have drawn for 2a can lead to this product. 0N H300 CHEM 236 — Spring 2011 4 Exam IV 3. [9 points] Provide a definition for: a. an aromatic compound (A ComPowAd wkich has (Lil/H- 2} fl {\edYDViS Ma 0103c. pmvxav. infirmpkd 1‘1 sws+em 3/3 b. resonance stabilization The MMM modvm owvnc got'm Prom W‘Q Cam drum/stow 0-? Chavgfl. c. a concerted reaction CHEM 236 — Spring 2011 5 Exam IV 4. [21 points] Fill in the blanks with correct product(s) or reactant(s) for the following reactions: a. :32; u... q, Pol-C <1 Br/:>—< 2% ’ b. COLCH’) / COZCH3 g + X + E Q Cotwg HNo3 N02 0 3/ l “' H so 0 3 z 2 4 O . NO2 d . O Q H O O 3 [show stereochemistry] CHEM 236 — Spring 2011 6 Exam IV 5. [12 points] DO TWO - Starting from any organic compounds containing six carbons or less show how TWO of the following compounds could be synthesized. Show the structures for any isolable intermediates. 0 or O I \ / 9 CI 0 _" c; A B u 0 “a (not 6 H ___3_; \ \ [HUI-5 was RN ""8 /G> \ / o ' " C9. “My CR 0 ‘L Xx A ll H1. 6/9 ‘5" (j + H “‘ EL? ._. ( ( r 0 ° 0 CHEM 236 — Spring 2011 Exam IV 6. [6 points] Draw a curved arrow mechanism for the carbon-carbon bond forming reactions in your syntheses. o3 + Q . 6° (Tao/“V E‘ .. =7 Q’Afigu E "7 610‘“ + )\ a I? H q 0 a? 3/“): C 7’ “‘ —=r VKQ 4, / <21 09 “i "' *A O K’fiK —% /l k r 91'» Of 7 CHEM 236 — Spring 2011 8 Exam IV 7. [12 points] The 1H NMR spectrum shown below is of one of the following compounds: rm (4) The signal shown on the upper line above 8.2 is at 10.0 ppm. The numbers in ( ) are relative areas of the signals. (a) Circle the structure above which would give this spectrum. “In. CHEM 236 — Spring 2011 9 ExamIV (b) Make assignments to specific protons for each set of signals. 0 A O S; V“? ' \‘NYH Ha H D W H‘Hs H.“ q E B (c) Explain the large splittings for the signals centered at 1.2, 2.3 and 6.4 ppm. E . ' ~ ' \d' '3“ (HQ . .3 39h" mto tut-HP 5 L1 : E T lot 5 S‘SVVA 3“ng bq W kwa QPW W5 C I espins IEC (“\\ TN c siS NA is sr“+ b") 1“ “‘0 and MM. B 393% in“? “qwmfl’ 1“ (“3‘ 5 1359"»: c’ :Bctua ‘ f5 mum SPUW‘V‘UJ (5 aide". 3“ (m . - w, q 1 P) TlM E signed 13 94?“ ‘1 2Y” Ms) S c. “M” TN spun 0": TN Q— QVDTMS ‘l /(1 89m, spun S9lifi'il’19 / CHEM 236 — Spring 2011 10 Exam IV 8. [12 points] The reaction of CSH5CECCH3 with HCI gives the E and Z alkenes. 0' CI \ H \ CH3 CH3 H E 2 At short reaction times the major product is the E isomer. At long reaction times the major product is the Z isomer. If either isomer is treated with HCI under the reaction conditions the same product ratio of E and Z isomers is observed as from the long reaction time. (a) Provide an explanation of the different product rates at short and long reaction times. CR c9 0V1 \4 H k‘ éI/ R1. 043 m as or «a a cw, E S.M. E Shov-lhrws \ . n. > lo. \L‘MfiL Th.¢ Epmcluc’r is Qormadi W\0(‘{ («Huck—“1 l’l’m“ 2’ L 73 ( .mefl tong TN 2: PMW/l' LS vhoN. s’raaflok , lam‘l' whim? law‘s J QCHVafi OW Bonn/{er {—0 Sienna Mm; 1-...” Ida on m SWIM/x} Becaufi’ 0; W1 Qqut‘lt'brnkm Wl— (was, :33 com go loot - mde‘ c [,4 lat Comerol to i‘ che 1’: ‘5 form<0l mph N‘Crhfwfiwm a PM m 9‘ wwmudqmamrcwell becausfi 0‘ _‘ {5 so high MP (is) Draw a reaction profile to illustrate your explanation. rt OLqu 0“ Elh* " alkvnflle" _ ~ bog/(WT awtrfi 2 TM mth‘mmv‘ *0 form E W W «All»; In“ é PM PM M1 n ch (%‘ “new NW‘ *W’V‘ “Cum 5-,! Howwwrw Z " m Quay. Veamow M5 “HM ‘ cccri Mo» twat/i 2 H19 CHEM 236 — Spring 2011 1] Exam IV (c) Provide a mechanism for the isomerization of one of the isomers with HCI. u r» u q “‘5 aura + my; L1, (Sky \ “a. s ah) rbm / ca; 1 E ‘1/‘4 9. [6 points] One of the following compounds undergoes ionization (5N1) much more readily than the others. 56:5 0' (a) Circle the most reactive compound. (b) Provide an explanation for its high reactivity. ca . - _ . . g "S amm‘hc’ Sfodgi‘i W ’ \ \ {4—7 - 3/3 CHEM 236 — Spring 2011 12 Exam IV 10. [5 points] (a) Draw curved arrows and the product for a 4Tt+ 2n cycloaddition between the allyl anion, H2O:CH—CH2 and ethylene, HZCZCHZ. 9 Q -. C‘Afifi" Ht "9. u \ of k» —-‘> u 6/ TH" C“:- L \ CHL m/ CHL/ on; ° / e ,8 9‘ D --‘7 0 av (b) Show the Homo—Lumo orbitals for the reaction in (a). [The Homo of the allyl anion is shown below.] 9/0H\O ® O 0 E1: O/EHHO GD “20 0 CH2 0 O cfixgmp WHOMO 0P O\\\k\\ (MAR/v1 63/ @ v.10 O“ @ F Q—aniieimf ...
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2011.Exam4 - First Three Letters of Last Name NAME &amp;lt;...

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