PracticeExamIII_2005

PracticeExamIII_2005 - Wu.“ W K67 ORGANIC CHEMISTRY LAB...

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Unformatted text preview: Wu.“ W K67 ORGANIC CHEMISTRY LAB 309 NAME EXAM [11,2005 ' TA Please write clearly and answer the questions directly and concisely. Partial credit will be given where appropriate. The total number of points in this exam is 50. Total scores will be multiplied by 2 to obtain the final score out of 100 pts. 1. (12 pts) (a) Write detailed mechanisms for the consecutive reactions shown below, which are similar to those that you performed in the synthesis of dimedone. Indicate all formal charges, use curved arrows to indicate all electron movements, and show every intermediate. (Continue your answer on the back of this page, if necessary.) O )K/ 9'9 . o _ Na OCH3, NaOl-I, H , + CH3 H,A H20,A HZO,A ? O O Q 0 ¥ \0 (J O/ : \O/lVKQ/ /3’\ “30033 H H A \ 0/ 0 V" 1 + 9 LQ Q6 \ // °A° 09 mafia (‘0‘ +H® ‘ O (s \aH / Gm Giza“) )K § 0" ———A. \j‘ 0 ———> K) V" /\§&3 I ‘ pQ\V—’ -HQ —k to K’I (‘3 \ b o/\\ e I D ' w 9 H [o Nm0H_HLO) 0 g? Q O o “'“H 0 A] V\// ()W 2. (10 pts.) Assume that you have dehydrated the pure compound shown below, by heating it with cone. sulfuric acid and distilling over the product(s). C“3 s ;\fi( '5 (a) Draw the structure(s) of the product(s) you would expect from dehydration by an El mechanism. 0H Assume that rearrangements can occur. or»; CH; Q43 (MIL Pl C \\ g I”, H C . H56 \ Ir’\ ‘ ’4 \//‘\ :BCI/l” 4t CH3 H300," II“\OH (b) Draw the structure(s) of the product(s) you would expect from dehydration by an E2 mechanism. (A3 H3 CM, my V 9ch «5C @7an (c) Draw the structure(s) of the product(s) that you expect to be present in increasing quantifies in the distillate as the reaction and the distillation proceed. {H3 CH H 1 . 1 W o 3 ’/ H199,” NQJR' FA {- / + K ) g \ / iimz/ Sui/xch Haw LS (“AH mm (M magma: oi; Hut QM kW 08 Shawna 2 2" maxim,“ T 15 WM my Mae“ 3. (9 pts.) Consider the pairs of carbonyl compounds shown below. For each pair, cimle the compound that is expected to give the highgn frequency carbonyl stretch absorbance in its IR spectrum. Explfl; ur reas ‘n to et O A and H30 CH3 'll‘fiQ%rcMY‘S‘\\‘“~ «\AMQS' Jim mfilfi w-Bwlx <18 WW1 {‘3 N“ u \ _ f . b H C é—B / H C“ \o / \ C ' 3 H3 HXC ® K/ \H H O O )k and )k H30 CH3 H30 CF3 flat-firm Ma, ($3 l—VQEB :l’mlefitém Hm (RH‘nCW‘CX DQ l \m (J ” C i \3 ® C93 0 and i 0 H30 N’ H3 ( 3 l 0330 “H (D ‘ G? (k /C%\ / 3 l - C\ (“H "‘06: h§ ED hXQ/ \ ‘y/ 3 SEN?» {15* H N 4. (6 pts.) (a) Why is it important to keep water out of the reaction mixture, when preparing and using a Gri gnard reagent? wok” 'w'\\;\ dde thYL the vented? wLux Kl terms: Myst + H19 A (HA (+ Mom Wozl‘v «\so oaks“ XML m kamov. I sliding J(last (rt\\'{o.\{m (Km Mim ta $0M Hail G'NiffitkA* (b) Why are ether and THF commonly used as the solvent for Grignard reactions, although they are both highly flammable? Give two reasons. (0 mm m mmm a slam; was) mix 3a all “a and: NW W Wax Jamil 1Cme (73 Thu) siMitgt 5M L745 Ming 0\ WW3R\O/ll " R—Jllh’g‘ 5. (5 pts.) In experiment 16, you made an alkane clathrate by adding a mixture of two alkanes to a solution of urea in methanol. (a) Why was the straight-chain alkane favored for inclusion in the complex over the branched-chain alkane? 1kg W M am a wk?me Hymn—W W M m s‘rMchwh W, mm? _ atwts at ‘am Mm. waist 93 a SMM was a M M m W M Ask \AL pm'M‘ (b) What do you think is the energetic driving force for formation of the clathrate? (Hint: think about the solvent) ma W amva mm— vs WW www firm m marmwam Mammal“ mu W‘ MW MIW'Kw 4 gmwamm mm mm mm (mam. VMMWW ($33“er (“A/vbbe mm. W.W.-fl.mmw..._r.,_.__ "w -w-..» v...” . AW- “W, “WWW 0......“ WW..." mm”-.- 6. (8 pts.) Draw a structure in the empty box that is consistent with the given spectra. Assign the peaks in the proton-NMR spectrum, by writing a letter matching the ones shown in capitals in the proton-NMR spectrum next to each proton in your structure. ‘ MICRO!“ 2.2 5.5 C 1 I i 10 11 12 ll ‘4 ‘3 II 17 ‘I 1' 21 23 15 1” i I. _ , _ .._...-., ._J_,.. _,.,..L_...‘..‘.,,.,. ..J__._.“..,-.L ... .i ._ -4..-..._7... .hl .. . , 4!. .. .-.1, _ Am”, l..._...l.. .. L. .!.. L.._L _|_J...L.J 1..» N I. . s __ ..-, _ __ . __ -_ ..n. _ _ - _ n ‘ u . ""‘ “ " ‘ ‘ " ” _ "WIJ n H; ~ — ~ _. - h w“ — ~ * - — » II! ‘ 4.: D _ - _ _, _ __ - _ . 3" § 5 . .‘: D M», —<« - -... _- _ - -_ .. ,_ .Rpu I E l : ‘ - v — r - " r - — E‘le a '3. V _ _ - _ _ _ M _ __ 5-0.5 é +0.: . ~ ~ - 70.1 9-0 10 ._ .'.' mwmmmmmmmmmmm am 1m an ‘M I!” mo no In I“ coc:a 200 ...
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This note was uploaded on 04/04/2008 for the course CHEM 309 taught by Professor Several during the Spring '08 term at Rutgers.

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PracticeExamIII_2005 - Wu.“ W K67 ORGANIC CHEMISTRY LAB...

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