C343S2009Exam1KEY

C343S2009Exam1KEY - {Exhaust}? €343 fTSeJ't.'r1._._/,}...

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Unformatted text preview: {Exhaust}? €343 fTSeJ't.'r1._._/,} 29.253 Arman .3, 259:9? ' 0343 EXAM 1 Printed Name Check the lab section in which you would like your exam returned. If you do not choose your correct section, you will not get your exam returned to you as promptly. Check Here AI Check Here Al Sam Barnes I Laskar J on Butensky-Banlett Wenjun Liu Vincent Cavaliere Kevin McDonald I bavid Dye " Fese Mokube "Gladen mm” Raghu Ramahhadran John Hutt " Tohn Tipping _Junyong lo I I I Darci Trader Ben Wicker There are 13 essay-style questions with a total of 158 points possible. Please look through the entire exam before starting to ensure that the entire exam is included. Finish the problems that you know you can answer easily, and then proceed to the problems on which you need to spend more time. RELAX! 13 points 10 points 16 points 13 points 13 points 11 points 13 points 6 points . 12 points 10. 13 points 1 l. 16 points 12. 10 points 13. 12 points @PQTJQ‘P‘PPJE‘J.“ Total / 150 (although 158 point possible) Regrades: Any requests for regrades must he submitted in writing within 1 week following the return of the exam in discussion. Yen must explicitly state what has been misgraded and provide an argument as why it should be regraded. Be aware that the entire exam will be regraded when it is submitted for a regrade. Regrades late in the semester on earlier work will not he consideredjust because you never went to pick up your assignments in discussion. nJ,.-_,. ,' n.— ,.-. '— ,,',, y L: . L.-:.:;"/L-...raw :‘z,’ i_.-_1"r'.:../_E:IDI b/l-L-fJ .206} ,3 ’nAfil-flq'l? 1: '7'.- 11.1. . _. _ - .. __, _- L . Experimental Questions: 1. a. List 3 safety regulations that you must follow while in lab. (3 points) —.— .I-III. J5 .: _‘ ‘- i - t r If i - r . - . '- .--- ; I. .‘k 1‘. rm. : '-. I ' -‘ I _ _ o -—:'1 A mixture contains two of the following: hexane (b.p. 69°C), benzene (hp. 80°C), 2—butanol (b.p. 99°C) and toluene (b.p. 110°C). b. Which mixture of two compounds above will give the best possible separation between the two using distillation techniques? Would you use simple of fractional distillation for separating these two? Explain your choices. (4 points) . ' ' j. r _r ____ .' .-~. : _ h - -. tiwa. air? H«#aaaiaga.ea~ugqx=«s«a~ wet r ._"- -’ .-" i' !2' .' . l I IF‘JIAZ'ix -— - .“N; 2 .._ 0. Describe what vapor pressure is and how it relates to a compound’s boiling point. Which compound above (among the original four) has the highest vapor pressure? (3 points) I . I . r . - 'l. ' 1 I l— J —— impair"! "g r i __.J - . . 1 t. can i _. pm": , '. -.' -. ' Nib-“vi” flj'l' l ., .. .. J (1. While distilling 50 mL of aniline which you prepared in the lab, you record a boiling point of 1840C. The temperature remains at this value throughout most of the distillation. However, you talked to your friend who attends a university in Denver, Colorado who performed the same experiment with a boiling point of 180°C. Explain. (2 points) 1. r | I H..- . a . _ ' ._ I _ ' _ -' I ' li._ _.._ _ F1 "(a ill" l; r," .' . I_ : . - . - w. . v . 4. ,i ., ‘. _ a,” ,1” ;--"r i I_ -. .- ' i -- __ : ‘ ' “g I l ' : I. _ fé' . . [II I 4'- ‘l . - I _.., \ i . r, -' ' " l ' . _ I. l . " Ji' -. c r' r. . . . = ' .t . . ” 2 . . c. When distlillii1g...an ideal binary mixture 01 hqu1ds through an effic1ent column the pot temperature Wlll be (circle one):’higfieiig/ {ourer than the head temperature. ( 1_ point) ‘- .._._.-’ £375.15 3 Char/145553,! (3.34.3? {Star/5mg: 25.36 March 3, 205).; 3. a. Calculate approximate Rf values for the following compounds, A-C, and then place them in order of relative polarity. (6 points) "I. .m A 7 C 7 E“- (ii 4-P- -p ("I I Y"! ’3' C) 'l . g_ _, . II I y .- B [0-1" | . 7;. 1/ P 2: , he i (2 points) - fl ‘ - . .1 H (1‘ {fig-1y.- t_.u- Fab/var: A r. {’L_.3.‘\C__ 4;} .- t ., -/ . _ c. In contrast, what is the purpose column chromatography? (2 points) x . «7.77m ._ l 0 Elm;- r; w. - ‘ t“ "i /T l"' : I-_'-‘ d. What are the two common stationary chromatography phases for TLC or column chromatography? What bonds are found in each respective stationary phase? (Sentences are not required here.) (2 points) / l 1: ' -"_ :‘hr _ ' I: i "‘5; l _-‘ :' I- ‘ _ .- .._. I. gil. ' _,__. lr“; I I‘I‘. @l LL W‘fl- 'n ~-'~.. "-m A l2 0 "3,, l. I- r l Z c. In all types chromatography, compounds equilibrate between the mobile phase and a stationary phase. How does this allow for compounds to be separated? Organic compounds adsorb to the stationary phase through intermolecular forces. What are the different types of intermolecular forces? What is the relative order of their strength? H l (4 points) but m m»- Pow-m 22+“: 2;, v r ~ -.- .._ Fir ,1 I If), r l- 3-, _. I t '.-I ' J . w --._J‘ F e" ‘—l""_ _f"—JfiT-l , I If lr l l r Ii (fl r I i h- l I l l mar -—-J H_J , r .a n Fr"! 2-“ x _ (3/1 a " t , ~ ' _ i l I f I I . l”; l? Pfié£5rlfif qr“ l Ottawa'er 034-3/5primgr 20g? March 3, 294;: 4. Draw out a separation scheme to demonstrate how you would separate the following compounds from each other. Include the types of reagents necessary (yes, provide real reagents, not just acid and base written about the arrows) to bring about the separation. (10 points) Ci a“ [ I A B c NH [\J org} 1.: I #73:» " a. After you separate an organic phase from the water layer, you might add a drying agent. What is a common drying agent? M S O N 30 a? (1 point) 0\ a ( a O > b. What is the Purpose of the drying step and how do you know that you have added enough? (2 point) 4/ I ‘ \l/ ‘ :. _ u. 1‘ I J ' . . I r—Ie' .refifll W: fur-101A? 'I til-.1. but“? in: a..-r_J.r___.-. ,r, _ ._ g _. tub W I I. .- " -~ - - --'.—- _. 3; I": 3w j + ' its; Pagaépf 15 0" 1:35:59: a ; ‘~... I; L a. w I H .3, _._..- c Cthtt-IJSEJE; 034.13 {Spray-.3! 2&5?!) wow-5;,- once 5. a. List one way to prevent/remedy emulsions during an extraction. (1 point} ' ' m at l; _. .. ' 3' y y . . J J. l... Ii.- EI- :21- IL} I I I [Jim-flew” ._ -I- ;_ . Jr H.— I In“ . ‘ ._.. I r 13. Naphthalene has a KB of 13 when extracting into toluene and a Kn of 3.4 when extracting into hexanes. Indicate which solvent you would use for extraction to reclaim the most amount of compound. (I point) ‘\ toluene) or hexanes (Circle one) c. Once you have isolated a sample of naphthalene, you want to recrystallize it. Based on the data below. which solvent would you choose for recrystallization? (2 points) — hexanes (100 mU toluene (100 ml.) l benzene (100 mL) l Boiling solution l Cold solution A w or toluene or benzene (Circle one) . I‘ ' -..'...- r r i ' c: - Em ' ' C‘ '7” T [CV/l '- 5 ‘3' "r " Briefly explain your choice: s-JOI L’i" :- ' i I" _' 4 J {If}: i/[___1f_,1" ' _: 1r". Jr“ C. t_.a m t “’1'” ’ t d. A 350-mL aqueous solution contains 5.0 g of acetaminophen, and 100 mL of diethyl ether was used to extract the analgesic. The partition coefficient (Kn) of acetaminophen in diethyl other is 4.6. SET UP the calculation to detemiine how much acetaminophen would be obtained after one extraction with diethyl ether baSed on the following data. You do not need to give a final answer, just the set-up is necessary. (3 points) \. Xj/too m i__ ‘c i - 4..."...— ; : Li. 3.; -- - ' — '- Kc b c. To extract an organic material from an aqueous solution, would it be better to do one extraction with 100 mL ether or 2 extractions with 50 mL each of ether? _,, ‘ y I...» f" i (1 point) Z If - it“ 1‘ t L... f. In an extraction involving dichloromethane which phase will be on top? (Circle one) (1 point) PZlQIBBéjlmL VP '5‘ i‘Oag/rrilfl 0. What is the remedy if too much solvent is used in the recrystallization process and no material crystallizes? (2 points) ‘ --~ _-.., .f." ,-- . r“ “.53 .-. . f“ if." Me a J/Irfl trim '7'" i 1:) I 2,4 I '- J" 'r...‘ ’7. C0 a...) .,rv' “an -1?- . I ~-: {[0 lmpure solids generally melt at (circle one@ higher / the same temperature as a pure solid. (1 point) h. What piece of specialized glassware is used in the laboratory to perform liquid — liquid extractions? (1 pt) ( . 3:: f _ : ..—~:’ g f I i ' 1‘ A3! | H—l’ Parr 55:5 851::- mTStxyg 63%;: 'Spmrtg 9009‘ Marc}? 3:1”: 7' 6. a. Draw the arrow pushing reductiOn mechanism for 9-fluq' none with sodium borohydride. (4 points) _-t ‘I I f lair-ff;— mq—fi 2’"- , /"\ ‘ ' “3"” '“ -‘ a '-'.:“= r 5:;- / .- L l, 1 a ass/“L15 _ /,_I.__._—\—e- f l I ___ i --...w_ ’_i'-._ - ./"' all”! ‘ 'Ig'ifgf' ‘ \ IR ,.__r...__wh__ \LI/ 13. List 2 reasons why sodium borohydride is a better choice for the reduction of fluorenone instead lithiu111___ aluminum hydride? (2 points) I if... Jig-I _.- ,.-— ,Lr _J__:.T:l {11" T#; r . . .f. I“ " I" W '1 Ir?" if ' ti .' e. In this experiment, the reducing agent was allowed to react with 9-fluorenone, and after the reaction was complete, sulfuric acid in water is added. What is the purpose of this step? {2 points) - _.. .ir a .r i 4 tr - t: T. , 1. ,1 n ' .1 =r-;;.u._ r a -- -. _ __3- aw, 0 ‘En 3'72-“ m.- -c.. I; - n . I » I .. - . _.. , —-. ,.:-_t,_" r" r' 7f a . La. .-’}:T” Merrill. 5,33)“ L g.._...,.~;;;.-. Ls at.“ m 7,;- w «v a I d. Write an equation for the reaction that might occur during the recrystallization of fluorenol from methanol if all of thefisfiil'fiJr-ie acid has noLhcen removed by washing. . I. _ ,.__-_._1 (3 points) 'n-‘r .‘ - "at “"r'q‘l‘ ' '5 - .1 ft} . I t. _ l' t \ ‘ ' 3,73 i L 1 _. _--—— __ if I' ‘In 1-' I / s, 1 u...- Qt,“ .' I ' ’1 I "i.— ffl} J’; a f ' .-" -‘ /‘ 3:52 Ff“ ‘— I/ r r 4" raga", I,»— ' I “ "—‘M"" 1/ -———__“'!,r raw-fl" ‘ _\ I I Jaw. " . Ir I. \R‘ I EK/ .1qfs‘n+---. tji 'i I “X ‘ .,_. ‘“ 1 f ' “r” x , Chem Err/f {3543,13 gar-E: :._-.'.I 2.417%} Mgmh 3.; 5,149.41 Spectroscopy questions: 7. Provide brief answers to the following questions regarding IR. 21. Briefly explain what occurs when R energy interacts with a molecule. How is a spectrum achieved? (4 pls) T l"; n . re, a». _ f' --’1" " "" Ur” ".':7' ' ..: ,. Ti ~' ' -..r {/9 -- ' -- ‘ - ./ _.« I ' H' we W - —’ - ‘" _.__, .- w." a J I: , a 4 .. “a; E I _ I i! 'Ii‘ - ' t _ - ........ —- H i - .-'-‘* ;" .Ih . - 1‘.._I .. 4_ r; .r" '. --.l . 2‘. ‘ 1 '- Iii‘ l ‘I ' I u “I. I ._ . I. . . .4‘nfl . b. What is the one requirement for a bond stretch to show up in the 1R? (2 points) . -- ' .- ‘ 1 ' m - .. .—, ' . mg”, -' .- - . . 1 _- _ ii. ‘41-- i._ his I, i. I-c _. 6.. 4.; . .. h I. L I ,. .I _ :- FE“; \ r“ I ’ Ié' .‘I -"' r_ .‘ I Ra ' c. Put the following bonds in order of their relative stretching frequencies: (2 points) (3—86, (3—8, C—O r c" ' '" C” o 1 a “W a «w '- / K M c a / v’ i A ~ ~ . "e “9 / 2c» t ' if! .17? rm”; “(I The clear disks used in sampling as thin films for IR spectroscopy are made of what material? (Provide a d. {3. AA) '3 I 2- ‘IL I .... i. I I I" ". B [ii?zwarl “ chemical formula.) (1 point) _ _,.c ' 1‘ .. .. Explain why you see a difference in the IR signals for A and B. Explain which species you would expect to have a lower frequency in the IR. Providing some kind of structures in your answer would be elegant for full credit. :11?) (4 points) )i :t t ‘3' u; l l If. ":54... (-1» ‘f'fi! ‘ HN N/am; I r- a | _. ' I ._ . “A! -‘ I I: ' - ' ‘ ' Li—I lli ' ' .II 1 , iv \ x 1..- \__. t“! .: .. 7-1 :‘ . .r'. {II 'J ":— I _ Sean/Lisa? 83+3'CSFJ'59L9 20.953 Mmrh 3, 2099 8. Clrcle the correct structure which corresponds to each IR spectrum. Indicate on the Spectrum the major peaks that allowed you to make your decision. (6 points) [all TFFIICHIYTH‘KEIKI I _ dLIIII annn Mm: two man aid :1. Hum»: IIZII-d [DD 0'5 LC) 1'! INS" [TTHNE El 21 to OH / OH 0' CI \\ o . I . . . . I MK man man man ulna 1500 no b HHI‘ENUI'IIERl-II IUD 5|) 2 “I Ilm‘snilllllunl . . I . . I . I . I- . I I won EDDI Imcl JDDD 5;! NRHNUHI ERI 1| Chemisd‘g; C343—Spris-Lg 2&9? Mai-1min 5200:? 9. a. Forensics chemists often have to identify various illicit drug samples which are all white powders. . l3 _ . . . . . Explain how IR and C could be used to dlfferentiate between morphine and herom. Be as spemfic as pOSSible' Bu Sui" Cor-:3 -_-. Owe. “HM? 5w . (6 points) ...r ini ill see cm H“ OH to ER “that -:‘-'-..x'~€-- Fl“i”"’i””~i""~._n MN; NH ii» A -“ ‘ ‘ u a ' _~ -F-- f I}: L M Q c:._t:,, at C #0 it Tm » . J: a V' -’ I_..- v, _.. an.» ‘ w r! fl {if} I :3 I. I, .1 I S'tflnofi Ca. 2OK-3 ’ '.- . ' t I — V h. *- Ol“ ,H’Qflu’ L, If T I’ ' / b. The following spectrum is for the compound, 2-{dimethylamino)ethyl benzoate. Assiun all the signals usina U C! the letters a—g. There are four signals crammed between 128-133 ppm, but I trust in your ability to use arrows and assign the signals clearly. (6 points) l9 (2? C/ e P A 0”" C O l I e d O f I I I I' I I 1 I I I I I I I I I I TH g 200 180 léO FIFO 120 100 80 80 4O 20 0 a // CBS-02‘213 b Page 1: of}? Cher/Mistral CEéEKSpfl’mg 2.099 March 3, 2.0.99 10. Provide brief answers to the following questions regarding NMR. 3. Write the stmctm‘e of the compound which serves as a chemical shift reference for 13 C NNIR (5 = 0.0 ppm). ([1H3 (1 point) H Ce— ‘Si #043 5’) is; b. Explain how an NMR experiment works in simple terms. What part of the electromagnetic spectrum is used; what it the point of this frequency? What happens to the nuclei in the presence of a magnetic field? _‘ (5 points) :l- a _ ' ' : i. ' Pfll 1mm; [3 { lance +'/2 0*” ”" /Z 5PM ~ I“ “L {9"{33 . ‘ I I. . ~ .' I . —' u -'f'\__ ,‘1 . , .. . [Np-0- .x: rig-Jr {I I w JMQA Lia/P ‘Iflu “HAO (Jul/wt” LM‘FYN. O! 'i at pl“. )L I) "- l :" ,ir .L 4. a. M We $1.1»- .. =- - M V" by; .. .. l- is; I ‘MA 15:”; W a) gm” 0L +0 lift/{1 iii it. “if? r’"-. 'ifi..-a"._.’.aLLLJ E"-- n _ . f ‘ I i .\ I, ~-,.F»’{,‘. i: . 4‘ '. ; ’LFJ. 'fi'"..'=: '1‘“? lL-{r‘ L. “id-f" ’ ’ " “' ‘ ' :3 “Va 0..» am #’ --’ ‘— -‘ ‘HAO. mm 59,1, 1 _ l C (a? l a 1 “if _ f, ‘r- cr .3, air to iv... an it”? e -* * a “r "3 \ , . ._ 1 c. Name one benefit of using an 800 MHz NMR over a 300 .MHZ NMR to obtain spectra. (3 points) ‘ - w 1.. _ _('_‘ . J “lax-rum gist—{3 “"19 3"""'"' '-*=""l‘--3“:i~~ ' so (if d. The compounds below are all isomers; these compounds should look familiar from class. Now determine which one of these compounds corresponds to the following I3C spectrum. Briefly ex ' . points) OH ,. C O " ’ ' .' ,. r' .3 4 tom if »‘. gflJpw-rfl_"l'l-LM o? 51 [,3ch {lbw/Vb 200 180 160 140- 120 100 80 60 40 20 O EDS-DJ-Sfia ppm Skirmish-M 0343/5 5114.54 200-? Mai-195:3 205.163 L- .2 _- ’ _./ l l. a. For each structure, determine how many carbon signals that would be observed in the 13C NMR. (7 pts) 1ft r3 L1]"nf*‘i-{? ‘ b. For the following compound, 3,4—dihydro-2H-pyran, use the letters next to each carbon to label the carbon spectrum below with the correct signals. (5 points) D a g C, 0/1 ‘9 Fl A E / " 41': z {ff}? 1 Jr ._——‘ —I—|—‘I—‘—|—I—[—‘I T I I 4 | : B D "R 200 180 160 140 12's 150 8'0 6'0 4'0 20 ti C cos—nu—4s4 ppm c. The two methyl groups on DMF show different signals in the carbon NMR at 31.1 and 36.2 ppm. Determine the reason why the methyl groups are nonequivalent. Finally, predict which methyl groups would have which resonances. ('4 points) .0 ~— - .Tlm; r‘: a: r‘ ;'..:-._- i‘v -'= '- 5:2. -- _ __ (3 Fri. “- ' ' "4'42 “w” H N/‘< 7 H QM ‘ .. , . \\ \ r 1 r H— -P..__.~.‘-k1.u (fix-331533;"? __r'_ I! {E'I’SIfi-l'fi-Lg: 214.13; 1-:.-"-,: 3:, jflf-i? 12. Circle the UC NMR spectrle for thc following compound and then label the carbons on the structure a-c, etc, and then assign each carbon on the spectrum appropriately. The arena =C—H signals do not have to be perfect for full credit, but the ipso carbons do. (10 points) ctrgylnistsy 034323prl'n9 2093 March .3, 20.34} 13. Determine a Viable structure for the following compound with the chemical formula COHIUOZ. The '3C and IR spectra are below. Once you determine the structure, label your compound clearly and assign the carbon Signals to your compound. (12 points) | ' l ‘ | ' I. ' I ' | ' | 200 180 1.60 140 120 100 80 Dfl—IECI ppm mos+ dou-J'fl Hal O‘v 01w}. ~l~o Your final answer " \.. \ J. V n/\ I N“ do“ 1"- L4 0 na/Q’ .. ‘1' C3 Gfi/b' T (P f F” {3N L / y .- \“x NO / \k, Page 15,935.15 ...
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