Exam 1 - Singlet Doublet Triplet ’ Quartet Li :1 (fig?...

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Unformatted text preview: Singlet Doublet Triplet ’ Quartet Li :1 (fig? oublet Triplet Quartet Quintet (CH3C520)2CHCH3 CH3OCH2N(Cfl3)2 (CH3)3COCHZCE3 Singlet Doublet Triplet VHextnet Doublet Triplet Quartet Quintet Singlet Doublet Triplet” Quartet 7. What splitting pattern in the 1H NMR spectrum would you expect for the designated hydrogen atom(s) in the compounds shown below? Select your answer from the listed choices. CHEM 3112 Exam 1 March 8, 2011 TA (Circie one) Todd @ Madhavi Derek Naresh Gaumani Gerard Travis Sathish Keep your answers short! For credit, SHOW ALL OF YOUR WORK! It is expected that the atomic masses of C, H, and O are known at this point in the semester. IR and NMR tables are provided on the last page. This page may be detached. Practical Tips and Tidbits A. What causes the pressure build up during an extraction? .52“ 3mm « B. During an extraction, what is the most common cause for layers not draining quickly? (it (1.63; L; at». has; 5 I ."a a m i1 3} , : J :n = 3 ~19 Kristian“ arcane? firm . Tiwm N 00% CL “5W 53%.x‘wfl4 bitta We“... “vii/xi 5:51. .5: 43;“ 5:2,!“ D. What could happen if an extraction mixture is shaken too vigorously? emu is i <3 1“: Mam/Mae; g... racer?!" How do you fix this problem? aims; m b5 Haw/a ‘., "71% 535% 3‘ s . = M {Fa/l E. When cooling during recrystallization, you use a 600-mL beaker as your ice bath for a 10-mL Erlenmeyer. What is likely to happen? . x 45.! A ' m a 7:. K '1 ! fut: OW)? Cat/.23 n3 Cfi‘yifiaii '33 {at {43.2% i; "1’. M... aw. can: i’ What technique would you employ to fix the problem and recover your product if crystals couldn’t be seen? 0 felt the. iCflZ » r5; a in .14 \ is rawa . ~ In sublimation, a vacuum is applied to the system before filling the cold finger with ice. Why are these steps not switched? v’fifliuum F. 3r} ‘ Y'i/l 5‘ ya . v I ~ A r Sflbiz rm {$33, “Vagragaza {if 7 7:1; ‘ 1 YR _ r. aggr. drying has absorbed water from an fr 5;». fl». . .5? ‘ u i' 15.5%, tixrxi Qfgxd a gig». G. Describe the appearance ofl‘a organic solution. + Q r v 5 f v f“ ( I ‘2’ fl 1. ._ > . ,v j C l Um 329‘; T&Q\ {mega E fifth - *flfé? “ I 25/ Lari} T f‘wN. v I Vi f'fi s m 649' ar“ u a i ’ V I” ‘ b V“: “’9 \I‘v ‘ /’i’ 59010.33 ‘ t a z a 1'; w ,t. 4- H all; . a , r (w a 1 Q_ i» gr % I f 3 it" {I H. In a column separation, a large sample was loaded onto a small diameter column causing wide bands of compounds to elute with little separation. What 2 changes could be made to the column to improve separation in a second attempt? a) C(AQQZQQ (L wider {363.59} It“ (’1 l. Why is using a cracked filter flask more dangerous than using a cracked Erlenmeyer flask? ‘1,» _ > , ,myv. '» ’ . , it 7 JP ‘ '°“ 5 f BQL’XEJ. if; 3.3% Her {95% r film; W". “m; attics]: .5; ‘4 «V : v p wvx a) _ ‘e: g F ama‘ We breast: W PGQC‘Q‘Q 1”“ *UVM/{g Qa Vi wasted are 5‘ "‘3" 1. Organic compound 3 has a solubility of 1.6 g/lSOmL in H20 and 1.3.2 g/lSOmL in ethyl acetate. - if 0.8 g of E is dissolved in H20, how much solvent is required to dissolve % ( Leg... \, 25a w. c) “ QC 5! 1,; 120.0%"): Mi :: iJQC‘» )C X 4.353 F}, the sample? Maya—mm Once dissolved, the sample is extracted with 25 mL of ethyl acetate. How much of B could be isolated from the ethyl acetate? gen/L- "/50 ms: X 3 [I K. The Rf value of Compound A is 0.25 when developed in hexanes and 0.35 in ethyl ’ acetate. Compound B has an Rf value of 0.68 in hexanes and 0.95 in ethyl acetate. Which solvent would be better for separating a mixture of A and B? Explain. .1 "r i an ,- ._ . 57... —‘ / bi?me £7.31? ' 4”: ii. if”? t ate/w L ethyl deflect—{e L. Use the graph to the right to answer questions 1—4. 1. .Does this data show a distinct 80 _ separation between 2 compounds? 75 70 i 265 ' Ma 3:60 . 2. What is the boiling point of the 50 s more volatile component? :37 j . . o 5 10 l‘ 15 20 25 Vol of Distillate :5 . . {3257'} . :4", 3. How much "pure" liquid could be collected for the more volatile component? NlQML 4. List 2 ways to change the set—up in order to improve the separation. a. F filesth 32:" Us i no}: mn‘QFQ ; . b. {‘(OwaéiCb/é {341; i a”??? {1“23’V’Ei’tigv a??? ‘3 :C‘ «13 "IM " j Sikh“ - M. The water solubilities of oxalic acid and sodium oxalate at room temperature are 10 g/lOO mL and 3.7 g/lOO mL, respectively. a) Could you prepare oxalic acid by adding HCl to a solution of sodium oxalate? ' No b) Can oxalic acid be isolated by filtration? Very briefly explain. ' viii-2': {,1 (Q 3 Yea- ] HMOE (MA (£335in l 9 2:32.. f a gig W; ~. ; 5151.3; 44:, a r t ;" " v , N. The melting points of pure urea and pure trans-cinnamic acid are 133-135°C and 133-134OC, respectively. Given a sample thought to be one of these two compounds, describe a procedure to determine the identity of the sample. Include any observations you would expect. €719 & maul rhimfi ,. v» I g - .. _, ~ A , 1-. ,x: ‘v ,, ~_ ‘ v .R W 1&9. 5 l .5 F Pg?) 3 is}: + 1,. K a” l 1 . lg. V c}« ‘" . :3, V?" \ x 5 7’7, 0 .{fi/ . v. r a; <2 I} a. I. s‘ '1' I” ’( . V. éi’fig 4‘; 3 r._ l g ‘3 s Jr} r . “(as A A _ x L a), f f z ‘ Wkth l rm meow chL use yd c vt cat: 1/ A L» r c. I v' t a ‘6 [:3 in 131 P « / t , / H ‘ ’ 0. You have a choice of two columns to use for a fractional distillation. The first column is 15 cm long, and has a HETP value of 5 cm. The second column is 16 cm long and has a HETP value of 8 cm. Which column will do a betterjob of frattionating a mixture? Show calculations to support your answer. P‘ . ' ‘ W ' l 1 A 4 a” o “ v } "‘ Y (V g V/L/r“ {JKJVMW’G Hi H. L , 33,311 ?» {\d:a: 3 yr‘ 5 if .t if? y. . V y)» .11 :1 :0; fi..}?@fl($ mafia aw a I f} ‘ If: ‘ _. (A, raft/Y“ d u . .. _. . A ., not. 5;“ .r V 4' ‘7‘“ ? fit .- ap %; a? v. ‘0 c; an r . Use the temperature vs. composition diagram for a mixture of acetone and ethyl acetate to answer the following questions. Temperatm‘e (WED) w‘i—“i. 0.5 (3.6 0'5? {m 0.1 0.2 0-3 0-4- 0.3 9.9 '11) Mote; Fraction Acetone What is the normal boiling point of acetone? If a mixture of 15 % acetone:85% ethyl acetate is distilled through the less efficient column in question 0, what would be the composition of the initial 5:? ‘ distillate collected? Show how you came to your answer. $372; if ff 5% (a Q. A student obtained the silica TLC plate shown by spotting several standards and an unknown drug and developing with 200:1 ethyl acetatezacetic acid. No spots were observed visually when the TLC plate was removed from the developing chamber. How might the student quickly visualize the spots? gut, {’O’tfl. $31339 s" » ,l p. :‘ l .1 m, «at Two spots appear at approximately the same Rf value. What visualization technique could be tried to differentiate the two spots? ll » n. s m fl . r r s; {363 .1. l ’ {ill I ' l Gaff tbu Acetam ASA Unk What are the R: values for caffeine? 0 l 7 . ff: Acetaminophen? . a «5 Based on the TLC analysis, what are the main ingredients in the unknown drug? . QQSQEQJ 3 Fl $3.53“ 5 1;; it. What is the identity of the drug? Circle the drug name. Drug AcetylsalicylicAcid Acetaminophen Ibuprofen Caffeine Advil 200 400 32 Aspirin 325 Excedrin 250 250 65 Tylenol 325 Which compound is most polar? gaff What is the mobile phase? 3”? ir a a '3 a 1. - 5v” ' . ,. ‘ . ,- ' i “=1 ’x {71‘ f“ 5‘35»: i a t ‘ ‘. “'r ' :1 Multiple Guess 1. Which of the following has lowest polarity? methanol ’ exane acetone » water 6”) 2. Choosing a solvent for recrystallization, ideally the product should be a) Soluble in the solvent L b) More dense than water c) insoluble in the solvent @Soluble in the solvent only when heated 3. Which 2 protons are in the same chemical environment (are chemically equivalent)? landil mandlv land IV r um W 4. What is he reason for MgSO4 in several experiments? 0‘ s a drying agent to remove trace amounts of water from an organic solvent. . b) During extractions, it pulls water molecules from the organic layer and helps force the organic compounds into the organic layer. c) To separate the organic compounds from the inorganic salts. cl) To convert the benzoic acid to benzoate ion, which partitions into the aqueous layer. 5. Which of the following chemicals will elute last from a chromatography column? Explain the basis for your choice. 6. Compound A shows the following solubility data: 0.32 g/100 mL H20 at 5°C and 6.44 g/100 mL H20 at 100°C. What is the theoretical recovery in the first crop from a solution of 4.68 g ofA in 75.0 mL of H20 cooled to 5°C? 4.36 g 4.51 g 4.59 g ' '17? $1582": V s" o ’3‘ “e H 2 Separation theory Complete the following flowchart to show how the three compounds could be separated by chemically active extraction. Fill in the blanks and boxes. The boxes should contain the structures of the compounds as they would exist in solution at that point of the extraction process. Don’t forget to show ions where necessary, Car 53 O ©OH MOH OAOH . dissolve in ether 3;“ r 4;...» ,i I extract with dry with £3 (1;; evaporate The spectral data are given for an unknown compound below and on the next page. 0 Calculate the molecular formula. 0 Calculate the number of unsaturatlons (lHD). 6 ‘ Give an organized interpretation of each spectrum. a Assign a structure for the unknown consistent with the data and your interpretations. PLEASE COMPLETE YOUR lNTERPRETATlONS ON THE SPECTRA C, 22.90% H, 6.67% MW = 150 mw’ ff/J‘MGM‘ "£3113. e g c ‘ 71‘ .fl \J‘\ ‘9»813}: so» Cl E0 Jig'mirif T 1 ii: i‘ r: 5": 2‘ 16 w _,fifi‘fi: n . l3?) ’i/lfifiv ‘0}; ; 2 5 CC: H30 i, ‘4 w magma, j Q r {m , fi/ if”? IHD = » r \ Structure / 3 / " “J 0 [DD 5 I] E : SD {@19 g as? ‘3 E m/r“ /‘ 4‘25} 4 t. 4701‘ C543 D “00 3000 EDD“ 15m lOUU 1 f. HfiuENUHfl EF" -ll 5|: Extra Credit The spectral data are given for an unknown compound below and on the next page. 0 Calculate the molecular formula. @ Calculate the number of unsaturations (lHD). e Give an organized interpretation of each spectrum. a Assign a structure for the unknown consistent with the data and your interpretations- I PLEASE COMPLETE YOUR INTERPRETATlONS ON THE SPECTRA C, 57.49% H, 5.39% N (at. wt. 2 14-), 8.38% MW = 167 (DEW. :1 W72? S” ‘ $393M WW" ‘ ‘11" €.§Smol H /,5qu: q W5; CS/Hq N333?) 8.323;“ ::- . Sagswzwms : l j M” U3“»ia53( lmoli “1 ls'f‘lfz 316235 “'4 3 M“ I s NQQ “74M . ,a |HD= e 5’ Structure V. [DD Inintml mural U C: IHD = (2C+2-H-X+N)/2 CHARACTERISTIC INFRARED ABSORPTION FREQUENCIES Compound Type Frequency range, cm'1 2960—2850(5) stretch 3080-3020(m) stretch 3100—3000(m) stretch 3333—3267(5) stretch 2850 and 2750(w) 1680—1640(m,w)) stretch 2260-2100(w,sh) stretch 1600, 1500(w) stretch * 1250-1000(5) stretch 1760—1670(5) stretch 2260—2220(v) stretch 1550—1490, 1355-1315(both s) TABLE 9:1 Approximate P amical Shifts A. cf Proton Chemical Shift («3. PPM} _ 1" Alkyl, RCH3 0.8—1.0 2° Alkyl, RCHzR 1‘2— 1 .4 3° Alkyi. R3CH 1.4“ 1. .7 Allylic, Rgc=$-ca3 1.5-1}? R Ketcma, RCfiCfig 2.1 5-2.6 '1 C} Eenzylic, Ang-ég ' 2.2—2.5 Acetyienic, BEECH 25:3.1 Alkyl icdide, RCHZI 3.14.3 Ether, RQCHZR 33:33 ' Almhoi, HDCEgfi 33:41.) Alkyl hmmidef RCfigEr 3=4=3.é Alkyl chlmids, RCHQCI 3.5“35 Vinylic, R2C=fiLH ' 5.2..5‘7 E if Aramatic, ArH V é.O=8.S Aldehyde, Rfifi 9.5-10.5 0 Aicahol hydréxyl. ROH 05—6135 Ammo, R~NH2 1.0—S.O° Phenalic, ArCH 4.5-7.7?“ - ' E a Carboxyhc, R(IS'QH 1O 13 Egg m 7 n ., : I. if 13 r _ i O r r r r *— Tm “cm” . Chemicafshffl f. “The chemical shifts of thasa prawns vary in different salven’cs and ‘f‘ Alkyl, RCHB fl_4o with temperamre and cancantration. 2’ mkfi‘ RCHZR m_50 rum. RCHR; 1540 Alkyl halide or amine. -—é—ax (X =0, Br, or N-—-) 10-65 1 0r Alkyne, —CP=II ’ 60-30 7 \ Alkane. C; 1m_1?0 / AWL ©—‘ ago—170 ‘u’ C“) Carboxyli: acids. esters, —-C—O 160-185 0 I! Aldehydes. kemnas, --ca— AT<___«—v;rv:>r;r.;uca 1.21:3: mum.» ~4xn'1ln .4 M ma ~ wrch ‘rvf Cw j _1 wrap up) PD" 5‘ | DE 3 183 '22 ‘Bcfiys I“. 03 5195.5 128‘746 5 ‘ w ‘ a: a5Ie.3 '14359 \ 1 r“ , i as 9933.? 77,407 i / 26"! a 05 554334! 77.8% 5/ G? 553 08 53a cu? rns‘,‘ r 220 200 180 160 140 120 100 B Off Scale: 5 12.85 broad'singlet (1H) 2 ENDEX FRED BI 02 65 BI 65 95 67 @3 59 18 II 1: l3 IA 15 IS }? i5 re 23 2) 1335.58 2933.52 :53:.43 2929.21 2925.83 2522.55 2922‘52 25:3.19 ZSIDVSS 2358‘56 1503.13 V485.94 1488.75 \ARI.S? E 72 3»-D pPu 7 INTENSITY 253 ll.BSS 40.735 4549MB [80. ".747 .539 .558 .723 .453 ,585 .464 .38! 4339 ‘558 , ESE . 25 542 UfiilAM AL-JGE SFECTRfiL LINES FCR TH= EFL- 8223.2 INDEX 91 02 03 04 65 05 e7 99 ES |@ FRED 193E3.2 iaESE.3 12539.5 1233!.5 12810.7 7775.8 7?44.7 7712.7 JSS!.E IB|4.5 EFF: PPH 181.645 133.657 123.554 127.579 137.373 77.322 77.203 75.635 45.354 13.6:5 7.47 7744.4 INTENSITY 3.823 l7»589 141.5G2 137.21E 81.576 l4.7EE 15.457 iS.SB£ EE-Sl! 74.55: Fill in the Blank aZeotro 331 are constant boiling mixtures that cannot be further purified by distillation. 53.2 is the special name for the solution separated from an original hatchet purified crystals. A mixture of two different compounds which melts over a narrow range is at its Eu +0oQ'l‘i‘L point. .‘ Ea are present. in many distillations a small portion of low boiling impurities is observed. The precursor to the main component is called tors:- 2'1; The ratio of the amount of condensate returning to the stillpot (original flask) and the vapor removed as distillate per unit time is the (‘5);ng u:v.—'<rr:¥i"*55" ratio. (Qfll‘m ‘ 'u VET . Solvent travels up a TLC plate via To lower the bp of a liquid, one must (increase/d@ the atmospheric pressure. Spectroscopy If you needed to distinguish the compounds in the following pairs (A&B) from each other, which spectroscopic method (IR or 1H NMR) would be better? Mark (X) your choice. Compound A Compound B NMR NEG—CHg-CHz-CEN Cl—Q—OCZH5 l (/3 3 If“ ...
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This note was uploaded on 01/08/2012 for the course CHEM 3112 taught by Professor Staff during the Fall '11 term at Oklahoma State.

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Exam 1 - Singlet Doublet Triplet ’ Quartet Li :1 (fig?...

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