SS05 NMRproblems

SS05 NMRproblems - A3. Soft Reserves NAMEW .. 1 pattern)...

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Unformatted text preview: A3. Soft Reserves NAMEW .. 1 pattern) expected for the 1H NMR resonances of the hydrogens indicated by bold type. “$221. (10 pm) For each of the following compounds indicate the multiplicity (i.e. the coupling _ HBr assume a pure sample 2b. (5 pts) For each of the following indicate if the drawing represents a transition state or arr intennediate 8) 8Br circle one: “H transition state intermediate Shoes b) H \B/H _ I I H30 , , \H Circeone. H w H transition state intermediate H c) H _. H circle one: (9 H3O transition state intermediate la. NAME: (10 p15) Mark] and coworkers oxidized [24]porphyrinogen I to [22]porphyrin dication I! (Angew. Chem. Int. Ed. Engl. 1994, 33, 1151). Notice that II is a dication because two electrons have been removed from I in the oxidation reaction. Both compounds exist in the cis, trans, cis, trans configuration as shown. In the 1H NMR spectrum of 11, two of the four underlined hydrogen atoms appear 20.5 ppm upfield of where they resonate in I. Furthermore, two of the four underlined hydrogens of II resonate 8.4 ppm downfield of where they resonate in I. i) What do the numbers {24] and [22} refer to in the names for I and II? ii) CIRCLE the underlined H atoms which shifted upficld upon cenversion OH to 11. iii) Put a BOX amund the underlined H atoms which shifted downfield. iv) Briefly (one or two sentences at most), explain why there is such a large chemical shift difference upon conversion of I to II. (5 pts) Give the structure for a molecule of formula (33H8 which exhibits only a singlet at 8 5.8 (the vinyl hydrogen region) in the 'H NMR spectrum. 4. (15 pie) (a) How many degrees of onsaturation are there for a molecule of formulae C5H302? . ' Wf‘ (b) What is the structure of the 051—1302 molecule which exhibits the 1H NMR spectrum shown below? (0) How many quartets would be observed for this molecule in the proton coupled 13C NMR spectrum? “ NAME: ' - o o 4 at >0 we >< >< o_ 0—0 CH3 Has—0:0: Li H3C—CEC—H + 04%CH3 (L + CH3 H3 “\0 CH3 CH3 (10 pts) From each group of three molecules shown below, circle the one whose structure is most consistent with the proton decoupled 130 NMR data given. 8) (CH3)20=C(CH3)2. (CH3)2(OH)CC(OH)(CH3)2. (CHsiaCHCH(CH3)2 6 = 19.5. 33.9 'ppm b) 1-chiorobutane, 1-chloropentane, 3-chioropentane 5 =13.2, 20.0. 34.6, 44.6 ppm (5 pts) You have a sample of an organic molecule which you suspect may contain a tetrasubstituted double bond. Which spectroscopic techniques (iFi, 1H NMR, 13C NMR) will allow you to unambiguously establish the presence of the carbon-carbon double bond? #2. 2b. - NAME: (5 pts) For each of the following compounds indicate the multiplicity (Le. the coupling pattern) expected for the 1H NMR resonances of the hydrogens indicated by bold type. assume a pure sample (5 pts) In the space provided indicate the number of different carbon atom environments for each of the following molecules. CMG3 NAM E : (5 pts) A laboratory student was attempting to convert cyclohexanol to cyclohexyl bromide using 1 equivalent of sodium bromide in a large excess of concentrated sulfuric acid. The major product she recovered was not cyclohcxyl bromide but a compound of formula CéHm' which gave the 13 C NMR spectrum shown below. In the box provided, draw the structure of _ this compound. _ Dfi—fi . ..r...l..... .. ISO 100 140 1:0 100 so no 40 20 0 803me 3b. (Spts) A compound of formulae CSI-IDO2 gives the 'H NMR spectrum shown below. In the box provided, draw the structure of this compound. (-2.0 7.0 50 5.0 4.0 3.0 2.0 1.0 0' PPMer} 6 .Feb «1 c200“ NAME: " q- 2 . (10 p15) Shown below are two 'H NMR spectra. Compound A has the formula CmI-I”, and Compound B has the formula CSHSNBIZ. In the box provided by each Spectrum, draw the structure corresponding to that Spectrum. J ‘ Compound A (CmHu) 2H PPMLS) £- Compound B (CSHSNB 1‘2) Moms TH-‘Jw dmé'fiomffl wrufl #36 4((«597‘256' $5 Cor‘lflécl", (some {flow 0mg, _ t “T m jgflLg {1 33‘}— AH it. ‘ M F T {it la “P 0700 R - NAME: 3 3a. (opts) For compound B in Problem #2, the resonances between 5 6 and 8 are shown again , in expanded form below. Write your structure for compound B in the box provided. Label each of the resonances shown below as “A”, “B”, etc.; starting with the lowest field resonance labeled as “A” and proceeding to higher field in alphabetical order. Now label the hydrogens in your drawing to indicate which hydrogen corresponds to which resonance in the spectrum. J” I j ‘ ll \ fi—u—h_ L M *v—-- v w- 1 u -1- —r-— 7.50 7:00 1‘; 3b. (6 pts) For each of the IR spectra shown below indicate if the compound is an alcohol, - ketone, alkene, alkyne, or carboxylic acid. List all functional groups that are present. More than one functional group may be present. For compound X there are bands at 2200 and 1675 cm"; but nothing around 2?00 cm". For compound W there are bands at 1650 and 3335 cm". Compound X “a; x} at a: 1:: :3 1}!) 3 !_} 1 a} g 1;: ram” 3 g g I; III ‘ Ill ._; u u- n u u n I: u n (“H—L, n—‘r-WVW‘W—F—‘w—F F“ “M 1 '1 fl _ a“ u 1‘; ... f, m: Mimi m— u ME; ‘_ I “ NEAT .- 03300 I626" {.095 I‘M I390 m M m m 3” m no: "0.1 M 7;” m was I Ilm I {ml ’ IMI I”. m I I N! H-n" uuuw-ru meme—t 2-95}. l-‘r-rfi Compou ntl W _ mucus I I. II! {I :_< {I a; :_r z_- 2_- 3 Ill : In 3 i} E E t_u I: 13 Ill 1': 1‘1 I} E! 1_. I‘D I III _:Is_ it” W L'wa f,» accflv .n W a .: f l “\WW‘N ” : \ 1it 1' f l ” NEAT / 5:: “. 3339c . "T" .r . . .r if? urtwnus HICOLEI' :31 um: NAME: q 5. (10 pts) Three '3C{ lHlNMR spectra are given below. Decide which spectrum belongs to which of the following compounds and write the letter for that compound in the box _. provided for each spectrum. The three lines labeled CDCl3 are due to the carbon signal from the CDC}3 solvent. Q coca, J ' l ‘ fl.- I. :901w?o1so1somm725nowoso so ?D so so 4050 20 to o .5: - a - I - -. -_,__, ., ... mmmmmmmmnomm3011:6050 £03320 ‘0 05¢ ...
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This note was uploaded on 08/25/2009 for the course CHEM 140A taught by Professor Whiteshell during the Spring '04 term at UCSD.

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SS05 NMRproblems - A3. Soft Reserves NAMEW .. 1 pattern)...

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