SampleFinalKey Schore

SampleFinalKey Schore - Page Name a ’g Chemistry 118A...

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Unformatted text preview: ! : : / Page] Name a ’g Chemistry 118A Student ID No. Final Fall 2002 December 10, 2002 — This exam contains 10 pages and 5 problems. When youiare told to start, check to see that all the pages are there. If not, ask for help now; No adjustments will be made later. 1. ( 24 pts) The molecule pictured below (a steroid) contains many functional groups. From the list of names below, identify as many functional groups as you can in the molecule, by circling the group and writing by the circle the letter corresponding to the correct name. One is done for you to illustrate how. ‘3 quhi ‘ I [m dun:le :i’l/uz/ Coy ~84; lava" A- alcohol G— carboxylic acid M- nitrile B— aldehyde H— ester N— sulfone C- alkene I- ether 0- thiol D- amide J- haloalkane ‘ E- amine K- ketone F- benzene L- lactone Page 2 Name 2. ( 48 pts) Multiple choice — circle the 12g; answer. 3 Qc‘wm) Most stable has highest has lowest is a strong is low energy content energy content acid in entropy (b) Strong acid is aprotic is a good source can form a stable and polar of hydrogen atoms conjugate base (0) HF is > . ’ ionic polar, protic ' polar, aprotic nonpolar (d) Molecules with strong covalent bonds are stabilized by resonance low in energy content ionic high in energy content (c) Compared to chlorination, bromination is: faster and _ faster and SEE slower and more selective less selective more selective less selective (f) Iodination of alkanes is: is too endothermic to occur at all faster than unselective occurs multiple bromination times (g) Cycloalkanes with four or more carbons are non-planar because: torsional they are bond angle they are strain is better acids strain is resonance minimized that way minimized stabilized (h) Molecules with one chiral carbon are sometimes are chiral are always have many chiral if they are chiral enantiomers polar Page 3 Name (i) Molecules with more than one chiral carbon 4 are sometimes are chiral are always have many chiral if they are chiral enanu'omers polar H3 DMSO 0') (333— f_ CHr-Br + NaOH ————> is a bad 8N2 reaction because CH3 the nucleophile the leaving the solvent the substrate . is bad group is bad is bad is bad (k) CH3OH ’ + NaI JIM—Si» is a bad SN2 reaction because the nucleophile the leaving the solvent the substratel is bad group is bad ' is bad is bad (1) Necessary to displace OH group from an alcohol use strong use aprotic make better reduce steric base solvent leaving group hindrance (m) Strongest acid H O/OH NOH (n) Strongest acid 5 a a (0) Best reagent to convert a primary alcohol into a chloroalkane HCl NaCl c12 (p) Best reagent to convert a tertiary alcohol into a chloroalkane @ NaCl soc12 c12 he We OK ’ Page 4 Name 3. ( 60 pts) Propose plausible mechanisms for each of the reactions illustrated below. Mechanisms should be shown using structures, NOT WORDS. Fill in major product structures if they are not already shown. (a) CH3CH3 + Brz JEL CH3CHzBr + HBr _ (show only propagation steps) l“ W .. .. ' .- AW» CH2.ng fit». We CHzeH z r HEP z .A I ., V L» )5}- (5‘ 3T?) H 1:! \\ \‘d/ - / y . ' r4 9.: '5 ,, a I + O ' _ CH3 CH; ‘Br ' @Jr“ ’9 CH3CHLBV .3” M PC LC 3 . 3 K ,, (S) cm H [0.873443 f“ .A lx (b) Na+ ‘8 CH3 l Q ‘~‘ C’ ‘ ~ ‘ t ./ \ CHflHz/Cé r H DMF CLH3CH-L/ “tu ‘ (5") CH3 S u 2. Lg x... "x A 5W9 (WWW‘SWD \ 2‘ )3 ‘4 4; (c) Determine the configurations (R/S) of the stereocenters in mm the starting materials and the producfls) in part ‘b’ above. Is (are) the product molecule(s) optically active? /—-\ J /¢’ Show“ «Love. Yes < /M\ { O (m CL'.l S .+ f/ ‘ J \ Page 5 " Name 3. (cont) m cm; H r. (d) ,H-- \ I, [33; CH3CHZ/H/ CH3 CH3¢\¥{H/ \CHJ QR”) + H CH3\+K/——fl:dgr cuscm ’Zvciwg f; /C «Chub Ax) H CHJC H1 0H) CH3 CHzé-C/qub (‘22, (e) What is the full name of the starting compound! in part (d) above? (Include R/S designations.) (119)35) “ B‘MHLQ/L “1* f-CmLomel (f) Assuming the starting material in part ‘d’ is the single, pure stereoisomer shown, what do you expect the stereochemistiy of the product to be? The, is Cid/HM. Page 6 Name 3. (cont) (g) Attempted acid-catalyzed dehydration of 1-pentanol to give 1-pentene instead produces mostly 2-pentene: - A 00110. I h CH3CH2CH2CH2CH29H —A——* CH3CH2CH=CHCH3 mostly (instead of CH3CH2CH2CH=CH2) Suggest a mechanism 0 explain this outcome. M 1/1, + QM} calculéti'“ 044115;? H I l H |/\ + 050% cu y«CH ~CH3 l CH3 cuLcHr—Cfi CH 3 (h) How does the rearrangement of a primary alcohol differ from the rearrangement of a secondary alcohol, mechanistically? WWW “F O‘ \DV’V‘M Q‘Qo‘usj/ obs/20 lev‘t 7V1\4’;LII?/}7rll/‘Lnéiuj) Cow So ark/m Wmdkfin . rm ky—hggj 6a Wain mom ai; Mm G\(3K05Mcltwj) CMLOOQ .M‘ 71;, gait? Page 7 Name _________________ 4. ( 32 pts) Show how you might synthesize each of the target molecules below, from the indicated organic starting materials and any inorganic reagents. Use equations, NOT WORDS. Show the reagents needed for each reaction you use, but DO NOT SHOW MECHANISMS. H ’3‘ HQ,“ (a) Target is ‘c\ Start with /‘c\ . CH3 CH2CH3 CH3 CH2CH3 ‘ I" 9 W W as (\ MS & W TSC’Q 2 Br / Polar ofwl'm 8 0‘9 1H“ H ’3‘ 1-; ion (b) Tar et is ‘ a ain, but in this case start from ‘ g CH3 C\CH2CI-13 g CHg/C\CH2C1-13 1, (57— 131:3 a“ %v QKMV‘ Ol r / P $0\V€’{:fl‘ Page 8 Name (c) is the target. Use any molecules you like, containing any functional groups but NO MORE THAN FIVE CARBONS EACH. \ ‘ Am / 0H0 + / £3 (-1 L D'WP‘ @ Li) uy3 m3 3‘ “30"” ’ g A / v/ 747 *9" 05/”? Page 9 Namem 5. (36 pts) Formulate reasonable structures for each of the compounds described below. In each case you are given a molecular formula and NMR and IR data. Show work for partial credit. 2000 [500 loo 0 I —CH1~CH3 QNCQ choc/chow) L; M W (all Page 10 Nam“ { 1. (c) The molecular formula is CsHmO and the NMR and IR spectra are shown below. 3500 3000 1500 2000 1800 1600 1400 '200 1000 800 wavenumber (cm") ,«- \ z: 0 A _ a ‘ /C(‘~» l )M 5) l 8.0 7.0 6.0 5.0 4.0 30 2.0 LO 0 .0 ;-).Uy‘:“\“‘l' v zen-L “en; " :, ' l i I l ‘ . ' :' E i l 1 ' ‘ rl\1“5 I! i I I ! ‘ ‘ /“ I” y: i E . . ' l l ‘ Vt!“ ' f l I l i i l ‘ W? 3' i l l I l l ,5 l I , 1 s l l 5500 3000 2500 2000 1800 1600 1400 1200 1000 800 >N wavcnumber (cm ") ...
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SampleFinalKey Schore - Page Name a ’g Chemistry 118A...

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