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CHEM223Asum11_MidQuarter_Key

CHEM223Asum11_MidQuarter_Key - CHEM 223 Sum 2011 MidQuarter...

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Unformatted text preview: CHEM 223 Sum 2011 MidQuarter p. 1 KEY sec (06) 1. The benzyl cation, one representation of which is shown below, has additional resonance contributors. Draw them. [prob. 4.49] 7+ / CH2?» \‘ :6! + +// (14) 2. Fill in missing reagents for the following synthetic transformations. 7 . x X53!” 1 age on “Hg/o . !- 3H3 0H 6. Qty 6 “Raging w‘[email protected]|b§34 3A: \ ' (10) 3. The sulfonation of toluene is shown below. Provide a detailed mechanism for the process. Be sure to include the step that generates the electrophile that adds to the benzene ring. . O / \ $031+ ‘cus [isoq CH3 .‘ o + — aphasia.“ __... so.” + Hsoq 3w / ‘ H '0 a 14501:) H s H H u 0/503“ ~* )3“ g <-7 \ H \ +' 0‘5 C 3 CléEM 223 Mithr p. 2 K5 ' sec (1}) 4. Drawing and Interpreting Lewis Structures -- (b) A. The nitrite ion is written as N02 _ . Draw its Lewis structure, be sure to indicate resonance if this can occur. ' " ,joj'iQOf 5"" ¢ TO, * .' O" 4 4‘ 2 res. (2) B. Protonation of nitrite affords nitrous acid. Draw the Lewis structure of nitrous acid. - fos H\O/N§Oz no (esovtaMCe/ /L0.%. (2) D. What IS the expected ( ‘N/ bond angle based on the Lew1s structure you drew above? answer ‘80 ° \ZO° 15 5‘31 0K (07) 5. Rank in order of increasing proton affinity (basicity): (USE — 1 is strongest base, 4 is the weakest base) ' CH3OH - "‘1‘ YEIA-‘HUQ order . ths ' Zpes , (07) 6. Identify and name the functional groups in . NULL“ C =C 2 HOC Hz / cuo C (W >0 /" 0 K———~ aldeigda G) Aiwhoi ' CZ) - L2HMX( 1 > (13) 7. Provide unambiguous names for the three structures drawn below. ‘ s . H ' V - i 5 ‘ ClCHzgl-lz 3 , 0H - 3 1 . 2 CH3 ‘ Br q , CH3 ' . a CHZCH3 . ‘ .V A B C - A = 2"..£h.../.0r O - 3 ’etfi I elnl‘l‘a ne/ 4,01: aha/firm = Zfi-s B = 5- 5—6}! Iara —3re£*hfi/—- teen—£37512 5ft? E: 2ft: . 2 ar3—pen-éene if-b, c: 2rbrama—4—mech/2/mna/ . or I I 3 "Aroma ~ Sir-{lyt/rlfy fa/uene. 4,2; CHEM 223 Mithr p. 3 K5 sec (15) 8. Isomers. The formula C7H16 corresponds to 9 isomeric structures (all of which could be called heptanes). Employ a systematic approach to drawing as many of these isomers as you can. 96” W /t\/\/ /\‘/\\/ 2ft Per Mu»: M sfis all wine/ no repeat-£5 I (10) 9. Draw a reaction course diagram (energy versus extent of reaction) the equilibration shown immediately below. /M6V1 $415 la :d‘// 4] so \ / paSStlDle. OK at I l (#0.,er r» n call-CA7 The reaction occurs in the presence 9"“ 1 3P4” of a catalytic amount of H2804. + . velkl'We \ Dan/la!” 3ft wW_v.... H - MM. .mna—w‘ 1+ ls ml» \lugl'W/A‘LQ Cal")! (74 ;p§ec( . 3’05: (09) 10. Draw the two chair conformations of trans-1,2-dimethylcyclohexane. Underline the more stable of these forms. [ prob. 2. 59 ] CHEM 223 Mithr M ‘1 sec (08) 11. Show the organic products that would result when the diene below IS treated with excess KMnO4 under acidic conditions (H3OJr present). (07) 12. You’ve seen carbenium ions in many processes so far this quarter. Most carbenium 1ons have the potential to be both(either) Lewis acids and(or) Bronsted acids. Use (CH3)2CH+ as the example carbenium ion to illustrate both types of reaction behavior. (CH3)2CH+ acts as aLewis acid: . a . CH 3 CH 4-- . n3 -+«» --> / H @_ M2 ('9 H ~CH’L/ A H/\fl \4(W;5F‘L 1’0f 045a, (CH3)2CH + acts as a Bronsted acid: .u'. fey 0H 6“ ll ‘v‘L—H' +Z< z @ . “Meme Or be» mg, (08) 13. As you probably recall, conjugated dienes often give multiple products which can include what appear to be rearrangements in the location of n—bonds. The reaction of any of the E _ or Z isomers of 2,4—hexadiene react with iodine chloride ( I-Cl ) to give a single product (shown below). What kind of a reaction is this (Give its name)? How does it work? C9. ' ~61 .\ \ ----———>- / 1 IAW; C03. or l,4’o\44l+1514 ZF‘kS ...
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