322asu09_plq3

322asu09_plq3 - CHEMISTRY 3223L -Hkpeé%-%?T‘2fifl9...

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Unformatted text preview: CHEMISTRY 3223L -Hkpeé%-%?T‘2fifl9 -—SPRTNG-GGGG flractl’u. @f- Wmomwf MMM 200? BY 2392 NAME l.(l3) 2.(13) Lab time 3.(10) T.A. TOTAL (36)._____ This test comprises this sheet and three numbered pages. Tee 8 will be av lab ‘ from your TA - l.- and of vurs Ap 27 - 29, ard if y-u initial herr --- > : , '.ll be put olt in tre Study Room -y 5 y.m. M, Ma- 4. ALL ests, whet -r in t a Study Room «r Dr Ellern‘s «ffi-e, will 'be thrown r t on Ma 26. EJNBL :t;t is Wed, ay 6, 11- in SGM 23, as -re all ea er exams -.d quizzes in this co se. 1. (13) For the methylpentene -1- (MP) prep from 4-methyl—2-pentanol, (CH3)2CHCH2CH(OH)CH3 (SM), and 50* or 70% aq 32304: (a)(5) Even at 90°, the water solubility of the SM is low. But at room T, the reaction mixture was initially one phase. (i) Explain, using a chemical equation and <15 words. (ii) As MPs distill out, an Organic Layer appears in the pot (b)(4) As the GC analysis showed, (4) although the pot T ~ 90° and [H 804] has increased. Explain in <15 words; refer to what is in this new organic layer. some of the MP9 must come from rearranged carbocations. (i) Draw structures of two such MPs actually formed. (ii) Explain why the rearranged MP traction is larger from the stronger acid. Refer to competing process- es among carbocations; use <25 words total. Note the gas chromatogram of a MP mixture: The area of a peak is estimated as “Mb-h“. Tell how Kb is found, using <10 words, then draw the baseline and mark Mb on the arrowed peak. numl ill}!!! Elli!!! _ .I; ~ » iiiir'. ‘i-III-I-l iggllillllllllllllIIIIIIM ‘5 II” itiliilii lgifiilli Iiiiiffii R I I I s 335' Q '93:- hi. Illi’ IFS?! “'"inm “I!!qu Iii l c J r u 3. (13 points this page) - 2 - (23) In the last experiment, you studied the Brz-catalyzed isomeri- zation of I, gia-x—CH=CH-X (X a COOMe) to the trans isomer, III. The Br—containing radicals II-gauche and II—anti, gener- al structure Br—fH-—-$HO, are intermediates. X X (a)(3) Brz in solution rapidly attacks 2-butene danidnigaily. (b)(4) Brz addinidn to I, is a two—step aide reaction. ?? (c)(6) Explain why this mode of addition does n9; occur with I. Refer to the key difference in the groups attached to the alkene C's in the two compounds; use <15 words. Its second step is a tarminatidn step of the radical chain with respect to the I a III isomerization. Draw the missing structures for the halangad reaction below (disregard stereochemistry): + Br-Br -————i> ?? + Br. The "successful" reaction mixture contained initially 100 mg Brz, MW 2 160, and 2.2 g I, MW = 144. (i)(2) If all the Brz forms a solid additign product (AP) with I, calculate the mafia of the AP. (ii)(2) If the conversion of I a agiid III is 75%, calculate the purity of the solid III, as mass %, assuming all the AP also precipitates. (iii)(2) Tell what one should do after filtering off the solid to obtain pure III; use <10 wds. - 3 - 3. (continued, 10 points on this page) (d)(8) One can view I a III as two steps: (1) I in DCM.....“""III as supercooled liq, Keq - 1; then (2) IIIscl a IIIsolid. (i)(4) At equilibrium in solution with 48.0 mmol DCM, the sum of the (e)(6) (i)(3) (ii)(1) mole fractions of I and III - 1/5, i.e. X(I+III) - 0.20. Calculate (1) mmols I+III in soln, and (2) mmol solid III obtained from 30 mmol I. At 102°(375 K), the mp of III, (N3 tln a 0 and thus thln = 1. Taking R a 2.0 cal/mole-K, and (3 a 20 cal-(AI), one can use [55 a —R(375 +¢3T)1n thln to calculate T for a given thln. For thln a 8, calculate the T (Tsatd) at which an ideal solution in DCM is just saturated in III. In <10 words, tell what thln means. (iii)(2) Tell what the maximum possible yield of total III is as a fraction of I if the reaction is run at 2T satd (all Brz con- sumed) then cooled. Explain in <20 words. ...
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322asu09_plq3 - CHEMISTRY 3223L -Hkpeé%-%?T‘2fifl9...

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