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Exam3Test1 - Chemistry 32ZaL/325aL —2- {Exam N0. 3...

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Unformatted text preview: Chemistry 32ZaL/325aL —2- {Exam N0. 3 Nameimfimee, (1) (15) Complete the Chemieai reactions beiow by providing the correct missing structure within each box. You do not need to balance the equations. my..me CH3CHZOH + HBr ‘6 (9M (:Hgmzcrimg + KMHQ; WWWW (PH H9504 cmczacm KOH/ Alcohei» ;- "._.,\.l. cmgcmlgacm CH3 (ii) CH3CH28r “"“TT’” - --- *5“) ‘ "L ’X ' w x "w - I l! M” _____, __.. ........ _. ‘‘‘‘ n J a} a .xt‘ n"- v- J ‘ r "u" c m s 1 ~, Chemistry BZZaL/ 325a}; -3~ Name Kij T 5 K9 {if}. - Exam No. 3 U (2) (15) When t—butyi bromide (2-bromo—2«methylpropane) is dissoived in methyi ‘ I alcohol, the rate of disappearance of the starting material isgiven by all“. 7‘ rate a k[t-bu.£y1 bromide]. The products of the reactions are t~butyl methyi ether (80%) 553 2~metfifii§fopene (20%). ..-;:':'2 Fr fl /CH3 w ' (trigger—13 WMH OH eagle—0mg + CH2=G\ o C. '. CH (A) (11) Write out a reaction scheme that expiains this result. Your scheme should inciude all important intermediates and a step-by-step accounting of bondmaking and 'boncibreaking. Indicate t . ‘ - mining step by the label "slow step.” .2 2 (B) (4) The names the m hanisms responsible for the two products are: H ether Product =- .15 5* 2'»- and aikene Product g" “-';' (3;; -r.--:.:‘.:..:?€'le..3w- \ I. Ir ? I "x 1 .. Chemistry 322aL/3253L -4- Name Exam No. 3 0 ¥ - (3) (10) The choice of solvent often is important in ruzming an organic chemicai reactlon. 1 a CflgCHZOfi CH3COOH (acetic acid) CH350CH3 (dimethyi suifoxide) I—izO {it (C‘- CH3CE~N (acetogtgtriie) C6H14 (mhgxane) Fig"; mm 10’ ‘\ (A) Which of the above are poiar pfotic soivents? H 1.0 C ii, ‘v-i .J C. aa- c a. ow (8) Which above solvent has the Iowest dielectric constant? (’3. 1,71 . r M. 4w. _ I 1 Lh‘ (C) Which two above solvents interact well with cations, but are less effectiv e in Stabilizing anions? ({3} In which above soivent will eiectrostatic interaction between ions be the ggeggest? Fiat—Ea twat: l 1‘7"“; (E51) Select one nonaqueous solvent from the .. of an 5N1 nucleophilic substitution reaction " \“soivems. _ \;_.1 a!“ {h If 3}; _ J I. .. a; {El—r 3 PM. above iist that should accelerate the rate relative to the other above nonaqueous 1 Chemistry 322211; /325aL 6» Name 0551K is“? Exam No. 3 (4) (10) A sample of (Sulfgfputaool with a specific rotation of [0L] +1350 ()2) is reacted with an aryl suifonyl chloride (ArSOgCi) to form a Secvbutylsulfonate ester (H). Reaction of II with aqueous base (HO“/H30) yields sec~butyl aicohol with a specific rotation of [oz] 113:5" (HZ). Complete the scheme below showing the structures and stereochemistries of I} and 111. Answer the two questions inside the box to the left below. .._,- Hey/Hp The mechanism for the reaction IE MIHiS bestgte "oed'as __ (circie one) [8N1 (8N2. £1 33—2] and the stereochemz a res 1424 v- (Circle one) {retention racemization]. Zebutanoi [0t] “13-50 III {2 Exam No. 3 Chemistry 322aL/325aL ~6~ Namem 1 ‘1 u (5) (30) Circie the correct answer to each statement or question below. (A) When each of the fokiowing aaions is added to {gothanol solution, the one with the largest solvent-smote stabifiizafioflenergy is \“ I" Br‘ Cl“ F“ {8) Which statement is not true about carbOW «They rearrange rapidiy to more stable carbocations. milligoy react. with bases in a ,deprotonotion:eactiontoyieidalkenes. 1T. (1/ éBecauso of their tetrahedrai. geometry, they are. chWn there are three m.wlififched to the carbocation cgogglrflim _ -- "The? “‘5”? 53513i313?W'iaiafio'éafimag.‘ Q (C) ’i‘he order of base strength of the following anions C‘pr C1“ _\ NH; / z I: I ______ ./ \x is I>11>III3~IV III>IV>I>H @bbfij . M/[/ (75)) Which obsorvafion is not true about the E2/1iilechanism? 3111mm..9f.,fi3s2.£¢§<5t10n m 14199ma§§]...,;=am (iffhe major aikene “hpxmtwlggfio tabie carbocagofl -A prixfigry .kwi'fégfigcwfgotope effect is obs rved enfieutenum 15 éfibstituted f0? ” hydrogen at the beta-carbon. ~ Skeietal réarrangements are not observed. - (E) Geometric isomers existin which aikene beioyy?‘ $1 $1 4‘": (f1 (orighcmccnzcm 1K emcwfic CH22CCHZCI~13 CH3CH2€H=-CC12 Chemistry 322aL/325aL ' u7— Name QJLLQ. Exam Na 3 (5) Con. (F) The most reactive aicohol in the réaction ROH + i—IX WW RX + Ego is ,.//””_"“\ - OH 3” OH (EH CHkHCHZCE'L; CHTTECHZCFQ cascfizcflzcfizofi CH3CH2 HCHQCH: H3 fa? \- (G) The stability ordéf'of-the foibwin fies (ignoring geometric isomers) .2” '3 3?, CH3CH2CHmCHCH2CI-i3 (CHflzcmcl-HCQCHa CI-122CHCHZCHZCHZCH; I II _ III is: §>IIL>IZI ZII>H>I II>IH>I (H) The most reactive alkyi bromide in the dehydrobromination reaction (KOH/ aicohol) is I. H.- 531” 5:" C1-I3CHgBr CH3CHCH3 CH3CH2CHCH2C53 (I) ’fhe correct names of the foliowing aikenes E. . H 1 / (,3: 3 (\CH3 1 I} CHZmCHCHZCEh ($3);me C III are 12: ZWbutene II 1-butene III 1-methyipmpene ,lgiggjngu‘tggggu II Z-butezze 1211 'lwmethyipropene @;2£utene I It LE’2‘wbd?€fiémwfl”FEifi‘t€fi‘éwmI 1'2": “é? fléfii‘fi’fié‘fié” ' (1} Which hybrid state of carbon forms the shortest C-H bond? W , y,” (F/ n" .; 5133 892 r" Sp La/ . WWW... ......... .__,.._uwmm—w~ .... “mmuw “mwmmmm..nfi .. Chemistry 322aL/325aL —9- Exam N0. 3 (7) (10) Sketch the reaction scheme for the acid~cataiyzed dehydration of isopropyl alcohol (Ia—propaflol) to propane in concentrated suifuric acid. Show 311 important intermediates and cleariy Show why the reaction is catalyzed by acid. E". i. E “ : . . I a _ a". J sq- “3‘ i . I . .. -‘ _ _.-._ _. .I ‘ ‘I . ‘ 1" ". mw~mwmm....,..:\“ H 1 2'. '- '= ' I .. i 1. -- . 5 E \' . x] I“ - I". It; E ;-- \ f 'z . _i_ 1 .5“ 1 =‘ V w- 1' A. ' r " W. \. f. _;_I ;\_J' fi-I w“ 2‘ L Piaf-a { I I 9' Ir . t _ [ -—... \l H) ( .I K J r “‘3‘ E X ./ x ,3 9 c x r in?! H 13. f‘ 1a * i (a u..— i «L H .rzki _" a Y \\ Chemistry BZZaL/SZSaL Exam No. 3 Namew Lia/QC" (6) (10)The reaction of t—butyl bromide and sodium methoxide in dimethylsuifoxide (DMSO) (an aprotic solvent) gives isobutyiene as the major product. The rate of the reaction doubles if the concentration of sodium methoxide is doubied. f'fi‘i Cid-5’“ (5) Sketch the mechanism for this reaction clearly showing all bonding changes. What is the name of this mechanism? Fr ffis CH3(rCI"I3 + CfigONa *" [gm—*limethylwifoxide CH2:C\ CH3 CH3 1 Mechanism: Name of this mechazxism? is .. -_ 233. q - ' W... ‘a H filth i..- I\\ I h { .i L ‘ I; h/ , . J W \xxmk M j (3) Carefully draw the transition state fer the rate~determimng step in sufficient stereochemical detaii to show‘ the reiationship of the leaving greups and the bond orbitais undergoing change. :' Va \ 9 r : , a nae” (2) If the same feactioh is run with the deuterated t-butyl bromide, II(CD3)3CBI‘, wifi the reaction rate. be siower, faster or unchanged? Why? Is "I H ‘ I": 'I- a IK ') f f’ ’ g 1 '- “"a \ I . . =,.._. L'- t ‘L "1 '3 __ - L.» 'i - «gain. «I W‘- J] . 1 g a M l- l . ,r.. ., r" i l l 3" a 1') L'.___ i Mil-“1'; (:- ’ W, ‘w I it ' \t J 1 H, ...
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This note was uploaded on 03/01/2008 for the course CHEM 322AL taught by Professor Jung during the Spring '07 term at USC.

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Exam3Test1 - Chemistry 32ZaL/325aL —2- {Exam N0. 3...

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