322as09_e3_key

322as09_e3_key - CHEMISTRY 322aL Please .ieilx EXAM NO. 3...

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Unformatted text preview: CHEMISTRY 322aL Please .ieilx EXAM NO. 3 Print Last Name MARCH 30, 2009 First Name USC ID No. TA's Name Grader (1) (15) __._ (2)(15) ___.__ _____ (3) (20) __ __ (4) (10) ______ ___._ (5) (15) __ ___ (6) (15) __ __ (7) (10) __ _____ (100) first letter of last name I will observe all the rules of Academic Integrity while taking this exam. Chemistry 322a CZL/ —2- Exam No. 3 3 ’64 ____________________ (1) (15) Complete the chemical reactions below b C6H5CH2/$\CH2CH281' + CH3CHZONa CH3 I 4 ethanol .r-chM (100% ee) CH} @ocuéu Cal-{160 + - + Na CN acetonitrile {‘0 1‘: a “331% H H 3 - + D + CH S Na ( ) \Br 3 CH2C6H5 9- % sf- 100% ee \ “A ( l C‘ n V (E) BFCH2CH2OCH2CH2C1 + CH3ONa methanol one equivalent 1 % HIM?) C4 TM 0‘} mUMI product does not Brz/CCl4 solution - ecolorize CSHUOX where X is a Kama remaining halogen atom. r Chemistry 322a -3- Name Exam No. 3 (2) (15) Answer the questions below. ‘1... (A)(‘ Provide short but clear explanations for the below, as requested. In all these reactions, th sure your explanation addresses this competition. observed products of the reactions ere are competing reaction pathways. Be N OEt (i) (6) a CH3CH2CH2CH2CHZOCH2CH3 EtOH ma'or roduct CH3CH2CH2CH2CHZBI‘ ] p M, CH3CH2CH2CH=CH2 t-BuOH major product What are the Hughes-Ingold notations for the competing reaction mechanisms? Explain why the different reaction conditions give different types of major products. Tko, hbhpgfimq rcmgfiomfi mrfi 3N1 OVAA b.) wk bagsgfiztflExwa o. n , , A o ‘ N OEt H3 a CH3CH=C(CH3)2 + CH3CH2C=CH2 Br EtOH major product minor product Draw and circ e - a 'cture of the TS for the major product. Explain why it is __. favored (i.e. has lower : ergy) over the TS for the minor product. E’r "-\-\- I HM aux-H —- eré‘p‘C-nma r r—g\ cc'fio‘KSk‘c {D 0’?— -H~\ \moK—m 'F°V+k( mtg—Ho“ , Timer-1 \3 dqwmlopma rm Jrkk Tug fir ’rlxv. E1 Rag-Hay ocs +k Wang 11:1,“: 3 - ow¢km3 ’t‘!‘ No \S fiwhvu-AS. 3W 3 Simgb’zigfl ("5 0-? “N'lhk G~\K<w\'\ Pt—oAvCl’S are \‘K \— Re ew P3 u : e9W4'i-“Rmimé3 Misfit!“ 'e~\ a—e—Lfig’ (B) (3) Indicate the major reaction pathway (8N1, 8N2, E1, or E2) of RX compounds with the conditions given below. (i) A CH3X compound with NaOEt/ EtOI-I. gm '1. K 1 (ii) A secondary RX compound with Nal / acetone SM L ‘ (iii) A tertiary RX compound heated in EtOH. S m S P Chemistry 322a Exam No. 3 W A?» M528 20) Circle the answer that correctly completes each statement or question below. (3) ( (A) Nucleophilic substitution by either the 5N1 or the 5N2 mechanism does not occur with which of the following organic halide s? (circle answer below Ar-X RCHZX RR'CHX RR'R"CX RCH=CHX aryl loalkyl 2° alkyl 3°a1kyl vinyl L IV'V @ 1 11 111 1V V only I only V (B) Which of the following chemical species are potential nucleophiles in nucleophilic substitution reactions? (circle answer below NH3 3H3 CH3CH20H H30“ I ‘ onlyV 1,11,111, v I II III IV V (C) The better leaving group in a nucleophilic substitution reaction in each pair of compounds below is, (circle answer below + ROH/ROHZ ROH/ROCCH3 A I, B I A I, B II I II V LYL AILBI A B g observations are consistent with the 5N1 mechanism for nucleophilic substitution? (E) In each pair of compounds b with KI in acetone will be (CH3)3CCI, CH3CH2CH2CH2C1 CH3CH2CH2CH2C1 CH3CH2CH2CHZBr 1 11 I II A B (circleanswer) AI,BI AI,BII AILBI elow, the faster reacting compound in an 8N2 reaction Chemistry 322a l 5 “r k, -5- ame Exam No. 3 bromocyclohexane, 1—bromo-1-methylcyclohexane (circle answer below) I II ALBI ALBII 2-bromo-2-methylpropane, 2-chloro~2-methylpropane I II B (G) The relative stabilities of the three alkene isomers (I, II, III) may be determined W W M experimentally by I H In (circle answer below) ~only measuring their heats of hydrogenation. —onl measurin their heats of combustion. - - s of hy rogenation of their heats of combustio —neither mthod. (H) The stability order (most stable to least stabl e) - - “a. enes in Problem (G) is (circle answer) I>II>III II>I>III III>II>I W (I) The reactivity order dehydration reaction is H (circle answer below) H AX/ I>II>III II>III>I OH + CH3 H C1 EtOH H3 menthyl chloride I EH3 (circle answer) (i) Very fast reaction with (ii) Very fast reaction with I the major product. II the major product (iii) Very slow reaction with I the major product. II the major product. Chemistry 322a ‘6- Name Exam No. 3 (4) (10) Answer the questions below. (A) (7) Draw to scale below a free energy diagram for the two-step process: k A L. B A C where k1 is much smaller than k2 and B is 20 kcal/mol higher in free energy than A, while kcal /mol 1" A and C have comparable stabilities. C Progress of Reaction N In the above diagram: (1) Show the locations of A, B and c. 1 446k (ii) Indicate the transition state for the rate-determinin e . 9‘ (B) (3) What does the Leffler-Hammoncl postulate predict about the structure of the transition state for the rate-determining step in the above diagram? Act .r-clcrk‘r «k. +\~¢~. MCGK¢t~+§mmmowd @es‘I‘VQQ—H/ $.r— ‘ kvi gmézrsowfq 8+2 @ Cos; ~\-\fi\‘1 \S ‘Cot‘ A%%\‘ 4r'\-\¢. *‘V‘O-Ksrfiom s—‘Va‘j‘g COMQS Lm‘l‘z o.\¢~\J +l~2 (‘1‘. L‘HO‘M Coot-ing Csmx‘i “SAKLJ\¢J we (shatters—(BX as +ke+ 3422?. W Chemistry 322a Exam N0. 3 F (A) (5) Calculate the initial rates of the nucleophilic substitution reaction in methanol for iodide and fluoride, when [CI-I31] = 0.050 M and [Nuz‘] = 0.100 M, using the information in the table. Place your answers in the boxes. Show your calculations! i _ » _ ~.I o (i) For Iodide (ii) For fluoride rate = "3. \ $1 0 I "S" .3 roll = k (c “Skills/$33 3 3.4K» M-‘S’ao.05otj_$c.\0fl Foils. Rowe?” 0c :: (.1 x.;5r'wot-E/:_.s_ use-tom- : Q-{Wo‘ AL \O’K AQ<K / irks Roast-Hut ‘0 t K lO’K \3 'ho‘t‘ mb‘clc‘gik MULK b7 9°(v¢_+rom Q‘K‘L a_\3§ is Vmgklj “girl-{Mix l \DLC «LMA 1+ L$ ob k‘gfi‘~\\c ?O\O-N1.Ll3\0\ ¢+bw. (C) (5) When these two reactions a ' rate accelerations compared with than 60,000,000 times faster. Explain the rate acceleration in changing from methanol to DMF as solvent in the reaction with fluoride. 9V“: ‘3 c" Eblof‘ Rmfik Sh‘V1m_‘\+\~¢'\‘ trrc’ttnct-S \Qa-CL-‘e-\ Hid—K kfi‘umi. lie-Hm I“ QnAA. ’F“ OLPK d 3+“ \ Mort. Ra: v-q'ctwk \')\ EMF Compare. F\“L°"\“‘°\ ‘0 M Shakes ox firmed“? Y‘LLTL qekgkrafio-«m hkcwxsa \fi— \3 Q shamazcx bung (SAN-.msczr’ "Au~.\ko +V‘Q‘K \Odfdkgo“ \¢\\ +4.4. 0J53‘L’KKK OF- Slmlotlrzcc’r—tom L.. n I ‘7 e G“: CH3? “ CH Chemistry 322a Exam No. 3 (6) (15) When 3,3-dim and II are formed. (EH3 QH CH3¢ “CHCH3 a CH3 3,3-dimethyl-2-butanol -8- ethyl-2-butanol is heated in the presence of a strong acid, alkenes I H+ 9H3 (FHE’ CH3q2=CCH3 + CHaqHC=CH2 W20) CH3 CH3 I II (A)(2) Provide the IUPAC names of these two alkenes ‘ ’30 hylwufifik I - K. intermediates. ff“ ‘ a 56% + carxzzqct—sCCHE) *9 en; Chemistry 322a Exam N0. 3 product and needed reagents. @ (A) 1~bromo-1-methylcyclohexane Br .- _________ -_, 0 Oh Qt E-r OH m;ia IN «— (if Z "\x’K‘W‘ é . (B) BF )3’ Hw —C wH \ CH!C CH3 mesa-2,3-dibromobutane LL35 Q'A3CHBVQ“ B rC—E‘ 3 c=c\ CH3” CH3 (Z)-2‘butene Z MMH 1% “.‘K Lt? NH: methylcyclohexane CH3L1QCH 3 LPOKSO’Rt J\ ...
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This note was uploaded on 10/12/2009 for the course CHEM 322AL taught by Professor Jung during the Spring '07 term at USC.

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322as09_e3_key - CHEMISTRY 322aL Please .ieilx EXAM NO. 3...

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