322af06_e4_key

322af06_e4_key - CHEMISTRY 322aL/325aL Please Kt \g EXAM...

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Unformatted text preview: CHEMISTRY 322aL/325aL Please Kt \g EXAM NO. 4 Print Last N me NOVEMBER 15, 2006 First Name First 4 digits of USC ID No. _ _ _ _-XXXX-XX TA's Name Grader (1) (30) __ _ Lab Day a Time (2) (10) __ _ (3) (20) __ _ (4) (15) __ __ (5) (10) _ _ (6) (15) __ _ (100) first letter of last name I will observe all the rules of Academic Integrity while taking this exam. Chemistry 322a / 325a —2- Name ExamNo.4 (1) (30) Complete the chemical reactions below by providing the missing structures in the: boxes for reactants or products, as requested. . You do not need to show byproducts of the reactions or any mechanisms. Provide stereochemical details in the structures wherever they are important. NaOEt H H CH B (A) CH3C 2C 2 2 r ethanol ( s \ major product minor product 1 “‘C I l %‘ 7m “"6 W‘ “W’f éoxa CH3 KOBu—t tert—butyl alcohol CH3 (C) ..\\\\OH heat conc. H2804 (D) B{ ‘ /Br (E) H‘WC— CXHHHH CH3 CH3 single diastereomer Chemistry 322a / 325a Name Exam No. 4 3 C K M (1) Contd. H2 Pt H3C H mild heatin 3,, + CH N ——g H /CH 2 2 diethyl ether ; ; 3 as a racemic form \ , Chis 2 C (H) CHBCHz‘x pH2CH3 (i) 0504, pyridine C:C\ —.—_. H/ H (ii) aqueous NaHSO3 (FH3 CH3CH2CZCH2 + BIZ H20 (I) (i) O3/CH2C12,-78°C $9 9 —-—-——> CH3CCH2CH2CH2CH (11) Zn, H20 4M7 ovz‘af‘ZZfl/f éK) Wf 41 gm (re/ore ur‘m Chemistry 322a / 325a -4- Name Exam No. 4 (2) (10) Answer the following questions. (A) (2) Provide a detailed structure inside the box for (Z)-1-chloro-2,3-dimethyl-2-hexene. (B) (3) Provide the index of hydrogen deficiency ("U" number) on the line below each structure. - /\/ ' CH3CIHCH2CHBI‘CH2BI' 1 CH3 “611/ L i L (C) (5) The diagram below illustrates the principle of the nmr experiment . Identify the missing features in the diagram, as requested, below. Give your answers in just a few words. What is Y and what is X? Y \S E‘Kd—r‘s . X LS Swimsw 0"? MO-S’NL‘HC "GI K4 8 . ~A “3% AL wvwd‘ I C What are A and B? L .aA O'KCL 3 «mi-K «waLocw ‘5le 3 “5‘15 - F KQS Magma h‘q iw'ifl g \tbegru\\¢\ +0 30‘ 1 B has Ike—S ’VV-‘h‘c ~ $0K2 km“ PQFAKA +9 Be. In no more than two sentences, quali atively describe the physical phenomenon behind the nmr experiment using point C on the X—axis with reference to D. AAF pech L, 0-3" 0L Sixfii'c't‘q M¢1M1h\‘g‘l\<‘ WKS—tkr {—ka‘ mLLC.\L0_r~ SPVxxsvk-o—tts it-Hdt‘ Tkimfl‘xf b7 TK< QM“) M-l— Q, A +V1’K5'kh0’K Ron A—vB ockuws whoxn- k Pko'l'OM 0-9 ?"°P¢P l’Nfl‘Sj (AE:V<U~\ —\-o QOKKKK\ D ... AL- \.\ 1/ ‘1‘ Chemistry 322a / 325a Name -5- Exam No. 4 Ad 1 MC (3) (20) Circle the answer that correctly completes each statement or question below. (A) The reaction below is best carried out in which of the following solvents in order to observe the greatest rate of reaction and to obtain the desired product? cN CH3CH2CHBrCH3 + NaCN CH3CH2CHCH3 1000/0 ee (3 1000/0 ee (Cerle answer CH3SOCH3 HCNH2 H20 CH3OH dimethyl sulfoxide formamide water methanol (8 = 47) (E = 111) (E = 78) (E = 33) (B) Which factors below promote the E2 reaction over the 5N2 reaction in the reaction of RX With Bf? a stronger base A higher cone of B;' a sterically hindered B:' C D B,C and D A,B and D all of them (C) Which statement correctly describes the alkene product mixture for the reaction below? Pr ‘ 2° and 3° alkyl halides B AandB (circle answer) "WGHBVHGHGHE wKOEt A CH2=cCH2CH3 CH3CE=CHCH3 CH3 HCH=CH2 H3 ethanol CH3 CH3 H3 I II 111 (circle answer below) -II is the major product and I and III are minor products. -II is the ma'or nu. - .- u . t. —II is the ma'or roduct and III is the minor product. -111 is t e major pro uct an e minor pro uct. (D) The more stable alkene in each pair below is (circle answer below) >: M \Q Q IA,IIA IA,IIB‘ A B A B I B, II A I B, II B gv—J %—/ pairs I II (E) The reactivity order (fastest to slowest) of the isomeric alcohols below in the acid- catalyzed dehydration reaction is QH CH3CH2 CHZCH3 H3 1 11 (circle answer below) I>II>II qgllblb II>III>I III>I>II (FH3 QH CH3CH2CH2CH2CH2CHZOH CH3CHCH2CHCH3 III J Chemistry 322a/ 325a —6- Name Exam No. 4 (3) Contd. (F) Which of the following reactions of 1,2—dimethylcyclopentene are stereospecific in some particular mode of addition (syn or anti) to the double bond? H C A B C D (circle answer below) 3 D HI BIZ/CO4 COld’ aq' KMHO‘l Cold conc. A'B and C B and D HSC H2504 B,C and D ( B and C > (G) Catalytic hydrogenation with H2/ Pt of C5H8 (compound A) yields CST-112 (compound B). Treatment of A with a solution of silver nitrate in aqueous ammonium hydroxide gives no reaction. The structure below consistent with these observations is (circle answer) D CH3CH2CH2CECH W (H) An organic compound is soluble in concentrated sulfuric acid and does not decolorize a solution of Br2 in CCl4. The structure below consistent with these observations is (circle answer below) CH3CH2CHBrCH3 CH3CH2CH=CH2 CH3C ECCH3 (I) The most reactive alkene in the acid-catalyzed hydration reaction is (circle answer below) MW (J) How many different resonances (signals), ignoring spin-spin coupling, will be seen in the 1H NMR spectra of the two structures below? /\/\ (circle answer below) H C/CCH3 14,113 15,114 H): CH3 \CH3 I 5,11 3 1 II Chemistry 322a / 325a —7— Name Exam No. 4 (4) (15) Answer the questions below. (A) (7) Provide detailed structural formulas for A, B and C in the boxes below based on the information provided. You should read through the entire scheme before assigning structures in boxes A and B. Give the names of A and B on the lines below the boxes. B ocyclooctane reacts with NaOEt in ethanol to produce products A and B. WM 5 NaOEt ethanol bromocyclooctane \ sié— CY: Looc%¥§ tram? ‘WCLDiCKENE Reaction of either A or B by the two step synthetic sequence below produces C. AOIB L (')2e NaNH inli NH,—33°C CCl " k 'tha o sNH c1 @ 4 (11) wor up W1 que u 4 m2- Compound C reacts under the hydrogenation conditions below to specifically form A or B. H2, Pd / C catalyst C (1) Li, liq NH3, -33°C catalyst is poisoned (ii) workup with H20 with an amine C (B) (2) Catalytic hydrogenation of A and B give the same product, D. Draw a structural formula of D in the box. Heats of Hydrogenation AH:I 2 A -24.3 kcal /mol B -34.5 kcal/mol @ (C) (6) The heats of hydrogenation of A and B are given in the table above. According to the data, which compound is more stable? A R Based on the structures assigned to A and B, is this relative stability surprising? Why? What structural factor might explain the observed difference in stability of A and B? A4,. ’Crrs’t , \12.$’ bLQQng +vocm5—«c\\gzq\¢g avg ngqq-xo‘\\ Nova S+uciro\g gléfioAkgkk \SOMLPS. \x “Figs. K049 @ 0‘“ O‘Aic‘l‘h’q’VLA $1L+¢P \$ +\\d\ S-l-x-ocrwx {W635 r ck s o r + w? S Q a. LA +l\ +\~£ ‘i‘T‘Q'VLS K doc;le EOWZKK CA“ 8'“ M( M‘ofi WCA V'V’WS, Uktgk a??qnfl\k~\ \S MGM— —\-'\I\Aw\ +l~( MSWKA S’iLFVQ S+r~oC‘irr\ 6% C}:- ___‘ 0~\‘€‘\/\ 31‘04?3- Chemistry 322a / 325a ~8- Name Exam No. 4 (5) (10) Answer the questions below about the addition of H1 to (S)-1,3—dirnethylcyclohexene. (A)(4) Draw structures of the two isomeric products (A and B) using the cyclohexane rings provided in the boxes below. Your structures must show stereochemical details but conformational features (such as the cyclohexane chair) are not needed. two isomeric products C8H151 A and B we, ’41 H3 ("I HQH + H1 + ~‘ (9 “(A "H S'H H\ CH3 ‘ ‘ l Lum W {‘0 *- SphnuL-KVLS coukh bk TLVLFSQ& (100% ee) ‘1 Ch“, ‘ x f _ (B) (5) Write a mechanism for this reaction that explains the formation of A and B. Your mechanism should be a series of chemical reactions showing all key bond making and bond breaking steps with the curved arrow formalism. Identify the rate-determining step and circle the key intermediate, which must be drawn as a stereostructure. Your mechanism. 0 (C) (1) Are A and B produced as single stereoisomers or as a racemic form in the above reaction: S\m3\¢ S—lmx—go\%9tv\¢ #3 0 A Gu'md B GLHL E c, \S o h c.,\\\ excl-(v1 \ (a. PIC ( >\(€mcm£ddmm) Chemistry 322a / 325a 9- Name Exam No. 4 3 4646’ (6) (15) Provide the missing structures in the boxes below. All important stereochemical details in the struct res Eiust e clearly shown. r (Tim c km [7‘ M. H” H KOEt CH 7‘1 IQ r.)( A) trans-1-bromo-2—metl?ylcyclohexane ————> \/ 3 _ ethanol (B) C6H5CH2C ECH C6H5CH2BI H2, NizB catalyst CHZIZ, Zn(Cu) ether solvent ...
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322af06_e4_key - CHEMISTRY 322aL/325aL Please Kt \g EXAM...

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