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322b_07spring_sample_exem4_key

322b_07spring_sample_exem4_key - Kafi CHEMISTRY 322bL...

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Unformatted text preview: Kafi/ CHEMISTRY 322bL/ 325bL Please EXAM NO. 4 Print Last Name APRIL 11, 2007 First Name First four digits of USC ID __ _ _ _ -XXXX-XX TA's Name Grader (1) (15) Lab Day 8: Time (2) (15) _ _ (3) (15) _ _ (4) (20) ____ _ (5) (10) _ __ (6) (10) _ __ (7) (15) w — (100) first letter of last name I will observe all the rules of Academic Integrity while taking this exam. Chemistry 322bL, 325bL -2- Name Exam No. 4 3,4331; (1) (15) Complete the reactions below by providing the missing products inside the boxes. Be careful to give all the important organic products, as requested. It is not necessary to give the byproducts or minor products of the reactions. "Workup" means treatment with water and bringing the reaction mixture to neutral pH. 1' (i) Mg/ diethyl ether a A ( ) (ii) C02 kor H CH3 (iii) H+, workup (i) SOC12 (B) CH3§HCH2COOH CH3 EH3 'd' + me (ii) l-fi‘OH Pym CHZCH3 (100% ee) (C) C61'15COOH + (CH3)2CI‘INH2 + C6H11N=C=NC6I'111 diethyl ether (i) NaOEt/EtOH heat (D) C6H5CH2COOEt (ii) workup (Pb - (RC-5’ Col/x") (i) NaOEt/EtOH heat (E) CH3§CH3 + CI’13CH2CO2Et (ii) workup Chemistry 322bL, 325bL -3- Name ExamNo.4 3 “CL (2) (15) Complete the reactions below by providing the missing products inside the boxes. Be careful to give all the important organic products, as requested. It is not necessary to give the byproducts or minor products of the reactions. "Workup" means treatment with water and bringing the reaction mixture to neutral pH. (i) 1.0 Eq NaOEt/EtOH (ii) 1.0 eq (CH3)2CHCH2CHzBr (A) Et02CCH2C02Et (i) NaOEt, ethanol 13 E ( )CaH5C MEE: + C6H5CH2C02 t (ii) KOH, H20. heat C [of C 006% (iii) H30+, heat (via H2C6H5 (i) 11071120 heat (C) C02Et (ii) H30+, heat @? (i) KOH (D) f‘H (11) CH3CH2CH2CHzBr NO2 ”H2. (i) Fe/HCl/HZO, heat @ (E) (ii) KOH/H20 (“C—CH 3 CH(CH3)2 Chemistry 322bL, 325bL —4— Name Exam No. 4 (3X15) (A) (10) Provide correct structural formulas inside the boxes to match the names below the boxes. Mm 3-phenylpentanenitrile N,N-dimethyl-p-ethy1aniline (B) (5) Provide the general mechanism (using the curved arrow formalism) for the generic case of nucleophilic substitution at acyl carbon, as shown below. Circle and identify key intermediates Chemistry 322bL, 325bL ~5— Name Exam No. 4 l “C (t /_—_-/ (4) (20) Circle the correct answer for each statement or question below. (A) The least reactive compound in nucleophflic substitution among the following is (circle answer) C6H5§OCH2CH3 CéHsgCI C6H5§£C6H5 (B) The reactivity order (fastest to slowest) of the carboxylic acids below in the following esterification reaction is cat H+ RCOZH + CH3CH2OH RC02CH2CH3 + H20 (3-13 circle answer below) CH3CH2CH2CH2COOH CH3CH2 HCOOH CHanOOH bllblbl CH3 I II III III>I>II they all proceed at the same rate (C) The rate of hydrolysis of a nitrile will be slowest at (circle answer) pH 2 4 ® 10 (D) In the two alkaline hydrolysis reactions below (A and B) with enantiomerically pure substrates, the 1-phenyl-1-ethanol product in each reaction will be (A) 100% ee (S) C5H5309HC6H5 KOH HOqHCeHs + c6115coz- H o, TI-IF CH3 2 CH3 (B) 100°/ ee(S) c H 9 CGH KOH H HCGI-I c H ° 6 sfioqfl 5 + ' 0CH3 H20, TI-IF OEHS 5 6 5503 (circle answer below) (A) 100% ee (3) (B) 100% ee (R) (A) 100% ee (3) (A) 100% ee (R) (A) racemic form (B) 100%ee (S) (B) 100°foee(R) (B) 100%ee(R) (E) Among the acids below, decarboxylation will occur upon heating >100°C with (circle answer below) OOH 3 only 11 11,111 CHSCHZCHz COOH CH3CH2CHCOOH I, II ILIIIJV COOH I II III IV Chemistry 322bL, 325bL —6- Name Exam No. 4 - (4) Contd. / (F) Which of the following derivatives of carbonic acid are stable structures? (circle answer below) 03001ch3 ClébH HzNg0CH2CH3 H2N§OH L1H: 1" onlylll I II III IV all of them (G) The order of base strength (strongest to weakest) among the anions below is (circle answer below) CH3CH20' 'CHngCHfiHs CH33CH30mZCH3 I>II>III 111>1>11 I II 111 I>III>II (H) The order of base strength (strongest to weakest) among the compounds below is (circle answer below) 5;} H2 @NHZ <:>’NH2 I>II>III III>I>II 1 11 111-11>m>1 (I) The order of acid strength (strongest to weakest) among the anilinium ions below is NH3+ NH; + (circle answer below) 3 I>II>III - III>II>I II>III>I CH3 NO2 1 n 111 (J) Which statement below correctly describes the relative base strengths of I and II? @133 43> benzoquinuclide quinuclidine (circle correct statement below) -I is a stronger base than [I because the inductive effect stabilizes the nonbonding electron -II is a stronger base than I because the inductive effect stabilizes the nonbonding electron a air in I. -I is a stronger base than II because resonance stabilizes the nonbonding electron pair in I. -II is a stronger base than I because resonance stabilizes the nonbonding electron pair in I. Chemistry 322bL, 325bL -7- Name Exam No. 4 (5) (10) Enamines are useful derivatives of aldehydes and ketones for introducing alkyl and acyl groups into the 2-position of the aldehydes and ketones. Answer the questions below. (A) (5) Outline below a reaction pathway for the formation of cat H” Z 3 N—(l-cyclopentenyllpyrrolidine + F + H20 from cyclopentann. and _. .9“! Cau\é )urf- Elm-Mn.) loss 5"? “3.0 ‘CMM aldtho-Kprodue'P. (B) (5) Provide the entire reaction pathway (showing all W) for the following enamine synthesis of 2-ethylcyclopentanone. e o curved arrows to show movement of electron pairs at key points in the scheme and show alt charges. how????? T + CH3CH2BI' """" " ------- -> --------- 4.. Chemistry 322bL, 325bL Name -3- Exam No. 4 1 “Ca 6 05 WW (6) (10) Provide the missing structures (reagents or products) inside the boxes below in a synthesis of phenobarbital, a barbiturate drug, starting from phenylacetic acid. (i) Cl23 P (N C6H5CHCOOH (ii) C?“ a—cyan0phenylacetic acid C6H5CH2COOH (i) HO'/H20 heat (ii) Iago+ C13H1604 (391-1304 (i) 1.0 eq NaOEt in ethanol (ii) 1.0 eq CH3CHZBr C15H2004 phenobarbital Chemistry 322bL, 325bL -9- Name Exam No. 4 (7) (15) Provide reasonable syntheses in (A) and (B) below from the indicated starting materials. (A) (6) Provide a reasonable synthesis for either of the two compounds below from the indicated starting materials using any other needed reagents. If you work both problems and do not indicate which one is your answer, only the first will be graded. FéHs H NCH A ’CGHs . H w __________________ _ 2 2\\ (I) B! “CHZCHB HACHZCHE, (R)-1-bromo-1—phenylpropane (S)-2—phenyl-1-butanarnjne (Cog-5' %(\-nvn.rs u, “A Ice“? + Ha C10 7 ”Err, H/y \: m: I. m .-t u.- ‘.( a. ‘ B r H zcu H H794 3 3 L')l~lAlt-\ql1'\'l\1\" H hl' 30$ O 1’ 1-) " V“ A H u.) o t- (u 'P (3 ‘ (“‘3 H o f 6!: HINGEIR \C “Lg .43 H2 © ------------------- (o p-bromotoluene p-toluidine ‘P. Coou CndhE-l—l-mr I L '— NH'L HQ}? . NH __ / :l 3°C“. «5\| 1 '~ Er Ho 0 once-.1 ? KC?) ’ @F (t. 2 t“; @ Lam-1 o9 C ‘ ' CH3 (+5 CH3 Chemistry 322bL, 325bL -10- Name Exam N0. 4 (7) Contd. (B) (9) Provide a reasonable synthesis of 4-methyl-3,5-pentanedione from ethyl bromide by way of ethyl 2-methyl-3-oxopentanoate, as sketched below. You may use any other needed reagents and solvents. Hint: remember to use NaH in an ether solvent at a critical point in the synthesis. In the shadow box below, explain why this base / solvent was needed. CH3CHzBr --------- - CH3CH2CQHC02Et CH3 CH3 ethyl 2-methyl-3-oxopentanoate (flM'EE-tlmr as H Kim C01 > QHBCHLQOOH :m H369 “‘“fl 4-methyl-3,5—pentanedione Cl—chLBr ) Qt\3CHJ’QOt_E4y (0 140.054; .E—Amol k! of? Q Ham—31.2% Q 00 H kL-N' a 'I-. 31-! r. ...
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