322bf07_e4_key

322bf07_e4_key - 0 CHEMISTRY 322bL Please—I<J_— EXAM...

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Unformatted text preview: 0 CHEMISTRY 322bL Please—I<J_— EXAM NO. 4 Print Last Name NOVEMBER 19, 2007 First Name First four digits of USC ID _ _ _ _ -XXXX-XX TA‘s Name Grader (1) (15) __ (2) (15) __ __ (3) (10) __ __ (4) (15) __ __ (5) (20) __ __ (6) (10) __ __ (7) (15) __ __ (100) Lab Day 8: Time first letter of last name I will observe all the rules of Academic Integrity while taking this exam. Chemistry 322bL, ~2- Name Exam No. 4 3 each /______. (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, and show stereochemical details, wherever they are important. 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) NaCN m (A) CeHsCHzBI' H H 0+ H O h CbH(C\'\1C,OOH %\ N C (11) 3 , 2 , eat ‘ p ’600//. soluble in aqueous NaHCOa l/t C (i) soc12 (B) CH3CH2CH2COOH o l c H3CH 2:14 zé QM (CH3) CHQH L / /<:) f + h t \ (excess) ea 0 (D) C130 + NH ———’ HNgN 3 1 H2— (excess) (i) 1.0 eq NaOEt/EtOH, heat (E) C6H5C02Et + CH3C02Et H 510w addition (11) Workup Chemistry 322bL, -3— Name Exam No. 4 (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, and show stereochemical details, wherever they are important. 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. g (i) 1.0 eq NaOEt/EtOI—I 6| A c H CH CH co Et ————’ ‘ . CHLC 5H ’- C19142003 OzEt AL COzEt (i) HO‘, H20, heat Dept CM, {.5 (B) (ii) H3O+ [In ¢~ {-21 (iii) 180°C CHZCH3 (C) + (D) CH3|Iy\ (i) NaCN C6H5 3’ (ii) H2, Ni 100% ee (S) H2 H 2.. z LL 3 (E) + CH3CH2CH2CH2NH2 Ni O Chemistry 322bL, -4- Name Exam No. 4 (3) (10) Answer the questions below. (A) (6) Provide correct structural formulas inside the boxes to match the names below the boxes. 3-methyl-2—butenoyl chloride (B) (4) You are asked to prepare a sample of ultrapure butylamine from butyl bromide, with no contamination by dibutyl- or tributylamine. Which synthesis would you select, direct ammonolysis or the Gabriel, and why? Illustrate your answer with chemical equations. E Gabriel (i) / 616 (ii) hydrolysis \ CH3CH2CH2CHZBr ---------------- --* CH3CH2CH2CH2NH2 direct ammonolysis TIA—L ilficf Ca-Mnb“o\r‘§({ CQU‘t-k P¢Su\+: 1M $°M¢ A31" (ski +1‘3a\‘€ (QM? «k Chemistry 322bL, " c ' Name Exam No. 4 (4) (15) A sample of 100% ee (R) 2—butanol (sec-butyl alcohol) is used to prepare sec-butyl benzoate (I) and sec-butyl p-toluenesulfonate (II). (A) (4) Provide the structures of I and II inside the boxes, showing stereochemical details. . Reaction of I in an aqueous alkaline solution, as shown below, yields the benzoate salt and optically active sec-butyl alcohol that shows a specific rotation of [a] = -13.52°. Reaction of II under the same conditions produces the p-toluenesulfonate salt and optically active sec-butyl alcohol that shows a specific rotation of [a] = +13.52°. (B) (2) On the horizontal lines below, indicate the enantiomer of the alcohol product: R or S. NaOH C6H5C02‘ Na+ + sec-butyl alcohol H20, THF [(1] = -13.52° NaOH H p-CH3C6H4SO3' Na+ + sec-butyl alcohol __5 H20, THF . [a] = +13.52° (C) (6) Sketch the multi-step mechanism for the alkaline hydrolysis of I that explains the above result. Use the curved arrow forma ' - u - - o ' - and identify the key intermediate. Stereochemical details must ' ' ' C.“ H” [CH5 6 (Lo/CI 3 (‘HS Tod-rch Ami I + H D \ \‘Ab v: ml- 4 lmk \ u °s<w< gzo: (D) (3) Sketch the mechanism for the above reaction of II. Use the curved arrow formalism and clearly show all stereochemical details. :1: /\1 /CH3 [0'2— 3_ 5— Ext 0 sozct-HHCHS H Er H0 4- i7 \ w. - Chemistry 322bL, _ (a... N me No.4 ' Exam 2 M( k /. (5) (20) Circle the correct answer for each question or statement below. (A) The order of reactivity (fastest to slowest) of the following acid derivatives in an alkaline hydrolysis reaction will be acid derivatives C6H5é?x HO- C6H5C02_ CéHsngz H20 1 II III IV (circle answer) IV>II>I>III I>IV>II>III IV>III>II>I (B) The products of the complete hydrolysis of a nitrile at pH = 1.0 will be (circle answer) RCOZH and NH3 RC0{ and NH3 RCOZH and NHq!+ RCOZ' NHq!+ (C) Esterification with methanol of benzoic acid containing 180 isotOpic labels as shown below will give products with the following distribution of180 labels. (circle answer below) 18 18 H* C6H5380CH3 + H20 C6H5§30CH3 + H2180 18 C6H5 + H2180 (D) Vigorous heating above 100°C will result in facile decarboxylation of which of the following compounds? 18 (3611588011 + CH3OH (no labels) 18 excess C6H5 OCHs + H2 0 (circle answer below) H02C 02H COZH 11,111,1v 11 cozu I III IV (E) The product of the following synthetic sequence that starts with the Dieckmann condensation is (circle answer below) (i) NaOEt, EtOH C023 "(11) Hflws)!_1sl_12)__-__-- \\ 02Et (iii) HO‘, H20, heat 3 (iv) H3o+, heat (4:02) diethyl adipate Chemistry 322bL, .. 7 - Exam No. 4 (5) (Contd) (circle answer) HCOZH CO CC14 (G) The order of acid strength (strongest to weakest) among t e bolded H in the compounds below is CHBCOZEt CH3COOH CH3CI-IZOH EtOOCCHzCOOEt I II III IV (cirde answer) II>III>IV>I IV>II>III>I II>IV>I>III (H) The order of acidity (strongest to weakest) of the bolded H in the compounds below is / (circle answer below) / /e O |/ O l I>II>III 11>1>111 N-H N-H \ III>I>II ‘b I II III (I) The order of base strength (strongest to weakest) of the anilines below is NHZ NHZ NHZ (circle answer belowL I>II>III II>I>III I>III>II III>I>II CH3 NO2 I II III (I) The Hofmann rearrangement is carried out on the diastereomeric 4-t- butylcyclohexanecarboxarnides (A and B) producing 4-t-butylcyclohexylamine (C). Which statement below best describes the stereochemical features of this reaction? H2 H2 H Brz/HO- (CH3)3C ' ‘ - ' _ I H A H 9 2 CH3_ ‘CH3 CNHz - - CH3 (CH3)3C B H20 c H (circle answer below) -Starting with either A or B gives the same mixture of cis and trans C. -Starting with either A or B gives trans C, the thermodynamically more stable product. TA gm ns C while B gives cis C. ‘ -A gives cis C w i e B gives trans C. ‘ Chemistry 322bL, -' 33 " Name Exam N0. 4 (6) (10) The stoichiometry of the classic Claisen condensation (shown below with ethyl acetate) involves two equivalents of the ester and one equivalent of sodium ethoxide to produce the B- ketoester product after workup. Na+ 2CH3C02Et + NaOEt CHggéliCOzEt + EtOH + kaupl—L 0 CH3 CHQCOZEt (A) (6) Provide a mechanism for the above reaction using the curved arrow formalism. Circle the key nucleophile in this reaction. ‘7“.— (sq H D G) A -J + E-r o H ‘ amo\«7\"~ and 0-“ (4 o o r)- -<>_'_ Eugen {015+ < CHLECHZCOZE+ (OE-r V 4— E-HDGD (B) (2) Why is one full equivalent of NaOEt needed for the Claisen condensation? Explain by providing approximate pka values for key compounds in your above mechanism. u? “AK-‘4‘ +L“ aglé-bQSL T1¥¢+¢0m x$ Cc..+«\Z-\-—rg Tr“ afiakbg 0"? “‘ka A o“: +'\I\L VS-Kl-Foflsh r“ \f' r7... (7:le Wac+3 norm Tkts 34;? (9, s-(voxgktoMa-hq‘q \‘4/\ bus: 1Comso~aw~j +ki- 21 u'i u“ \ner- oo‘F E+D® (C) (2) Why does the Claisen condensation fail with ethyl 2-methylpropanoate? Be clear. (393143 (CH3)2CHCOZEt + NaOEt ----- ------ n- (CH3)2CHCCCO2Et ethyl 2-methylpropanoate Tu (\utSa—m 'ewéuc’c do” «0+ kaw— a btgk‘j «adv: H. (Jr (avsmofl— rough“; A‘Pm'W’Ko-R_QQLS ahavLB -\-o m “Mi 0% -\ V‘Si 5+5 mvcvoé%l€Q QhCK/C \KQVayk . ’COCH) Q C?__ \ ACCHS) CHCO‘E—F < (4+2) CHtLéFCOz—gf ‘l'E-VO P—‘(CH3\,§_HC| (\COLE-t C 3-64- Chemistry 322bL, JR,“ Name Exam No. 4 (7) (15) Provide reasonable syntheses, as requested below. (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 (i) will be graded. (i) CH3CH2C02Et + h - - _ — - - — - - - ' - - - — - - " any RX compound and needed reagents CH3 (a) NaOEr E+ou O Zei+3c~+7507§f ——_’_.____> CH CHaa$HCoLET ({3} 3 C% l.oQ°\ (73 NmOP-r- (F'tVeHgGLBV V )(oo°c o CQsz‘r - “ H 0 Q$HL§<N <¥_\t_L+C(43C£-ha—&C‘oou (3&3: c\43CH2LC——Cozg («Co \ ‘ t~~3H+ ‘ T 7,, CH3 “ CH3 + any RX compound and needed reagents (ii) EtOOCCH2CH2CH2CH2COOEt __________ u- §CH2CH2CHZCH3 Chemistry 322bL, «4 o — Name Exam No. 4 (7) Contd. (B) (9) Provide a reasonable synthesis of amobarbital (I), a sedative and hypnotic, from 1-bromo— 4-methylpentane by the route shown below, using any needed RX compounds and reagents. You may not use diethylmalonate as a starting reagent. Br CH3QHCH2CH2CHZBr """""" ' ' ’ CH3CEHCH2CH2CHCOOH CH3 CH3 1-bromo-4-methylpentane 2-bromdS-methylhexanoic acid H OQ/N\/ i CH3CH2 " ' ' ' ' ' ' ' ' ' ' ' ' ' ' (CH3)2CHCH2CH2 CH3 I amobarbital (;\ M 3 / E 44v r— CHJC‘HCH5HIC'I-f'zflr- CusclH¢u§ “szcooH Br 43 c H k’ A d L C H 2 J A 1. av U LI' 5 H O® v ’4' u 8“ Q N «CA! CHJ§HCH2CH2LH C °° H C(°°” git:— CH mantel-55H M,“ C H . 3 COO .lrlfiH<|~£Ctg_C\l-i H29, \ué‘ 8% A H (I\NnOE-+({.Ot7) L. LC”: ____————._a CHscHQt—i CH Cfico : CH Q\-\Q\-\ CH CHé “ \ a. r. :,~-\- 3‘ 2. 2 Cozgg (aflQHJCt-I gr CH g _ CH3 2 ’- 3 “LC‘t ...
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This note was uploaded on 07/13/2008 for the course CHEM 322AL taught by Professor Jung during the Spring '07 term at USC.

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322bf07_e4_key - 0 CHEMISTRY 322bL Please—I<J_— EXAM...

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