spring06-MT2-exam

spring06-MT2-exam - .l .. Chemistry 3A -- Spring 2006,...

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Unformatted text preview: .l .. Chemistry 3A -- Spring 2006, Midterm Exam #2 Your full signatur Print your full name Your sro \b l 577 Please check the section number and name of your 3A Laboratory 63!. Your exam will be returned to you during your lab section, Lecture only students should see the Head GSI, Shelley Claridge for their exam. Professor Jean Fréchet April 5, 2006 __ 101 M 9-1 Wenging Shui 102 M 9—1 Joshua Wong 103 M 9-1 Lin Li ______ 104 M 9-1 Michael Oar __ 105 M 9—1 Isaac Milier ______ 106 M 9-1 Aaron Esser-Kahn __111 M 1-5 Jessica Wu _ 112 M 1—5 Diana Chien _ 113 M-1-5 Sophia Kim _ 114 M 1-5 Serena Li ____115 M 1-5 Jennifer Tsai __ 116 M 1-5 Dave Kavulak __ 201 T 9-1 Jennifer Lee __. 202 T 9—1 Ben Huang __ 203 T 9—1 Steve Pedersen 211T1-5 Luci Chi 212 T 1-5 Yue Xu Making up an I grade __ 301 W 9-1 Judy Chang _____ 302 W 9—1 Craig Reeder __ 311 W 1—5 Kevin Koiahi ____ 312 W 1-5 Lucy Chi _______ 401 Th 9-1 Don Bui ____ 402 Th 9-1 Aaron Phillips _ 411 Th 1-5 Amanda Samuel __ 412 Th 1-5 Cynthia Young __ 501 F 9-1 Aaron Lee 502 F 9-1 Yazman Rose-Bauza ____ 503 F 9—1 Dan Kelly m 504 F 9-1 Mitch Anstey _______ 5-11 F 1—5 Kevin Phung __ 512 F 1-5 Katrina Lin ._ 513 F 1-5 Jonathan Choy ._ 514 F 1-5 Zin Min Tun h ..—._. Do not Write in this box. ALI-estu—reonly 1. Z [12) 2 a £12) ‘3. {2. (12) This exam has 10 pages; make sure that you have them all. We will only grade answers that are in the designated spaces. Please do your scratch work on the backs of the exam pages. Write oniy grLe answer to each problem; multiple answers will receive m credit, even if one of them is correct. Note: This examination runs for a total of 100 minutes. No questions will be answered by proctors after the exam begins. Please write Iegibly; ambiguous or messy answers will receive no credit. © 2006 J.M.J. Fréchet, Berkeiey, CA Chemistry 3A — Spring 2006, Midterm Exam #2, April 5, 2006 - r Page 2 of 10 - 1 . 12 Poineméfimure for the following compounds (IUPAC nomenclature). Be sure to pay atten n to stereochemistryLNote that most of these questions are taken directly from the end of chapter problems of the textbook! z r I C l "r cus-1- romomefityl)—2—(2—ch|oroethyl)cyclobutane Meso-1 ,2,3,4,butanetetraol (show as a Fischer projection) ~ Chemistry 3A — Spring 2006, Midterm Exam #2, April 5, 2006 Page 3 of 10 - 2. 12 Points (a) How many stereoisomers are possible for the compound below? 6 , Br Answer: Ll, ' WHsC (b) Draw a Fischer projection for the compound below using the template to the right. Note that the stereochemistry O of some 0 atoms is specified (R) (S) (R) O a: I i H (2, A” v v v - >—CH—CHWCH-—CH20H H. CH H0 cl ('3: cH3 I 3 CHZOH (0) Circle any compound below that is identical to compound A (shown in Fischer projection) D OH OH H0+CH3 H+D D+H H CH3 CH3 Compound A (d) Choosing amongst the compounds below circle TWO that are enantiomers OH H OH H Hicm chiOH H30 H HO CH3 H30 H HO H H30 H H3C OH " OH CH3 - OH H \ Chemistry 3A — Spring 2006, Midterm Exam #2, April 5, 2006 _ Page 4 of 10 r 3. 12 Points. (a) A distracted student measured the boiling point (bp) of four organic molecules as 38°C, 82°C, 118°C, and 157°C but forgot to write these vaiues next to the name of the molecules. Given the known trends for boiling points, write in the boxes below th alue that matches each of the individual compounds named below: 1 _ H OM pentane 2—methyl—2-propanol bp=33° bp= 81°C 1-butanol bp= “33°C (b) Write the structure of two different alkyl magnesium chiorides (Grignard Reagents) that would react with water to reduce ro ane. Chm, [4 62: (c) Draw the structure of the CHIRAL CYCLOALKANE with the lowest molecular mass (no isotopes are allowed) H O (K V“ \ \\ \oH OH (d) In a famous experiment carried out in 1848, Pasteur discovered the optically active enantiomers of tartaric acid. Draw their structures in Eisher projections. H q (‘3 || || 0: Ho—c—cH—cH—c—OH OH OH H O H Tartaric acid H o H O: C OH 1 l O H (e) Another stereoisomer of tartaric acid was discovered in 1906, ' _ Draw its structure in Fischer projection O“:— C O H l H O h. Chemistry 3A— Spring 2006, Midterm Exam #2, April 5, 2006 Page 5 of 10 o 4. 14 Points Complete the reactions beiow showing alt the missing reagents and solvents as appropriate. If several steps are involved, show the first step above the arrow and the next below the arrow numbering the steps _1, 2, etc. ..The reagents chosen must be such that the product shown is the major product of the reaction H Et...)'SCH3 H30 (E1 = CH20H3) 4? BxAc; . , (EH3 Hac—cle—CH2CH27LCI Hsc—cH—CHZCHzfc—OH CH3‘ CH3 CH3 as, E CH3CH20H20HZCH20H c‘o 1, w \~\C—-C' CH 3 (if—’1’ 5 0 CHacHZCHchZClF H H . (EH3 “BC—g:+CH3 I H3C-HC H 3 >—_—( H30 H ‘ Chemistry 3A — Spring 2006, Midterm Exam #2, April 5, 2006 Page 6 of 10 - 5. ‘1 0 Points. Complete the following'equations by showing the structure of the major product obtained (no mechanism needed). Note that structures are shown in Fischer projections where - relevant. HZOH —————> Ge C PH xx»; 7 W P CH3 H e'n 6) Ph H CHacHzO Na Ph H in CH3CH20H Br A Q CH 3 NC9 Hac+CH2—Br —> CH3 DMF PWVH r C CH3 CH3 Pr 69 (a H?) Ph H CH3CH20 Na PH H Br in' CchHZOH (A C Ph A 3 Pk CH3 _\<H 1) NaBH4 H3C—+CH2 + CH3 0 2) H H20 '1 Chemistry 3A — Spring 2006, Midterm Exam #2, April 5, 2003 Page 7 of 10 - 6. 10 Points. Propose a step-by—step synthesis of the following compounds from the starting materia|(s) indicated. Show all reagents & solvents needed for each step. No mechanism is needed. /\O/\ /\i5r ' @0/\ l HOC men3 A‘ I C H ' U A0 / 3\C\“3 90H HLO L O /.—/'\O/\+ HLO (b) OCH-ZCHZOH from cyciohexane and any other reagent with 4 C atoms or iess (1,, 84 , Orwchon é—- Ob % O—B (( ma \1/ ext/\er '. OW OCHLCHLOH é_:C_)_H._‘ CHZCHL HLO 3 ‘ Chemistry 3A — Spring 2006, Midterm Exam #2, April 5, 2006 Page 8 of 10 . 7. 10 Points (a) Explain the observation that compound (A) undergoes rapid substitution in water but compound (B) is unreactive despite the fact both are primary halides. (Your answer should show key structures or mechanisms) 0“ /OVCJL H 0 /O\/ (A) CH300H2CI fi—z—r CH30CH20H + HCI NCQ’ H20 (5) CH30H2CH20|f\No Reaction - 0 \C _ 0\0H + H c 050/ W 26v Wm , afio-ww WW 4% E: (b) When dissolved in ethanol, the compound below reacts rapidly, (i) Show the structure of the product, (II) write a mechanism explaining its formation, and (iii) write an expression for the rate of this reaction. HzN-CHz-CHz-CHz-CHz-Br (i) structure of product we (ii) Mechanism: . Chemistry 3A — Spring 2006, Midterm Exam #2, April 5, 2006 Page 9 of 10 3. 10 Points. ' (a) ' When 2-bro+mopropane CH3-CHBr-CH3 is dissolved in methanol and an equimolar amount of sodium Iodide Na I“ IS added, the concentration of iodide ion [ l'] quickly decreases then slowly returns to its original value. Explain with equations showing the various processes that take place sequentially. (b) Explain why compound (0) exists mostly in a chair conformation with OH axial white compound (D) prefers a chair conformation with OH equatorial ' (C) (yon (D) OOH o . ' Chemistry 3A — Spring 2006, Midterm Exam #2, April 5, 2005 Page 10 of 1D ’ 9. 10 Poihts. Show the structures of ALL the products obtained in the solvolysis of 2-bromo-1,1- dimethyicyclopentane in ethanol. Also showt s ru ture(s) of the key intermediate(s) involved in this reaction. ‘ / H3O Answer: structure(s) of the key intermediate(s) C H; CH3 ...
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This note was uploaded on 02/16/2010 for the course CHEM 3A taught by Professor Frechet during the Spring '10 term at UC Davis.

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spring06-MT2-exam - .l .. Chemistry 3A -- Spring 2006,...

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