CHEM 316 - PRACTICE EXAM 2 KEY

CHEM 316 - PRACTICE EXAM 2 KEY - CHEMISTRY 316 — FALL...

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Unformatted text preview: CHEMISTRY 316 — FALL ‘06 EXAM II — THURSDAY, November 16th .— ’1 wk NAME: Kl: 7 7X 4 (last) (first) 1’7 INSTRUCTIONS: 1. This exam consists of 5 questions. Do the ones you know how to do first, then come back to the others if you have time. 2. Please, scrupulously avoid even casual glances at other exams! ! ! l !! MAKE SURE YOUR EXAM HAS 7 DIFFERENT PAGES INCLUDING THE COVER Name: [<5 Y 1. a) For each of the following, indicate whether the reaction shown is a substitution (S), elimination (E), or addition (A) reaction: H0 i} 1. CchHZCHzMgBr 2. H20 nil/\J\ —::‘—" AA b) For each of the following, rank the reactive intermediates in order of stability (from least stable to most stable left to right as requested): "oboe A B least stable: 5 c: D c. < A :moststable m n n 9 e | | A B 1 C least stable: A c 5 < (I :mostslable iii} M m M _ __ _. A . .B .C n- I I leastslable: é < C} < :moslstable _ c) Circle the nucleophilic atoms and put boxes around electrophilic atoms in each of the fol (Ewing molecules: ‘ h 37": W d) Use correct arrow formalism to show a reasonable heterolytic bond cleavage and products for the C-1 bond in the molecule below: a _, ii» a CHg-I -=; CH; + l ;L .— Name: 2. Circle the correct response for each of the following: a) The two structures shown here represent: enantiomers meso compounds , )1 b) The expected major product of bromination of 3-methylpentane is Br M l Br w /W/\/ c) a carbon-carbon double on stretch shows up at ~100-150 ppm ~0-50 ppm ~200 pp@ d) The molecule shown below should have how many peaks in the proton— decoupled 13C NMR? diastereomers none of these choices 10 11 12 14 none of these choices 6(8)» e) A signal that has a chemical shift of 5 ppm taken on a 60 MHz NMR would appear where if obtained using a 300 MHZ NMR? 1 ppm none of these choices f) Which of the following structures represents a diastereomer of (2R, 3R)-3— bromo—2—h droxypent—4—enal? 25 ppm g” ‘ 9H E H/mfv H/KA/ on 5H none of these choices g) Relative to TMS, the C atom in CH3C1 appears where in the 13C N MR? Upfield doerfQ outfield infield O h) The correct IUPAC name for /\/lKNH4 is: .w“/:\ butanamide ammonium butanoic acid ammonium butanoate ammonium butanoyi leftfield Name: Provide the correct IUPAC nomenclature or structure (whichever is missing) for each of the following. Be careful to include any stereochemical designations when necessary: gréfifl l" U (Ix/1'14- 6/1 — 21:sz c) m-ethoxybenzaldehyde d) (R)-4-hydroxyoct-S-yn—Z—one Name: E L- Y 4. a) Circle the compound with molecular formula C5HBO that is consistent with the 13C NMR and IR shown below (put reasoning on back for full credit): 15934..” 1555 128 .— 5 Sgcfflt-lS rm: 27 4'" [18 191 .._ . J - lease»? “of? , ‘Y‘ I’L‘ 150 f .i I J __ ma, {1,0, “flat”. 3‘ I " NIL £~ H l.“ 1 4Jll .Il I-ul II I '— v‘r-‘a r n- I“ '1!n liar-LT" Al” 0) A I *9: "I1 1‘I‘l II ‘ Mil \ I il‘ I i + £22 lir‘ I i Mi b) For each of the following pairs of compounds, indicate whe e ey are enantiomers (E), diastereomers (D), meso (M), or something else (SE). 3, 3 Name: 5. Complete the following regarding the free-radical halogenation shown below: F light + F? > + other products a) For the reaction above, show the two propagation steps only. Use correct arrow formalism. 4M7» “ /‘l /‘f I F 4’ F a Step 2: + F ' F a \ K /+21<]/mol jinx/[j 0 77/ b) Assume that the change in enthalpy is approximately equal to the change in Gibbs free energy, and calculate AG for each step above. Show work here, and put your numbers in the boxes provided above. W ., -— LJ /A/\i7() Step 1 calculation: § 3 -- 5' 20 Z I , ,r .. . ', : ‘— . r * I“ Step 2 calculation: {3 L} " "H ll 5 k.) /m c) Now, using the numbers you calculated, construct an energy diagram for these two steps. Indicate on your graph transition states with the appropriate symbol, and clearly label your graph. 1' l G — )c‘n‘ R l l_ |_ reaction coordinate 1) Which step is the rate-determining step (step 1 or step 2)? W 2) What is AG for the overall reaction? "I 711 E.) N v 3) In our assumption that AG ~ AH, what else did we assume? A3 [pawl] vs; Ml ...
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This test prep was uploaded on 04/09/2008 for the course CHEM 316 taught by Professor Kantorowski during the Fall '08 term at Cal Poly.

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CHEM 316 - PRACTICE EXAM 2 KEY - CHEMISTRY 316 — FALL...

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