Fall 2007 Test 2

Fall 2007 Test 2 - Chemistry 227, Fall 2007, Dr. Well-'5,...

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Unformatted text preview: Chemistry 227, Fall 2007, Dr. Well-'5, Test 2 Halloween - scarvjl Name: 1C“\9°L\ i I score=0pscan * (80:20) +essay=Q* (8993)+l_0=flb ( 0 Essay. Ionic reactions . 10 points. Write the complete mechanism (show electrori p/ai'removement with curved arrows for each step) forth eaction below. - Draw all lone pairs of electrons. - Identify the rate determining slow step and any fast steps. - Identify any intermediates (with [ ]) or transition states (with [ ]1) - Draw the product with correct stereochemistry. - Write the rate equation for the substitution. (i.e. rate = k ........ ..) Reaction: . Draw products in box: El Chemi'stra 227, Fall 2007, Dr. Well-s, Test '2 Halloween -— "Scary! score = opscan * (80:90) +essay = * (89730) + = l. v‘ . . . . . ‘I‘U ’ — Essay. Ionic reactions . 10 pomts. Write the complete mechamsm (show electron movement with curved arrows for each step) forth N2 eaction below. - Draw all lone pairs of electrons. - Identify the rate determining slow step and any fast steps. - Identify any intermediates (with [ ]) or transition states (with [ ]l) - Draw the product with correct stereochemistry. - Write the rate equation for the substitution. (i.e. rate = k ........ ..) Reaction: Draw products in box: I I I I I i I I I I I I I I I I I I I I I I I I I l I l I I I I I I I I I I I I I I I I I a i . i : 5r E \ 0H9 ; _ x a : H\“u|‘C Br '—"' E }' l'F‘ ‘— L a L 1/\ E Me i f": E (L. I I Et\ E ‘- '1. Br “'7 B" i ‘ \ Me it I _ H l ____ : " IA {Vi}. / 1 IL.“ L l _ X ‘1' (Ll‘bl "‘(FXW ' \/ RAJ” 9 " [~l :— <_- i” k t Consider molecules 1—5 and relationships for questions 1 - 7 -.. H CI H . H 0' ’4, ' H CH 'CHa CH '\§‘ ‘3' \géz/CHs 3 x Br 3.. l R“. I re Hum“ \ Hum”? / CH3 / CH3 Bi" 1 Br 2 Relationships | A. identical B. enantiomers C. diastereomers D. identical and meso E. constitutioual isomers \/ I . Molecules 1 and 2 are C, . 5. The best name for 3 is 2. Molecules 2 and 3 are u _ A. 2-bromo-3-chlorobutane .. (2R,3R)-2-bromo—3-chlorobutane 3. Molecules 3 and 4 areC % '/ . C. (2R,3S)-2-bromo-3-chlorobutane 4. Molecules 5 and 4 are g 2E D. (2S,3R)-2-bromo-3-chlorobutane E. (23,3S)-2-bromo-3-chlorobutane E5 ex 6. [a] of 4 is r A. +152” B. —15.2° C. 0.0“ D. —30.4° ®not zero Kx.“. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Diastereomers have A. identical boiling points B. optical rotations equal in magnitude, but opposite signs I identical melting points K, D. All ofthese ® None of these r. Consider molecules 1-5 and relationships for questions 1 - 7 " " rv ~ _;".:-\ ”“\_ H“\ll"Cg kuwCer / CH3 / CH3 Br 1 Br 2 Relationships A. identical B. enantiomers C. diastereomers D. identical and meso E. constitutional isomers K Molecules l and 2 are C . 5/. The best name for 3 is Z Molecules 2 and 3 are C, I A. 2-bromo-3-chlorobutane )t B. (2R,3R)-2-bromo—3-chlorobutane 3(- Molecules 3 and 4 are l - C. (2R,3S)-2—bromo-3-chlorobutane 44 Moleculessand4are k _ Q. (2S,3R)-2-bromo-3-chlorobutane E. (28,3S)-2-bromo-3-chlorobutane \ '1 Y ‘I ‘31. [(1] of4 is _ Cl E.) C, {m {ml / A- +152” B. —15.2° c. 0.0“ D. —30.4° l-Ey'not zero " " \h, .{f q. Diastercomers have A. identical boiling points ‘?~ B. optical rotations equal in magnitude, but opposite signs I“ C. identical melting points is D. All ofthese 3k None of these --/I ,. / <./ n : O _ rl H 1 ’ L m) 8. Which graph is the most accurate for the following reaction? 3 0 “(3H O __ L __ U 1) r’ _1 ,1 l e .. H I we : 9—CHn(CH3)(3_n_J n a t, 5 5411.7 1; ‘1sz " ether product + alkene product , _ . . _ n . . _ _ . . . . . . . . . _ _ _ . . . -_ ‘5 D FD - a use fins :5 coordinate System 5 fl.) o\° D mo 90 BO 70 I 60 i 33*- ‘r— *— + 30 20 . *3. ' H I o 1 2 a r1 ref-“'4 1') 9. Which 13C NMR spectrum represents the 8N2 product of the reaction below? ,4 I r l H H I H 9a CH W" "5)“ Cfiév ”‘ l l l “ 3 En“ VH3 m _ _ I__ _ . f H T T T H " products 1" l l H H H o A 6% ' . i j i) | .r\ ‘ ‘ I I E E .' A'wlsh'ab'PpMah‘2o'1b'figao‘fousb'éulpfld so 2010 o E | ! 10.. as...3D._25....2h.:..1:5_...1.0,,..S...:é ....‘:5:...‘;D.,..,:;%.i...3:o=...2.§ 20..15.'.:1:0 C PPM D PPM Study the ring flip equilibria of compounds 6 and 7 below for questions 10 — l3. fy-{r - ~" |AG°| = 9 kamol H .—..._.—h.._ e H H H 63 iBU H H —_._._.L._ F H _ tBu 7b tBu u 1“ II;\.) / _ ll ' kn“ / Et = ethyl, tBu = IerI-butyl I 0. The most stable conformation of compound 7 is A. 7a "KB-I'm C. neither; they are degenerate D. not enough information .d \/ K L t, .- "Hip-L {r 1:” .vk IL "*3 (5 L4,; Layer” i. \\ I I o If compound 6 is at equilibrium at room temperature we would expect to find % of the molecules as conformation 6a. A. 98 B. 94 C. 50 D. 6 @92 J ' i V\.;~ hind-f! an}; l'}Z l I Q. The absolute value of the free-energy difference between 7a and 'x'b would be kamol. A. greater than 9 a less than 9 <3 f- 9 D D. 0 E. not enough info 4' g‘r/ -{_ Liver «a: [5 if). (fink I 3. Compound 7 is . @a chiral compound B. an achiral compound {3V Consider the reaction below for questions 14 - 16 H H I e | e H—C—L =NU —)~ H—C—Nu :L I solvent l H H I 4. The rate of the reaction above is greatest if 0 H ii /H H o methanol \C/ \C \ / \ / \ l / \ H H H H H acetone methanol methanol 0 O OH i I acetone/ 9 \\ a \\ ( . / II N 0 one 0 one I 5. A kinetic study of this reaction was performed with L = I, Nu = Br, and solvent = ethanol. The missing number in the chart below should be initial [substrate] initial [Nu—1 initial rate (mol L " s") (./ /A. 5.5 13.11 13.44 E.88 valves?“ 7; KUMQ @‘ii’ - 61:34)“! 5-mier (laud-g? Yt‘k I ‘5. An optical rotation study of this reaction was performed with L = I, Nu = Br, and solvent = ethanol. Which plot below is the most accurate? 5 10 15 [a] degrees '3 I _x U1 [[1] deg rees time {min} Consider the substitution reaction coordinate below for questions 17 - 19. I 7. The activation energy for the SN2 reaction is klfmol. ®/A.1 3.15 (3.5 13.2 I 8. The transition state is labeled by . A. m n C. o % J D. It is not labeled in this plot E. there is no transition state to label! I 9. This reaction is endergonic p. B. isogonic | . _ C. exergonlc J. 20. is known as the founder of the field of stereochemistry because of his separation and studied- of the enantiomers of tartaric acid. A. Lewis B. Schrodinger / C. Prelog E. Ingold 17 it) *. ’k w 16 15 14 13 12 11 10 energy kamol (no:me y Data section: Free-Emmi w Difference. AG" More Stable lsomer (kJ mol") (‘56) 0 50 1.7 67 ‘ 2.7 75 3.4 80 4.0 83 5.9 91 11 ‘ ' >9915 17 99.9 23 99.99 [a]mix : ‘36 [a]pure ee = |%A — %B| r (%A + %B) %ee =ee x100 ...
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This note was uploaded on 06/19/2008 for the course CHEM 227 taught by Professor Wells during the Fall '07 term at Campbell.

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Fall 2007 Test 2 - Chemistry 227, Fall 2007, Dr. Well-'5,...

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