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ExamIIKey2009 - IX PRINT NAME(14 points Using as man of the...

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Unformatted text preview: IX. PRINT NAME (14 points) Using as man of the templates as needed, fill in the correct stereochemical representations of the major products f e best conformation! of the following reactions. Name the indicated starting material, including stereochemical designation; .. I 0% l H. ' K+ 'OtBu ‘ (Hamsc DMSQ v . ‘ m > . CH3 2 ' ' ” III. I l V K+ "OtBu H C C ~———“"" ( a )3 CH3 DMSO 2 22M a? \ l4j/4/Ep Z IV. . , Br 'Na+ ‘CN U/fibdé Mm . 1m“ tic/mm % | DMSO V Br CM l Na+ “CN ! C] DMSO NC ' % name of F 1 308 EXAM n DRAFT . FALL 2009 , 3 PRINT NAME IY (14 points) Using as many of the templates as neededhflllwinmthe correct stereochemical representations of the ma'or roducts f the best conformatioii of the following reactions. Name the indicated starting material, including stereochemical designation. Br Na+ ‘CN , ' 111101 / \ ' {<7\CI ———-——-——~>NC : <7 CL {<7 DMSO 2 Br v Na+ 'CN Cl CXCBSS N C % DMSO , V. I + — t H K OtBu / CH3 308 EXAM [1 DRAFT FALL 2009 - 4 PRINT NAME ‘ 2X. (12 points) Assume that a 30:70 mixture of the (S,S)- and (R,R)—enantiomers of 2,3— dichlorobutane has an optical rotation of +8°. Using as many of the templates as needed, show the confect stereochemical representation of these compounds and their - stereoisomers and show their optical rotations. ’ designation: 2i; 3B designation: 2___; 3 [06]! O” .[Otii m 636 308 EXAM II DRAFT FALL 2009 5 PRINT NAME 2Y. (12 points) Assume that a 40:60 mixture of the (S,S)— and (R,R)~enantiomers of 2,3— dibromobutane has an optical rotation of —6°. Using as many of the templates as needed, Show the correct stereoehemioal representation of these compounds and their stereoisomers and Show their optical rotations. designation: 2;; 3 é [at 30° designation: 2_S__; BB designation: 2___; 3 2 [on]: Ca [on]: ‘ "144650 308 EXAM 11 DRAFT _ ' FALL 2009 6 PRINT NAME 3X. (16 points) Draw all the isomers of C5H9C1 that do not have a double bond or a quaternary carbon (a carbon with no hydrogen attached) and are chiral (use as many boxes as required). You need only draw one of each enantiomeric pair. Use dotted line/wedge projections'to clearly Show stereochemistry. 308 EXAM 11 DRAFT FALL 2009 7 PRINT NAME BY. (16 points) Draw all the isomers of C5H9Br that do not have a double bond or a quaternary carbon (a carbon with no hydrogen attached) and are chiral (use as many boxes as required). You need only draw one of each enantiomeric pair. Use dotted line/wedge projections to clearly show stereochemistry. «£66. WWW; 5/, fly - VIII v - 308 EXAM H DRAFT FALL 2009 8 PRINT NAME 4X. (12 points) Starting from any compounds of three carbons or fewer that contain only H and halogens and using any inorganic reagents propose a synthesis of the S-enantiomer N. ' C . HZN . of . Use as many reaction steps as needed. Put reagents and solvents above the arrow; separate reagents from each other by commas and from solvents by a slash (/). Once you write a structure of a compound. you may designate it with a Roman numeral and thenvuse the numeral instead of writing the structure again. It’s easier for the grader and confused graders are less likely to give partial credit. /\,{f.a¢‘ 'NHg/aprbzzib , flint Br 308 EXAM n DRAFT . FALL 2009 9 4Y. PRINT NAME (12 points) Starting from any compounds of three carbons or fewer that contain only H and halogens and using any inorganic reagents propose a synthesis of the R—enantiomer /J\/NH2 C % of N . Use as many reaction steps as needed. Put reagents and solvents above the arrow; separate reagents from each other by commas and from solvents by a slash (l). Once you write a structure of a compound you may designate it with a Roman numeral and then use the numeral instead of writing the structure again. It’s easier for the grader and confused graders are less likely to give partial credit. 308 EXAM 11 DRAFT FALL 2009 10 ’ PRINT NAME 5X. (12 points) Using the template as a guide write out the complete mechanism for the solvolysis of (R)—'3-chloro~3—methylhexane in methanol. Be sure to show all lone pairs, any charges and indicate the movement of electrons by means of appropriate curved m“ P: wl’fvs/éfll/OQV M ' Ca 0% a» I for WES—Tagged )QCLW C3’V, \261/4iéiélw ' On the axes provided, sket 1 a qualitative reaction coordinate diagram for this reaction. . Reaction Coordinate ‘ v . v- .7, W Si? 308EXAMIIDRAFT w \ FALL 2009 a; PRINT NAME SY. (12 points) Using the template as a guide write out the complete mechanism for the solvolysis of (S)~3—iodohexane in methanol. Be sure to Show all lone pairs, any charges and indicate the movement of electrons by means of appropriate curved arrows. On the axes provided, sketch a qualitative reaction coordinate diagram for this reaction. Reaction Coordinate 308 EXAM u DRAFT FALL 2009 12 PRINT NAME 6X. (10 points) Using the templates provided draw the Newman projection of two conformers of the compound D (place C-4 up front) and draw line structures of the products you expect to be formed from these conformers by reaction with the KO—t-Bu in DMSO. H ~~CI—I(CH3)2 \ 4 .:’/CH3 .-C 308 EXAM II DRAFT FALL2009 13 PRINT NAME 6Y. (10 points) Using the templates provided draw the Newman projection of two conformers of the compound E (place C-4 up front) and draw line structures of the products you expect to be formed from these conformers by reaction with the KO~t~Bu inDMSO. H CH \4 C3H(CH3)2 .c—c/ 308 EXAM 11 DRAFT FALL 2009 14 PRINT NAME 7X. (8 points) For the rate determining step of each of the reactions shown indicate the effect of increasing solvent polarity on a) the energy of the reactants, b) the energy of the transition state and c) the overall rate of the reaction; Write the appropriate response, increase, decrease, or no change in the appropriate space in the grid provided. NOTE the solvent type is under the arrow + /\/NH3+I- ____.___.>. /\/| + NH3 ' 1 ' aprotic + + 1— _____..__.> I + NH3 NH3 ' H pI'OtIC ' t -- ———-—>— CN /\/NH3 + CN aprotic + NH3 7L\CI + NH3 ""3 +NH3 + 01- IV protic I A 308 EXAM II DRAFT FALL 2009 ' 15 PRINT NAME 7Y. (8 points) For the-rate determining step of each of the reactions shown indicate the effect of increasingsolvent polarity on a) the energy of the reactants, b) the energy of the transition state and c) the overall rate of the reaction. Write the appropriate response, increase, decrease, or no change in the appropriate space in the grid provided. NOTE the solvent type is under the arrow mel+‘CN”"‘f‘+ mm +01— + H " --———->' CN IL /\/N 3 + CN aprotic + NH3 “L aprotic 13170th %\C} + NH3 M ‘ +NH3 + C1— Vt protic ” ' C 308 EXAM 11 DRAFT FALL 2009 a 16 PRINT NAME The correct order (least nucleophilic first) of increasing nucleophilicity of the following Species in protic solvents is " u. CH30'; v. F‘; w. NH3; x. r; y. HS“; 2. CH30H; ‘ is Q Z: V) W3 u! X3 y . mammmy C. v, x, y, u, w, z D. ' y,u,x,v,w,z E. z, w, v, x, y, u 2. Rank the following substituents in the order of increasing stereochemical (Kahn, Ingold, Prfelog) . no priorities (lowest first, highest last). PH _ OH - o ,_ “CHZCI ———CH “CEO—Br z - \ CHZBr CHzBr OH CHzBr ' 1 2 3 4 5 A. 4, 2, 3, s, 1 4, 3, 2, 5, 1 C. 4, l, 2, 3, 5 D. 3, 4, 2, 5, 1 . E. 3, 5, 4, 1, 2 3. The most important reason why iodide ion is a better nucleophile than fluoride ion inmetlianol is because I A The iodide complexes with the methanol B. The iodide is more polarizable @' The iodide is relatively poorly solvated D. The iodide is more basic ’ E. Steric effects dominate 308 EXAM n DRAFT FALL 2009 l 308 EXAM ll DRAFT FALL 2009 PRINT NAME 4. Which statements are false regarding nucleophilic substitutions at a stereogenic center? a. All nucleophilic substitution reactions result in the formation of some inverted product. b. SNl reactions result in a large excess of product with retained configuration. 0. 8N2 reactions can result in the formation of racemic product. (1. SNl reactions can result in the formation of a large excess 'of inverted product. . e. In SNl reactions, inversion of product configuration does not occur with carboc'ation rearrangement. ‘ ‘ A. a, c, e B. a, b, d C. b, c,~ d D. d, e, a ® b, d, e 5. What is the color of your exam? A. White ‘ B. Yellow ‘ 'V' V C. Pink D. Blue ...
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