CH251FINALAU2009

CH251FINALAU2009 - Callam Chemistry 251 Autumn 2009...

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Unformatted text preview: Callam Chemistry 251 Autumn 2009 Final Exam 300 points H! 131 – Tuesday, December 8, 2009 – 1:30 p.m. – 3:18 p.m. Name (PRINT)_____________________________________________________________ I have neither given or received aid on this exam(SIGN)___________________________________________________________ Place an X in the column next to your recitation section. Failure to mark your correct recitation section will result in –5 points from your exam total. Day Time Room Teaching Assistant Tuesday Tuesday Thursday Thursday Tuesday Tuesday Thursday Thursday Tuesday Tuesday Thursday Thursday 1:30 pm – 2:18 pm 1:30 pm – 2:18 pm 1:30 pm – 2:18 pm 1:30 pm – 2:18 pm 2:30 pm – 3:18 pm 2:30 pm – 3:18 pm 2:30 pm – 3:18 pm 2:30 pm – 3:18 pm 3:30 pm – 4:18 pm 3:30 pm – 4:18 pm 3:30 pm – 4:18 pm 3:30 pm – 4:18 pm AV214 MP1008 SM2186 MP1008 SM2186 MP1008 SM2186 MP1008 KL330 AV214 KL330 AV214 Christopher McDaniel Chad Eichman Christopher McDaniel Chad Eichman Christopher McDaniel Chad Eichman Christopher McDaniel Chad Eichman Chad Eichman Christopher McDaniel Chad Eichman Christopher McDaniel Section 1 2 3 4 5 6 Extra Credit Total Points 120 35 40 20 35 40 15 300 Score Please read all of the directions for each section of the exam carefully. There are 13 pages including this cover page for the Final Exam, please check to make sure you have all of the pages. Make sure your answers are clear. Any structures or answers that are unclear or ambiguous are considered wrong. 1/13 Points Earned = Callam Chemistry 251 Autumn 2009 Part 1. Predict the Product. Predict the organic product(s) of the following reactions. When appropriate, be sure to indicate stereochemistry. If more than one product is formed be sure to indicate the major product, if stereoisomers are produced in the reaction be sure to indicate the relationship between them. Draw all answers in skeletal form. You will be graded on the product you draw from the reaction no other information is needed for this question. (6 points each for a total of 120 points) O Cl (a) Br NaCN, H 3C N H CH3 O (b) Br 1. NaBH4, CH3OH 2. HCl, H2O 3. NaH OH (c ) H2SO4, heat 1. Mg°, ether 2. O H (d) Br 3. H2O, HCl 1. NaH (excess) OH (e) 2. Br (excess) HO Points Earned = 2/13 Callam Chemistry 251 Autumn 2009 CH3OH (f ) Br heat Br D (g ) D NaOC(CH3)3 O ( h) 1. NaBH4, CH3OH 2. H 2 O , H C l O H 1. MgBr (i ) O 2. H2O, HCl 1. Mg°, ether 2. O O (j ) Br 3. D2O, DCl H 3/13 Points Earned = Callam Chemistry 251 Autumn 2009 (k ) O HBr (excess) NaOCH2CH3 (l ) SH O (m ) O 1. NaBH4, CH3OH 2. H2O 3. NaH 4. CH3CH2Cl (n) 1. Br2, CCl4, hv 2. KOC(CH3)3 OH (o ) 1. PBr3 2. Mg°, ether 3. O 4. H2O, HCl 4/13 Points Earned = Callam Chemistry 251 Autumn 2009 (p) O CH3OH, H2SO4 1. 2. 3. 4. 5. (q ) OH CrO3, H2SO4, H2O CH3CH2MgBr HCl, H2O NaH C H 3I 1. D (r) OH 2. O Cl S O N SeLi O H3C Br H (s) H O NaOCH3 NH2 CH3 (t ) O OH 5/13 Points Earned = Callam Chemistry 251 Autumn 2009 Part 2. Provide the Reagents. (5 points each for a total of 35 points) Provide the reagents or starting materials to perform the indicated transformations. More than one reaction may be required. You should number your steps if it is important for the synthetic transformation to take place OH OH O O OH OD D Br OH OH O OH O O CH3 6/13 Points Earned = Callam Chemistry 251 Autumn 2009 Part 3. Mechanisms. Provide a mechanism for the following 2 reactions. Be sure to include all intermediates, formal charges and arrows depicting electron movement. (20 points each for a total of 40 points) (a) O H (b) OH CrO3, H2SO4, H2O, O OH H2SO4, CH3OH O CH3 + 7/13 Points Earned = Callam Chemistry 251 Autumn 2009 Part 4. Synthesis. Provide a synthesis of the following ether. All of the carbons in the molecule below must come from alkanes containing six carbons or less. You may use any other reagents that you find necessary. (20 points) O 8/13 Points Earned = Callam Chemistry 251 Autumn 2009 Part 5. Explain. (a) Acid and Bases. Rank the following compounds in order of increasing pKa (1 = lowest pKa, 4 = highest pKa). Explain your rankings using pictures and words. (15 points) OH OH Br H Cl Cl H Br O O (b) Functional Groups. Identify the functional groups in each of the molecules. (15 points) O O OO S Cl N O N O O N H N H O H O N O O O O SH O OM g N C O 9/13 Points Earned = Callam Chemistry 251 Autumn 2009 (c) Conformations. For the following di ­substituted cyclohexane draw the two possible chair conformations and Newman projections looking down the C1 ­C2 bond. Label the more stable chair conformation and estimate the energy difference using A values (CH3 = 1.70 kcal/mol, (CH3)2CH = 2.25 kcal/mol) and (CH3, CH(CH3)2 gauche = 1.5 kcal/mol). (15 points) H3C CH3 2 1 CH3 10/13 Points Earned = Callam Chemistry 251 Autumn 2009 Part 6. Explain. Answer 2 of the following 3 explain questions.. Please indicate with an X which of the 2 that you want graded. Failure to indicate your choice will result in the first two questions being graded. (a) Elimination Reactions. Using Newman projections down the appropriate bond predict the E2 elimination product(s) for each of the following compounds. (20 points) Br Br NaOC(CH3)3 NaOC(CH3)3 CH3 CH3 Br NaOC(CH3)3 CH3 Br NaOC(CH3)3 CH3 (b) Grignard Reactions. The following synthesis does not proceed with any yield of the product when one equivalent of lithium acetylide (LiCCH) is used in the reaction. When two equivalents of lithium acetylide are added the reaction proceeds to give a very high yield of the product. Explain why two equivalents of lithium acetylide are needed. You answer should include a complete mechanism.(20 points) O OH H 1. Li (2 equiv.) 2. HCl, H2O HO HO 11/13 Points Earned = Callam Chemistry 251 Autumn 2009 (c) Epoxides. The following epoxide (X) reacts with the indicated nucleophile in excess to produce molecule (Z), the proposed intermediate is molecule (Y). (20 points) CH3 H 2C S O CH3 (Excess) O X O Z Y 12/13 Points Earned = Callam Chemistry 251 Autumn 2009 Extra Credit. (10 points) For each of the following pairs of molecules identify them as one of the following: constitutional isomers (I), same molecule (S), enantiomers (E), diastereomers (D), or none of the above (N) by placing the appropriate letter in the space provided. (2.5 points each for a total of 10 points) Cl (a) H3C F F CH3 Cl O (d) OH (b) OH H H CH3 NH2 OH CH3 H 3C O NH2 CH3 OH H 3C (e) H OH O OH OH OH HO H OH H OH O OH CH3 Br Br Br H Br (c ) H H 1 2 3 4 I H Li Na K II Be Mg CS Partial Periodic Table III IV B C Al Si Ga Ge V N P Ar VI O S Se VII F Cl Br VIII He Ne Ar Kr 13/13 Points Earned = ...
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This note was uploaded on 03/22/2011 for the course CHEM 251 taught by Professor Stambuli during the Spring '08 term at Ohio State.

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