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OldExams - Chem 2262, Sections 1 and 2 EXAM 2 March 17, 2003

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Unformatted text preview: Chem 2262, Sections 1 and 2 EXAM 2 March 17, 2003 NAME________KEY__________ Professor___________________ The exam has 7 printed pages of questions, 1 grade sheet and 2 tables. Check now to make sure you have all 10 questions and 10 total pages. Put all answers on these sheets and write clearly. The exam is worth a total of 125 points. WRITE YOUR NAME and Professor on the front sheet. Write your Name, SS# and Professor on the grade sheet (page 8). Multiple Choice (5 points each, 30 points total). Circle the one best answer for each problem. 1. Which of the following would be the least reactive with a nucleophile: O O A B C O H D O H 2. Which molecule would undergo nucleophilic aromatic substitution most readily? Cl Cl Cl Cl Cl OCH3 CH3 OH NH2 A B C D E 3. Which of the following is a hemiacetal? O O O O OCH3 O OH Cl O O Cl HO HO OH O OH OCH3 A B C D E 4. Which of the following phenols is the weakest acid? OH OH OH OH OH OH Cl Cl NO2 NO2 A B C D F NH O F E 5. Which of the following would exist as a hydrate to the least extent in the presence of H2O? O H A O H H 3C B O CH3 H 3C C O H Cl 3C D H 1 6. Which of the following cannot be used as the halide starting material in a Wittig reaction? Br Br Br Br Br A B C D E 7. Draw one structure in each box for the major organic product or starting material of each of the following reactions or write N.R. for no reaction, if applicable. Place only one appropriate structure in each of the thirteen boxes (5 points each, 65 points total): N OH H O O Cr Cl O N O 1. O3 2. Zn, H2O O O 1. SOCl2 COOH 2. CuLi 2 -78 C O HCN H O C OH N 2 Cl O H2 Lindlar's catalyst H O 1. H3C MgBr 2. H3O+ CN O O EtO O H HO OH (excess) O EtO O O H HCl (dry) O NH2NH2 KOH 200 C HO O OH MgBr 1. CO2 2. H3O + O OH 3 H3CO OCH3 H3O + O H OH 1. NaOH 2. O CH3 O O S O O (0.5 equiv) Br H O 1. NaCN 2. DIBAL 3. H20 1. PPh3 2. BuLi O 3. DIBAL = * Al H 2 4 8. (10 points) Draw a detailed arrow-pushing mechanism for the following reaction: Br 1. PPh3 2. 3. O Li (1) Formation of the quaternary phosphonium salt (Arbuzov reaction) (3 points) Br Br :PPh3 PPh3 (2) Ylide formation (3 points) CH2 H PPh3 PPh3 (3) Addition of ketone to afford product olefin and triphenylphosphine oxide formation via betaine (4 points) O O P Ph3 PPh3 O PPh3 5 9. (10 points) Use any needed reagents to effect the following transformation: COOH CH3 C OH H3O+ or -OH , heat N OH HCN NBS O Br CH2 NaCN N CH2 C 1. DIBAL CH2 CH 2. H3O+ 6 10. (10 points total) Compound W of molecular formula C10H14O. The IR and 1H NMR for W are shown below (tables of IR and NMR data are attached on the back of the exam). (i) Clearly label on the IR spectrum 2 key stretching frequencies spectrum with the functional group they represent (2 points). (ii) Draw the structure of this compound in the box at the bottom of the page (4 points). (iii) Clearly label each type of proton A, B, C, D (1 points each) on your proposed structure. O-H C-H D 6H s A 5H B 2H s C 1H s Compound W B C OH H3C CH3 A D 7 Chem 2262, Sections 1 and 2 EXAM 3 April 21, 2003 NAME_____KEY____________ Professor___________________ The exam has 6 printed pages of questions, a grading sheet, and 2 tables. Check now to make sure you have all 9 questions and 9 total pages. Put all answers on these sheets. The exam is worth a total of 125 points. Please write your name and other required information on cover page and page 7. Multiple Choice (5 points each, 25 points total). Circle the one best answer for each question. 1. Which of the following compounds would be the most susceptible towards nucleophilic attack at the acyl carbon? A) CH3 O Cl B) CH3 O O O CH3 C) CH3 O NH2 D) CH3 O OCH3 E) A-D are of similar reactivity 2. Which of the following is an anhydride? O O O O O O O O O O A B C D 3. Which of the following statements concerning nitriles is incorrect? A) Nitriles can be transformed to carboxylic acids via acid, water and heat. B) Nitriles can be formed from alkyl halides by nucleophilic substitution by cyanide ion. C) Nitriles can be reduced with excess lithium aluminum hydride to primary amines. D) Nitriles can form via cyanide's preference to react at the a-carbon of an a,bunsaturated carbonyl. E) Nitriles can be transformed to carboxylic acids via base, water and heat. 4. Which of the following compounds would be the most acidic? A) CHF2CH2CH2COOH B) CH2FCHFCH2COOH C) CH3CF2CH2COOH E) CH3CH2CH2COOH D) CH3CH2CF2COOH 5. Which of the following would not undergo an aldol reaction with benzaldehyde (PhCHO)? O O O O B, C and D A B C D E 1 6. Draw a structure for the major organic product or starting materials as indicated for each of the following. Place only one appropriate structure in each box (5 points each, 70 points total): O Br2, H2O, H3O+ O Br O Br2, excess H2O OH- excess O O +CHBr3 +NaBr + H2O O O Ph NaOH H2O heat O crossed aldol condensation product O O NaOH H2O heat O C10H16O2 O NaCN O CN O LiAlH4 OH 2 O O R O OH O O O O Cl O-Na+ O O O O O OH O CH3 O CYCLIC DIKETONE 4-CARBON a,b-UNSATURATED CARBONYL O O HO O OH H2N NH2 heat O O N H H N n KMnO4 heat HO O O OH H2O CN H3O+ heat C O OH 3 7. (10 points total) Show the complete arrow-pushing mechanism for the following reaction: 2 H NaOH, H 2O O OH CH3 O A. Deprotonation to form enolate (4 points) O HO H O + H2O B. Nucleophilic attack (4 points) O O CH3 O O C. Protonation to form product alcohol (2 points) CH3 O O H O H CH3 O + HO OH 4 8. (10 points) Propose an efficient synthesis to effect the following transformation using any necessary organic or inorganic reagents. Show the product of each synthetic step: O OH O O CN O OH Br2, P O Br Br O HO Br NaCN O O O CN 5 9. (10 points total) Propose a structure for the unknown acyl compound whose 1H NMR and IR spectral data are shown below (2 points). Clearly indicate your assignment of all proton resonances as well by labeling protons a-d on the structure (2 points each). Refer to the attached tables of IR and NMR data if necessary keeping in mind that chemical shifts are approximate and vary with varying neighboring magnetic environments. C5H10O2 1H NMR: (a) triplet (b) triplet (c) quartet (d) quartet d d d d 1.12 ppm 3H 1.27 ppm 3H 2.32 ppm 2H 4.13 ppm 2H IR: 1740 cm-1 (strong) C A CH2 CH3 O O CH2 D B CH3 6 Chem 2262, Sections 1 and 2 EXAM 4 May 5, 2003 NAME________KEY__________ Professor___________________ The exam has 4 printed pages of questions, a grading sheet and two pages of tables. Check now to make sure you have all 9 questions. Put all answers on these sheets. The exam is worth a total of 125 points. Multiple Choice (5 points each, 25 points total). Circle the one correct answer for each problem. 1. Which of the following compounds is the strongest acid? O H3N N H N H N A 2. B C D NH2 Which of the following compounds is the weakest base? NH2 N NH2 H N A 3. B C D E Which is the correct IUPAC name for the compound below? A. N-ethyl-N-butyl-1-ethanamine B. diethylaminobutane C. N,N-diethyl-1-butanamine D. N-butyl-N-ethyl-1-ethanamine 4. Which of the below cannot be the direct product of a reductive amination. reaction? H2N N N N A-D are all reductive amination products N A 5. B C D E Which of the following is a sulfa drug? S N S H2N CO2H O HN S O NH2 N N H2N CO2H H2N SO3H A B C 1 D E 6. Fill in the following fourteen boxes (5 points each, 70 points total). 1. NBS, hn 2. O N K O 3. H2NNH2 + OH NH2 N N N OH N Br Br EtOH CH2CH3 N CH CH 2 CH3Br 3 CH2CH3 N CH CH 2 3 CH3 O H3C CH3 1. CH3NH2 2. LiBH3CN HN CH3 O 1. NH3 2. H2/Ni heat NH2 CH3 CH3 1. HOSO2Cl CH3 2. excess NH H3C O S N O a sulfonamide O 1. LiAlH4 NH2 2. H2O NH2 excess NH2 Br2 and NaOH I C N KI F CuCN N N HBF4, heat H2O Br CuBr H3PO2 OH 2 7. (10 points) Show the complete arrow-pushing mechanism for the following transformation: NH2 NaNO2 dilute HCl A. Formation of nitrous acid and nitroso ion. (3 points) H H O O H N N O N O H H O N O H H H O H H O H H H O N H O N O H O B. Attack by amine on nitroso ion to form nitrosoamine (3 points) O H O H N O NH2 N O N H N H N H C. Formation of Diazonium ion (through loss of water from diazohydroxide) (4 points) H O N O H H H O H H N N O H N H N OH H O H N N N N N N N H 3 8. (10 points) Propose a reasonable synthetic route to effect the following transformation: C N Br NO2 Br2, Fe HNO3 H2SO4 Br Br plus ortho NH2 Br NaNO2 dil. HCl C N N CuCN N Br Br 9. (10 points total) Propose a structure for the compound whose NMR and IR data are listed below (5 points). Clearly indicate your assignment of the proton resonances as well (1 point each). C9H13N 1H NMR: A. B. C. D. E. triplet broad singlet quartet singlet multiplet d d d d d 1.0 ppm 1.4 ppm 2.6 ppm 3.8 ppm 7.2 ppm 3H 1H 2H 2H 5H IR: 3300 cm-1 (m) BH C A N D CH2CH3 H2C E 4 ...
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