Final%20Exam%20A[1]

Final%20Exam%20A[1] - NAME(Please print First Last 1(8...

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Unformatted text preview: NAME (Please print) First Last 1. (8 points) There are four diastereomers A-D of (4S)-2-bromo-4-phenylcyclohexanol. Formulate their structures and draw each diastereomer. Use bond-line formulas only. Show the stereochemistry by using dashed and/or wedged lines if necessary. 2 or 0 OH OH Br Fast O 2 or 0 OH OH Br Slow O A B 2 or 0 OH OH Br Fast OH OH Slow 2 or 0 OH Br C O D 2. (6 points) Freshly cut garlic contains allicin, a compound responsible for the true garlic odor. Propose a short synthesis of allicin, starting with 3-chloropropene. Use bond-line formulas only to draw the structures of the products. condition HS Na Cl 3-chloropropene 1 or 0 SH 1 or 0 condition 1 euiv. of H2O2 condition I2 1 or 0 S S S O S 1 or 0 2 or 1 or 0 allicin 2/9 NAME (Please print) First Last 3. (12 points) Give the major product of each of the following reactions. Use bond-line formulas only. 1. Mg O 2. Cl 3. H , H2O 1 or 0 H3C OH 1. HBr 2. Mg 1 or 0 H3C MgBr 1. H O H 2. H , H2O 1 or 0 H3C CHO PCC CH2Cl2 1 or 0 H3C OH Br 1. Mg O 2. H 3. H , H2O 2 or 0 OH 1. PBr3 2. Mg 3. O 2 or 0 OH 1. PBr3 2. NaSH 3. KMnO4 2 or 0 SO3H OH 2 or 0 Conc. HCl Cl 3/9 NAME (Please print) First Last 4. (12 points) Give the major product of each of the following reactions. Use bond-line formulas only. Show the stereochemistry by using dashed and/or wedged lines if necessary. 1 or 0 O NaNH2 NH3 HO NH2 O H H3C NaSCH2CH3 CH3CH2OH 1 or 0 OH S 1 or 0 O Excess conc. HBr Br Br O CH3 CH3 1 or 0 Dilute HCl in CH3OH HO OCH3 1 or 0 O CH3 CH3 NaOCH3 CH3OH H3CO OH O CH3 CH3 1. LiAlD4 (CH3CH2)2O 2. H , H2O 1 or 0 D OH I 1 or 0 H2O HO H O H KSH 1 or 0 SH OH 1 or 0 SH I2 S S O S Excess H2O2 1 or 0 O O S O CH3 OH 1 or 0 CH3CH2OH H2SO4 H3C OCH2CH3 O CH3 CH3 2. H , H O 2 1. (CH3)2CHMgBr (CH3CH2)2O 1 or 0 OH 4/9 NAME (Please print) First Last 5. (12 points) Give the major product of each of the following reactions. Use bond-line formulas only. Show the stereochemistry by using dashed and/or wedged lines if necessary. O Cl DMSO 1 or 0 O H3C O 1 or 0 CH3I DMSO H3C OCH3 1 or 0 Cl O HMPA or Br O 1 or 0 O (CH3)2CHOH OH 1 or 0 conc.HCl Cl CH3 OH CH3 1 or 0 PBr3 Br CH3 CH3 1 or 0 Br OH H2SO4 130C Br O Br Na2S 1 or 0 O S 1. OH, H2O 2. PCC, CH2Cl2 3. Li Cl (CH3CH2)2O 4. H , H2O 2 or 0 OH 1. CrO3, H2SO4, H2O 2. LiAlD4, (CH3CH2)2O 3. H , H2O 2 or 0 D OH 5/9 NAME (Please print) First Last 6. (15 points) Taxol is a complex, functionalized diterpene isolated from the bark of the Pacific yew tree, Taxus brevifolia, in 1962 as part of a National Cancer Institute program in search of natural products exhibiting anticancer activity. 3 or 0 O O N H (S) (R) Taxol contains O O O O H3C 11 4 26 5 stereocenters, (R)-configurations, (R) OH (S) (S) CH3 OH CH3 (S) (S) CH3 (R) (S) HO O (S) O O O H (R) O CH3 sp2 carbons, primary carbons, and quaternary carbons. 2 7. (16 points) Give products (four constitutional isomers) to form for the monochlorination of the molecule (shown below) at 25C. Use bond-line formulas only. Give their IUPAC names. Structure Structure 2 or 0 2 or 0 Name 2 or 0 Cl 3-(chloromethyl)pentane Cl 2 or 0 Name Cl2 Structure 1-chloro-3-methylpentane Structure 2 or 0 2 or 0 Name Cl 2 or 0 Cl 2 or 0 Name 2-chloro-3-methylpentane 3-chloro-3-methylpentane 8. (7 points) What does IUPAC stand for? IUPAC = International Union Pure Applied Chemistry of and 7 or 0 6/9 NAME (Please print) First Last 9. (15 points) (a) Please count the number of stereocenters in the following molecules and determine whether achiral or chiral or meso compound for each. CH3 H3C H CH3 CH3 H3C Number of stereocenters CH3 Circle achiral or chiral or meso H Number of stereocenters Circle achiral or chiral or meso HO Number of stereocenters CH3 Circle achiral or chiral or meso 0 2 2 2 or 1 or 0 H3C H H3C 2 or 1 or 0 H CH3 H3C 2 or 1 or 0 H CH3 H Number of stereocenters CH3 Circle achiral or chiral or meso H Number of stereocenters Circle achiral or chiral or meso H Circle achiral or chiral or meso Number of stereocenters 4 2 4 2 or 1 or 0 2 or 1 or 0 2 or 1 or 0 (b) Sodium hydrogen (S)-glutamate, [a]D25C = +24, is the active flavor enhancerknown as MSG. The condensed formula of MSG is shown below. (a) Draw the stucture of the S enatiomer of MSG by using bond-line formulas with the stereochemistry (dashed and/or wedged line). (b) If a commercial sample of MSG were found to have a [a]D25C = +12, what would be its optical purity? what would be the percentage of the S and R enantiomers in the mixture? (a) Structure 1 or 0 NH2 (S) (b) Optical purity and ratio NH2 O HOCCHCH2CH2CO Na O 1 or 0 O Na 50%ee 75% of (S)-enantiomer and 25% of (R)-enantiomer HO O O 1 or 0 7/9 NAME (Please print) First Last 10. (20 points) (a) Please count the number of stereocenters in the following molecules and determine whether achiral or chiral or meso compound for each. H OH CH3 Number of stereocenters Circle achiral or chiral or meso Number of stereocenters OH CH3 Circle achiral or chiral or meso H3C H Number of stereocenters Circle achiral or chiral or meso CH3 1 3 4 2 or 1 or 0 2 or 1 or 0 H3C H CH3 CH3 H Number of stereocenters Circle achiral or chiral or meso H3C 2 or 1 or 0 CH3 CH3 CH3 Number of stereocenters Circle achiral or chiral or meso H3C H Number of stereocenters H CH3 H Circle achiral or chiral or meso 2 3 2 2 or 1 or 0 1 or 0 2 or 1 or 0 1 or 0 2 or 1 or 0 circle circle slow exothermic (b) The Hammond postulate states that , reactions are typically characterized endothermic fast circle 1 or 0 starting material by early transition states, which are similar in structure to the . product circle circle slow exothermic On the other hand, fast , endothermic processes usually have late transition states. 1 or 0 1 or 0 (c) The system to determine the (R)- or (S)-designation of an enantiomer was developed by three chemists, Cahn , Ingold , and Prelog . 1 or 0 1 or 0 1 or 0 8/9 NAME (Please print) First Last 11. (15 points) Please draw a Lewis structure (dots only) for each of the following molecules. Add formal charges if necessary. (a) Nitric acid, HNO3 (b) Sulfuric acid, H2SO4 (c) Phosphoric acid, H3PO4 3 or 0 O H O N O 3 or 0 O H O S O O H 3 or 0 H O O P O H O H (d) Thionyl chloride, SOCl2 (e) Hydrazoic acid, HN3 3 or 0 O Cl S Cl 3 or 0 H N N N 12. (12 points) Draw the structures of the species present at all points on the energy curves marked by capital letters. A C A B Energy (CH3)3CBr + HOCH2CH3 E B 2 or 0 CH3 H3C C d+ Br d- CH3 D 2 or 0 CH3 H3C C CH3 F Reaction Coordinate C 2 or 0 CH3 H3C C OCH2CH3 CH3 H d+ d+ D 2 or 0 CH3 H3C C OCH2CH3 CH3 H E 2 or 0 CH3 H3C C CH3 d+ F 2 or 0 CH3 H3C C OCH2CH3 CH3 OCH2CH3 H d+ 9/9 CHEMISTRY 140A FINAL EXAMINATION Mar 21, 2007 NAME (Please print): First Signature (written): ID NUMBER: Major: Last College: Revelle Muir Marshall Warren Roosevelt Sixth Other DO NOT OPEN THE EXAM UNTIL YOU ARE TOLD TO DO SO. - Please print your name in top right corner of pages 1 through 9, and sign in the first page. - Please check that you have 9 pages (including this one). - Answer only in the space provided. Do not write answers on the back of a page. - Please find partial periodic table below. Your midterm exams score: 1st /50 2nd /50 3rd /50 4th /50 Question 1 2 3 4 5 Total Points 8 6 12 12 12 50 Score Question 6 7 8 9 10 11 12 Total Points 15 16 7 15 20 15 12 100 Score Periodic Table (partial) 1H 3Li 11Na 4Be 12Mg 5B 13Al 6C 14Si 7N 15P 8O 16S 9F 17Cl 2He 10Ne 18Ar 1/9 ...
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