PracticeExam3

PracticeExam3 - Page 1 PRACTICE EXAM Spring 2009 Exam 3 –...

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Unformatted text preview: Page 1 PRACTICE EXAM Spring 2009 Exam 3 – CH 0320 NAME ___________________________________ Good luck! Page 2 1. Give an example for each description. Use Fisher, Haworth, or conformational representations. a) An aldopentose: b) A ketohexose: c) Methyl β-D-ribopyranoside: d) L-xylose: e) Xylitol: f) Any reducing sugar: Page 3 2. Provide products for each of the following transformations. HO HO CHO H H CH2 OH HO HO a CHO H H CH2 OH b Br2 /H2 O HCN O c H O Mannich O d e f CH3 NH2 /H+ H HS H H H HO H HO HO H H CHO OH OH H OH CH2 OH CHO H H OH OH CH2 OH SH BF3 NHNH2 2 equivalents HNO3 /H2 O C7 H13 NO Page 4 3. For each of the following transformations, provide mechanisms. (8 points each) a) Show each bond forming step, including deprotonations and protonations. b) Show correct formal charges on each atom that is not neutral. c) In base catalyzed reactions, show an appropriate source for protonation. (for example, H2 O or HOR). a. OH HO HO OH + HOCH 3/H HO O H3 CO O 3 (continued – Show the mechanism). Page 5 b. 1) MeI (excess) 2) Ag2 O/H2 O/heat N H (H3 C)2 N Page 6 4. Show you would prepare glucose from a pentose using the Kiliani-Fisher method. Show all reagents. Choose the appropriate starting material. Show all intermediates, but it is not necessary to show mechanism. Page 7 5. Devise a preparation of the following amine using the reductive amination conditions. H N CH3 Page 8 6. a) Draw a hexose that will give an optically active product after treatment with nitric acid. b) Draw a pentose that will afford an optically inactive alditol. 7. Ruff degradation of Aldose A affords a pentose. The same pentose is formed through a Kiliani-Fisher synthesis beginning with D-threose. Treatment of Aldose A with NaBH4 affords an achiral product. What is Aldose A? Show your reasoning. ...
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