0320Midterm3

0320Midterm3 - reactions shown below. Include...

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1 Chemistry 0320 Midterm Examination 3 November 24, 2008 Name: _____________________________ 1. Functional definitions. Provide structures that fit the following descriptions. (15 points) (a) A furanose. (b) A nucleophile that preferentially gives 1,4 addition products with α , β -unsaturated ketones. (c) A carboxylic acid derivative that is less reactive than a ketone toward nucleophilic addition. (d) A functional group that absorbs between 2000 and 2500 cm -1 in its IR spectrum. (e) A pyranose.
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2 2. Theory. a) Tetrahedral intermediate A breaks down faster than tetrahedral intermediate B . Explain this observation with structures. (10 points) MeO OLi A Me 2 N OLi B
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3 b) S N 1 reactions occur exclusively at the anomeric position of carbohydrates, as shown below. Explain this selectivity with structures. (10 points) O OH HO HO HO OH MeOH HCl O OH HO HO HO OMe
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4 3. Reaction recognition. Provide plausible identities for the unknown entities in the
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Unformatted text preview: reactions shown below. Include stereochemistry where relevant. If no reaction is expected, simply write NR. Some transformations might require more than one reagent or step. (40 points) (a) NH 2 O Br 2 NaOH ???? (b) Cl O H O ???? (c) O O ???? 5 (d) Br O ???? (e) C N H O ???? (f) OH O ???? CH 2 N 2 6 g) C N ???? NaCN h) O ???? O OH 7 5. Synthesis. Propose a synthesis of the following compound from organic compounds that contain four carbons or fewer and any inorganic chemicals. If you can't complete the synthesis with the starting material restrictions, use any starting material you want to get partial credit. (10 points) O 8 6. Mechanism. Write a stepwise mechanism for the following transformation. Use arrows! (10 points) NMe 2 O HCl H 2 O, ! NMe 2 O 9 7. pK a question. Which compound has the lower pK a ? Explain. (5 points) O O O O O...
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This note was uploaded on 05/17/2010 for the course CHEM 0740 taught by Professor Professor during the Spring '10 term at Pittsburgh.

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0320Midterm3 - reactions shown below. Include...

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