HW #18 Key - Finally, if B is treated with H 2 over Pd...

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Bocknack CH 310M/318M Fall 2008 Graded Homework Problem #18 – Answer Key Deadline : 3:00 p.m., Monday, 11/17/08 LATE WORK WILL NOT BE ACCEPTED OR GRADED!!! This problem is worth a total of 20 raw points. Compound A is optically active, and has molecular formula C 4 H 8 Br 2 . When A is treated with 2 equivalents of NaNH 2 , Compound B (C 4 H 6 ) is formed as the major organic product. When B is treated with H 2 over Lindlar’s catalyst, only 1 equivalent of H 2 is absorbed, and Compound C (C 4 H 8 ) is produced as the major organic product. If B is treated with 2 equivalents of sodium metal in NH 3 ( l ) as the solvent, Compound D , a diastereomer of C , is isolated as the major product. When either C or D is exposed first to O 3 , followed by (CH 3 ) 2 S, acetaldehyde (shown below) is the only ozonolysis fragment obtained.
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Unformatted text preview: Finally, if B is treated with H 2 over Pd metal, 2 equivalents of H 2 are absorbed, and Compound E (C 4 H 10 ) is isolated in high yield. Compounds B , C , D , and E are all optically inactive. Propose structures for the unknown compounds A , B , C , D , and E by completing the reaction scheme provided below. Be sure to show stereochemistry clearly and unambiguously where necessary! NaNH 2 (2 equiv.) H 2 Pd (cat.) A (C 4 H 8 Br 2 ) (optically active) B (C 4 H 6 ) (optically inactive) E (C 4 H 10 ) (optically inactive) H 2 Lindlar cat. Na (2 equiv.) in NH 3 ( l ) C (C 4 H 8 ) (optically inactive) D (C 4 H 8 ) (optically inactive) (DIASTEREOMERS) H 3 C C H O 2 Acetaldehyde 1) O 3 2) (CH 3 ) 2 S 1) O 3 2) (CH 3 ) 2 S Br Br Br Br OR...
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This note was uploaded on 02/07/2009 for the course CH 310M taught by Professor Iverson during the Fall '05 term at University of Texas at Austin.

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