3BL-Lecture2 - Welcome to Chemistry 3BL Lecture 2 A

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Welcome to Chemistry 3BL Lecture 2 A Dehydrogenation/Hydrogenation Reaction David Rabuka
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Opening Remarks • Additional questions for the lab 2 report will be posted on bspace. • Write all assignments for a proposed structure directly on the spectra. Be thorough. • Show as many details as possible that support your structural assignment (i.e. characteristic absorbances for functional groups in the IR, J- values, etc.) • We will also continue our discussion of NMR
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Transfer Hydrogenation Step by Step: 3 Pd/C heat 2 + Pd/C heat + H 2 Pd/C heat + H 2 Pd/C Pd/C + heat + heat
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Transfer Hydrogenation • We can see that benzene and cyclohexane are the “thermodynamic sinks” of this reaction. • The equivalent of H 2 extracted from the cyclohexene gives 1,3-cyclohexadiene which only needs one more equivalent of H 2 to be extracted in order to form benzene. • Note that the processes are reversible up until you reach the thermodynamic sinks.
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Some Heats of Hydrogenation
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A Mechanistic View of Hydrogenation
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Another Example of “Transfer” Hydrogenation + 2 O OH trans-Cinnamic Acid Pd/C heat + 2 O OH 3-Phenyl- propionic Acid • The equivalent of H 2 extracted from the cyclo- hexene now reduces the trans-Cinnamic Acid instead of only reducing other cyclohexene molecules. • This type of reaction can be convenient from the standpoint of isolation of the 3-phenyl propionic acid.
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Other Transfer Hydrogenation H 2 Sources H O O NH 4 Ammonium Formate Pd/C heat H 2 CO 2 NH 3 + + Pd/C heat H 2 + Anthracene 9,10-Dihydro- Anthracene
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Substrates with Other Functional Groups? O
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This note was uploaded on 01/26/2009 for the course CHEM 3BL taught by Professor Chunmei during the Fall '08 term at University of California, Berkeley.

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3BL-Lecture2 - Welcome to Chemistry 3BL Lecture 2 A

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