Chapter 22 CHEM 140B

Chapter 22 CHEM 140B - Chapter 22: Benzene Substituents I....

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Chapter 22: Benzene Substituents I. A. Benzylic resonance stabilizes adjacent radical, cationic, and anionic centers B. Recall B.1.Radical Halogenation B.2.Halogenation C. Methylbenzene also goes through radical intermediates & are resonance stabilized D. Free electron is delocalized over 7 carbons good stabilization E. This can also happen with carbonium ions and carbanions II. Benzylic Oxidation A. Any alkyl group is oxidized all the way down to the ring to give a carboxylic acid B. Can be done with KMnO 4 or Na 2 Cr 2 O 7 , H 2 SO4, H 2 O C. Proceeds 1 st through benzylic alcohol ketone C-C bond cleavage D. Important detoxification process in the body benzoic acid can be excreted E. MnO 2 can be used for selective oxidation of benzylic alcohols III. Benzylic Reduction A. R group can be basically anything B. Benzylic position can be more highly substituted C. Reaction specific for benzylic C-O bonds D. Benzyl group can be a good protecting for alcohols which can then be removed with reduction
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This note was uploaded on 03/27/2012 for the course CHEM 140B CHEM 140B taught by Professor Theodorakis during the Spring '10 term at UCSD.

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Chapter 22 CHEM 140B - Chapter 22: Benzene Substituents I....

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