alpha_and_beta_carbon_reactions - Selected reactions at -...

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Selected reactions at α - and β -carbons and related reactions RCH 2 R' O HO or H 3 O + RCH R' OH Keto-enol interconversion RCH 2 R' O R' X R O ! -halogenation in acid gives monobrominated product; X 2 = Cl 2 , Br 2 , or I 2 RCH 2 R' O X 2 , HO R' X R O X R CH 3 O X 2 , HO R O O HCX 3 X = halogen Haloform OH H R O 1. PBr 3 (or P) 2. H 2 O OH Br R O ! -halogenation of carboxylic acids - Hell-Volhard-Zelinsky Reaction R' H R O Base R' R O R' E R O E + X 2 , H 3 O + When ! -hydrogen is removed the enolate becomes a nucleophile that can react with an electrophile RCH 2 R' O R' Br R O Br 2 , H 3 O + R' Nu R O Nu ! -Halogenated compounds can react with nucleophiles R' Br O R R R' O R R ! -Halogenated compounds can form ! , " -unsaturated compounds by dehydrohalogenation R' H R O 1. LDA, THF R' CH 2 R'' R O 2. R''CH 2 X Alkylation of preformed enolates using LDA. Applicable to aldehydes, ketones, esters, and nitriles X = halogen ! -halogenation in base gives perbrominated product; X
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This note was uploaded on 05/13/2010 for the course CHEM ORGANIC CH taught by Professor Dotsevisogah during the Spring '09 term at Cornell.

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alpha_and_beta_carbon_reactions - Selected reactions at -...

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