Dolbier HW Solutions 422

Dolbier HW Solutions 422 - 516 CARBOXYLIC ACIDS (e)...

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( e ) Carboxylic acids react with alcohols in the presence of acid catalysts to give esters. ( f ) Chlorine is introduced at the a -carbon atom of a carboxylic acid. The reaction is catalyzed by a small amount of phosphorus or a phosphorus trihalide and is called the Hell Volhard Zelinsky reaction. The a -halo substituent is derived from the halogen used, not from the phosphorus trihalide. ( g ) In the case, bromine is introduced at the a carbon. ( h ) a -Halo carboxylic acids are reactive substrates in nucleophilic substitution. Iodide acts as a nucleophile to displace bromide from 2-bromopentanoic acid. ( i ) Aqueous ammonia converts a -halo acids to a -amino acids. ( j ) Lithium aluminum hydride is a powerful reducing agent and reduces carboxylic acids to pri- mary alcohols. ( k ) Phenylmagnesium bromide acts as a base to abstract the carboxylic acid proton. CH 3 CH 2 CH 2 CH 2 CO 2 MgBr Bromomagnesium pentanoate 1 CH 3 CH 2 CH 2 CH 2 CO 2 H Pentanoic acid C 6 H 5 MgBr Phenylmagnesium bromide 1 C 6 H
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