Concept Summary

Description and Properties

Reactions of Carboxylic Acids

Carboxylic  acids   contain a   carbonyl    and a   hydroxyl    group   connected   to  the same    carbon. They

are always  terminal    groups.

Carboxylic  acids   are indicated   with    the suffix  –oic    acid.   Salts   are named   with    the suffix  –oate,  and

dicarboxylic    acids   are –dioic  acids.

Physical    Properties

Carboxylic  acids   are polar   and hydrogen    bond    very    well,   resulting   in  high    boiling points. They

often   exist   as  dimers  in  solution.

The acidity of  a   carboxylic  acid    is  enhanced    by  the resonance   between its oxygen  atoms.

Acidity can be  further enhanced    by  substituents    that    are electron-withdrawing,   and decreased

by  substituents    that    are electron-donating.

β-dicarboxylic  acids,  like    other   1,3-dicarbonyl  compounds,  have    an  α-hydrogen  that    is  also

highly  acidic.

Carboxylic  acids   can be  made    by  the oxidation   of  primary alcohols    or  aldehydes   using   an

oxidizing   agent   like    potassium   permanganate    (KMnO 4 ),  dichromate  salts   (Na 2 Cr 2 O 7  or  K 2 Cr 2 O 7 ), or

chromium    trioxide    (CrO 3 ).

Nucleophilic    acyl    substitution    is  a   common  reaction    in  carboxylic  acids.

A   nucleophile attacks the electrophilic   carbonyl    carbon, opening the carbonyl    and forming a

tetrahedral intermediate.

The carbonyl    reforms,    kicking off the leaving group.

If  the nucleophile is  ammonia or  an  amine,  an  amide   is  formed. Amides  are given   the suffix

• amide. Cyclic amides are called lactams.
  If the nucleophile is an alcohol, an ester is formed. Esters are given the suffix –oate. Cyclic
  esters are called lactones.