If the nucleophile is another carboxylic acid, an anhydride is formed. Both linear and cyclic
anhydrides are given the suffix anhydride.Carboxylic acids can be reduced to a primary alcohol with a strong reducing agent like lithium
aluminum hydride (LiAlH 4 ).
Aldehyde intermediates are formed, but are also reduced to primary alcohols.
Sodium borohydride (NaBH 4 ) is a common reducing agent for other organic reactions, but is
not strong enough to reduce a carboxylic acid.β-dicarboxylic acids and other β-keto acids can undergo spontaneous decarboxylation when
heated, losing a carbon as carbon dioxide. This reaction proceeds via a six-membered cyclic
intermediate.
Mixing long-chain carboxylic acids (fatty acids) with a strong base results in the formation of a salt
we call soap. This process is called saponification.
Soaps contain hydrophilic carboxylate heads and hydrophobic alkyl chain tails.
Soaps organize in hydrophilic environments to form micelles. A micelle dissolves nonpolar
organic molecules in its interior, and can be solvated with water due to its exterior shell of
hydrophilic groups.