Carboxylic Acid Functional Group:

(What is “R” ??)

Naming Carboxylic Acids

• Use prefixes to indicate the number of carbon atoms.
• Acids end with “-anoic acid.”

Example:

  is propanoic acid.

(3 carbons = “prop-” prefix, then add “-anoic acid” ending)

Physical Properties

• Polar due to hydrogen bonding
• Short carboxylic acids are soluble in water
• High boiling points
• Strong odors

Acid Behavior

In a solution, one of the hydrogen atoms can separate from a carboxylic acid and become H⁺:

Anything that causes excess H⁺ ions to form in a solution is an acid. See Acid/Base notes.

Chemical Properties

Acids can react with alcohols to make esters:

Carboxylic acids are an ingredient for making lots of interesting molecules in living things and in industry. See Wikipedia’s summary of carboxylic acid reactions for examples.

Some Important Carboxylic Acids

• Ethanoic acid (more commonly known as acetic acid) is found in vinegar.

• Butanoic acid (also known as butyric acid, derived from the word “butter”) gives vomit and rancid butter their lovely smells.

• Amino acids such as alanine are what protein is made of.

• Stearic acid is a common fatty acid found in milk, beef fat, chocolate, and many other foods. It is also found in soaps, detergents, and cosmetics.

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