Carboxylic Acids and Their Naming

Definition

• Carboxylic acids are organic compounds containing a carboxyl group.
  • Carboxyl group: Carbon atom double-bonded to an oxygen atom and single-bonded to another oxygen atom, which in turn is bonded to a hydrogen atom.
  • This structure resembles the combination of a carbonyl group and a hydroxyl group.

Naming Conventions

• Compounds containing a carboxyl group are termed carboxylic acids.
• They receive the suffix -anoic acid.
• Naming involves identifying the longest carbon chain that includes the carboxyl group and applying traditional organic naming rules.

Example: Ethanoic Acid

• Identify the longest carbon chain: 2 carbons → eth
• Contains a carboxyl group: carboxylic acid → ethanoic acid
• Note the use of two separate words in naming: "ethanoic acid"

Example: Propanoic Acid with a Methyl Branch

• Longest carbon chain: 3 carbons → prop
• With a carboxyl group: propanoic acid
• The carboxyl group is always on carbon number 1.
• If there is a methyl branch on the second carbon, it is named as: 2-methyl propanoic acid (note the space in naming).

Key Points

• Always start naming from the end nearest to the carboxyl group.
• Ensure all substituents are named and positioned correctly based on the carbon chain numbering.