Structure of Carboxylic Acid

Carboxylic Acid consists of -COOH atoms. The open bond attached to the C atom shows that a long carbon chain can be attached to it. Among the two Oxygen atoms, one is attached to the C atom with a double bond, while another O atom is attached to C with an H atom as an alcohol group. For better understanding see the below attached picture.

Examples of Carboxylic Acid

Some examples of carboxylic acids are as follows:

• Formic Acid (HCOOH)
• Ethanoic or Acetic Acid (CH₃COOH)
• Citric Acid (C₆H₈O₇)
• Lactic Acid (C₃H₆O₃)
• Fumaric Acid (C₄H₄O₄)
• Oxalic Acid (C₂H₂O₄)
• Stearic Acid (CH₃(CH₂)₁₆COOH)

Nomenclature of Carboxylic Acids

To name any carboxylic acid chain, we can use the following steps:

Step 1: Identify the longest chain: Find the longest continuous carbon chain that contains the carboxyl group (–COOH). This chain serves as the parent chain for the name.

Step 2: Number the carbon atoms: Start numbering from the end closest to the carboxyl group, and assign the lowest possible numbers to the carbon atoms bearing the carboxyl group.

Step 3: Name the alkyl groups: If there are alkyl groups attached to the parent chain, identify and name them as substituents. Use prefixes like methyl, ethyl, propyl, etc., to indicate the number of carbon atoms in the alkyl group.

Step 4: Name the carboxyl group: The carboxyl group is named “-oic acid.” The carbon atom directly attached to the carboxyl group is numbered carbon 1. For example, a carboxyl group attached to a two-carbon chain is called “ethanoic acid.”

Step 5: Use prefixes for multiple carboxyl groups: If there are multiple carboxyl groups present in the compound, use Greek numerical prefixes like “di-” (two), “tri-” (three), etc., to indicate the number of carboxyl groups. The carbon chain containing the carboxyl groups becomes the parent chain.

Step 6: Include substituents: If there are other functional groups or substituents present in the molecule, name and locate them according to the IUPAC rules.

Example: IUPAC name of compound CH₃CH₂COOH.

Solution:

This compound contains a two-carbon chain with a carboxyl group i.e., 3 carbon atoms in parent chain. The parent chain is propane, and the carboxyl group is named “oic acid.” Therefore, the name of this compound is “propanoic acid.”

Example: IUPAC name of compound CH₃CH₂CH₂COOH.

Solution:

This compound contains a three-carbon chain with a carboxyl group i.e., 4 carbon atoms in longest chain. The parent chain is butane, and the carboxyl group is named “oic acid.” Therefore, the name of this compound is “butanoic acid.”

Carboxylic Acid is a chemical compound that has a functional group that consists of -COOH atoms. Carboxylic acids are sometimes also called Fatty acids. All fatty acids are carboxylic acids but not all carboxylic acids are fatty acids. Fatty acids are aliphatic carboxylic acids that are found in natural fats in the form of glycerol esters and range in length from C12 to C18. The word carboxylic acids come from a carbon molecule that has both a carbonyl and a carboxyl group. Carboxylic acids are precursors for a variety of important organic compounds such as acid chlorides, esters, anhydrides, and amides, among others.

In this article, we will learn about Carboxylic acid, its structure, physical and chemical properties, preparations and others in detail.