How to Identify Carboxyl Groups

The rubber hits the road when it comes to the functional groups of organic molecules.

The functional group, or groups, of an organic molecule make the molecule what it is. If an organic molecule is an acid or a base, or is hydrophilic, attracted to water, or hydrophobic, repelled by water, you can usually look to a functional group for the reason why. A carboxyl group is a functional group characteristic of carboxylic acids. This group's ability to release its single hydrogen atom without becoming unstable makes carboxylic acids relatively strong acids.

Instructions

1. Note that chemists conventionally show functional groups such as carboxyl groups attached to a generic organic molecule represented by a capital letter R.

2. Look first for a carbon atom, represented by a single capital letter C, attached by a single bond to the R that represents the generic organic molecule. A single bond looks like a long hyphen.

3. Look next for an oxygen (O) atom attached by a double bond to the carbon atom. Chemists usually draw double bonds like two long hyphens side by side.

4. Look finally for a hydroxyl (OH) group attached to the same carbon by a single bond. These four atoms (COOH) represent a carboxyl group.

References

• "Organic Chemistry"; John McMurry; 2007
• Clinton Community College: Organic Chemistry, Biochemistry
• California State University, Dominguez Hills; Synthesis of Carboxylic Acids: Why Are Carboxylic Acids Acidic?