Carboxylic Acid Functional Group

Carboxylic acids are organic compounds (hydrocarbons) that contain the element oxygen. We've already encountered organic compounds containing oxygen those were called alcohols and ethers. Carboxylic acids are different from alcohols and ethers in that the oxygen interacts with carbon differnetly than in the case of alcohols and ethers. In carboxylic acids there are TWO oxygen atoms bonded to the carbon atom. One of the oxygen atoms double bonds to the carbon the other is a single bond. What does this carboxylic acid functional group look like?

Notice there are four bonds to the carbon atom and two bonds to each of the oxygen atoms in this functional group.

The simplest carboxylic acid is formic acid, HCOOH. The structure of formic acid is shown below.

Formic acid is secreted by ants when they bit human beings. Most of us probably recall how uncomfortable an ant bit is.

The carboxylic acids have much different formulas compared to alcohols or ethers. Notice the carboxylic acid has an -OH group just like the alcohols, but in the case of the carboxylic acid the -OH group is bonded to a carbon double bonded to another oxygen atom. In the case of the alcohol the -OH group is bonded to a carbon with hydrogen atoms only.

The next simple carboxylic acid is acetic acid.

Acetic acid is the important ingredient of vinegar. We use vinegar to clean and we also ingest vinegar. It is found in salad dressings. We can even find flavored vinegars that are excellent for cooking.

What are some other interesting compounds which contain carboxylic acid groups? Carboxylic acids are acids just as the name indicates. Acids taste sour and carboxylic acids add the sour taste we are all most familiar with in foods. Carboxylic acids are also found in fats. So lets look at some examples of common carboxylic acids.

Some other examples of compounds with carboxylic acid functional groups contain some other functional groups. Citric acid is the carboxylic acid found in citrus fruits, lactic acid is found in sour milk and is produced by the body during exercise, and tartaric acid is found in fruit, wine and grape juice.

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