Definition: Keto acids are organic acids containing a ketone functional group and a carboxylic acid group.
Common types of keto acids include:
alpha-keto acids, or 2-oxo acids, such as pyruvic acid have the keto group adjacent to the carboxylic acid.
beta-keto acids, or 3-oxo acids, such as acetoacetic acid have the ketone group at the second carbon from the carboxylic acid.
gamma-keto acids, or 4-oxo acids, such as levulinic acid have the ketone group at the third carbon from the carboxylic acid.