Aldaric acid
Aldaric acids are a group of sugar acids, where the terminal hydroxyl groups of the sugars have been replaced by terminal carboxylic acids, and are characterised by the formula HOOC-(CHOH)n-COOH.
Synthesis
Aldaric acids are usually synthesized by the oxidation of aldoses with nitric acid. In this reaction it is the open-chain (polyhydroxyaldehyde) form of the sugar that reacts.
An aldaric acid is an aldose in which both the hydroxyl function of the terminal carbon and the aldehyde function of the first carbon have been fully oxidized to carboxylic acid functions. (Oxidation of just the aldehyde yields an aldonic acid while oxidation of just the terminal hydroxyl group yields an uronic acid.) Aldaric acids cannot form cyclic hemiacetals like unoxidized sugars, but they can sometimes form lactones.
Structure
Nomenclature of the aldaric acids is based on the sugars from which they are derived; for example, glucose is oxidized to glucaric acid and xylose to xylaric acid.
