A Sugar acid or acidic sugar is a

monosaccharide Monosaccharides (from Greek ''monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. They are usually colorless, water-solub ...

with a

carboxyl group In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

at one end or both ends of its chain. Main classes of sugar acids include: *

Aldonic acid An aldonic acid is any of a family of sugar acids obtained by oxidation of the aldehyde functional group of an aldose to form a carboxylic acid functional group. Thus, their general chemical formula is HOOC-(CHOH)n-CH2OH. Oxidation of the termi ...

s, in which the

aldehyde group In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...

(−CHO) located at the initial end ( position 1) of an aldose is oxidized. * Ulosonic acids, in which the −CH₂(OH) group at the initial end of a 2-

ketose A ketose is a monosaccharide containing one ketone group per molecule. The simplest ketose is dihydroxyacetone, which has only three carbon atoms. It is the only ketose with no optical activity. All monosaccharide ketoses are reducing sugars, be ...

is oxidized creating an α-

ketoacid In organic chemistry, keto acids or ketoacids (also called oxo acids or oxoacids) are organic compounds that contain a carboxylic acid group () and a ketone group ().Franz Dietrich Klingler, Wolfgang Ebertz "Oxocarboxylic Acids" in Ullmann's En ...

. *

Uronic acid 300px, The Fischer projections of glucose and glucuronic acid">glucose.html" ;"title="Fischer projections of glucose">Fischer projections of glucose and glucuronic acid. Glucose's terminal carbon's primary alcohol group has been oxidized to a ...

s, in which the −CH₂(OH) group at the terminal end of an aldose or ketose is oxidized. *

Aldaric acid Aldaric acids are a group of sugar acids, where the terminal hydroxyl and carbonyl groups of the sugars have been replaced by terminal carboxylic acids, and are characterised by the formula HOOC-(CHOH)n-COOH.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 usual ...

s, in which both ends (−CHO and −CH₂(OH)) of an aldose are oxidized.

Examples

Examples of sugar acids include: * Aldonic acids **

Glyceric acid Glyceric acid is a natural three-carbon sugar acid obtained from the oxidation of glycerol. CH2OH-CHOH-CH2OH+O2→CH2OH-CHOH-COOH+H2O Salts and esters of glyceric acid are known as glycerates. Biochemistry Several phosphate derivatives of glyc ...

(3C) **

Xylonic acid Xylonic acid is a sugar acid that can be obtained by oxidation of the hemiacetal/aldehyde group of xylose. The C-2 epimer is known as lyxonic acid. References Sugar acids Monosaccharides {{organic-compound-stub ...

(5C) **

Gluconic acid Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH2(CHOH)4COOH. It is one of the 16 stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid. In aqueous solution at neutral pH, gluconic acid f ...

(6C) **

Ascorbic acid Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) an ...

(6C, unsaturated lactone) * Ulosonic acids **

Neuraminic acid Neuraminic acid (5-amino-3,5-dideoxy-D-''glycero''-D-''galacto''-non-2-ulosonic acid) is an acidic (in particular ulosonic) amino sugar with a backbone formed by nine carbon atoms. Although 9-carbon sugars do not occur naturally, neuraminic ...

(5-amino-3,5-dideoxy-D- ''glycero''-D- ''galacto''-non-2-ulosonic acid) **

Ketodeoxyoctulosonic acid 3-Deoxy--''manno''-oct-2-ulosonic acid (ketodeoxyoctonic acid; KDO; IUPAC symbol Kdo) is an ulosonic acid of a 2-ketooctose which is used by bacteria in the synthesis of lipopolysaccharides. The -''manno'' prefix indicates that the four chiral ...

(KDO or 3-deoxy-D- ''manno''-oct-2-ulosonic acid) * Uronic acids ** Glucuronic acid (6C) **

Galacturonic acid -Galacturonic acid is a sugar acid, an oxidized form of galactose, -galactose. It is the main component of pectin, in which it exists as the polymer polygalacturonic acid.Debra Mohnen "Pectin structure and biosynthesis" Current Opinion in Plant B ...

(6C) **

Iduronic acid -Iduronic acid (IUPAC abbr.: IdoA) is the major uronic acid component of the glycosaminoglycans (GAGs) dermatan sulfate, and heparin. It is also present in heparan sulfate, although here in a minor amount relative to its carbon-5 epimer glucuro ...

(6C) * Aldaric acids **

Tartaric acid Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes, but also in bananas, tamarinds, and citrus. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally ...

(4C) ** ''meso''-Galactaric acid (

Mucic acid Mucic acid, C6H10O8 or HOOC-(CHOH)4-COOH (also known as galactaric or meso-galactaric acid) is an aldaric acid obtained by nitric acid oxidation of galactose or galactose-containing compounds such as lactose, dulcite, quercite, and most varietie ...

) (6C) ** D-Glucaric acid (

Saccharic acid Saccharic acid, also called glucaric acid, is a chemical compound with the formula C6H10O8. It is derived by oxidizing a sugar such as glucose with nitric acid.