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-solu ...
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 acids, in which the
aldehyde group (−CHO) located at the initial end (
position 1) of an
aldose
An aldose is a monosaccharide (a simple sugar) with a carbon backbone chain with a carbonyl group on the endmost carbon atom, making it an aldehyde, and hydroxyl groups connected to all the other carbon atoms. Aldoses can be distinguished from ket ...
is oxidized.
* Ulosonic acids, in which the −CH
2(OH) group at the initial end of a 2-
ketose 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 acids, in which the −CH
2(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Aldaric acids are a group of sugar acids, where the terminal hydroxyl and carbonyl groups of the sugars have been replaced by terminal carboxylic acids, and are characterised by the formula HOOC-(CHOH)n-COOH.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 usually ...
s, in which both ends (−CHO and −CH
2(OH)) of an aldose are oxidized.
Examples
Examples of sugar acids include:
* Aldonic acids
**
Glyceric acid (3C)
**
Xylonic acid (5C)
**
Gluconic acid (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 (5-amino-3,5-dideoxy-
D-
''glycero''-
D-
''galacto''-non-2-ulosonic acid)
**
Ketodeoxyoctulosonic acid (KDO or 3-deoxy-
D-
''manno''-oct-2-ulosonic acid)
* Uronic acids
**
Glucuronic acid
Glucuronic acid (from Greek γλεῦκος "''wine, must''" and οὖρον "''urine''") is a uronic acid that was first isolated from urine (hence the name). It is found in many gums such as gum arabic (c. 18%), xanthan, and kombucha tea ...
(6C)
**
Galacturonic acid (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
Heparan sulfate (HS) is a linear polysaccharide found in all animal tissu ...
(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) (6C)
**
D-Glucaric acid (
Saccharic acid) (6C)
References
External links
* {{MeshName, Sugar+Acids