In
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...
, 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.
Chemically, monosaccharides are polyhy ...
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 often written as or , sometimes as with R referring to an organyl group (e.g. ...
at one end or both ends of its
chain.
Main classes of sugar acids include:
*
Aldonic acids, in which the
aldehyde group () 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
hydroxymethyl group () at the initial end of a 2-
ketose
In organic chemistry, 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 keto ...
is oxidized creating an α-
ketoacid.
*
Uronic acids, in which the group at the terminal end of an aldose or ketose is oxidized.
*
Aldaric acids, in which both ends ( and ) of an aldose are oxidized.
Examples
Examples of sugar acids include:
* Aldonic acids
**
Glyceric acid (3C)
**
Xylonic acid (5C)
**
Gluconic acid (6C)
**
Ascorbic acid
Ascorbic acid is an organic compound with formula , originally called hexuronic acid. It is a white solid, but impure samples can appear yellowish. It dissolves freely in water to give mildly acidic solutions. It is a mild reducing agent.
Asco ...
(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 (GCA, from ) is a uronic acid that was first isolated from urine (hence the name "uronic acid"). It is found in many natural gum, gums such as gum arabic ( 18%), xanthan, and kombucha tea and is important for the metabolism of ...
(6C)
**
Galacturonic acid (6C)
**
Iduronic acid (6C)
* Aldaric acids
**
Tartaric acid (4C)
** ''meso''-Galactaric acid (
Mucic acid) (6C)
**
D-Glucaric acid (
Saccharic acid) (6C)
References
External links
* {{MeshName, Sugar+Acids