What is Anomeric Carbon?
The anomeric carbon is the carbon on which the anemone spins. The carbonyl carbon found in the open chain becomes the odd carbon in the crystallized structure, which is also the most ionized carbon found in the ring. Emory University states that depending on the orientation of the group belonging to the anomeric carbon, ketotic carbohydrates and cyclized aldosis can adopt an anomeric configuration A or B.
The anomeric carbon has a property known as the anomalous effect, which is a preference for an electronegative one for an axial orientation over an equatorial orientation. This explanation also included carbohydrates, the cyclic system, and the saturated heterocycle. It is known that in the odd case the electronegative one exists as an axial performer. This is called the anomeric effect.
According to Biology Online, the carbon present in monosaccharides, such as glucose, on which rotation occurs, is a good example of anomalous carbon. In most cases, the asymmetric carbon can be recognized by a carbon atom attached to two oxygen atoms and joined by single bonds.
This rotation results in two different configurations, an alpha and a beta. As such, carbohydrates are able to spontaneously change between alpha and beta configurations, a process commonly referred to as mutagenesis.
Anomeric carbon is the carbon that exists in cyclic form which is present in acyclic form as carbonyl carbon.
Aldehydes have the general formula RCHO and are characterized by the presence of a specific functional group called carbonyl >C = O in which the carbon is sp2 hybridized.
In the reactions of compounds in which the carbonyl group is present, between an aldehyde and an alcohol.
Formation of hemiacetals and subsequent acetals characterized by the presence of two -or groups attached to the same carbon.
Monosaccharides such as glucose that contain an aldehyde group and are therefore aldose, can present themselves as an open chain with a linear skeleton represented by the Fischer projection.
However, they mainly occur in a cyclic form. In the case of glucose, the ring closure, represented by the Haworth formula, is due to the presence of the -OH group on carbon 5 and the aldehyde group on the first carbon, which undergoes nucleophilic attack of the hydroxyl.
The carbon in the cyclic form, called anomeric, is the carbon that, in the open chain form, is the number one carbon, or the aldehyde carbon.
Cycling forms two diastereomers that differ in the position of the -OH group which can be in an axial or equatorial position.
Identification of the Anomeric Carbon
To identify the anomeric carbon in the cyclic form, it is necessary to identify the oxygen that is part of the ring. Therefore it is necessary to consider the two carbon atoms to which it is bonded. One of them is attached to the -CH₂ OH group while the other is the anomeric carbon.
The anomeric carbon is of particular importance because when the hemiacetal group -OH bonded to the anomeric carbon, binds with the alcohol group of another molecule, a glycosidic bond is formed.
Since the -OH group can be attached to another monosaccharide, a disaccharide is formed consisting of two monosaccharides linked together by a glycosidic bond.
An example is sucrose C₁₂ H₂₂ O₁₁ contains one molecule of α-D-glucose and one molecule of β-D-fructose.
They are linked together by a glycosidic bond between the anomeric carbon 1 of glucose and the anomeric carbon 2 of fructose. This bond is actually called 1,2-glycosidic.