Properties of Monosaccharides

Asymmetric Carbon

A carbon atom to which four different atoms or group of atoms are attached

Anomeric

Anomers are diastereoisomers of cyclic forms of sugars or similar molecules differing in the configuration at the anomeric carbon (C-1 atom of an aldose or the C-2 atom of a 2-ketose). The cyclic forms of carbohydrates can exist in two forms, α- and β- based on the position of the substituent at the anomeric center.

Epimers

Carbohydrate isomers that differ only in configuration around only one specific carbon atom (except carbonyl group) are defined as epimers of each other.

Anomeric Carbon

During the conversion from straight chain form to cyclic form the carbon atom containing carbonyl oxygen, called the anomeric carbon.

Example of epimer

Glucose and galactose are C4 epimers, glucose and mannose C2 epimers. However galactose and mannose are not epimers they differ in C2 and C4 therefore they are just isomers

Vant Hoff's Rule of n

The no. of possible isomers of any given compound depends upon the number of asymmetric carbon atoms the molecule possess. Possible no. Of isomers are 2n

D & L series

The orientation of H and OH groups around the carbon atom just adjacent to the terminal primary alcohol carbon. E.g. C atoms 5 in glucose. When the OH group on this carbon is on right then it belong to D series and when OH group is on the left it is a member of L- series

Optical Isomerism

The presence of asymmetric carbon atoms also confers optical activity on the compound. When a beam of plane polarised light is passed through a solution exhibiting optical activity, it will be rotated to the right or left in accordance with type of a component

Stereoisomerism

The presence of asymmetric carbon atoms in a compound give rise to the formation of isomers l. Such compound which are identical in composition (same chemical formula) but differ only in spatial configuration (structure) are called stereoisomerism.

Resolution

The separation of optically active isomers from a RACEMIC mixture is called Resolution

Racemic

When equal amounts of dextrorotatory and levorotatory isomers are present the mixture has no optical activity. Such a mixture is called RACEMIC

Dextrorotatory

When it is rotated to right or clockwise it is termed as dextrorotatory (d or + sign). Eg. Naturally occurring glucose is dextrorotatory and called dextrose

Levorotatory

When rotated to left counter clock wise it is termed levorotatory. Such components are called isomers or enantiomers

Isomers

each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties.