Chemistry of Carbohydrates

Carbohydrates are compounds composed of carbon, hydrogen, and oxygen. These molecules get their name from the empirical formula of many monosaccharides that have two atoms of hydrogen and one atom of oxygen for every carbon.

Simple carbohydrates are monomers called monosaccharides and dimers called disaccharides. Complex carbohydrates are polymers called polysaccharides.

A monosaccharide can be classified as an aldose or a ketose by its functional group. Those having an aldehyde group are called aldoses and those having a ketone group are called ketoses.

Monosaccharides usually contain three to seven carbon atoms in their chains. Each of the carbons can be numbered starting with the number one from the end closest to the carbonyl carbon.

Sugars can form non-planar ring structures and in nature mostly exist in this cyclic form. Ring structures form when the carbonyl group reacts with a hydroxyl group at the opposite end of the molecule through a condensation reaction. The carbon attached to the reactive aldehyde or ketone is also known as the anomeric carbon.

These carbon-oxygen ring structures can exist as two anomers: alpha and beta. Anomers are diastereomers that differ in the configu