ABSTRACT
Further Reading ............................................................................................................................ 52
The generic term carbohydrates covers a fairly well-defined group of organic substances —
namely, aliphatic polyhydroxy aldehydes and ketones — as well as compounds obtained from
them by reduction of the carbonyl groups (alditols) or oxidation of one or more terminal groups
to form carboxylic acids. Derivatives are formed by replacing one or more hydroxyl groups with
hydrogen (deoxy derivatives) or with amino, thiol or similar heteroatomic groups. Due to the
presence of multiple functional groups, carbohydrates contain several chiral centers and thus
form many stereoisomers. They can be divided into two groups: the monosaccharides, which
cannot be split into smaller subunits by treatment with aqueous acids, and the complex
saccharides, which are formed by two or more monosaccharides via an acetal (glycosidic)
linkage and can be split into the former by hydrolysis. The complex saccharides comprise
oligosaccharides and polysaccharides, depending on the number of subunits attached to each
other. With the increase in the number of subunits, there is a gradual change in chemical and
physical properties. Polysaccharides are typical macromolecules; their behavior contrasts sharply
with that of the monosaccharides.
