Cellobiose is a disaccharide - formula C12
- consisting of two glucose units (12 carbon atoms, and 2 ring-shaped structures, each containing an oxygen atom) - like maltose.
However there are major differences between maltose and cellobiose:
Each glucose unit is effectively the opposite way up, a reflection of the arrangement in cellulose. This can be seen when the carbon 6 and associated groups
Additionally, the two sugars are linked via a differently oriented glycosidic bond - a
β (beta) 1-4 bond
- between opposite ends of the 2 glucose molecules.
bonding carbon atom numbers.
This bond - effectively an oxygen bridge - is formed as a result of a condensation reaction.
This apparently linear linkage is the basis for cellulose, which forms microfibrils running parallel to others, stabilised by hydrogen bonds.
H bonds between these sections.
Note that as in maltose, one of these ring-shaped sections is in equilibrium with an
open-chain form in which Carbon 1 has a CHO aldehyde group
which gives it reducing properties
, so that it reacts with reagents such as Benedict's.