Aldohexose

An aldohexose is a hexose with an aldehyde group on one end.

Additional recommended knowledge

What is the Correct Way to Check Repeatability in Balances?

Safe Weighing Range Ensures Accurate Results

Essential Laboratory Skills Guide

The aldohexoses have four chiral centres for a total of 16 possible aldohexose stereoisomers (2⁴). Of these, only three commonly occur in nature: D-glucose, D-galactose, and D-mannose. The D/L configuration is based on the orientation of the hydroxyl at position 3, and does not refer to the direction of optical activity.

There are eight D-aldohexoses:

   CH=O           CH=O          CH=O            CH=O
   |              |             |               |
  HC-OH        HO-CH           HC-OH         HO-CH
   |              |             |               |
  HC-OH          HC-OH       HO-CH           HO-CH
   |              |             |               |
  HC-OH          HC-OH         HC-OH           HC-OH
   |              |             |               |
  HC-OH          HC-OH         HC-OH           HC-OH
   |              |             |               |
   CH2-OH         CH2-OH        CH2-OH          CH2-OH
D-Allose      D-Altrose     D-Glucose      D-Mannose

   CH=O        CH=O            CH=O            CH=O
   |           |               |               |
  HC-OH     HO-CH             HC-OH         HO-CH
   |           |               |               |
  HC-OH       HC-OH         HO-CH           HO-CH
   |           |               |               |
HO-CH       HO-CH           HO-CH           HO-CH
   |           |               |               |
  HC-OH       HC-OH           HC-OH           HC-OH
   |           |               |               |
   CH2-OH      CH2-OH          CH2-OH          CH2-OH
D-Gulose    D-Idose       D-Galactose        D-Talose

Deoxyaldohexoses

Aldohexoses can have one or more of their hydroxyl groups replaced by hydrogens to form deoxyaldohexoses. The following are well known cases of such compounds :

• L-Fucose (6-deoxy-L-galactose)
• L-Rhamnose (6-deoxy-L-mannose)
• D-Quinovose (6-deoxy-D-glucose)
  Quinovose is found as part of the sulfolipid SQDG.
• L-Pneumose (6-deoxy-L-talose)