Ruff degradation

Ruff degradation is a reaction used to shorten the open chain forms of monosaccharides.

[1] It is functionally the reverse reaction of Kiliani-Fischer synthesis.

In this reaction, the terminal aldehyde group is converted to a carboxylic acid group, using selective oxidation of the aldehyde using Bromine water and then converted to gluconate ion.

This reaction was an important tool used by Emil Fischer to show that D-Glucose and D-Mannose each formed the same product upon Ruff degradation (D-Arabinose) indicating them to have opposite configurations at C-2 (epimers).

Further Ruff degradation on D-Arabinose gave D-Glyceraldehyde, which established the stereochemistry of the chiral center on C-5.