L-rhamnose monohydrate

Plant Source: L-rhamnose is a kind of micro glucoside widespread in plants, which occurs in various plants glucoside (quercitrin, isohesperidin etc.) and polysaccharide, especially in pectin and colloid, also in rhus toxin, by means of combing with the form of sugar.Physical Property: Appearance: White-crystal or white-crystal-powder; solubility: soluble in water and methanol, slightly soluble in ethanol, shows in two types: α & β. Type α contains a molecular water of crystallization, it will transform into type β (M.W.: 164.16) after dehydration by heating. Type β with hygroscopic character, it will transform into type α after moisture absorption in the air. Usually presents as α-L-rhamnose (M.W.:182.11). Generally, α-L-rhamnose is a monohydrated crystal, a tabular crystal, M.P.:82-92℃, optical rotation: －7.7°→＋8.9°, soluble in water and ethanol; β-L-rhamnose (dehydrated) is needle-crystal with hygroscopicity, M.P.:122-126℃, optical rotation: ＋38.4°→＋8.9°, soluble in water and ethanol. Characters: sweet taste, occurring as pyran in water solution.
Chemical property: reducibility: it is oxidized to generate rhamnoic acid with bromine water, after that oxidized to generate L-α-three hydroxyl Ge acid with nitric acid, restore to rhamnite with NaHg.
Indications:  for the measurement of enteric permeability, used as sweeteners.