Q.What is glycerose ? How is it obtained ?

Glycerose is the collective term for the two three-carbon sugars, glyceraldehyde and dihydroxyacetone, obtained by carefully oxidising glycerol.

Glycerol, $CH_2OH-CHOH-CH_2OH$, has three hydroxyl groups: two primary (at C1 and C3) and one secondary (at C2). When glycerol is subjected to mild, controlled oxidation - classically with dilute nitric acid, or with bromine water/hydrogen peroxide in the presence of a ferrous salt catalyst (Fenton-type oxidation) - the alcohol groups are oxidised only as far as the aldehyde/ketone stage (over-oxidation would carry them further to carboxylic acids, which is avoided by controlling the conditions).

Oxidation of a primary $-CH_2OH$ group gives an aldehyde group ($-CHO$), producing glyceraldehyde:

$CH_2OH-CHOH-CH_2OH \xrightarrow{[O]} CH_2OH-CHOH-CHO$

Oxidation of the secondary $-CHOH-$ group gives a ketone group, producing dihydroxyacetone:

$CH_2OH-CHOH-CH_2OH \xrightarrow{[O]} CH_2OH-CO-CH_2OH$

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