Which of the following pairs form same osazone?

Options

A. `D-(+)-` Glucose and `(+) -` lactose
B. `D-(+)-` Glucose and `D-(-) -` arabinose
C. `D-(+)-` Glucose and `D-(-) -` fructose
D. `D-(+)-` Glucose and `(+) -` maltose

Answer

C

Explanation

Both aldose and ketoses react with excess of phenylhydrazine to form osazones (these contains two phenylhydrazine groups), anilne and ammonia, The overall equation may be written :

Osazones are yellow crystalline solids and are used to characterise the sugars. They may be hydrolysed with hydrochloric acid, both phenylhydrazino groups being eliminated, the dicarbonyl compound formed is known as an osone. e.g. glucosazone forms glucosone:

Osones react with phenylhydrazine in the cold to form osazones.
Since osazone formation involves only the first two carbon atoms in a sugar, both glucose and fructrose yield the same osazone :