Gluose yields a yellow precipitate when warmed to `100^(@)C` with an excess of

Options

A. hydrogen cyanide
B. hydroxylamine
C. phenylhydrazine
D. semicarbazide

Answer

C

Explanation

Both aldoses and ketoses react with exces of phenylhyrazine to form osazones:
`underset(":")overset(CHO)overset(|)(C )HOH overset(3PhNHNH_(2))rarrunderset(":")overset(CH=N NHPh)overset(|)(C)=N NHPh + PhNH_(2)+NH_(3)`
One of the difficulties of wrong with carbohydrates is their tendency to form syrups. These are fine for pouring on pancakes at breakfast but hard to work with in the laboratory. Treatment with phenylhydrazine converts corbohydrates into solid osazones, which are readily isolated and purified. They can be identified by their characteristic crystaline forms.