Question

Glucose molecule reacts with `X` number of molecules of phenylhydrazine to yield osazone. The value of `X` is:
A. Four
B. One
C. Two
D. Three

Answer 1

Correct Answer - D
As aldehydes, aldoses react with phenylhydrazine to form phenylhydrazones. If an excess of phenylhydrazine is used, the reaction proceeds further to yield products known as osazones, which contain two phyenylhydrazine residues per molecule while a third molecule of the reagent is turned into aniline and ammonia.

Osazone formation is not limited to carbohydrates, but is typical of `alpha` hydroxyl ketones in general (e.g., benzoin, `C_(6) H_(5) CHOHCO C_(6) H_(5))`.