Question

Write the product obtained when D-glucose reacts with \( H_2N - OH \).

Hint:

Hydroxylamine reacts with aldehydes and ketones to form oximes, which are useful intermediates in organic synthesis.

Answer 1

Reaction of D-glucose with hydroxylamine (\( H_2N - OH \)) yields D-glucose oxime. This occurs via condensation of D-glucose's C-1 aldehyde group with hydroxylamine, with subsequent water (\( H_2O \)) elimination.

Reaction:
\[\text{D-Glucose} + H_2N-OH \rightarrow \text{D-Glucose Oxime} + H_2O\]

Structure of D-Glucose Oxime:
The oxime group (\( C=N-OH \)) is formed at the C-1 position, replacing the original aldehyde group (\( -CHO \)). The remainder of the D-glucose structure is unaffected.

Key Points:

• This reaction is specific to the open-chain, aldehyde-containing form of D-glucose.
• Although D-glucose predominantly exists in its cyclic hemiacetal form in aqueous solutions, a small equilibrium concentration of the open-chain form enables this reaction.
• Oximes are stable and can be employed for the identification or protection of carbonyl groups in organic synthesis.

Final Answer:
The resultant product is D-glucose oxime (\( C_6H_{12}O_5N-OH \)), formed at the C-1 position.