Question

Write the reactions involved when D-glucose is treated with the following reagents: (a) HCN (b) Br\(_2\) water 

Hint:

Cyanohydrin formation is a typical nucleophilic addition reaction, and oxidation with bromine water converts aldehydes to carboxylic acids.

Answer 1

Reactions of D-Glucose 

(a) Reaction of D-glucose with HCN

When D-glucose is treated with hydrogen cyanide (HCN), it undergoes cyanohydrin formation. The reaction occurs at the aldehyde group, resulting in the formation of D-glucose cyanohydrin.

\[ \text{D-glucose} + HCN \rightarrow \text{D-glucose cyanohydrin} \]

(b) Reaction of D-glucose with Br\(_2\) water

When D-glucose is treated with bromine water (a mild oxidizing agent), it specifically oxidizes the aldehyde group at C-1 to a carboxylic acid, producing gluconic acid.

\[ \text{D-glucose} + Br_2\text{(water)} \rightarrow \text{Gluconic acid} \]

These reactions demonstrate the aldehydic nature of glucose and its ability to undergo addition and oxidation reactions.