Question

Which reagent among the following is used to confirm presence of aldehydic carbonyl group in glucose?

Options

• Dilute nitric acid

• Bromine water

• Acetic anhydride

• Hydroxylamine

Answer 1

Bromine water

Explanation:

The presence of an aldehydic carbonyl group in glucose is confirmed using bromine water.

\[\begin{array}{cc}
\phantom{...}\ce{CHO}\phantom{.............}\ce{COOH}\phantom{....}\\
|\phantom{..................}|\phantom{.......}\\
\ce{(CHOH)4 ->[Br2 water] (CHOH)4}\\
|\phantom{..................}|\phantom{.......}\\
\phantom{.....}\ce{\underset{\text{Glucose}}{CH2OH}}\phantom{..........}\ce{\underset{\text{Gluconic acid}}{CH2OH}}\phantom{..}
\end{array}\]

When glucose reacts with a mild oxidising agent, it forms gluconic acid, a six-carbon carboxylic acid (Br₂ water).