Question

Which from following tests confirms presence of aldehydic group in glucose?

Options

• Formation of oxime when reacted with NH₂OH.

• Formation of gluconic acid when reacted with Br₂ water.

• Formation of saccharic acid when glucose and gluconic acid treated with dil. HNO₃.

• Formation of pentaacetate when treated with acetic anhydride.

Answer 1

Formation of gluconic acid when reacted with Br₂ water.

Explanation:

Formation of gluconic acid when reacted with bromine water confirms that carbonyl group in glucose is in the form of aldehyde.

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