Which of the following statements is correct regarding gluconic acid?
A. Gluconic acid is a dicarboxylic acid
B. Gluconic acid is obtained by oxidation of glucose with $\mathrm{HNO}_3$
C. Gluconic acid can form a cyclic (acetal/hemiacetal) structure
D. Gluconic acid is a partial oxidation product of glucose
Glucose contains:
- one aldehyde group (-CHO)
- five hydroxyl groups (-OH)
When glucose undergoes mild oxidation (for example with bromine water), only the aldehyde group gets oxidized to a carboxylic acid group, forming gluconic acid.
So gluconic acid is a partial oxidation product of glucose.
$$
\text { Glucose } \xrightarrow[\text { mild oxidation }]{ } \text { Gluconic acid }
$$
Therefore, the correct statement is:
D. Gluconic acid is a partial oxidation product of glucose