Question

When glucose is oxidized with nitric acid, the compound formed is

• A. Gluconic acid
• B. n-Hexanoic acid
• C. Saccharic acid
• D. Cyanohydrin

Hint:

In carbohydrate chemistry, oxidation reactions can convert glucose into different acids. Mild oxidation forms gluconic acid, while strong oxidation (using nitric acid) forms saccharic acid.

Answer 1

The Correct Option is C

Step 1: Understanding the oxidation of glucose
Glucose (\( C_6H_{12}O_6 \)) is a monosaccharide that contains both an aldehyde (-CHO) group and hydroxyl (-OH) groups. When glucose is treated with nitric acid (\( HNO_3 \)), it undergoes oxidation.
Step 2: Oxidation process
- Mild oxidation: If glucose is oxidized using a mild oxidizing agent such as bromine water (\( Br_2 \)), only the aldehyde group (-CHO) is oxidized to a carboxyl group (-COOH), forming gluconic acid.
- Strong oxidation: When glucose is oxidized using strong oxidizing agents such as nitric acid (\( HNO_3 \)), both the aldehyde (-CHO) group and the terminal primary alcohol (-CH_2OH) group are oxidized to carboxyl (-COOH) groups, forming saccharic acid (also known as glucaric acid).
Step 3: Examining the given options
- Option 1: Gluconic acid → Formed under mild oxidation conditions.
- Option 2: n-Hexanoic acid → A fatty acid, not related to glucose oxidation.
- Option 3: Saccharic acid → Correct answer; formed when glucose is oxidized with nitric acid.
- Option 4: Cyanohydrin → Formed in reactions involving hydrogen cyanide (HCN), not nitric acid oxidation.
Step 4: Conclusion
Since nitric acid oxidizes both the aldehyde and primary alcohol groups of glucose to carboxyl (-COOH) groups, the correct answer is saccharic acid.