Question

Reaction of Glucose with Excess acetic anhydride gives:

• A. Diacetate
• B. Triacetate
• C. Polyacetate
• D. Pentaacetate

Hint:

The formation of a pentaacetate is chemical proof that glucose contains five hydroxyl groups.

Answer 1

The Correct Option is D

Step 1: Concept This is an acetylation reaction where hydroxyl (-OH) groups react with an anhydride to form ester groups.

Step 2: Meaning Glucose is a polyhydroxy aldehyde. In its cyclic pyranose form, it contains five hydroxyl groups.

Step 3: Analysis When glucose is treated with excess acetic anhydride in the presence of a catalyst (like pyridine or sodium acetate), all available hydroxyl groups are acetylated.

Step 4: Conclusion Since there are five -OH groups in the glucose molecule, the reaction yields glucose pentaacetate. Final Answer: (D)