Question

Write preparation of glucose from starch.

Hint:

This method produces glucose on an industrial scale. In the lab, it can be prepared from cane sugar (sucrose).

Answer 1

Step 1: Understanding the Concept:
Starch is a polysaccharide. Hydrolysis breaks the glycosidic bonds to yield its monomeric units (glucose).
Step 2: Detailed Explanation:
Commercially, glucose is prepared by boiling starch with dilute sulfuric acid (\(H_2SO_4\)) at 393 K under 2 to 3 atmospheres of pressure.
Reaction:
\[ (C_6H_{10}O_5)_n + nH_2O \xrightarrow[393 K, 2-3 atm]{H^+} n C_6H_{12}O_6 \]
After hydrolysis, excess acid is neutralized with chalk (\(CaCO_3\)), and the glucose is crystallized from the concentrated solution.
Step 3: Final Answer:
Glucose is produced by boiling starch with dilute \(H_2SO_4\) at 393 K and 2-3 atm pressure.