Question

How is glucose prepared from the cane sugar in the laboratory?

Answer 1

Glucose is prepared from the cane sugar (sucrose) by the hydrolysis of an alcoholic solution of cane sugar with a $4 \%$ solution of $\mathrm{HCl}$ in alcohol.

$$\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11} (Sucrose)+\mathrm{H}_2 \mathrm{O} \stackrel{\mathrm{H}^{+}}{\longrightarrow} \mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6 (Glucose)+\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6 (Fructose)$$

Glucose being almost insoluble in alcohol, crystallises on cooling while fructose would remain in solution because it is comparatively more soluble in alcohol.