When ethanol is heated with conc.${\mathrm{H}}_2{\mathrm{SO}}_4$ gas is produced. The compound formed ,when this gas is treated with cold dilute aqueous solution of Baeyer's reagent, is :

Reaction of Ethanol with Concentrated H₂SO₄ and Baeyer's Reagent

When ethanol is heated with concentrated sulfuric acid, it undergoes a dehydration reaction to produce ethylene gas (C₂H₄).

Reaction: C₂H₅OH → C₂H₄ + H₂O

When this ethylene gas is treated with cold dilute aqueous Baeyer's reagent (alkaline KMnO₄), it gives a vicinal diol (ethylene glycol) by syn-dihydroxylation:

Reaction: C₂H₄ + [O] → HO–CH₂–CH₂–OH (ethylene glycol)

Final Product: Ethylene glycol (ethane-1,2-diol)