Ethanol undergoes dehydration by heating it with concentrated H2SO4 at 443K.
C2H5OH→443KH2SO4CH2=CH2+H2O
Alkenes on reaction with cold, dilute, aqueous solution of potassium permanganate (Baeyer’s reagent) produce vicinal glycols. Decolorisatlon of KMnO4 solution is used as a test for unsaturation.
