What reagent can be used to distinguish ethane from ethylene?

| May 1, 2021 | education

What reagent can be used to distinguish ethane from ethylene? Give the equation of the ongoing reaction and name the resulting product according to the systematic nomenclature. Describe in detail the course of the experiment and the observed phenomena.

Ethane can be distinguished from ethylene using an aqueous solution of potassium permanganate or bromine water. Ethane as a saturated hydrocarbon does not enter into oxidation reactions with potassium permanganate and addition with bromine water.
1) CH2 = CH2 + Br2 -> CH2Br-CH2Br.
This reaction takes place under normal conditions. Ethylene obtained by dehydration of ethyl alcohol is passed through bromine water. As a result of the addition of bromine at the site of the double bond (1,2-dibromoethane is formed), its discoloration occurs.
2) 3CH2 = CH2 + 2KMnO4 + 4H2O -> 3CH2 (OH) -CH2 (OH) + 2KOH + 2MnO2.
Mn + 7 + 3e -> Mn + 4 | 2
2C-2 – 2e -> 2C-1 | 3
Mild oxidation (Wagner reaction) takes place at a temperature of 0 ° C. Ethylene is passed through an aqueous solution of KMnO4, discoloration occurs with the formation of ethylene glycol (ethanediol-1,2). A brown precipitate of MnO2 oxide precipitates.



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