Question

Baeyer’s reagent oxidises ethylene to:
A.Ethylene chlorohydrin
B.Ethyl alcohol
C.\[{\text{C}}{{\text{O}}_2}{\text{ and }}{{\text{H}}_2}{\text{O}}\]
D.Ethane-1,2-diol

Answer 1

Hint:Baeyer’s reagent oxidises the double bond to alcohol. Two molecules of alcohol are added up in one molecule and a saturated molecule will form.

Complete step by step solution:
Baeyer’s reagent is simply a cold and alkaline solution of potassium permanganate. It is a violet colour solution and is a very strong oxidising agent. When we react it with the double bond the colour of the solution turns colourless from violet colour.
Ethylene or ethene reacts with Baeyer’s reagent to form glycol of ethane-1,2-diol. The reaction occurs as follow:
\[3{\text{C}}{{\text{H}}_2} = {\text{C}}{{\text{H}}_2} + 2{\text{KMn}}{{\text{O}}_4} + 4{{\text{H}}_2}{\text{O}} \to 3{\text{HO}} - {\text{C}}{{\text{H}}_2} - {\text{C}}{{\text{H}}_2} - {\text{OH}}\]

Thus, the correct option is D.

Additional information:
Potassium permanganate is used in the chemical industry widely. It is used in laboratories as an oxidising agent and to carry out titrations. It is used for medical purposes such as disinfectant for cleaning wounds. It is listed by WHO as essential medicine. Potassium permanganate is also used in wastewater treatment to remove iron and hydrogen sulphide from wells. It is used to check the presence of unsaturation in a compound in the form of Baeyer’s reagent. If the unsaturation is present in the compound then the colour of solution turns colourless from pink.

Note:
Ethylene glycol is commonly used in the formation of antifreeze mixture and to form polyester fibre. It is a sweet tasting colourless liquid. It is mixed with water to form the antifreeze to decrease the freezing of water in the car engines. It decreases the freezing point of water so that water remains in a liquid state even at lower temperature. Ethylene glycol also acts as a dehydrating agent and is also known as desiccant.