Please can someone answer this right now for me? What is the purpose of adding conc. HCL to the solution after cyclohexene has been oxidised by KMnO4 in the reaction of Cyclohexen + KMnO4 +H2O.
The purpose of adding concentrated HCl to the solution after cyclohexene has been oxidized by KMnO4 is to neutralize any excess KMnO4 and oxidizing byproducts present in the reaction mixture.
Here's how to understand the reason behind this step:
1. In the given reaction, cyclohexene is being oxidized by KMnO4 in the presence of water. This oxidation reaction converts cyclohexene (an alkene) into a diol compound.
2. KMnO4 is a strong oxidizing agent, which means it has the ability to transfer oxygen atoms to other substances.
3. When KMnO4 oxidizes cyclohexene, it undergoes reduction itself, forming manganese(IV) oxide (MnO2) as a byproduct. This MnO2 is a brown solid.
4. However, when KMnO4 is used in excess or if the oxidation reaction is not completed fully, some of the KMnO4 may remain unreacted in the solution along with the MnO2 byproduct.
5. The addition of concentrated HCl serves two purposes. Firstly, it helps to neutralize any excess KMnO4 present in the solution. Secondly, it reacts with MnO2 to form soluble manganese chloride (MnCl2), which is colorless.
6. By neutralizing the KMnO4 and forming a colorless soluble compound with the MnO2, the solution becomes clearer and any color change becomes more apparent.
In summary, the addition of concentrated HCl after the oxidation of cyclohexene by KMnO4 is done to neutralize excess KMnO4 and convert the brown MnO2 byproduct into a colorless soluble compound.