Question

Which of the following chemical test can distinguish between:

2-hexene and 2-bromo hexane

1) action of bromine water

2) action of Lindlar's catalyst

3) action of Lucas reagent

Answer 1

To distinguish between 2-bromo-hexane and 2-hexene we can perform the Bromine Water Test. Bromine water, brown in colour, is decolourised by 2-hexene but not by 2-bromo-hexane.

This is because the bromine breaks the double bond in hexene (an alkene) to form an alkane.

However, when the compound is already an alkane (in this case 2-bromo-hexane) the bromine stays in the solution and the colour is not discharged unlike 2-hexene.

Hence, option 1 is correct.