Chemistry - Nomenclature Question with Solution | TestHub

The correct order of stability of carbocation is as follows:

Rate of dehydration of alcohol is directly proportional to the stability of the carbocation.

More stable carbocation will form then easy and faster will be the dehydration.

In$\left(\mathrm{III}\right)$,$2^{\circ }$carbonation will form on dehydration of alcohol and it is resonance stabilized and there is some extended conjugation is also present.

In$\left(\mathrm{II}\right)$$2^{\circ }$carbocation will form on dehydration of alcohol and it is resonance stabilized but there is no extended conjugation.

In$\left(\mathrm{I}\right)$$2^{\circ }$carbocation will form on dehydration of alcohol and it is not resonance stabilized. It can be stabilized by the hyperconjugation only.

As the above discussion, the priority of resonance over the hyperconjugation is more due to this fact the stability order is the$\mathrm{III}>\mathrm{II}>\mathrm{I}$.

Hence, The ease of dehydration of alcohol is directly proportional to the stability of the carbocation. The order of ease of dehydration is given below.