Out of the following compounds, which will be dehydrated most readily?

Explanation

The dehydration can take place in the acidic medium in the presence of conc. `H_(2)SO_(4)` . A carbocation us expected to be formed in each case as the intermediate in the rate dertermining step.

In the structures (A) and (B) the positively charged carbon atom is adjacent to the electron withrawing carbonyl group which tends to destabilise the carboncations by incresing the magnitude of the positive charge on these. However, in carbocation (C), the carbonyl group is not directly attached to the positively charged carbon atom. Therefore, its positive charge weakning effect is comparactively is more stable. This mean that the compound (C) will be dehydrated most easily.