Question

benzyl ethyl ether on reaction with HI gives benzyl iodide and ethyl alcohol.. why not ethyl iodide and benzyl alcohol?

Answer 1

Hi, please consider the answer given below;

When benzyl ethyl ether on reaction with HI gives benzyl iodide and ethyl alcohol and not ethyl iodide and benzyl alcohol.

What happens is that benzyl ethyl ether is a benzylic ether and thus SN1 path will be followed in the substitution.

Therefore it is evident that only two carbocations are possible in rate determining step which is the slowest step of the mechanism.

Benzyl carbocation and ethyl carbocation. Out of these two, benzyl carbocation is more stabilised hence more favourable and will form benzyl iodide. Remaining ethoxide will form ethanol.