Question

If you were unable to find phosphoric acid, would hydrochloric acid be a suitable substitute in the dehydration of cyclohexanol to cyclohexene? Explain

Answer 1

In this dehydration reaction we always use phosphoric acid (85% generaly) for dehydration.

We cannot use HCl as the reaction of HCl with water is not exothermic unlike phosphoric acid or sulphuric acid which show exothermic reaction. So this cause the reaction to be theromdynamicaly unfavourable in case of use of HCl as dehydrating agent.

So HCl will not be a suitable substitute here.

There is also literature that document that HCl, HBr or HI may cause nucleophilic substitution.