Question

Why is concentrated sulfuric acid used in this reaction and not aqueous acid? Hint: What is the big difference between concentrated and aqueous acids, and what role would that difference play in the reaction? (Explain and draw the reaction and show the equilibrium that is dependent on the acid.)

9-fluorenol + MeOH + H2SO4 -> 9-methoxy fluorene + what products?

Answer 1

Solution :-

Following image shows the reactions steps to produce the product from the given starting material.

There are possibility of the forming the reactant again from the intermediate carbocation if the more water is present in the reaction mixture. Therefore to avoid the formation of the reactant we have to use the concentrated H2SO4

Because Concentrated H2SO4 does not have large amount of water unlike it is present in the aqueous acid solution. Therefore using concentrated H2SO4 avoid having more water in the reaction which can compete with the methanol (MeOH) and gives back starting material.