Consider the reaction below

a) What is the functional group in the starting material?

b) Provide a mechanism for this reaction

c) Why is H3O+ used as the proton source in the mechanism instead of H2SO4 directly?

d) Could this hydrolysis reaction occur in basic conditions? Explain.

Solution:

a) Acetal

b) Two possible mechanisms 

c) H2SO4 is a strong acid, so it exists in water as H3O+. See my explanation in my post covering imine formation about why HCl exists as protonated amine in amine solution (same concept!).

d) No. 

In acetal hydrolysis, the leaving group must be protonated before getting kicked off. In basic conditions, there is no proton source for this! Therefore, acetals are stable in base.