Answer:
The reaction of 4-acetyl anisole (also known as p-methoxyacetophenone) with hydroiodic acid (HI) results in the cleavage of the O-methyl group of the anisole ring, leading to the formation of iodobenzene and acetophenone. The balanced equation for this reaction is C9H10O2 + HI → C6H5I + C8H8O.
So, the product of the reaction of 4-acetyl anisole with HI is a mixture of iodobenzene and acetophenone. The specific ratio of these products will depend on the reaction conditions, such as the temperature and concentration of the reactants.
It's worth noting that the reaction between 4-acetyl anisole and HI is an example of a nucleophilic aromatic substitution reaction, which involves the replacement of a leaving group (in this case, the O-methyl group) on an aromatic ring by a nucleophile (the iodide ion from HI).