The methyl benzoate is dissolved in concentrated sulfuric acid. Where does the proton add to methyl benzoate and why?
To understand where the proton (H+) adds to methyl benzoate when dissolved in concentrated sulfuric acid, it is important to consider the properties of the acid and the structure of methyl benzoate.
Methyl benzoate is an ester with the molecular formula C8H8O2. Its structure consists of a benzene ring (C6H6) attached to a carboxylate group (-3), with a methyl group (CH3) connected to the oxygen atom.
Concentrated sulfuric acid (H2SO4) is a strong acid, meaning it donates protons easily due to its acidic nature. In the case of methyl benzoate, when it is dissolved in concentrated sulfuric acid, the proton (H+) of the acid tends to add to the carbonyl oxygen atom of the carboxylate group (-COO-). This leads to the formation of a carbocation intermediate.
The addition of the proton to the oxygen atom occurs due to the presence of lone pairs on the oxygen atom, which makes it electron-rich and susceptible to protonation. Additionally, sulfuric acid can act as a dehydrating agent, facilitating the removal of a water molecule from the protonation.
The resulting carbocation intermediate can undergo further reactions depending on the conditions and reactants present. It could undergo proton transfer to water molecules or undergo further reactions with other species present in the system.
In summary, when methyl benzoate is dissolved in concentrated sulfuric acid, the proton (H+) adds to the carbonyl oxygen atom of the carboxylate group (-COO-) due to its electron-rich nature, resulting in the formation of a carbocation intermediate.