Write the mechanisms for the acidic and basic hydrolyses of benzonitrile.

Acidic hydrolysis of benzonitrile involves the following mechanisms: 1) Formation of imine intermediate Under acidic conditions, benzonitrile reacts with water, and the nitrile group gets protonated, behaving as a nucleophile attacking the oxygen of water. This results in the formation of an intermediate imine structure. \[ C_6H_5C \equiv N + H_2O \xrightarrow[\ce{H+}]{=} C_6H_5C(NH)(OH) \] 2) Imine hydrolysis to form a carboxylic acid The imine intermediate reacts with another water molecule, resulting in hydrolysis. Proton transfer reactions occur to form a stable carboxylic acid group, namely benzoic acid. \[ C_6H_5C(NH)(OH) + H_2O \xrightarrow[\ce{H+}]{=} C_6H_5C(O)OH + NH_4^+ \]

Basic hydrolysis of benzonitrile involves different mechanisms, as follows: 1) Formation of a tetrahedral intermediate Under basic conditions, the water molecule acts as a nucleophile to attack the carbon of the nitrile group, leading to the formation of a tetrahedral intermediate. \[ C_6H_5C \equiv N + H_2O \xrightarrow[\ce{OH-}]{=} C_6H_5C(N^--)(OH) \] 2) Proton transfer, forming a carboxylate ion The amide ion abstracts a proton from the hydroxyl group, resulting in the formation of a carboxylate ion. \[ C_6H_5C(N^--)(OH) + OH^- \xrightarrow[]{=} C_6H_5C(O)^{-} + N^-- + H_2O \] 3) Formation of the carboxylic acid (optional) The carboxylate ion may then react with an acidic solution, like hydrochloric acid (HCl), to form benzoic acid. This step is optional, as the carboxylate ion itself could be the final product in certain cases. \[ C_6H_5C(O)^{-} + H^+ \xrightarrow[]{=} C_6H_5C(O)OH \] In summary, both acidic and basic hydrolyses of benzonitrile lead to the formation of benzoic acid or benzoate ion, but through different intermediate steps and mechanisms.