Question

Write a mechanism for the hydrolysis of the following iminium chloride in aqueous \(\mathrm{HCl}\).

Short answer

Answer: The major steps involved in the hydrolysis of an iminium chloride are: 1) Identification of the iminium chloride structure. 2) Nucleophilic attack by water to form an intermediate species. 3) Proton transfer between the intermediate and a hydrogen donor (HCl) to neutralize charges. 4) Formation of the final products, which include a compound with a newly formed amine and hydroxyl groups, and chloride ions.

Step-by-step solution

Identify the iminium chloride

Firstly, we need to consider the structure of the given iminium chloride. The iminium ion is a positively charged nitrogen atom double bonded to a carbon atom. The chloride ion will be a counterion that balances out the positive charge on the nitrogen atom.

Nucleophilic attack by water

In the presence of aqueous HCl, water will act as a nucleophile due to its lone pair of electrons on the oxygen. The nucleophilic water molecule will attack the electrophilic carbon atom, which is double bonded to the positively charged nitrogen. This attack will result in the formation of a new intermediate species in which the carbon atom is now bonded to the oxygen of the water and the positive charge on the nitrogen has been neutralized.

Proton transfer

The intermediate formed in step 2 contains a positively charged oxygen atom bonded to the carbon. A nearby HCl molecule will act as a hydrogen donor, donating its proton (H+) to the negatively charged nitrogen atom while the chloride ion (Cl-) acts as a leaving group. This proton transfer results in the formation of a neutral species in which nitrogen is singly bonded to hydrogen and an additional OH group is newly formed on the carbon.

Formation of the product

The neutral species formed in step 3 now contains an alcohol and an amine on the carbon and nitrogen, respectively, signaling a successful hydrolysis of the iminium chloride. The products of this reaction will include the compound with the newly formed amine and hydroxyl groups, along with the chloride ions that were initially present.