Propose a mechanism for the hydrolysis of N,N-dimethylacetamide
(b) under acidic conditions.

Verified step by step guidance

1. Step 1: Protonation of the carbonyl oxygen - Under acidic conditions, the lone pair of electrons on the oxygen atom of the carbonyl group in N,N-dimethylacetamide will interact with a proton (H⁺) from the acid, leading to the formation of a protonated carbonyl group. This increases the electrophilicity of the carbonyl carbon.
2. Step 2: Nucleophilic attack by water - The water molecule acts as a nucleophile and attacks the electrophilic carbonyl carbon, forming a tetrahedral intermediate. This step involves the addition of water to the carbonyl group.
3. Step 3: Proton transfer - A proton transfer occurs within the tetrahedral intermediate to stabilize the structure. This step involves the movement of a proton from the water molecule to the nitrogen atom, making the leaving group more favorable.
4. Step 4: Cleavage of the C-N bond - The nitrogen atom, now protonated, becomes a good leaving group. The C-N bond breaks, leading to the formation of acetic acid and a protonated amine (N,N-dimethylamine).
5. Step 5: Deprotonation - The protonated amine loses a proton to regenerate the neutral amine (N,N-dimethylamine), and the acetic acid remains as the final product of the hydrolysis reaction.

Key Concepts

Hydrolysis Mechanism

Hydrolysis is a chemical reaction involving the breaking of a bond in a molecule using water. In the case of N,N-dimethylacetamide, the mechanism typically involves the nucleophilic attack of water on the carbonyl carbon, leading to the formation of a tetrahedral intermediate. This intermediate can then collapse, resulting in the formation of acetic acid and dimethylamine.

Acidic Conditions

Acidic conditions refer to an environment where the pH is less than 7, often achieved by adding a strong acid like HCl. In hydrolysis reactions, acids can protonate the carbonyl oxygen, increasing the electrophilicity of the carbonyl carbon. This makes it more susceptible to nucleophilic attack by water, facilitating the hydrolysis process.

Nucleophilicity

Nucleophilicity is a measure of how readily a nucleophile donates an electron pair to form a chemical bond. In the hydrolysis of N,N-dimethylacetamide, water acts as a nucleophile. The presence of acidic conditions enhances the nucleophilicity of water by stabilizing the transition state, thus promoting the reaction with the electrophilic carbonyl carbon.