Predict the products of the following reactions.
(c)
(d)

Verified step by step guidance

1. Step 1: Analyze the reaction in part (a). The reactants include a ketone (acetophenone) and an amine (aniline) in the presence of an acid catalyst (H⁺). This is a typical reaction for imine formation, where the carbonyl group reacts with the amine to form a C=N bond.
2. Step 2: In part (a), the mechanism begins with the protonation of the carbonyl oxygen by H⁺, increasing the electrophilicity of the carbonyl carbon. The amine (PhNH₂) then attacks the carbonyl carbon, forming a tetrahedral intermediate.
3. Step 3: In part (a), the intermediate undergoes dehydration (loss of water) to form the imine product. The final product will have a C=N bond between the phenyl group of the amine and the carbonyl carbon of acetophenone.
4. Step 4: Analyze the reaction in part (b). The reactants include an aldehyde (acrolein), hydrazine (H₂N-NH₂), and an acid catalyst (H⁺). This is a typical reaction for hydrazone formation, where the aldehyde reacts with hydrazine to form a C=N bond.
5. Step 5: In part (b), the mechanism begins with the protonation of the carbonyl oxygen by H⁺, increasing the electrophilicity of the carbonyl carbon. Hydrazine attacks the carbonyl carbon, forming a tetrahedral intermediate. The intermediate undergoes dehydration (loss of water) to form the hydrazone product, which contains a C=N bond between the hydrazine and the aldehyde carbon.

Key Concepts

Imine Formation

Imine formation occurs when a carbonyl compound (like an aldehyde or ketone) reacts with a primary amine. The reaction involves the nucleophilic attack of the amine on the carbonyl carbon, followed by the elimination of water. This process is crucial in organic synthesis, as imines can serve as intermediates in various reactions, including condensation and rearrangement.

Enamine Formation

Enamines are formed when a carbonyl compound reacts with a secondary amine. The reaction involves the nucleophilic attack of the amine on the carbonyl carbon, leading to the formation of a double bond between the nitrogen and the carbon adjacent to the carbonyl. Enamines are valuable intermediates in organic synthesis, particularly in alkylation and acylation reactions.

Acid-Base Catalysis

Acid-base catalysis plays a significant role in the formation of imines and enamines. The presence of an acid (H+) can protonate the carbonyl oxygen, increasing the electrophilicity of the carbonyl carbon and facilitating the nucleophilic attack by the amine. This catalytic step is essential for enhancing the reaction rate and ensuring the successful formation of the desired products.