Show how you would accomplish the following synthetic transformations. You may use any necessary reagents.
(a) N-ethylbenzamide → benzylethylamine
(b) ethyl benzoate → N-ethylbenzamide

Verified step by step guidance

1. Step 1 (a): To convert N-ethylbenzamide to benzylethylamine, first identify the functional group transformation. This involves reducing the amide group (-CONH-) to an amine (-NH-). Use a reducing agent such as lithium aluminum hydride (LiAlH4) in an appropriate solvent like ether to achieve this reduction.
2. Step 2 (a): After the reduction, the product will be benzylethylamine, where the carbonyl group is removed, leaving a secondary amine attached to the benzyl group and ethyl group.
3. Step 1 (b): To convert ethyl benzoate to N-ethylbenzamide, first hydrolyze the ester group (-COOEt) to a carboxylic acid (-COOH). This can be done using aqueous acid (HCl) or base (NaOH) under reflux conditions.
4. Step 2 (b): Once the carboxylic acid is formed, react it with ethylamine (CH3CH2NH2) in the presence of a coupling agent such as dicyclohexylcarbodiimide (DCC) or use an acid chloride intermediate (benzoyl chloride) to form the amide bond.
5. Step 3 (b): The final product will be N-ethylbenzamide, where the ethyl group is attached to the nitrogen of the amide functional group.

Key Concepts

Amide Hydrolysis

Amide hydrolysis is a reaction where an amide is converted into a carboxylic acid and an amine through the addition of water. This reaction can be catalyzed by either acid or base. In the context of the transformation from N-ethylbenzamide to benzylethylamine, hydrolysis can help in breaking down the amide bond, allowing for the formation of the desired amine.

Friedel-Crafts Alkylation

Friedel-Crafts alkylation is a method used to attach alkyl groups to aromatic rings using alkyl halides and a Lewis acid catalyst. This reaction is crucial for synthesizing benzylethylamine from N-ethylbenzamide, as it allows for the introduction of the ethyl group onto the benzene ring, facilitating the formation of the desired product.

Esterification and Transesterification

Esterification is the process of forming an ester from a carboxylic acid and an alcohol, while transesterification involves exchanging the alkoxy group of an ester with another alcohol. In the transformation from ethyl benzoate to N-ethylbenzamide, the reaction involves converting the ester into an amide, typically through the reaction with an amine, which is essential for achieving the desired synthetic pathway.